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Beach morphodynamic change detection using LiDAR during El Niño periods in Southern California

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Beach morphodynamic change detection using LiDAR during El Niño periods in Southern California

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Beach Morphodynamic Change Detection using LiDAR during El Niño Periods in
Southern California

by

Melodie Grubbs

A Thesis Presented to the
Faculty of the USC Graduate School
University of Southern California
In Partial Fulfillment of the
Requirements for the Degree
Master of Science
(Geographic Information Science and Technology)

May 2017

Copyright ® 2017 by Melodie Grubbs
iii
Table of Contents
List of Figures ................................................................................................................................. v
List of Tables ................................................................................................................................. xi
Acknowledgements ...................................................................................................................... xiii
List of Abbreviations ................................................................................................................... xiv
Abstract ......................................................................................................................................... xv
Chapter 1 Introduction .................................................................................................................. 16
1.1 Study Objectives ................................................................................................................16
1.2 Study Area .........................................................................................................................17
1.3 Organizational Framework ................................................................................................18
Chapter 2 Background and Related Research ............................................................................... 20
2.1 Sand Budgets .....................................................................................................................20
2.1.1. Sand Sinks in the Oceanside Littoral Cell ...............................................................21
2.1.2. Sand Sources in the Oceanside Littoral Cell ............................................................22
2.1.3. Wave Climate...........................................................................................................27
2.2 El Niño Coastal Storms ......................................................................................................28
2.2.1. Effects on OLC Sand Budget ...................................................................................28
2.3 Remote Sensing to Measure Coastal Change ....................................................................29
2.3.1. High-Resolution Aerial Imagery..............................................................................29
2.3.2. Light Detection and Ranging (LiDAR) ...................................................................32
Chapter 3 Methods ........................................................................................................................ 37
3.1 Data Sources ......................................................................................................................37
3.2 Processing Overview .........................................................................................................39
3.3 LiDAR Data Preparation and Formatting ..........................................................................42
3.3.1. LAZ Uncompression, Projection, and Clipping ......................................................43
iv
3.3.2. LAS Ground Classification ......................................................................................44
3.3.3. LAS Dataset .............................................................................................................45
3.3.4. LAS Ground to Multipoint Feature Class ................................................................46
3.4 LiDAR-derived Digital Elevation Models (DEMs) ...........................................................47
3.4.1. Empirical Bayesian Kriging (EBK) Analysis ..........................................................49
3.4.2. ArcGIS Processing Requirements ............................................................................50
3.5 Beach Sediment Volume Change Analysis .......................................................................50
3.5.1. DEM Differencing ...................................................................................................51
3.5.2. Shore Segments ........................................................................................................52
3.5.3. Volume Calculation .................................................................................................55
Chapter 4 Results .......................................................................................................................... 57
4.1 LiDAR Preparation and Formatting Results ......................................................................57
4.2 EBK Interpolation and DEM Creation Results ..................................................................61
4.3 Beach Sediment Volume Change Analysis Results...........................................................62
4.3.1. Dana Point ................................................................................................................62
4.3.2. San Clemente ...........................................................................................................66
4.3.3. San Diego North ......................................................................................................72
4.3.4. San Diego Central ....................................................................................................88
4.3.5. San Diego South ....................................................................................................104
4.3.6. Overarching Results ...............................................................................................128
Chapter 5 Conclusions ................................................................................................................ 132
References ................................................................................................................................... 135
Appendix A ................................................................................................................................. 138

v
List of Figures
Figure 1 The Oceanside Littoral Cell (OCL) ................................................................................ 18
Figure 2 A seawall in Encinitas (California Department of Boating and Waterways and State
Coastal Conservancy 2002) .......................................................................................................... 24
Figure 3 SANDAG 2001 Beach Nourishment Project Locations (Patsch and Griggs 2006) ....... 26
Figure 4 Sand Budgets – Winter versus Summer Profile (Patsch and Griggs 2006) ................... 27
Figure 5 The use of aerial imagery and transects to measure beach width changes over time -
La Jolla 2001 (Chenault 2007). ..................................................................................................... 30
Figure 6 Erosion analysis in southern Monterey Bay, Fort Ord, during the 97-98 El Niño
using LiDAR (Egley 2003) ........................................................................................................... 31
Figure 7 Transect method calculating shoreline change in southern California during the
09-10 El Niño (Coggan 2014)....................................................................................................... 33
Figure 8 Plot method of visualizing shoreline change during an El Niño and inter-El Niño
Period in Monterey Bay, CA (Quan 2013). .................................................................................. 34
Figure 9 DEM differencing technique to analyze coastal time-series LiDAR data
(Hardin 2014) ................................................................................................................................ 35
Figure 10 LiDAR time-series analysis to detect cliff failure (Young 2006) ................................ 36
Figure 11 LiDAR time-series datasets. ......................................................................................... 38
Figure 12 Processing Overview .................................................................................................... 40
Figure 13 LiDAR to DEM workflow............................................................................................ 43
Figure 14 ArcMap tool Create LAS Dataset input and output illustration (Esri 2016) ................ 46
Figure 15 LiDAR-derived Digital Elevation Model (DEM) Workflow ....................................... 49
Figure 16 Beach Sediment Volume Change Analysis Workflow ................................................ 51
Figure 17 Elevations datums (in meters) for La Jolla, CA (Station #9410230) (NOAA 2016) ... 53
Figure 18 Shore segment creation process.................................................................................... 55
Figure 19 Fall 2006 LAS dataset with all elevation points ........................................................... 59
Figure 20 Fall 2006 LAS Dataset with only ground (bare earth) classified points ...................... 60
vi
Figure 21 Fall 2006 LAS dataset 3D view with all elevation points ............................................ 61
Figure 22 Fall 2006 LAS dataset 3D view will only ground (bare earth) classified points ......... 61
Figure 23 Dana Point – Rate of sediment volume change by shore segment during the
06-07 El Niño ................................................................................................................................ 63
Figure 24 Dana Point – Rate of sediment volume change by shore segment during the
07-08 La Niña ............................................................................................................................... 64
Figure 25 Historical imagery showing the San Juan Creek mouth shift from open to closed
(Left: February 2006, Right: March 2007) (Source: Google Earth) ............................................. 64
Figure 26 Dana Point - Map of rate of sediment volume change by shore segments during the
06-07 El Niño ................................................................................................................................ 65
Figure 27 San Clemente (North) – Rate of sediment volume change by shore segment during
the 06-07 El Niño .......................................................................................................................... 67
Figure 28 San Clemente (North) – Rate of sediment volume change by shore segment during
the 07-08 La Niña ......................................................................................................................... 67
Figure 29 San Clemente (North) - Map of rate of sediment volume change by shore segments
during the 06-07 El Niño .............................................................................................................. 68
Figure 30 San Clemente (South) – Rate of sediment volume change by shore segment during
the 06-07 El Niño .......................................................................................................................... 70
Figure 31 San Clemente (South) – Rate of sediment volume change by shore segment during
the 07-08 La Niña ......................................................................................................................... 70
Figure 32 San Clemente (South) - Map of rate of sediment volume change by shore segments
during the 06-07 El Niño .............................................................................................................. 71
Figure 33 Trestles to San Onofre (SONGS) – Rate of sediment volume change by shore
segment during the 06-07 El Niño ................................................................................................ 73
Figure 34 Trestles to San Onofre (SONGS) – Rate of sediment volume change by shore
segment during the 07-08 La Niña................................................................................................ 73
Figure 35 Trestles to San Onofre (SONGS) - Map of rate of sediment volume change by shore
segments during the 06-07 El Niño .............................................................................................. 74
Figure 36 San Onofre State Beach to Camp Pendelton MCB (North) – Rate of sediment
volume change by shore segment during the 06-07 El Niño ........................................................ 76
Figure 37 San Onofre State Beach to Camp Pendelton MCB (North) – Rate of sediment
volume change by shore segment during the 07-08 La Niña........................................................ 76
vii
Figure 38 San Onofre State Beach to Camp Pendelton MCB (North) - Map of rate of
sediment volume change by shore segments during the 06-07 El Niño ....................................... 77
Figure 39 2006-2007 Elevation difference raster highlighting cliff erosion in shore segments
168 and 169 ................................................................................................................................... 78
Figure 40 San Onofre State Beach/Camp Pendelton MCB (Central) – Rate of sediment
volume change by shore segment during the 06-07 El Niño ........................................................ 80
Figure 41 San Onofre State Beach/Camp Pendelton MCB (Central) – Rate of sediment
volume change by shore segment during the 07-08 La Niña........................................................ 80
Figure 42 San Onofre State Beach/Camp Pendelton MCB (Central) - Map of rate of sediment
volume change by shore segments during the 06-07 El Niño ...................................................... 81
Figure 43 San Onofre State Beach/Camp Pendelton MCB (South) – Rate of sediment volume
change by shore segment during the 06-07 El Niño ..................................................................... 83
Figure 44 San Onofre State Beach/Camp Pendelton MCB (South) – Rate of sediment volume
change by shore segment during the 07-08 La Niña ..................................................................... 83
Figure 45 San Onofre State Beach/Camp Pendelton MCB (South) - Map of rate of sediment
volume change by shore segments during the 06-07 El Niño ...................................................... 84
Figure 46 Camp Pendelton MCB (South) – Rate of sediment volume change by shore
segment during the 06-07 El Niño ................................................................................................ 86
Figure 47 Camp Pendelton MCB (South) – Rate of sediment volume change by shore
segment during the 07-08 La Niña................................................................................................ 86
Figure 48 Camp Pendelton MCB (South) - Map of rate of sediment volume change by shore
segments during the 06-07 El Niño .............................................................................................. 87
Figure 49 Camp Pendelton MCB (South) to Santa Margarita Marsh – Rate of sediment
volume change by shore segment during the 06-07 El Niño ........................................................ 89
Figure 50 Camp Pendelton MCB (South) to Santa Margarita Marsh – Rate of sediment
volume change by shore segment during the 07-08 La Niña........................................................ 89
Figure 51 Camp Pendelton MCB (South) to Santa Margarita Marsh - Map of rate of sediment
volume change by shore segments during the 06-07 El Niño ...................................................... 90
Figure 52 Santa Margarita Marsh to Oceanside Harbor – Rate of sediment volume change by
shore segment during the 06-07 El Niño ...................................................................................... 92
Figure 53 Santa Margarita Marsh to Oceanside Harbor – Rate of sediment volume change by
shore segment during the 07-08 La Niña ...................................................................................... 92
viii
Figure 54 Historical imagery showing the shift of the Santa Margarita Creek mouth
(Left: June 2006, Right: March 2008) (Source: Google Earth) .................................................... 93
Figure 55 Santa Margarita Marsh to Oceanside Harbor - Map of rate of sediment volume
change by shore segments during the 06-07 El Niño ................................................................... 94
Figure 56 Oceanside City Beach – Rate of sediment volume change by shore segment during
the 06-07 El Niño (shore segments 405-412 no data)................................................................... 96
Figure 57 Oceanside City Beach – Rate of sediment volume change by shore segment during
the 07-08 La Niña (shore segments 405-412 no data) .................................................................. 96
Figure 58 Oceanside City Beach - Map of rate of sediment volume change by shore segments
during the 06-07 El Niño .............................................................................................................. 97
Figure 59 Carlsbad North to Carlsbad State Beach (Agua Hedionda Lagoon) – Rate of
sediment volume change by shore segment during the 06-07 El Niño ......................................... 99
Figure 60 Carlsbad North to Carlsbad State Beach (Agua Hedionda Lagoon) – Rate of
sediment volume change by shore segment during the 07-08 La Niña ........................................ 99
Figure 61 Carlsbad North to Carlsbad State Beach (Agua Hedionda Lagoon) - Map of rate of
sediment volume change by shore segments during the 06-07 El Niño ..................................... 100
Figure 62 Carlsbad State Beach (Agua Hedionda Lagoon) to Carlsbad State Beach (South) –
Rate of sediment volume change by shore segment during the 06-07 El Niño .......................... 102
Figure 63 Carlsbad State Beach (Agua Hedionda Lagoon) to Carlsbad State Beach (South) –
Rate of sediment volume change by shore segment during the 07-08 La Niña ......................... 102
Figure 64 Carlsbad State Beach (Agua Hedionda Lagoon) to Carlsbad State Beach (South) -
Map of rate of sediment volume change by shore segments during the 06-07 El Niño ............. 103
Figure 65 Carlsbad State Beach (South) to Encinitas (North) – Rate of sediment volume
change by shore segment during the 06-07 El Niño ................................................................... 106
Figure 66 Carlsbad State Beach (South) to Encinitas (North) – Rate of sediment volume
change by shore segment during the 07-08 La Niña ................................................................... 106
Figure 67 Carlsbad State Beach (South) to Encinitas (North) - Map of rate of sediment
volume change by shore segments during the 06-07 El Niño .................................................... 107
Figure 68 Encinitas (North) to Encinitas (South) – Rate of sediment volume change by shore
segment during the 06-07 El Niño .............................................................................................. 109
Figure 69 Encinitas (North) to Encinitas (South) – Rate of sediment volume change by shore
segment during the 07-08 La Niña.............................................................................................. 109
ix
Figure 70 Encinitas (North) to Encinitas (South) - Map of rate of sediment volume change by
shore segments during the 06-07 El Niño ................................................................................... 110
Figure 71 Encinitas (South) to Cardiff State Beach – Rate of sediment volume change by
shore segment during the 06-07 El Niño .................................................................................... 112
Figure 72 Encinitas (South) to Cardiff State Beach – Rate of sediment volume change by
shore segment during the 07-08 La Niña .................................................................................... 112
Figure 73 Encinitas (South) to Cardiff State Beach - Map of rate of sediment volume change
by shore segments during the 06-07 El Niño .............................................................................. 113
Figure 74 Cardiff State Beach to Del Mar – Rate of sediment volume change by shore
segment during the 06-07 El Niño .............................................................................................. 115
Figure 75 Cardiff State Beach to Del Mar – Rate of sediment volume change by shore
segment during the 07-08 La Niña.............................................................................................. 115
Figure 76 Cardiff State Beach to Del Mar - Map of rate of sediment volume change by shore
segments during the 06-07 El Niño ............................................................................................ 116
Figure 77 Del Mar to Los Penasquitos Marsh – Rate of sediment volume change by shore
segment during the 06-07 El Niño .............................................................................................. 118
Figure 78 Del Mar to Los Penasquitos Marsh – Rate of sediment volume change by shore
segment during the 07-08 La Niña.............................................................................................. 118
Figure 79 Del Mar to Los Penasquitos Marsh - Map of rate of sediment volume change by shore
segments during the 06-07 El Niño ............................................................................................ 119
Figure 80 Los Penasquitos Marsh to Torrey Pines State Reserve – Rate of sediment volume
change by shore segment during the 06-07 El Niño ................................................................... 121
Figure 81 Los Penasquitos Marsh to Torrey Pines State Reserve – Rate of sediment volume
change by shore segment during the 07-08 La Niña ................................................................... 121
Figure 82 Los Penasquitos Marsh to Torrey Pines State Reserve - Map of rate of sediment
volume change by shore segments during the 06-07 El Niño .................................................... 122
Figure 83 Torrey Pines State Reserve – Elevation difference raster highlighting cliff erosion . 123
Figure 84 Torrey Pines State Reserve to La Jolla Shores Beach – Rate of sediment volume
change by shore segment during the 06-07 El Niño ................................................................... 125
Figure 85 Torrey Pines State Reserve to La Jolla Shores Beach – Rate of sediment volume
change by shore segment during the 07-08 La Niña ................................................................... 125
Figure 86 Torrey Pines State Reserve to La Jolla Shores - Map of rate of sediment volume
change by shore segments during the 06-07 El Niño ................................................................. 126
x
Figure 87 La Jolla Shores Beach South - Map of rate of sediment volume change by shore
segments during the 06-07 El Niño ............................................................................................ 127
Figure 88 Total sediment volume change (m
3
) in the OLC summarized by region ................... 129
Figure 89 Rate of sediment volume change (m
3
per sq m) in the OLC summarized by region . 130
Figure 90 Average rate of sediment volume change by region during the 2006-2007 El Niño
winter .......................................................................................................................................... 131

xi
List of Tables
Table 1 Sediment Inputs into the Oceanside Littoral Cell (California Department of Boating
and Waterways and State Coastal Conservancy 2002) ................................................................. 21
Table 2 2001/2012 SANDAG Beach Nourishment Sites in the OLC (AMEC Earth &
Environmental, Inc. 2005, Coastal Frontiers Corporation 2015).................................................. 25
Table 3 LiDAR Datasets ............................................................................................................... 39
Table 4 LiDAR Instrument Settings and Parameters .................................................................... 39
Table 5 ASPRS standardized LiDAR classifications used ........................................................... 44
Table 6 Desktop system specifications used for LiDAR analysis and geoprocessing ................. 50
Table 7 DEM Differencing to Measure Elevation Change over Time-Series .............................. 52
Table 8 LAS Elevation Point Statistics ......................................................................................... 58
Table 9 Dana Point Sediment Net Volume Change Summary ..................................................... 63
Table 10 San Clemente (North) Net Sediment Volume Change Summary.................................. 66
Table 11 San Clemente (South) Net Sediment Volume Change Summary.................................. 69
Table 12 Trestles to San Onofre (SONGS) Net Sediment Volume Change Summary ................ 72
Table 13 San Onofre State Beach to Camp Pendelton MCB (North) Net Sediment Volume
Change Summary .......................................................................................................................... 75
Table 14 San Onofre State Beach/Camp Pendelton MCB (Central) Net Sediment Volume
Change Summary .......................................................................................................................... 79
Table 15 San Onofre State Beach/Camp Pendelton MCB (South) Net Sediment Volume
Change Summary .......................................................................................................................... 82
Table 16 Camp Pendelton MCB (South) Net Sediment Volume Change Summary ................... 85
Table 17 Camp Pendelton MCB (South) to Santa Margarita Marsh Net Sediment Volume
Change Summary .......................................................................................................................... 88
Table 18 Santa Margarita Marsh to Oceanside Harbor Net Sediment Volume Change
Summary ....................................................................................................................................... 91
Table 19 Oceanside City Beach Sediment Net Volume Change Summary ................................. 95
xii
Table 20 Carlsbad North to Carlsbad State Beach (Agua Hedionda Lagoon) Net Sediment
Volume Change Summary ............................................................................................................ 98
Table 21 Carlsbad State Beach (Agua Hedionda Lagoon) to Carlsbad State Beach (South)
Net Sediment Volume Change Summary ................................................................................... 101
Table 22 Carlsbad State Beach (South) to Encinitas (North) Net Sediment Volume Change
Summary ..................................................................................................................................... 105
Table 23 Encinitas (North) to Encinitas (South) Net Sediment Volume Change Summary ...... 108
Table 24 Encinitas (South) to Cardiff State Beach Net Sediment Volume Change Summary .. 111
Table 25 Cardiff State Beach to Del Mar Net Sediment Volume Change Summary ................. 114
Table 26 Del Mar to Los Penasquitos Marsh Sediment Net Volume Change Summary ........... 117
Table 27 Los Penasquitos Marsh to Torrey Pines State Reserve Net Sediment Volume
Change Summary ........................................................................................................................ 120
Table 28 Torrey Pines State Reserve to La Jolla Shores Beach Net Sediment Volume
Change Summary ........................................................................................................................ 124
Table 29 Total Sediment Volume (m
3
) change in the OLC ........................................................ 128
Table 30 Overall Rate of Sediment Volume Change (m
3
per sq m) in the OLC ........................ 128

xiii
Acknowledgements
I am grateful to my committee chair and mentor, Professor Kemp, and additional committee
members, Lee and Swift, for providing me direction to complete my thesis. I would like to thank
my two children, Nainoa and Olivia for their enduring patience and my parents John and
Nympha for their support of my academic pursuits. I would also like to thank Kevin Klemens
for his support through graduate school and willingness to always provide advice and edits to my
thesis.

xiv
List of Abbreviations
DEM Digital Elevation Model
dGPS Differential Geographic Positioning System
EBK Empirical Bayesian Kriging
GIS Geographic information system
GISci Geographic information science
LiDAR Light Detection and Ranging
MHW Mean High Water
NAVD88 North American Vertical Datum of 1988
NOAA National Oceanic and Atmospheric Administration
OLC Oceanside Littoral Cell
SOI Scripps Institute of Oceanography
SSI Spatial Sciences Institute
USACOE United States Army Corps of Engineers
USC University of Southern California
xv
Abstract
Light Detection and Ranging (LiDAR) technology combined with high-resolution differential
Global Positioning Systems (dGPS) provide the ability to measure coastal elevation with high
precision. This study investigates the use of LiDAR data and GIS to conduct time-series analyses
of coastal sediment volume shifts during the 2006-2007 El Niño winter, Summer of 2007 and
following 2007-2008 La Niña winter in the Oceanside Littoral Cell (OLC). The OLC, located in
Southern California, spans from Dana Point to La Jolla and includes over 84 km of coastline.
The ability to quantify sediment volume changes contributes to the scientific understanding of
the role El Niño storms play in the OLC sand budget. This study provides a method to analyze
LiDAR data to evaluate coastal geomorphologic changes over time. Additionally, identifying
specific areas of coastal beach erosion associated with historical El Niño events can aid beach
managers, planners, and scientists in protecting the valuable coastline. LiDAR datasets were
prepared and formatted which included ground classifying millions of elevation points.
Formatted datasets were inputted into an Empirical Bayesian Kriging (EBK) model, creating
high-resolution, 1-meter grid cell, Digital Elevation Models (DEMs). The EBK model also
incorporated uncertainty into the workflow by producing prediction error surfaces. LiDAR-
derived DEMs were used to calculate sediment volume changes through a technique called DEM
differencing. Results were visualized through a series of maps and tables. Overall results show
that there was a higher rate of beach sediment erosion during the 2006-2007 El Niño winter than
the 2007-2008 La Niña winter. Sediment accretion was evident during the intermediary Summer
of 2007. Future applications of this study include incorporating bathymetric datasets to
understand near-shore sediment transport, evaluating sediment contribution through cliff erosion,
and conducting decadal scale studies to evaluate long-term trends with sea level rise scenarios.

16

Chapter 1 Introduction
This study focuses on using Light Detection and Ranging (LiDAR) data coupled with
Geographic Information Systems (GIS) analysis to identify coastal zone sediment changes in a
region of Southern California known as the Oceanside Littoral Cell (OLC). The OLC, which
spans from Dana Point to La Jolla Point, is an area known to experience heavy coastal effects
from El Niño seasons.
Sand budgets are a way scientists can quantify sources and sinks of sand in the OLC and
begin to understand the processes that drive a dynamic coastal system. To understand the effects
El Niño winters play on the OLC sand budget, it is important to understand the history of sand
sinks and sources in the OLC. Sand deficiencies, caused by human modification to major sources
of sand, have changed the natural sand budget in the OLC driving the need for beach
replenishment to maintain valuable beaches.
El Niño seasons are marked by an increase in frequency and intensity of coastal storms
and can cause significant erosion to coastal areas. Additionally, El Niño storm events coupled
with projected sea level rise will amplify the effects of erosion into the future.
1.1 Study Objectives
The goal of this study was to determine if coastal time-series LiDAR datasets analyzed
using GIS methods can depict coastal sediment volume shifts associated with El Niño seasons in
the Oceanside Littoral Cell located in Southern California. GIS methods were used to estimate
beach sediment volume changes that occurred during the 2006-2007 El Niño winter, Summer of
2007, and following 2007-2008 La Niña winter. Sediment shifts during the 2006-2007 El Niño
were the primary focus, while the analysis of sediment shifts during the 2007-2008 La Niña
winter, and intermediary Summer of 2007 were used for comparison. El Niño winters in

17

Southern California are typically associated with increased coastal erosion and comparing
erosion trends during an El Niño winter to a non-El Niño winter provided key data to prove this
phenomenon. In general, beaches in Southern California are also heavily influenced by seasonal
variation, eroding in the winter and accreting during the summer months. For this reason, the
summer immediately following the 2006-2007 El Niño winter was also analyzed to identify any
sediment recovery. A series of maps and corresponding statistics were created to visualize the
spatial trends of coastal sediment volume shift.
1.2 Study Area
The Oceanside Littoral Cell (OLC) is one of many segments along the Southern
California Coast in which littoral sediment transport is bounded or contained (Figure 1).
Spanning roughly 84 km (52 mi) from Dana Point to the north and Point La Jolla to the South,
the coastal area of the OLC contains some of the most heavily used beaches in Southern
California (Chenault 2007). The OLC is also a major study area due to the nearby proximity of
Scripps Institute of Oceanography. Beach erosion in the OLC is particularly severe between the
cities of Oceanside and Del Mar and a study conducted by the United States Army Corps of
Engineers in 1991 identified the southern half of the OLC, from Oceanside Harbor to La Jolla, as
sites of critical erosion (USACOE 1991).

18

Figure 1 The Oceanside Littoral Cell (OCL)
1.3 Organizational Framework
This thesis document contains four additional chapters. Chapter 2 explores background
concepts related to sand budgets in the OLC and previous studies related to the use of remote
sensing to measure coastal change. Chapter 3 provides a detailed description of the methodology
used for this study. Chapter 4 presents the results of the time-series LiDAR analysis. Chapter 5

19

concludes with a discussion of the implications of the results, the successes and challenges
associated with the methodology, and future applications and opportunities.

20

Chapter 2 Background and Related Research
The following sections explore background information on the OLC sand budget, including the
sources and sinks of beach sand, the role wave climate plays in sand transport, and the effect of
El Niño winter storms on the coastline. Specific case studies that used remote sensing, including
aerial imagery and more specifically LiDAR technology to measure coastal change were
investigated and provide the foundation for the methods developed in this study.
2.1 Sand Budgets
Sand budgets quantify sediment in littoral cells by identifying sources and sinks of sand
and is a method that scientists use to better understand the processes that change beaches and
influence beach width. LiDAR data has been used to study various components of the OLC sand
budget, particularly changes in beach sand movement and erosion from sea cliffs. Previous
research in the OLC has identified fluvial streams and coastal rivers, erosion from sea cliffs, and
the human addition of sand from beach nourishment as major sources of sand (Chenault 2007).
Sand sinks, defined as processes that remove sand out of the OLC, include sand loss to offshore
submarine canyons, as well as sand loss via longshore and offshore transport. Coastal storms and
associated waves play a role in providing a source of sand by eroding sea cliffs. However, these
weather and climatic events also drive sand movement offshore, narrowing beach widths, and
initiating sand transport out of the OLC. Additionally, the effect of coastal storms on sand
budgets is perhaps the least understood of all processes (Chenault 2007). In 1997 the US Army
Corps of Engineers completed a study of the sand budget including erosion patterns in the OLC
and found patterns of sediment moving via longshore littoral transport in a southerly direction
(Hales et al. 1997).

21

Table 1 summarizes a breakdown of natural and actual sand inputs into the OLC and
shows that fluvial sediment and bluff erosion inputs have been altered through human
modifications, reducing natural inputs by 26% (California Department of Boating and
Waterways and State Coastal Conservancy 2002). “Natural” inputs as shown in Table 1 refer to
the amount of sediment per year fluvial streams, bluff erosion, and gullies/terraces would
contribute if not modified by humans. Fluvial streams have been modified by the building of
dams, channels, and diversions, all which alter the “natural” flow of sediment. Bluffs have been
modified from their “natural” state by high bluff-top development and cliff stabilization, which
also alter the amount of beach sediment created. The decline in natural sand supply has made
beach nourishment necessary and has prioritized research toward understanding processes that
drive the sand budget, particularly wave climate and high-intensity storms caused by El Niño
events.
Table 1 Sediment Inputs into the Oceanside Littoral Cell (California Department of Boating and
Waterways and State Coastal Conservancy 2002)
Inputs Natural (m3/yr) Actual (m3/yr) Reduction (m3/yr)
Fluvial Streams 219,045 (44.7%) 101,304 (27.9%) 117,741 (53.8%)
Bluff Erosion 51,455 (10.5%) 41,974 (11.6%) 9,480 (18.4%)
Gullies/Terraces 219,427 (44.8%) 219,427 (60.5%) 0 (0%)
Total Littoral Input 489,927 (100%) 362,705 (100%) 127,222 (26%)

2.1.1. Sand Sinks in the Oceanside Littoral Cell
Sand sinks in the OLC sand budget include the movement of sand into two nearby
submarine canyons as well as longshore transport of sediment exiting out of the southern

22

boundary into the adjacent littoral cell and offshore towards deeper ocean. Climatic and weather
processes can drive sand movement towards sinks through longshore and offshore transport.
2.1.1.1. Submarine Canyons
Submarine canyons are considered a sink in sand budgets, and in the OLC sand is
transported via longshore in a southerly direction until it eventually enters the beginning of the
La Jolla submarine canyon (California Department of Boating and Waterways and State Coastal
Conservancy 2002). Additionally, the Carlsbad submarine canyon located offshore the city of
Carlsbad, in the middle of the OLC, is a sand sink. The location of these canyons is shown in
Figure 1.
2.1.2. Sand Sources in the Oceanside Littoral Cell
Sources of sand in the OLC include sediment transported via fluvial streams, sand created
by sea cliff erosion, sand transported from gullies and terraces, and beach nourishment projects.
The natural processes of sediment creation and transport through fluvial streams and sea cliff
erosion has been greatly modified by human-built structures including dams, reservoirs, sea cliff
anchoring, sea walls, and rip rap.
2.1.2.1. Fluvial streams
While fluvial rivers and streams are a major source of beach sand for many California
beaches, the OLC is an exception. Dam construction inhibits sediment transport from fluvial
streams, and dams in the OLC have reduced the fluvial sediment contribution by 54% (California
Department of Boating and Waterways and State Coastal Conservancy 2002).

23

2.1.2.2. Sea cliff erosion
Cliff erosion is a source of sediment in the OLC sand budget, with most of the coastline,
73%, composed of semi-continuous sand or cobble beaches backed by sea cliffs (Masters 2006;
California Department of Boating and Waterways and State Coastal Conservancy 2002). While
the erosion process can provide valuable sediment to nourish beaches, it is a problem to local
property owners, businesses, and government. Sea cliff armoring, which aids to prevent erosion,
has reduced the amount of sand supplied to the OLC (Figure 2). Historically sea cliff erosion
contributed 11% of sand to the OLC; however, with an estimated 20% of the OLC sea cliffs
armored with some form of protection against erosion, sand contribution has been reduced by
18% (California Department of Boating and Waterways and State Coastal Conservancy 2002).

24

Figure 2 A seawall in Encinitas (California Department of Boating and Waterways and State
Coastal Conservancy 2002)
2.1.2.3. Gullies and Terraces
Sand transported onshore into the OLC from gullies and terraces historically accounted
for roughly 45% of the sand budget input (California Department of Boating and Waterways and
State Coastal Conservancy 2002). The reduction of sand input from the modification of natural
cycles associated with fluvial stream and bluff erosion has lowered the estimated annual
sediment input into the OLC, and sand input from gullies and terraces now accounts for a higher
percentage of total littoral input.

25

2.1.2.4. Beach Nourishment
Beach nourishment, a common method used in Southern California to restore and
maintain sandy beaches, has been conducted in many locations throughout the OLC since the
1940s (Chenault 2007). Previous studies indicate that beach nourishment projects in the OLC
have contributed an overall annual average ranging from 85,000 m
3
per year to 350,000 m
3
per
year (Chenault 2007; Patsch and Griggs 2006). Large scale beach nourishment projects have
been undertaken by the San Diego Association of Governments (SANDAG) including a project
in 2001 where approximately 1.4 million cubic meters of sand was placed on ten beaches and
another project ten years later, in 2012, where 0.8 million cubic meters of sand was placed on
seven beaches (Table 2) (Figure 3) (AMEC Earth & Environmental, Inc. 2005; Coastal Frontiers
Corporation 2015).
Table 2 2001/2012 SANDAG Beach Nourishment Sites in the OLC (AMEC Earth &
Environmental, Inc. 2005, Coastal Frontiers Corporation 2015)
Beach Nourishment Sites
Quantity (m
3
)
2001 2012
Torrey Pines State Beach 187,316 -
Del Mar 139,914 -
Leucadia 100,921 -
Fletcher Cove, Solana Beach 111,625 108,567
South Carlsbad State Beach 120,800 107,802
North Carlsbad 172,025 167,438
Cardiff State Beach, Encinitas 77,220 68,045
Moonlight Beach, Encinitas 80,278 70,339
Batiquitos 89,453 81,043
Oceanside 321,878 224,015
Total 1,401,429 827,248

26

Figure 3 SANDAG 2001 Beach Nourishment Project Locations (Patsch and Griggs 2006)

The location and amount of sediment placed on beaches in the OLC provide a baseline
comparison for analyzing beach sediment shifts following El Niño events. Beach profile
monitoring data, in the form of on-the-ground transect surveys, was collected at all the beach

27

nourishment sites beginning in 1996 and ending in 2003. Profile data collected through
November 2003, show that dry beach width receded and the overall profile became flatter,
suggesting that nourishment material eroded and moved offshore and towards the downcoast
beaches (Coastal Frontiers Corporation 2004).
2.1.3. Wave Climate
Beaches in Southern California experience a highly variable seasonal profile (Figure 4).
During the winter sand is eroded from the beach from storm-generated wave events and typically
forms an offshore sandbar, which often protects the shore from further events by causing waves
to break further offshore (Patsch and Griggs 2004). While winter beach erosion is a normal
process for the OLC, frequent high-intensity wave events, coupled with existing sand budget
deficiencies, and additional factors like high tides can cause permanent erosion.

Figure 4 Sand Budgets – Winter versus Summer Profile (Patsch and Griggs 2006)

28

2.2 El Niño Coastal Storms
During El Niño seasons, California experiences above-average rainfall, warmer sea-
surface temperatures, and large waves, resulting in increased coastal erosion. La Niña seasons
show the opposite, with colder sea-surface temperatures, drier conditions, and less severe storms
(Hapke et al. 2009). Recent research has shown that extreme El Niño events coupled with
climate change induced warmer water temperatures have the potential to double the frequency of
extreme El Niño events occurring (Cai et al. 2014). Additionally, the elevated water levels and
associated powerful waves that drive beach erosion will have a greater impact with sea level rise
(Barnard et al. 2014). Tropical storms in Southern California are a rare occurrence, and extreme
erosion is dominated by repeated storm events during El Niño (Ludka et al. 2016).
2.2.1. Effects on OLC Sand Budget
El Niño seasons bring increased storm frequency and intensity and a shift of wave
climate. These storms affect the OLC sand budget by shifting sediment. Large waves with
southerly storm tracks result in more direct wave effects on the coastline and increase sand
transport out of the system. In contrast, La Niña seasons are marked by decreased precipitation,
decreased sediment production, and a gentle wave climate resulting in less sediment lost from
the system.
Quantifying the volume of sediment that is transported out of the system due to El Niño
events can provide scientists and planners useful information towards understanding the OLC
sand budget as a whole. Comparing El Niño season sediment shifts to La Niña season sediment
shifts provides a control to begin to distinguish non-El Niño sediment trends from El Niño
sediment trends.

29

2.3 Remote Sensing to Measure Coastal Change
Remote sensing has been used to measure coastal change using a variety of techniques.
Traditionally, high-resolution aerial imagery combined with topographic maps enabled
researchers to digitize shorelines and measure change over time. The process of using high-
resolution aerial imagery required manual and often tedious digitization, repeated over time, to
begin to measure change. LiDAR combined with Global Positioning Systems (GPS) provides the
ability to collect large elevation point clouds and using GIS analysis, shoreline and sediment
volume can be quantified over a time-series. LiDAR provides the ability to go beyond measuring
shoreline shifts in 2-D and provides accurate 3-D elevation data that can be used to calculate
sediment volume trends.
2.3.1. High-Resolution Aerial Imagery
Prior to the development and use of GPS and LiDAR, aerial imagery and topographic
maps were the primary tool for beach and coastal profiling. Chenault provides an in-depth study
on beach-width change in the OLC, utilizing historical aerial photographs and transects
(Chenault 2007). Figure 5 shows a map of Chenault’s work where transects are used to measure
beach width changes over time. While transects have been the norm for coastal scientists
monitoring beach width changes, LiDAR data has the ability to calculate elevation changes at a
wider coverage. The following additional studies show the use of LiDAR to conduct time-series
analysis using a technique called DEM differencing.
Other studies have employed aerial photography as a supplement to LiDAR analysis. A
study conducted by Egley, from the Naval Postgraduate School, used LiDAR to examine erosion
in the southern Monterey Bay during the 1997-98 El Niño (Egley 2003). Egley used a DEM

30

differencing technique to measure elevation changes as well as transects to create elevation
profiles of the results (Figure 6).

Figure 5 The use of aerial imagery and transects to measure beach width changes over time - La
Jolla 2001 (Chenault 2007).

31

Figure 6 Erosion analysis in southern Monterey Bay, Fort Ord, during the 97-98 El Niño using
LiDAR (Egley 2003)

32

2.3.2. Light Detection and Ranging (LiDAR)
There have been many studies utilizing LiDAR data to measure coastal geomorphologic
change. In a thesis research project conducted by Brian Coggan from the University of California
– Santa Cruz, shoreline change in Southern California during the 2009-2010 El Niño season was
investigated using time-series LiDAR data (Coggan 2014). Using two time-series LiDAR
datasets, Coggan measured beach changes, identifying distinct areas of erosion and accretion as
well as volumetric beach sediment changes. Using GIS analysis tools and an ArcMap extension
called the Digital Shoreline Analysis System (DSAS), shoreline change was calculated using a
transect reference system. Figure 7 shows a visual representation of Coggan’s work, where larger
red circles indicate higher erosion along the corresponding transect and larger green circles
indicate higher accretion along the corresponding transect. The use of transects to measure
shoreline change is a common denominator in beach geomorphologic investigations.

33

Figure 7 Transect method calculating shoreline change in southern California during the 09-10
El Niño (Coggan 2014).
Quan used LiDAR data collected from an ocean vessel to measure coastal erosion
associated with the 2009-2010 El Niño event in Monterey, California (Quan 2013). This project
also analyzed 2008-2009 (non-El Niño) data as a control and 1997-1998 (El Niño) as another
comparison with a goal of conducting a hotspot analysis to determine location and magnitude of
coastal shoreline change. Figure 8 shows results from Quan’s study, the dashed line on the plot
indicates erosion along the coast during the 1997-1998 El Niño, while the solid line indicates
erosion trends during inter-El Niño periods from 1998-2009.

34

Figure 8 Plot method of visualizing shoreline change during an El Niño and inter-El Niño Period
in Monterey Bay, CA (Quan 2013).
In a book titled, GIS-based Analysis of Coastal LiDAR Time-Series, sediment volume
shifts are measured by time-series LiDAR analysis and represented through defined shoreline
segments (Hardin 2014). Hardin also details specific GIS methods to analyze coastal changes
through raster-based analysis, shoreline feature extraction and change metrics, volume analysis,
and visualization (Hardin 2014). Hardin outlines DEM differencing analysis, a method which
was used in this study (Figure 9).

35

Figure 9 DEM differencing technique to analyze coastal time-series LiDAR data (Hardin 2014)
Another study specific to the OLC was conducted by Young and Ashford, who
investigated the application of airborne LiDAR in detecting sea cliff and beach sediment change
during a relatively dry season from 1998 to 2004 (Young and Ashford 2006). They were able to
measure rates of volumetric sea cliff erosion and found that sea cliffs provided roughly 67% of
beach grain sediment through erosion processes. Young and Ashford used LiDAR data to create
high-resolution DEM rasters and their analysis included measuring and detecting changes
through DEM differencing (Figure 10).

36

Figure 10 LiDAR time-series analysis to detect cliff failure (Young 2006)

37

Chapter 3 Methods
This chapter outlines the methods used in this study. The first section discusses the sources of
LiDAR datasets used in the analysis and their corresponding metadata. The following sections
discuss in detail the methods used in preparing and formatting the LiDAR data, the creation of
Digital Elevation Surfaces (DEMs) using the Empirical Bayesian Kriging (EBK) method, and
the sediment volume change analysis.
3.1 Data Sources
Data included time-series LiDAR datasets taken from the Fall of 2006 to the Spring of
2008. This time period encompassed an El Niño winter event followed by a La Niña winter
event. Figure 10 shows the four individual LiDAR datasets that were used for analysis. For the
purpose of a time-series analysis these four datasets were grouped into three sets associated with
the following survey events:
Fall 2006 - Spring 2007 – El Niño winter
Spring 2007 – Fall 2007 – Summer of 2007
Fall 2007 - Spring 2008 – La Niña winter (control)

38

Figure 11 LiDAR time-series datasets.
All LiDAR datasets were derived through flights conducted in association with the
Southern California Beach Processes Study (SCBPS)/Coastal Data Information Program (CDIP)
as part of Scripps Institution of Oceanography (SIO) in cooperation with the Bureau of
Economic Geology, University of Texas at Austin. The SCBPS program is designed to improve
the understanding of beach sand transport by waves and currents with the goal of improving
local and regional coastal management. The National Oceanic Atmospheric and Administration
(NOAA) Office for Coastal Management was also involved, and the datasets are available
through a government data portal (www.data.gov) for download in the compressed LiDAR file
format (.LAZ) (Table 3).

39

Table 3 LiDAR Datasets
Year Season Event Name Extent Source (URL)
2006 Fall
El Niño
October 2006 LiDAR Point Data
of Southern California Coastline
– Scripps Institute of
Oceanography (SIO)
Long Beach
to
US/Mexico
Border
2006 October
LiDAR
2007 Spring March 2007 LiDAR Point Data
of Southern California Coastline
– Scripps Institute of
Oceanography (SIO)
Long Beach
to
US/Mexico
Border
2007 March
LiDAR
2007 Fall
La Niña
March 2007 LiDAR Point Data
of Southern California Coastline
– Scripps Institute of
Oceanography (SIO)
Long Beach
to
US/Mexico
Border
2007
November
LiDAR
2008 Spring November 2007 LiDAR Point
Data of Southern California
Coastline – Scripps Institute of
Oceanography (SIO)
Long Beach
to
US/Mexico
Border
2008 April
LiDAR

According to the metadata, datasets were generated by the processing of laser range, scan
angle, and aircraft altitude data collected using an Optech Inc. Airborne Laser Terrain Mapper
(ALTM) 1225 in combination with geodetic quality Global Positioning System (GPS) airborne
and ground-based receivers. Each survey recorded data for an approximate 500 to 700-meter
wide strip of coastline during low tide conditions. Instrument settings and parameters as
documented by metadata are summarized in Table 4.
Table 4 LiDAR Instrument Settings and Parameters
Setting or Parameter Details
Laser pulse rate (scanner rate) 25 kHz
Scan angle +/- 20-degree beam divergence
Narrow altitude 300-600 m
Ground speed 95-120 kts
3.2 Processing Overview
Conducting this analysis required three major stages: data preparation and formatting,
DEM creation using Empirical Bayesian Kriging (EBK), and beach sediment volume change

40

analysis. This section provides an overview of the workflow while later sections provide specific
details for each. Figure 12 shows the general workflow.

Figure 12 Processing Overview
First, compressed LiDAR datasets, in .LAZ format, were downloaded and extracted using
the LAStoZip tool in the LasTool suite. Time series LiDAR datasets comprised of a fall pre-
winter storm season and a spring post-winter storm season were analyzed for the 2006-2007 El
Niño event and following 2007-2008 La Niña event. Uncompressed .LAS files were then
projected from a geographic coordinate system into a projected coordinate system using the
LAStoLAS tool in the LasTool suite. Projected .LAS files were ground classified to distinguish
bare earth from buildings and infrastructure using the LasGround tool in the LasTool suite.

41

Transitioning to the ArcMap 10.4 platform, a LAS Dataset for each dataset in the time
series (Fall 2006, Spring 2007, Fall 2007, Spring 2008) was created using the Create LAS
Dataset tool. The creation of a LAS dataset allowed classified data to be visualized in ArcMap
and enabled faster rendering of the LiDAR point cloud by displaying points only when zoomed
into a local extent. Additionally, a suite of functions including the ability to filter classifications
so that only ground classified points and last returns were visible, as well as calculating point
statistics, enabled the ability to quickly conduct visual QA/QC checks against building footprints
and further prepare the LiDAR data for Digital Elevation Model (DEM) creation. Following
preprocessing, projection, and ground classification of the LiDAR data, final LiDAR points
classified as “ground” and “last return” were converted to a multipoint feature class using the
LAS to Multipoint tool in ArcMap’s 3D Analyst toolset.
An Empirical Bayesian Kriging (EBK) method was used to create an interpolated DEM
surface using the EBK tool in ArcMap’s Geostatistical Analyst toolset. An EBK interpolation
method to create a DEM surface provided the ability to account for error in the LiDAR analysis.
Four DEM surfaces were created, corresponding to the four LiDAR datasets in the time-series
and included the Fall of 2006 and Spring of 2007 (El Niño event) as well as the Fall of 2007 and
Spring of 2008 (La Niña Event).
In order to calculate beach sediment volume shifts a shoreline band partitioned by cross-
shore segments was created to delineate the dynamic shore area as well as segment the shore
band into manageable segments. A technique to measure coastal elevation change, DEM
differencing, was applied using the Raster Calculator tool in ArcMap’s Spatial Analysis toolset.
DEM differencing was conducted to calculate beach elevation changes that occurred during the
2006-2007 El Niño winter, Summer of 2007, and 2007-2008 La Niña winter. Shore segment

42

volume changes were performed by first calculating the volume of individual raster cells then
summing the volume of raster cells over the entire shore segment. The rate of volume change in
the shore segment was calculated by dividing the shore segment volume change by the area of
the shore segment. Maps and graphs representing the rate of sediment volume change per
segment over the time-series were created.
3.3 LiDAR Data Preparation and Formatting
Figure 13 details the workflow involved in preparing LiDAR data for analysis. The goal
of this step was to prepare the raw LiDAR datasets for input into the EBK Model to create
surface elevation DEMs associated with each of the four survey datasets. Following the
download and uncompression of the LiDAR datasets, the files associated with each survey were
projected into a NAV 1984 California State Plane coordinate system, clipped to a defined study
area, and ground classified according to ASPRS standards. LastoLas tools provided the
functionality to perform the majority of LiDAR data preparation and formatting with an
advantage of batch processing capability. Following the ground classification process, the
resulting LAS files were imported into ArcMap by creating a LAS Dataset associated with each
survey. After the LAS dataset for each survey was visually inspected to ensure the ground
classification process was accurate, the LAS to Multipoint ArcMap tool was used to create a
multipoint feature class of only ground (bare earth) points for each survey.
Infrastructure can affect the output of the DEM interpolation; therefore, it was necessary
to classify ground (bare earth) points from all other points. Only last-return ground points were
carried on to the DEM interpolation process. After LAS files were projected from a global to
projected coordinate system and then clipped to the study area to reduce the file size and
processing time, the LAStoGround tool was used to batch process the files and classify ground

43

points. Ground classified LAS files were visualized in ArcMap by creating a LAS dataset
associated with each survey time period (i.e. Fall 2006, Spring 2007, Fall 2007, Spring 2008).
LAS datasets were visualized in ArcMap and a visual quality assurance control check was
performed on the ground classification by overlaying ground only classified points on an Esri
imagery basemap.

Figure 13 LiDAR to DEM workflow
3.3.1. LAZ Uncompression, Projection, and Clipping
Original LiDAR files were downloaded in a compressed, .LAZ, format specific to
LiDAR data and using the open source software, LasZip, created by Martin Isenberg, as part of
the LasTools software suite, individual LAZ files were decompressed into .LAS files with
attributes of latitude, longitude, and elevation (Isenberg 2016).

44

Uncompressed .LAS files were then projected from a horizontal coordinate system
(WGS84 World Mercator) to a projected coordinate system (NAD88 State Plane CA VI) using
the LastoLas tool in the LasTools software suite. The vertical coordinate system of the .LAS files
is the North American Vertical Datum of 1988 (NAVD88). Units for both the horizontal and
vertical projected coordinate system remained in meters for analysis.
3.3.2. LAS Ground Classification
In order to create a DEM surface interpolated from only ground points within the LiDAR
point cloud, it was necessary to undergo the process of classifying ground points (bare earth)
from non-ground points (buildings, vegetation). Coastal infrastructure like buildings (i.e. ocean
front properties and lifeguard towers) and piers, harbors, other man-made features that extended
above the bare earth surface were filtered from the LiDAR point cloud in the ground
classification process. Most of the LiDAR datasets had no classification attributes assigned.
Table 5 highlights the LiDAR classifications used for this study, developed by the
American Society for Photogrammetry and Remote Sensing (ASPRS), additional classification
values for buildings, vegetation, etc. exist but were not necessary for this study.
Table 5 ASPRS standardized LiDAR classifications used
Classification
Value
Meaning
0 Created, never classified
1 Unclassified
2 Ground

Ground points in the LiDAR datasets were classified using the LasGround tool which is
part of the LasTool software suite. LasGround classifies ground points using an automatic
classification method which implements a contour/segmentation-based object-oriented approach.

45

In the background processing, LasGround generates contour lines from the highest elevation in
the area down to the lowest elevation in the area using relatively small intervals (0.5m) and
through a complex process of grouping and segmenting contours, the model is able to distinguish
surface objects from the ground (Hug et al. 2004).
3.3.3. LAS Dataset
Transitioning into the ArcMap interface, ground classified .LAS files were imported into
ArcMap using the Create LAS Dataset tool. Four separate LAS datasets were created associated
with each time-period in the time-series. The Create LAS Dataset tool, part of the LAS Dataset
toolset, allows the rapid read and display of LiDAR data in ArcMap. LiDAR attributes, including
classifications and returns, and spatial references are displayed as well. The LAS Dataset tool
displays individual .LAS files as tiles until zoomed into a close enough extent that distinguishing
individual points is possible, which allows for efficient processing and graphics rendering
(Figure 14). Additional tools allowing the removal and addition of individual .LAS files also
provide streamlined editing capability.

46

Figure 14 ArcMap tool Create LAS Dataset input and output illustration (Esri 2016)
Once LAS datasets were created, ground classification was verified by visually
comparing to background imagery. Point statistics were documented for each LAS Dataset
including original # of LiDAR points, # of ground classified points, and # of ground classified
plus last return points.
3.3.4. LAS Ground to Multipoint Feature Class
Following the ground classification process and creation of LAS datasets, LAS dataset
files were converted into a multipoint feature class. Using the LAS to Multipoint tool, in the LAS
Dataset toolset, parameters were set to convert only ground classified and last return points into
the multipoint feature class. The laser emitted from LiDAR systems has the capability of
measuring multiple elevations as the pulse reflects from high objects in the landscape first

47

(buildings or infrastructure) then lower vegetation, structures until finally, the pulse reflects off
bare-earth surfaces (Keranen and Kolvoord 2016). Carrying on points that were ground classified
and last returns ensured only bare earth points would be inputted into the next step of creating a
DEM.
3.4 LiDAR-derived Digital Elevation Models (DEMs)
Digital elevation models (DEMs) were created for each LiDAR dataset using an
Empirical Bayesian Kriging (EBK) interpolation method. While no statistical interpolation
process can produce a true elevation surface, the EBK interpolation method provides the ability
to incorporate uncertainty when creating DEMs (Krivoruchko and Butler 2013). The ability to
measure uncertainty is particularly important in a detailed time-series analysis. Calculating
elevation changes and volume changes at a high, 1-meter grid size, resolution requires
combining time-series data and error, if present, can persist and possibly increase in subsequent
stages of the analysis. Additionally, identifying sources of error in the individual DEMs was
necessary to conclude whether or not the next stages in the analysis were feasible in the terms of
producing a product that could accurately measure sediment volume changes over time.
Other interpolation methods, including inverse distance weighted (IDW), spline, natural
neighbor, and standard kriging were considered, but none provided associated error. Triangulated
Irregular Network (TIN) surfaces were also evaluated, as they are commonly used to display
elevation surface data. TIN surfaces are convenient for creating surfaces using irregularly spaced
known elevation points; however, the LiDAR datasets used for this analysis consisted of dense
and fairly uniform spacing of elevation points. Additionally, the TIN surface interpolation
methods, like the other interpolation methods discussed, did not offer statistical error outputs.

48

The EBK interpolation method accounts for error by running multiple simulations on the
dataset, estimating error through the underlying semivariogram (Esri 2016). The statistical basis
behind the semivariogram concept is rooted in spatial autocorrelation, meaning the closer things
are, in this case elevation points, the more similar they will be than points further away (Chilès
and Delfiner 1999). The semivariogram defines how the similarity of points diminishes over
distance (Krivoruchko 2012). The model repeatedly runs simulations, in the case of this analysis,
100 simulations were specified. The large elevation dataset, made up of millions of points, is
automatically broken into a subset for model runs, due to model computational limits. The
default subset setting was used, 100 points per subset. After specifying the parameters and
desired number of model runs the EBK process uses the following statistical logic outlined in
four steps (Esri 2016). Step 1 produces an initial semivariogram, estimated from a subset of
known elevation data. Step 2 uses the initial semivariogram as a model, to calculate data and
produce predicted elevation points within the subset. Step 3 creates a new semivariogram which
is estimated from the predicted elevation points. Then, Step 4 repeats Step 2 and 3 for 100 model
runs. The model then moves to another subset of known elevation points and repeats the process
in entirety until all subsets have been covered. Understanding how the EBK interpolation method
works provides insight into the enormous computational modeling involved, especially when
dealing with LiDAR datasets that contain millions of elevation points.
Using the ArcMap EBK tool a 1-meter grid resolution DEM and associated error surface
was created for each of the four LiDAR datasets as shown in Figure 15. Each dataset required
individual EBK interpolations; therefore, the EBK model was run with the same settings four
separate times.

49

Figure 15 LiDAR-derived Digital Elevation Model (DEM) Workflow
3.4.1. Empirical Bayesian Kriging (EBK) Analysis
The multipoint feature class for each LiDAR dataset, consisting of only ground (bare
earth) elevation points, were used to create a digital elevation model (DEM) surface using the
Empirical Bayesian Kriging (EBK) tool. The EBK method was chosen because the ArcMap
EBK tool automatically calculates and adjusts parameters to receive accurate interpolation
results and also estimates the level of error associated with the interpolation. A total of four
DEM surfaces corresponding to the following four LiDAR surveys in the time-series were
created: 1) Fall of 2006, 2) Spring of 2007, 3) Fall of 2007, 4) Spring of 2008.
Output cell resolution for each DEM was set to a 1-meter grid cell size. The raster grid
size to use for DEM creation was chosen based on the criteria of a minimum of one LiDAR data
point per grid cell and a low range of elevation variation within each cell. Additional parameters
as discussed previously included setting the number of model runs (simulations) to 100 and the
subset size to 100 points. Following the creation of the initial Fall 2006 DEM, all other three

50

datasets were set to snap to the Fall 2006 raster. Raster snapping was necessary to ensure that
individual raster cells in all datasets aligned for the later DEM differencing process. This snap
raster parameter was specified in the EBK tool’s Environment Settings under Processing Extent.
In order to minimize processing time, the extent of the Raster Analysis was masked to the
Study Area Boundary. Masking the raster analysis avoided a default rectangle raster output and
the processing of data outside the study area.
3.4.2. ArcGIS Processing Requirements
Due to the large amount of elevation points in each dataset individual EBK interpolation
processes took approximately 3-5 hours to complete. This required high-end processing ability.
Standard ArcMap conducts background processing in 32-bit, and in order to improve processing
speeds, the 64-bit Background Processing option available through ArcGIS was downloaded and
installed. The 64-bit Background Processing option replaced the regular 32-bit, allowing EBK
interpolation analysis and DEM grid surface creation to be computed using more system
resources. All LiDAR analysis and geoprocessing were conducted on a stand-alone, high
performance, desktop with the system specifications listed in Table 6.
Table 6 Desktop system specifications used for LiDAR analysis and geoprocessing
Component Detail
Processor 3.4 GHz Intel Core i7
RAM 64 GB DDR Memory
Hard Drives 128 GB Solid State Drive + 1 TB SATA Drive
Graphics Dedicated Graphics Card – 2 GB Nvidia GeForce GT 730
Operating System Windows 10
3.5 Beach Sediment Volume Change Analysis
The beach sediment volume change analysis consisted of three processes including DEM
differencing, defining shore segments, and calculating sediment volume change. These processes

51

are shown in Figure 16 and discussed in detail below. The final results consisted of tables of
actual sediment volume change in cubic meters and the rate of sediment volume change per
square meter for each shore segment. The rate of sediment volume change per square meter
during the 2006-2007 El Niño winter was joined to the shore segments and visually displayed in
a series of maps. Detailed tables of actual sediment change in each shore segment over the 2006-
2007 El Niño winter, Summer of 2007, and 2007-2008 La Niña winter were created and included
in this manuscript as Appendix A.

Figure 16 Beach Sediment Volume Change Analysis Workflow
3.5.1. DEM Differencing
The four DEMs created using the EBK process were used to calculate elevation change
over the 2006-2007 El Niño winter, summer of 2007, and following 2007-2008 La Niña winter.
ArcMap’s Raster Calculator tool was utilized to perform DEM differencing over the datasets and

52

Table 7 shows the three time-series calculations that were made. Each DEM differencing
calculation resulted in a new raster (1-meter cell size resolution) representing elevation change.
Table 7 DEM Differencing to Measure Elevation Change over Time-Series
DEM (time y)
(meters)
minus DEM (time x)
(meters)
equals DEM difference (time y – time x)
[Elevation change in meters]
Spring 2007 - Fall 2006 = 2006-2007 El Niño Winter
Fall 2007 - Spring 2006 = 2007 Summer
Spring 2008 - Fall 2007 = 2007-2008 La Niña Winter

3.5.2. Shore Segments
In order to compute and visualize volume change for the large study area, the coastal
zone was broken up into manageable segments. A shoreline band was created by using a
combination of calculating the minimum shoreline based on local tidal datums and manual
digitization with the aid of contours. The shoreline band was then broken up into manageable
segments which were assigned unique identification numbers. Transects were used to aid in the
process of segmentation; however, it is important to note that segmentation was arbitrary and not
based on any physical landmarks.
The seaward boundary of the shoreline band was delineated by calculating a minimum
Mean High Water (MHW) shoreline. MHW is one of several different tidal datums that are
calculated at tidal stations. Figure 17 shows the various elevation and tidal datums associated
with the La Jolla tidal station (#9410230). Tidal datums are computed by averaging long-term
tidal data (1983 to 2001) collected by the station. Since tidal influences are uniform throughout
the OLC, meaning changes in tide observed in La Jolla will be the same in Dana Point, the long-
term data from the La Jolla tidal station provided sufficient data to calculate a MHW shoreline.

53

Figure 17 Elevations datums (in meters) for La Jolla, CA (Station #9410230) (NOAA 2016)
In order to calculate the minimum MHW shoreline, all four DEMs were inputted into
ArcMap’s Cell Statistics Tool, and the minimum elevation for each cell was calculated. This
process produced a minimum raster elevation surface. The minimum MHW shoreline was
derived by drawing a contour across the minimum raster elevation surface at the Mean High
Water (MHW) tidal datum. As Figure 17 shows, the difference between the NAVD88 vertical
coordinate system and the various tidal datums for the La Jolla station. In the NAVD88 vertical
coordinate system, a contour drawn at zero would actually lay at 1.389 meters in the tidal datum,
closer to Mean Lower Low Water. With the assumption that zero meters in the NAVD88 vertical

54

datum equals 1.389 in the tidal datum, the MHW was calculated by drawing a contour at 1.344
meters, the difference between MHW and NAVD88 values in Figure 17.
The shoreline band extends landward to include the sandy beach with the landward
boundary defined as the end of sandy beach and the beginning of stabilized dunes, infrastructure,
or cliff faces. The landward boundary of the shoreline band was created using a combination of
elevation contours created from the DEMs, identifying sharp elevation gradients, and manual
digitization using imagery as guides. The landward boundary of the shoreline band was typically
between the 4 and 6-meter elevation contours.
Transects were generated by creating transects every 100-meters perpendicular to an
offshore shoreline as a base. The offshore shoreline was available through the United States
Geological Service shoreline project and is commonly used to generate perpendicular transects
(USGS 2005). Using an offshore shoreline as an anchor for transects minimized the occurrence
of transects crossing each other. A minimal amount of editing was required to clean up transects
that crossed over each other, primarily around coastal areas that had sharp turns in the shoreline
direction. Transects were generated off the USGS offshore shoreline in ArcGIS using the
Perpendicular Transects tool created by M. Ferreira (M. Ferreira 2014). Figure 18 shows the
process of creating shore segments using the Mean High Water (MHW) shoreline, elevation
contours, and transects.

55

Figure 18 Shore segment creation process
3.5.3. Volume Calculation
Beach sediment volume change between the time-series was calculated using the
elevation difference rasters associated with each time-series. The three elevation difference
rasters identified in Table 9 were individually inputted into ArcMap’s Zonal Statistic as Table
tool to calculate statistics per shore segment necessary to derive total volume change per segment
and the rate of volume change per segment.
The volume per individual cell (Vcell) was calculated by multiplying the area of the cell
(Acell) by the elevation difference of the cell (zcell), as shown in Equation 3.1. In the case of this
analysis, all grid cell sizes were one meter by one meter, making all Acell values equal 1m
2
.

56

𝑉𝑉 𝑐𝑐𝑐𝑐 𝑐𝑐 𝑐𝑐 = 𝐴𝐴 𝑐𝑐 𝑐𝑐 𝑐𝑐 𝑐𝑐 𝑧𝑧 𝑐𝑐𝑐𝑐𝑐𝑐 𝑐𝑐 where; 𝑧𝑧 𝑐𝑐𝑐𝑐𝑐𝑐 𝑐𝑐 = elevation difference (m) of cell and 𝐴𝐴 𝑐𝑐𝑐𝑐 𝑐𝑐 𝑐𝑐 = 1 𝑚𝑚 2
(3.1)
To calculate the total change in volume per segment, (Vcell) was summed for all the cells
within the segment. This calculation is represented by Equation 3.2. Vsegment represents the total
change in sediment volume in cubic meters for a shore segment, and a negative value represents
erosion while a positive value represents accretion.
𝑉𝑉 𝑠𝑠 𝑐𝑐 𝑒𝑒𝑒𝑒 𝑐𝑐 𝑒𝑒𝑒𝑒 = ∑ 𝑉𝑉 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 𝑠𝑠 𝑐𝑐 𝑒𝑒𝑒𝑒 𝑐𝑐 𝑒𝑒𝑒𝑒 (3.2)
Individual shore segments had varying areas and to normalize sediment volume changes
in both maps and graphs, the rate of sediment volume change in the form of cubic meters per
square meter was calculated for each shore segment. In some cases, shore segments with high
amounts of sediment volume shift (Vsegment) were associated with large areas of beach; however,
these segments did not necessarily have high rates of sediment volume change compared to
smaller shore segments. Normalizing data visualized in the graphs and maps allowed for a more
accurate representation to use for comparing shore segment volume changes. The rate of
sediment volume change (Rsegment) in cubic meters per square meter was calculated by dividing
the total sediment volume change of a shore segment (Vsegment) by the total area of the shore
segment (Asegment) as shown in Equation 3.3.
𝑅𝑅 𝑠𝑠 𝑐𝑐 𝑒𝑒𝑒𝑒 𝑐𝑐 𝑒𝑒𝑒𝑒 = 𝑉𝑉 𝑠𝑠 𝑐𝑐 𝑒𝑒 𝑒𝑒𝑐𝑐 𝑒𝑒𝑒𝑒 ÷ 𝐴𝐴 𝑠𝑠 𝑐𝑐 𝑒𝑒𝑒𝑒 𝑐𝑐 𝑒𝑒𝑒𝑒 (3.3)
Detailed graphs of the rate of sediment volume change by shore segment were created for
the 2006-2007 El Niño winter and 2007-2008 La Niña winter. Graphs and tables were created to
summarize overall actual sediment change and rates of sediment change for the whole study area
for the 2006-2007 El Niño winter, Summer of 2007, and 2007-2008 La Niña winter.
Additionally, Appendix A was created to include actual sediment changes by shore segment in
the form of detailed tables for all time periods.

57

Chapter 4 Results
Chapter 4 discusses the results of this study. The results from preparing and formatting the
LiDAR datasets for analysis focus on the ground classification process and include elevation
point statistics, 3D visualization, and the creation of multipoint feature classes. Next, the results
from using the EBK interpolation method to create DEMs is discussed. Finally, the results from
the beach sediment volume change analysis are presented. The beach sediment volume change
analysis includes the final data represented by a series of graphs, tables, and maps along with
detailed narratives of erosion and accretion patterns observed along the coast in the OLC.
4.1 LiDAR Preparation and Formatting Results
Figure 19 and Figure 20 show a snapshot of the Fall 2006 LAS dataset with all elevation
points and only ground elevation points, respectively. Buildings, tall manmade infrastructure,
most roads, lifeguard towers, and piers were filtered out. ArcMap tools also provided the
capability to view LAS dataset segments in a 3-D rendering. Figure 21 shows a segment in San
Clemente as part of the LAS Fall 2006 dataset with all elevation points while Figure 22 shows
the same segment with only ground classified points; elevation points associated with buildings
and the pier structure are not displayed. Table 8 shows the point statistics of each LAS dataset
including the total number of elevation points in the delineated study area followed by the
number and percentage of those points that are ground (bare earth) classified. The percentage of
ground classified points ranged from 23.7% to 37.6% of total elevation points. Table 8 also
shows the minimum and maximum elevation point of each dataset, which ranged from -8.24 m
to 110.12 m. Negative elevations were often associated with intertidal and ocean environments

58

while elevations on the higher end of the range were associated with tall bluffs and cliffs
extending from the beach area.
Using the ArcMap LAS to Multipoint tool in the 3D Analyst toolbox, classified LAS files
for each survey were exported into a multipoint feature class. Settings for the export filtered out
all elevation points except those that met the criteria of ground (bare earth) and last returns.
These multipoint feature classes were used as input to create ground (bare earth) digital elevation
models using an Empirical Bayesian Kriging interpolation technique.
Table 8 LAS Elevation Point Statistics
LAS Dataset All Points
in Study
Area
Boundary
Ground (Bare Earth)
Classified Points
Elevation Range (meters)
# of points % of
points
Min Max
Fall 2006 100,078,983 23,773,745 23.7% -8.02 110.14
Spring 2007 79,085,737 28,257,867 35.7% -8.24 108.32
Fall 2007 103,299,390 38,065,726 36.8% -5.36 107.00
Spring 2008 120,057,674 45,155,213 37.6% -5.12 107.13

59

Figure 19 Fall 2006 LAS dataset with all elevation points

60

Figure 20 Fall 2006 LAS Dataset with only ground (bare earth) classified points

61

Figure 21 Fall 2006 LAS dataset 3D view with all elevation points

Figure 22 Fall 2006 LAS dataset 3D view will only ground (bare earth) classified points
4.2 EBK Interpolation and DEM Creation Results
The EBK interpolation process was the most time-consuming of all steps in this study.
After many failed attempts at running the EBK model, successful model runs were completed

62

using a computing machine with multiple core processors and high memory capacity. The EBK
tool took approximately 4 hours to create each of the four DEMs.
The EBK tool also outputted error rasters corresponding to each interpolation elevation
raster. These error rasters provided the ability to quantify and spatially reference error associated
with the created DEM. As expected due, to the high density of elevation points in the study area,
elevation error was found to be minimal. Higher elevation error was typically seen in areas
where points corresponding to buildings and infrastructure had been removed during the ground
classification process.
4.3 Beach Sediment Volume Change Analysis Results
A total of 792 shore segments were created along the coastline from Dana Point to La
Jolla and covered a total area of just under 3.5 million square meters. The following sub-sections
describe in detail the results of the beach sediment volume change analysis. Appendix A includes
detailed results of sediment volume changes by shore segments during the 2006-2007 El Niño
winter, the Summer of 2007, and following 2007-2008 La Niña winter.
4.3.1. Dana Point
Shore segments one through 38 comprise the Dana Point region, the northern most
section of the OLC, and include an area of just under 200,000 m
2
(Figure 26). Beach sediment
volume change analysis showed overall stability for Dana Point beaches during the 2006-2007 El
Niño winter, with a net deposition of 3,682 m
3
of sediment. The harbor jetties and infrastructure
likely played a role in protecting Doheny State Beach from southerly storm tracks and associated
waves during El Niño storms. The decrease of sediment in Shore Segment 6 can be explained by
the San Juan Creek mouth and associated berm shifting from open to closed conditions (Figure
25). The shore segments just south of Doheny State Beach display erosion during all time

63

periods. Overall spatial patterns of erosion and accretion were similar for both the El Niño and
La Niña winters; however, the rate of erosion per square meter was significantly greater during
the La Niña winter (Figure 23 and Figure 24). Interestingly, the Dana Point region experienced
the greatest overall erosion relative to other areas of the OLC during the intermediary summer
2007 period, with a sediment loss of 30,257 m
3
, a rate of roughly -0.15 m
3
per square meter.
Table 9 Dana Point Sediment Net Volume Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
1 - 38 199,655 3,682 -30,257 -31,241

Figure 23 Dana Point – Rate of sediment volume change by shore segment during the 06-07 El
Niño

-1.20
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

64

Figure 24 Dana Point – Rate of sediment volume change by shore segment during the 07-08 La
Niña

Figure 25 Historical imagery showing the San Juan Creek mouth shift from open to closed (Left:
February 2006, Right: March 2007) (Source: Google Earth)

-1.20
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

65

Figure 26 Dana Point - Map of rate of sediment volume change by shore segments during the 06-
07 El Niño

66

4.3.2. San Clemente
For this study, the San Clemente region is divided into a north and south region,
arbitrarily separated by the San Clemente pier landmark. San Clemente (north) is defined as
shore segments 39 through 75 and San Clemente (south) is defined as shore segments 76 through
113. Collectively, the San Clemente shore segments total area is 235,846 m
2
.
4.3.2.1. San Clemente (North)
The San Clemente (North) area, defined by shore segments 39 through 75, represent a
total area of 95,593 m
2
(Figure 29). The spatial pattern of erosion and accretion during the 2006-
2007 El Niño winter is indicative of longshore sand transport (Figure 27). A spatially similar
longshore sand transport pattern is also visible during the 2007-2008 La Niña, only with muted
erosion and accretion amounts (Figure 28). During the Summer 2007, longshore sediment
deposition and erosion patterns are reversed from both winter observations. During the 2006-
2007 El Niño winter the San Clemente (North) area lost 6,608 m
3
of sediment; however, 6,874
m
3
of sediment was deposited back onto the beaches during the Summer 2007 (Table 10). The
following La Niña winter showed a total sediment loss of 5,054 m
3
, only a slight decrease
relative to the previous El Niño winter.
Table 10 San Clemente (North) Net Sediment Volume Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
39 - 75 95,593 -6,608 6,874 -5,054

67

Figure 27 San Clemente (North) – Rate of sediment volume change by shore segment during the
06-07 El Niño

Figure 28 San Clemente (North) – Rate of sediment volume change by shore segment during the
07-08 La Niña

-1.20
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
1.20
39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-1.20
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
1.20
39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

68

Figure 29 San Clemente (North) - Map of rate of sediment volume change by shore segments
during the 06-07 El Niño

69

4.3.2.2. San Clemente (South)
San Clemente (South), defined as shore segments 76 through 113, showed overall greater
erosion during the 2006-2007 El Niño winter than the 2007-2008 La Niña winter (Figure 30 and
Figure 31). During the 2006-2007 El Niño winter 30,875 m
3
of beach sediment was lost, and
most shore segments experienced erosion. Shore segment 76, which includes the San Clemente
pier showed some accretion and shore segments 111-113 had significant accretion likely due to a
combination of increased sediment flow out of Cristianitos Creek and a shift in shoreline
direction. During the Summer of 2007, the San Clemente (South) shore segments gained 14,058
m
3
of sediment, almost half of the sediment that was lost during the previous winter (Table 11).
The following 2007-2008 La Niña winter showed a net sediment loss of 6,034 m
3
(Table 11).
Table 11 San Clemente (South) Net Sediment Volume Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
76 - 113 140,253 -30,875 14,058 -6,034

70

Figure 30 San Clemente (South) – Rate of sediment volume change by shore segment during the
06-07 El Niño

Figure 31 San Clemente (South) – Rate of sediment volume change by shore segment during the
07-08 La Niña

-1.20
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-1.20
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

71

Figure 32 San Clemente (South) - Map of rate of sediment volume change by shore segments
during the 06-07 El Niño

72

4.3.3. San Diego North
The San Diego North region consists of shore segments 114 through 313. For the purpose
of this study, the San Diego North region was arbitrarily defined to span from San Onofre to
Camp Pendelton Marine Corps Base (MCB). Higher rates of sediment volume loss during the
2006-2007 El Niño winter were seen in southern portions of San Onofre State Beach and Camp
Pendelton MCB. Cliff failure was also observed in the San Onofre State Beach area. Individual
sub-regions and results are discussed in the following sections.
4.3.3.1. Trestles Beach to San Onofre State Beach/ Nuclear Generating Station
Shore Segments 114 through 151 represent the area from Trestles Beach to San Onofre
State Beach ending adjacent to the decommissioned San Onofre Nuclear Generating Station
(SONGS) (Figure 35). Collectively shore segments 114 through 151 represent 173,772 m
2
of
coastal beach. Both the El Niño and La Niña winters showed similar distribution trends of
accretion and erosion, with the narrow beach area north of San Onofre Creek along the point
showing the greatest erosion rate as signified by Shore Segments 121 through 122 (Figure 33 and
Figure 34). During the 2006-2007 El Niño winter, this area showed a net loss of 5,568 m
3
of
sediment followed by a recovery of 6,479 m
3
sediment during the Summer of 2007. The 2007-
2008 La Niña winter showed a greater loss of beach sediment in this area than the preceding El
Niño winter with a net loss of 6,479 m
3
(Table 12).
Table 12 Trestles to San Onofre (SONGS) Net Sediment Volume Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
114 - 151 173,772 -5,568 6,594 -6,479

73

Figure 33 Trestles to San Onofre (SONGS) – Rate of sediment volume change by shore segment
during the 06-07 El Niño

Figure 34 Trestles to San Onofre (SONGS) – Rate of sediment volume change by shore segment
during the 07-08 La Niña

-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

74

Figure 35 Trestles to San Onofre (SONGS) - Map of rate of sediment volume change by shore
segments during the 06-07 El Niño

75

4.3.3.2. San Onofre State Beach to Camp Pendelton Marine Corps Base (North)
San Onofre State Beach to the northern extent of Camp Pendelton Marine Corps Base
(MCB) are identified as shore segments 152 through 191 and cover an area of 88,000 m
2
(Figure
38). Dense nearshore development ends following the San Onofre Nuclear Generating plant, and
the physical characteristics of the beach are primarily natural with beach faces transitioning to
steep bluffs. Sand transport is visible in both the El Niño and La Niña winters as indicated by
alternating erosion and accretion trends as shown in Figure 36 and Figure 37. Unlike most
regions within the OLC which showed net sediment accretion over the summer months, this
region showed erosion during the Summer of 2007. Rates of sediment volume loss during the
2006-2007 El Niño winter were only slightly higher than the 2007-2008 La Niña winter;
however, the rates of sediment volume accretion, specifically at shore segments 168 and 169
were significantly greater during the 2006-2007 El Niño winter. Figure 39 shows a close up of
shore segments 168 and 169 that are parallel to unstable cliff bluffs and a tributary/creek outlet,
which could explain the increased accretion rate during the 2006-2007 El Niño.
Table 13 San Onofre State Beach to Camp Pendelton MCB (North) Net Sediment Volume
Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
152 - 191 88,000 -6,208 -1,762 -8,235

76

Figure 36 San Onofre State Beach to Camp Pendelton MCB (North) – Rate of sediment volume
change by shore segment during the 06-07 El Niño

Figure 37 San Onofre State Beach to Camp Pendelton MCB (North) – Rate of sediment volume
change by shore segment during the 07-08 La Niña

-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

77

Figure 38 San Onofre State Beach to Camp Pendelton MCB (North) - Map of rate of sediment
volume change by shore segments during the 06-07 El Niño

78

Figure 39 2006-2007 Elevation difference raster highlighting cliff erosion in shore segments 168
and 169

79

4.3.3.3. San Onofre State Beach/Camp Pendelton MCB (Central)
Continuing down the coast, San Onofre State Beach and Camp Pendelton MCB are
identified by shore segments 192 through 231 and represent a collective area of 164,192 m
2

(Figure 42). This section of coastline remains relatively undeveloped, with California Highway 1
offset and adjacent to the coastline and scattered military training facilities present. Overall, the
2006-2007 El Niño winter showed a higher rate of sediment volume loss than the 2007-2008 La
Niña winter (Figure 40 and Figure 41). Sediment accretion was visible in segments 229-231
during the 2006-2007 El Niño winter, and further investigation identified a small tributary/creek
outflow that likely contributed sediment from increased flow caused by winter storm runoff.
During the 2006-2007 El Niño winter 11,032 m
2
of sediment eroded from the beaches, followed
by 5,375 m
2
of sediment accreting during the following Summer of 20078 months (Table 14).
The net amount of sediment loss during the subsequent 2007-2008 La Niña winter was 2,752 m
2
,
substantially less than the preceding El Niño winter (Table 14).
Table 14 San Onofre State Beach/Camp Pendelton MCB (Central) Net Sediment Volume
Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
192 - 231 164,920 -11,032 5,375 -2,752

80

Figure 40 San Onofre State Beach/Camp Pendelton MCB (Central) – Rate of sediment volume
change by shore segment during the 06-07 El Niño

Figure 41 San Onofre State Beach/Camp Pendelton MCB (Central) – Rate of sediment volume
change by shore segment during the 07-08 La Niña

-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

81

Figure 42 San Onofre State Beach/Camp Pendelton MCB (Central) - Map of rate of sediment
volume change by shore segments during the 06-07 El Niño

82

4.3.3.4. San Onofre State Beach/Camp Pendelton MCB (South)
The San Onofre State Beach and Camp Pendelton MCB (South) region is represented by
shore segments 232 through 272, covering an area of 234,367 m
2
(Figure 45). During the 2006-
2007 El Niño winter, all shore segments in this area showed sediment loss, with sediment
volume loss rate ranging from 0.01 to 0.21 m
3
per sq m (Figure 43). Overall, this area showed
over three times the net loss of sediment during the 2006-2007 El Niño winter compared to the
2007-2008 La Niña winter (Figure 44). Following a net loss of 24,829 m
3
of sediment during the
2006-2007 El Niño winter, nearly half this amount of sediment (12,989 m
3
) was deposited back
onto the beaches over the Summer of 2007 (Table 15). The large degree of seasonal variability in
sediment erosion and accretion points towards a highly dynamic beach system, which could be
confirmed by further investigation into long term trends.
Table 15 San Onofre State Beach/Camp Pendelton MCB (South) Net Sediment Volume Change
Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
232 - 272 234,367 -24,829 12,989 -7,373

83

Figure 43 San Onofre State Beach/Camp Pendelton MCB (South) – Rate of sediment volume
change by shore segment during the 06-07 El Niño

Figure 44 San Onofre State Beach/Camp Pendelton MCB (South) – Rate of sediment volume
change by shore segment during the 07-08 La Niña

-0.40
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-0.40
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

84

Figure 45 San Onofre State Beach/Camp Pendelton MCB (South) - Map of rate of sediment
volume change by shore segments during the 06-07 El Niño

85

4.3.3.5. Camp Pendelton MCB (South)
The southernmost extent of Camp Pendelton MCB is identified by shore segments 273
through 313, and also marks the end of the larger San Diego Central region (Figure 48). This
area, spanning just over 300,000 m
2
of beach, experienced a high degree of erosion during the
2006-2007 El Niño winter. Even greater than trends seen in shore segments to the north, the
erosion rates in this region ranged from 0.06 to 0.20 m
3
per sq m during the 2006-2007 El Niño
(Figure 46). A substantial amount of sediment, 12,269 m
3
, was deposited onto the coastline
during the following Summer of 2007 (Table 16). During the 2007-2008 La Niña winter only
2,279 m
3
of sediment was lost, orders of magnitude less than the preceding El Niño winter
(Table 16 and Figure 47).
Table 16 Camp Pendelton MCB (South) Net Sediment Volume Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
273 - 313 304,278 -43,756 12,269 -2,279

86

Figure 46 Camp Pendelton MCB (South) – Rate of sediment volume change by shore segment
during the 06-07 El Niño

Figure 47 Camp Pendelton MCB (South) – Rate of sediment volume change by shore segment
during the 07-08 La Niña

-0.40
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-0.40
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

87

Figure 48 Camp Pendelton MCB (South) - Map of rate of sediment volume change by shore
segments during the 06-07 El Niño

88

4.3.4. San Diego Central
The San Diego Central region consist of shore segments 314 through 509. This area
spans from the southernmost extent of Camp Pendelton MCB to Carlsbad State Beach. Camp
Pendelton MCB to the mouth of the Santa Margarita Marsh and Oceanside City Beach showed
the highest rates of erosion in this region during the 2006-2007 El Niño winter. Shore segments
surrounding the Santa Margarita mouth showed the highest rates of sediment accretion during
the Summer of 2007. Individual sub-regions and results are discussed in the following sections.
4.3.4.1. Camp Pendelton MCB (South) to Santa Margarita Marsh
The southernmost sections of Camp Pendelton MCB to the beginning of the Santa
Margarita Marsh outflow is designated by shore segments 314 through 354 (Figure 51). This
subset of shore segments covers some of the widest beaches in the OLC with an area of 434,560
m
2
. This large area of beach was severely impacted during the 2006-2007 El Niño with 112,231
m
3
of sediment lost and sediment loss rates ranging from 0.08 to 0.87 m
3
per sq m (Figure 49).
Interestingly, this area also displayed the highest sediment accretion rates compared to the rest of
the study area, with 257,176 m
3
deposited back onto the beaches during the Summer of 2007
(Table 17). While sediment loss was high during the 2006-2007 El Niño winter, more than
double the sediment amount deposited onto beaches. During the following 2007-2008 La Niña
winter a mere 15,952 m
3
of sediment was lost from the shore segments, minimal compared to the
previous El Niño winter (Table 17 and Figure 50).
Table 17 Camp Pendelton MCB (South) to Santa Margarita Marsh Net Sediment Volume
Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
314 - 354 434,560 -112,231 257,176 -15,952

89

Figure 49 Camp Pendelton MCB (South) to Santa Margarita Marsh – Rate of sediment volume
change by shore segment during the 06-07 El Niño

Figure 50 Camp Pendelton MCB (South) to Santa Margarita Marsh – Rate of sediment volume
change by shore segment during the 07-08 La Niña

-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

90

Figure 51 Camp Pendelton MCB (South) to Santa Margarita Marsh - Map of rate of sediment
volume change by shore segments during the 06-07 El Niño

91

4.3.4.2. Santa Margarita Marsh to Oceanside Harbor
Beginning at the Santa Margarita Marsh mouth and including Oceanside Harbor, shore
segments 355 through 388 include both natural landform features and highly modified coastal
infrastructure (Figure 55). Erosion was visible throughout most of this area during the 2006-2007
El Niño winter, with over 35,000 m
3
lost during this time period (Table 18). The following
summer showed a deposition of 11,657 m
3
of sediment (Table 18). The most noticeable change
in sediment volume during the 2007-2008 La Niña winter was around the Santa Margarita Creek
mouth, where major shifts in the mouth opening and berm morphology occurred. Between the
Summer of 2006 and Spring of 2008, the creek mouth shifted southeast from shore segment 355
to 357 causing a major redistribution in sediment. The shift of the Santa Margarita Creek mouth
was confirmed in by comparing historical imagery (Figure 54). During both the El Niño and La
Niña winter, sediment build up was visible in the shore segments north of the harbor entrance,
where a large rock jetty structure is present (Figure 55). Small sections of beach inside the
protected harbor showed minor erosion during the 2006-2007 El Niño, but otherwise remained
relatively stable.
Table 18 Santa Margarita Marsh to Oceanside Harbor Net Sediment Volume Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
355 - 388 450,785 -35,290 11,657 -1,802

92

Figure 52 Santa Margarita Marsh to Oceanside Harbor – Rate of sediment volume change by
shore segment during the 06-07 El Niño

Figure 53 Santa Margarita Marsh to Oceanside Harbor – Rate of sediment volume change by
shore segment during the 07-08 La Niña

-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

93

Figure 54 Historical imagery showing the shift of the Santa Margarita Creek mouth (Left: June
2006, Right: March 2008) (Source: Google Earth)

94

Figure 55 Santa Margarita Marsh to Oceanside Harbor - Map of rate of sediment volume change
by shore segments during the 06-07 El Niño

95

4.3.4.3. Oceanside City Beach
Oceanside City Beach is designated as shore segments 389 through 429, and make up an
area of 128,119 m
2
(Figure 58). This section of beach is a popular recreational destination for
both local residents and tourists. Additionally, this subset of shore segments following the
Oceanside Harbor marks the beginning of a highly developed San Diego County coastline, with
residential and commercial properties. A small data gap in the Spring 2007 and Fall 2007 LiDAR
dataset prevented sediment analysis in shore segments 405 through 412. This data gap covered
14,685 m
2
of narrow beach in front of residential properties (Figure 58). During the 2006-2007
El Niño winter nearly 21,399 m
3
of sediment was lost in this region, with 8,564 m
3
sediment
gained during the following summer months and 9,805 m
3
sediment lost during the following
2007-2008 La Niña winter (Table 19). Overall, the rate of sediment loss in this region, during the
2006-2007 El Niño winter, was 0.35 m
3
per sq m, higher than the 2007-2008 La Niña sediment
loss rate of 0.20 m
3
per sq m (Figure 56 and Figure 57).
Table 19 Oceanside City Beach Sediment Net Volume Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
389 - 429 128,119 -21,399 8,564 -9,805

96

Figure 56 Oceanside City Beach – Rate of sediment volume change by shore segment during the
06-07 El Niño (shore segments 405-412 no data)

Figure 57 Oceanside City Beach – Rate of sediment volume change by shore segment during the
07-08 La Niña (shore segments 405-412 no data)

-1.20
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
1.20
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-1.20
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
1.20
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

97

Figure 58 Oceanside City Beach - Map of rate of sediment volume change by shore segments
during the 06-07 El Niño

98

4.3.4.4. Carlsbad North to Carlsbad State Beach (Agua Hedionda Lagoon)
Shore segments 430 through 469 represent the area from North Carlsbad to Carlsbad
State Beach (Agua Hedionda Lagoon) (Figure 61). These shore segments cover a total area of
124,673 m
2
, characterized by high beach front development, publically used beaches and two
lagoons. Buena Vista Lagoon to the north is an intermittently open/closed mouthed lagoon, while
Agua Hedionda Lagoon to the south has a bridge abutment and rock jetties to keep the mouth
open. During the 2006-2007 El Niño, these shore segments collectively lost 23,155 m
3
of
sediment from the beaches (Table 20). During the following Summer of 2007, 16,922 m
3
of
sediment was regained (Table 20). Overall rates of erosion were less during the 2007-2008 La
Niña winter versus the 2006-2007 El Niño winter; however, more shore segments in this region
experienced erosion during the 2007-2008 La Niña winter which resulted in a net loss of 24,996
m
3
of sediment (Figure 59 and Figure 60). During the 2006-2007 El Niño winter, the rock jetties
near the Agua Hedionda Lagoon played a role in trapping sediment which was likely transported
from the nearby shore segments to the north (Figure 61).
Table 20 Carlsbad North to Carlsbad State Beach (Agua Hedionda Lagoon) Net Sediment
Volume Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
430 - 469 124,673 -23,155 16,922 -24,996

99

Figure 59 Carlsbad North to Carlsbad State Beach (Agua Hedionda Lagoon) – Rate of sediment
volume change by shore segment during the 06-07 El Niño

Figure 60 Carlsbad North to Carlsbad State Beach (Agua Hedionda Lagoon) – Rate of sediment
volume change by shore segment during the 07-08 La Niña

-1.20
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
1.20
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-1.20
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
1.20
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

100

Figure 61 Carlsbad North to Carlsbad State Beach (Agua Hedionda Lagoon) - Map of rate of
sediment volume change by shore segments during the 06-07 El Niño

101

4.3.4.5. Carlsbad State Beach (Agua Hedionda Lagoon) to Carlsbad State Beach (South)
Continuing down the coast, shore segments 470 through 509 represent 85,606 m
2
of
beach from Agua Hedionda Lagoon to the north to the southern extent of Carlsbad State Beach
(Figure 64). Unlike other regions in the OLC where development hugs the coastline, this region
is characterized by narrow beaches bordered by cliffs and bluffs. Parking lots and campground
infrastructure line the tops of the bluffs with residential development inland. Shore segments 483
through 486 represent a section of particularly narrow beach lined by bluffs and during the 2006-
2007 El Niño winter this area experienced high rate of sediment accretion as shown by Figure
62, likely due to the contribution of sediment from cliff erosion. Even with high sediment
accretion rates in some shore segments during the 2006-2007 El Niño winter, this region lost
12,429 m
3
of sediment (Table 21). The Summer of 2007 saw no sediment recovery with a loss of
1,081 m
3
(Table 21). The 2007-2008 La Niña winter resulted in a net loss of 10,934 m
3
of
sediment, similar to the 2006-2007 El Niño winter amounts (Table 21).
Table 21 Carlsbad State Beach (Agua Hedionda Lagoon) to Carlsbad State Beach (South) Net
Sediment Volume Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
470 - 509 85,606 -12,429 -1,081 -10,934

102

Figure 62 Carlsbad State Beach (Agua Hedionda Lagoon) to Carlsbad State Beach (South) –
Rate of sediment volume change by shore segment during the 06-07 El Niño

Figure 63 Carlsbad State Beach (Agua Hedionda Lagoon) to Carlsbad State Beach (South) –
Rate of sediment volume change by shore segment during the 07-08 La Niña

-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

103

Figure 64 Carlsbad State Beach (Agua Hedionda Lagoon) to Carlsbad State Beach (South) - Map
of rate of sediment volume change by shore segments during the 06-07 El Niño

104

4.3.5. San Diego South
The San Diego South region consist consists of the southernmost portion of the OLC
study area and includes shore segments 510 through 792. This area spans from Carlsbad to La
Jolla Shores. High rates of sediment erosion were seen in most of this region during both the
2006-2007 El Niño winter and 2007-2008 La Niña winter. The highest rate of erosion during the
2006-2007 El Niño for the entire OLC study area was observed in the area of Torrey Pines State
Reserve, where cliff erosion was present. The rate of sediment accretion during the Summer of
2007 was high.
4.3.5.1. Carlsbad State Beach (South) to Encinitas (North)
Shore segments 510 through 549 represent the coastal area from the southern extent of
Carlsbad State Beach to the northern region on Encinitas. Collectively these shore segments
cover an area of 118,238 m
2
(Table 22). Wider shore segments are seen in the vicinity of the
Batiquitos Lagoon mouth (shore segments 527 to 532) where a bridge abutment and two rock
jetties are present (Figure 67). The Batiquitos Lagoon mouth, like Agua Hedionda to the north, is
maintained to remain open to the ocean. During the 2006-2007 El Niño winter, the beaches in
this region lost a total of 14,230 m
3
of sediment (Table 22). Sediment accretion during the 2006-
2007 El Niño was visible in some shore segments, with the highest sediment accretion rate, 0.43
m
3
per sq m, in the two shore segments just north of the jetty lining the Agua Hedionda Lagoon
mouth (Figure 65). Moving down the coast past the mouth of Agua Hedionda Lagoon, the beach
begins to narrow, and erosion rates up to 0.89 m
3
per sq m are seen (Figure 65 and Figure 67).
During the Summer of 2007, most shore segments south of the Agua Hedionda Lagoon mouth
showed accretion trends, and overall 3,519 m
3
of sediment was deposited in this region (Table
22). The following 2007-2008 La Niña winter showed greater overall erosion in these shore

105

segments, with 18,549 m
3
of sediment lost; however, the rate of sediment volume change per sq
m was less than the previous El Niño winter (Figure 66).
Table 22 Carlsbad State Beach (South) to Encinitas (North) Net Sediment Volume Change
Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
510 - 549 118,238 -14,230 3,519 -18,548

106

Figure 65 Carlsbad State Beach (South) to Encinitas (North) – Rate of sediment volume change
by shore segment during the 06-07 El Niño

Figure 66 Carlsbad State Beach (South) to Encinitas (North) – Rate of sediment volume change
by shore segment during the 07-08 La Niña

-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

107

Figure 67 Carlsbad State Beach (South) to Encinitas (North) - Map of rate of sediment volume
change by shore segments during the 06-07 El Niño

108

4.3.5.2. Encinitas (North) to Encinitas (South)
Shore segments 550 through 591 represent most of the beaches in the city of Encinitas
and cover an area of 98,529 m
2
(Table 23) This region is characterized by narrow beaches, with
the exception of Moonlight Beach (Shore Segment 575) and steep eroding bluffs. Cliff failure
and landslides sporadically occur on bluffs which become eroded from winter storms and over
30 percent of the City of Encinitas coastline has some form of shoreline armoring to protect
development as well as safety among beach goers (City of Encinitas 2010). Erosion rates were
similar during both the 2006-2007 El Niño and 2007-2008 La Niña winters; however, accretion
rates were substantially higher during the 2006-2007 El Niño winter (Figure 68 and Figure 69).
During the 2006-2007 El Niño winter, high accretion rates, up to 1.95 m
3
per sq m, were seen in
shore segments 581 through 586 and were likely caused by sediment contribution from cliff
erosion (Figure 70).
Table 23 Encinitas (North) to Encinitas (South) Net Sediment Volume Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
550 - 591 98,529 -7,911 7,180 -15,576

109

Figure 68 Encinitas (North) to Encinitas (South) – Rate of sediment volume change by shore
segment during the 06-07 El Niño

Figure 69 Encinitas (North) to Encinitas (South) – Rate of sediment volume change by shore
segment during the 07-08 La Niña

-1.00
-0.50
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-1.00
-0.50
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

110

Figure 70 Encinitas (North) to Encinitas (South) - Map of rate of sediment volume change by
shore segments during the 06-07 El Niño

111

4.3.5.3. Encinitas (South) to Cardiff State Beach
Shore segments 592 through 630 span the southern extent of the City of Encinitas to
Cardiff State Beach and San Elijo Lagoon. These shore segments cover an area of 100,196 m
2

and are less developed in terms of bluff-top residential properties compared to the Encinitas
(North) region. During the 2006-2007 El Niño winter 29,848 m
3
of sediment was lost in these
shore segments, and during the 2007-2008 La Niña winter a comparable amount of sediment,
25,194 m
3
, was lost (Table 24). Shore segment 613, which lines the mouth of the San Elijo
Lagoon was one of the few segments that showed an increase in sediment during the 2006-2007
El Niño winter (Figure 71 and Figure 73). The Summer of 2007 showed a net gain of 14,374 m
3
,
however not enough sediment to recover from both the previous and following winter erosion
(Table 24).
Table 24 Encinitas (South) to Cardiff State Beach Net Sediment Volume Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
592 - 630 100,196 -29,849 14,374 -25,194

112

Figure 71 Encinitas (South) to Cardiff State Beach – Rate of sediment volume change by shore
segment during the 06-07 El Niño

Figure 72 Encinitas (South) to Cardiff State Beach – Rate of sediment volume change by shore
segment during the 07-08 La Niña

-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

113

Figure 73 Encinitas (South) to Cardiff State Beach - Map of rate of sediment volume change by
shore segments during the 06-07 El Niño

114

4.3.5.4. Cardiff State Beach to Del Mar
Shore segments 631 through 669 represent the coastal area from Cardiff State Beach to
the City of Del Mar. The shore segments north of the San Dieguito Lagoon include the relatively
narrow beaches of Solana Beach. The majority of shore segments in this area experienced high
rates of erosion during both the 2006-2007 El Niño and following 2007-2008 La Niña winters,
with slightly more sediment lost during the 2007-2008 La Niña winter (Figure 74 and Figure 75).
Eight shore segments saw some form of accretion during the 2006-2007 El Niño winter, while
only one shore segment registered accretion during the 2007-2008 La Niña winter. Overall,
25,239 m
3
of sediment was lost from the beaches in this area during the 2006-2007 El Niño. The
Summer of 2007 showed only partial recovery of sediment with a 14,583 m
3
gain (Table 25).
Sediment accretion was seen in the large shore segment lining the mouth of the San Dieguito
Lagoon, which is mechanically maintained to remain open throughout the year (Figure 76). The
smaller shore segment (656) just north of the San Dieguito Lagoon experienced a very high rate
of erosion (-2.37 m
3
per sq m).
Table 25 Cardiff State Beach to Del Mar Net Sediment Volume Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
631 - 669 73,708 -25,239 14,583 -30,449

115

Figure 74 Cardiff State Beach to Del Mar – Rate of sediment volume change by shore segment
during the 06-07 El Niño

Figure 75 Cardiff State Beach to Del Mar – Rate of sediment volume change by shore segment
during the 07-08 La Niña

-2.50
-2.00
-1.50
-1.00
-0.50
0.00
0.50
1.00
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-2.50
-2.00
-1.50
-1.00
-0.50
0.00
0.50
1.00
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

116

Figure 76 Cardiff State Beach to Del Mar - Map of rate of sediment volume change by shore
segments during the 06-07 El Niño

117

4.3.5.5. Del Mar to Los Penasquitos Marsh
Shore segments 670 through 709 cover the area from Del Mar to the Los Penasquitos
Marsh. The beaches in this area are generally wider than the neighboring shore segments to the
north in the Solana Beach (Figure 79). These shore segments saw an overall trend in erosion
during both the 2006-2007 El Niño and 2007-2008 La Niña winters, with more sediment lost
during the La Niña winter than the El Niño winter (Figure 77 and Figure 78). Shore segments
south of the Los Penasquitos Marsh mouth experienced fairly high rates of erosion during both
winter seasons, with opposite high rates of accretion during the intermediary summer season
(Table 26). This area south of the Los Penasquitos Marsh mouth was also one of the two receiver
sites in Del Mar where sand was replenished during the 2001 SANDAG project. Collectively,
sediment recovery during the Summer of 2007 was minimal compared the level of erosion
experienced during both the 2006-2007 El Niño winter and following 2007-2008 La Niña winter.
This phenomenon warrants the need for further investigation into long term sediment erosion and
accretion trends.
Table 26 Del Mar to Los Penasquitos Marsh Sediment Net Volume Change Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
670 - 709 126,799 -28,153 8,253 -38,645

118

Figure 77 Del Mar to Los Penasquitos Marsh – Rate of sediment volume change by shore
segment during the 06-07 El Niño

Figure 78 Del Mar to Los Penasquitos Marsh – Rate of sediment volume change by shore
segment during the 07-08 La Niña

-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

119

Figure 79 Del Mar to Los Penasquitos Marsh - Map of rate of sediment volume change by shore
segments during the 06-07 El Niño

120

4.3.5.6. Los Penasquitos Marsh to Torrey Pines State Reserve
Shore segments 710 to 749 cover the area of the Torrey Pines State Reserve. These shore
segments represent 201,499 m
2
of protected beaches lined by coastal bluffs that have minimal
development (Table 27 and Figure 82). During storms, small creeks and tributaries cut through
the bluffs and form canyons which drain to the ocean. This hydrological interaction with the land
can cause cliff erosion, and historically cliff failure and landslides have occurred in this area.
Erosion rates were similar during both the 2006-2007 El Niño and 2007-2008 La Niña winters;
however, during the 2006-2007 El Niño winter a large amount of sediment accreted on shore
segment 727 caused by the nearby cliffs failing and depositing over 7,000 m
3
onto the beach
(Figure 80, Figure 81, and Figure 82). Further investigation into the DEM Differencing results
clearly shows this cliff failure as well as other nearby areas experiencing cliff erosion (Figure
83). Overall sediment erosion and accretion trends show that the Torrey Pines State Reserve is a
highly dynamic area, influenced not only by large seasonal changes in offshore and onshore sand
movement but also cliff landforms and hydrology.
Table 27 Los Penasquitos Marsh to Torrey Pines State Reserve Net Sediment Volume Change
Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
710 - 749 201,499 -58,755 49,780 -80,428

121

Figure 80 Los Penasquitos Marsh to Torrey Pines State Reserve – Rate of sediment volume
change by shore segment during the 06-07 El Niño

Figure 81 Los Penasquitos Marsh to Torrey Pines State Reserve – Rate of sediment volume
change by shore segment during the 07-08 La Niña

-1.00
-0.50
0.00
0.50
1.00
1.50
2.00
2.50
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-1.00
-0.50
0.00
0.50
1.00
1.50
2.00
2.50
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

122

Figure 82 Los Penasquitos Marsh to Torrey Pines State Reserve - Map of rate of sediment
volume change by shore segments during the 06-07 El Niño

123

Figure 83 Torrey Pines State Reserve – Elevation difference raster highlighting cliff erosion

124

4.3.5.7. Torrey Pines State Reserve to La Jolla Shores Beach
Shore segments 750 through 792 represent the southernmost extent of Torrey Pines State
Reserve to the end of the study area at La Jolla Shores Beach. This region experienced
consistently high rates of erosion during the 2006-2007 El Niño winter, with the exception of
two shore segments at La Jolla Shores Beach, an area where the beach face direction drastically
turns towards the north before La Jolla Point (Figure 86 and Figure 87). During the 2006-2007 El
Niño winter 72,220 m
3
of sediment was lost from these shore segments versus 37,637 m
3
of
sediment lost during the 2007-2008 La Niña winter (Table 28). Overall the rate of sediment loss
in this area was higher than any other region in the OLC during the 2006-2007 El Niño winter. A
high amount of sediment, 48,611 m
3
, was recovered during the intermediary Summer of 2007,
however not enough sediment to make up for the previous El Niño winter erosion (Table 28). A
small data gap covering shore segments 770 to 773, just north of the Scripps Pier, was due to
very minimal if no sandy beach present (Figure 87). Overall, this region like the neighboring
Torrey Pines State Reserve to the north exhibits a strong seasonal influence of sediment erosion
and accretion.
Table 28 Torrey Pines State Reserve to La Jolla Shores Beach Net Sediment Volume Change
Summary
Shore
Segment ID Area (m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
750 - 92 153,028 -72,220 48,611 -37,637

125

Figure 84 Torrey Pines State Reserve to La Jolla Shores Beach – Rate of sediment volume
change by shore segment during the 06-07 El Niño

Figure 85 Torrey Pines State Reserve to La Jolla Shores Beach – Rate of sediment volume
change by shore segment during the 07-08 La Niña

-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
Rate of Sediment Volume Change
(m^3 per sq m)
Shore Segment ID

126

Figure 86 Torrey Pines State Reserve to La Jolla Shores - Map of rate of sediment volume
change by shore segments during the 06-07 El Niño

127

4.3.5.8. La Jolla Shores Beach South

Figure 87 La Jolla Shores Beach South - Map of rate of sediment volume change by shore
segments during the 06-07 El Niño

128

4.3.6. Overarching Results
While sediment change showed local variation in patterns of accretion and erosion,
sediment change in the Oceanside Littoral Cell showed greater overall erosion during the 2006-
2007 El Niño Winter when compared to the 2007-2008 La Niña Winter. Table 29 and Figure 85
summarize the total sediment volume change in cubic meters during the 2006-2007 El Niño
winter, 2007 summer, and 2007-2008 La Niña winter. During the 2006-2007 El Niño winter a
total of 584,711 m
3
of sediment was lost from the OLC. Figure 87 shows the average rate of
sediment volume change by region during the 2006-2007 El Niño winter. The summer,
immediately following the 2006-2007 El Niño Winter showed a significant amount of sediment
recovery, with 458,766 m
3
of sediment deposited on beaches. The following 2007-2008 La Niña
winter showed a total sediment volume loss of 386,624 m
3
. While both the El Niño and La Niña
winters showed a net loss of sediment, overall net loss of sediment was nearly twice as greater
during the El Niño winter. The net sediment change over the entire time-series (Fall 2006 to
Spring 2008) was negative 512,569 m
3
.
Table 29 Total Sediment Volume (m
3
) change in the OLC
2006-2007 El Niño
Winter (m
3
)
2007 Summer (m
3
) 2007-2008 La Niña
Winter (m
3
)
Net Sediment
Change (m
3
)
-584,711 458,766 -386,624 -512,569

Table 30 Overall Rate of Sediment Volume Change (m
3
per sq m) in the OLC
2006-2007 El Niño
Winter (m
3
/sq m)
2007 Summer
(m
3
/sq m)
2007-2008 La Niña
Winter (m
3
/sq m)
Net Sediment
Change (m
3
/sq m)
-0.19 0.1 -0.12 -0.22

129

Figure 88 Total sediment volume change (m
3
) in the OLC summarized by region
-150000
-100000
-50000
0
50000
100000
150000
200000
250000
300000
Dana Point
North
South
Trestles:SONGS
San Onofre SB:Pendelton (N)
San Onofre SB:Pendelton (Cen)
San Onofre SB:Pendelton (S)
Pendelton (S)
Pendelton (S):S. Margarita Marsh
Oceanside Harbor
Oceanside City Beach
Carlsbad (N):Agua Hedionda Lagoon
Agua Hedionda Lagoon:Carlsbad (S)
Carlsbad SB (S):Encinitas(N)
Encinitas(N):Encinitas(S)
Encinitas(S):Cardiff SB
Cardiff SB:Del Mar
Del Mar:Los Penasquitos Marsh
Los Penasquitos Marsh:Torrey Pines SR
Torrey Pines SR:La Jolla Shores Beach
San
Clemente
SD North SD Central SD South
Sediment Volume Change (m^3)
2006-2007 El Nino Winter 2007 Summer 2007-2008 La Nina Winter

130

Figure 89 Rate of sediment volume change (m
3
per sq m) in the OLC summarized by region

-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
Dana Point
North
South
Trestles:SONGS
San Onofre SB:Pendelton (N)
San Onofre SB:Pendelton (Cen)
San Onofre SB:Pendelton (S)
Pendelton (S)
Pendelton (S):S. Margarita Marsh
Oceanside Harbor
Oceanside City Beach
Carlsbad (N):Agua Hedionda Lagoon
Agua Hedionda Lagoon:Carlsbad (S)
Carlsbad SB (S):Encinitas(N)
Encinitas(N):Encinitas(S)
Encinitas(S):Cardiff SB
Cardiff SB:Del Mar
Del Mar:Los Penasquitos Marsh
Los Penasquitos Marsh:Torrey Pines SR
Torrey Pines SR:La Jolla Shores Beach
San
Clemente
SD North SD Central SD South
Rate of Sediment Volume Change (m^3 per sq m)
2006-2007 El Nino Winter 2007 Summer 2007-2008 La Nina Winter

131

Figure 90 Average rate of sediment volume change by region during the 2006-2007 El Niño
winter

132

Chapter 5 Conclusions
This study provides a method to analyze beach erosion and accretion patterns over time using
LiDAR datasets. Beach sediment changes were analyzed for the coastal beach zone in the
Oceanside Littoral Cell (OLC), which spans from Dana Point to La Jolla in Southern California.
The study time period was from the Fall of 2006 to the Spring of 2008 and included four LiDAR
datasets which encompassed the 2006-2007 El Niño and following 2007-2008 La Niña winter
events. Beach sediment changes were also analyzed for the intermediary Summer of 2007.
Overall, this study shows that sediment volume loss was higher during the 2006-2007 El
Niño winter than the following 2007-2008 La Niña winter. Partial sediment recovery was
observed during the summer following the 2006-2007 El Niño winter. Local variation in
sediment changes was high during the 2006-2007 El Niño with effects from long-shore current
sand transport visible in portions of the study area. Coastal infrastructure, including rock jetties,
harbors, and piers, affected sand movement. High rates of sediment volume change were
observed at the Santa Margarita Marsh and Agua Hedionda Lagoon mouths. Additionally,
sediment accretion from cliff failure was identified at several sites.
The beaches in Southern California are a highly dynamic system, with the winter and
summer wave climate continually displacing and depositing sand. El Niño events bring an
increase in the frequency and intensity of coastal winter storms which can cause major beach
erosion. Erosion is a serious threat to the OLC and the use of LiDAR data to analyze beach
sediment volume changes over time can inform beach managers and coastal scientists. These
results can be applied to identify coastal areas prone to erosion, evaluate the interaction of
coastal infrastructure with sand movement, and identify ideal areas for sand replenishment
projects. Using the methodologies in this study, LiDAR data can be used to calculate actual

133

sediment volume change with high resolution. Rates of sediment volume change can be
summarized for a given shore segment, allowing beach managers and coastal scientists to
visualize the spatial distribution of sediment change over time.
Time-series coastal LiDAR datasets have the ability to go beyond traditional 2-
dimensional shoreline analysis and identify 3-dimensional sediment volume shifts; however, the
process of analyzing large and complex datasets comes with challenges. Like most LiDAR
datasets, the datasets used in this study were made up of elevation point clouds containing
millions of points. Working with such large datasets is time consuming, requiring a series of
steps to edit, clean, and prepare the data for use. The LastoLas software suite provides batch
processing functionality which allows processes to be run with minimal user supervision. The
ArcMap EBK interpolation process required heavy computing power and each elevation DEM
created took at least four hours to complete. Previous failed attempts in running the ArcMap
EBK tool on the LiDAR datasets was resolved by using a computer with multiple-core
processors with high memory capability and installing the ArcMap Background Geoprocessing
(64-bit) option so that additional system resources could be used for parallel processing.
The methods and results proposed in this study have many applications to future research.
Increasing time-series periods on the order of decades and including multiple El Niño winter
events may identify long-term trends in sediment erosion and accretion. The data results from
long-term time-series can inform prediction models and incorporate future sea level rise and
coastal storm scenarios. Future research can also include the incorporation of near shore
bathymetric surveys into the time-series analysis. Concurrent bathymetric time-series data would
unveil near-shore processes and provide information on the interaction of sediment movement on
and off dry beaches as well as offshore sediment loss into deep waters and submarine canyons.

134

The methods used in this study can also evaluate sediment contribution from cliff erosion and
identify cliff failure sites. Finally, this research has the potential to identify beach restoration
sites as well as provide information to prioritize shoreline protection.

135

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Hug, C. P. Krzystek. W. Fuchs. 2004. Advanced LiDAR Processing with LasTools. Paper
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138

Appendix A
Dana Point Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
1 9,624 194 -1,343 -467
2 9,805 1,016 -1,174 -397
3 6,887 1,105 -839 -335
4 6,928 904 -1,091 -483
5 6,866 468 -953 -613
6 5,525 -3,476 -979 -3,642
7 9,472 -1,712 -3,438 -3,842
8 18,528 -6,155 -2,078 -14,965
9 4,691 -1,353 1,021 -4,349
10 4,314 -335 648 -3,851
11 4,273 -149 -378 -3,033
12 4,127 -213 1,033 -4,246
13 4,696 -382 -899 -2,569
14 4,852 -403 -38 -2,288
15 4,967 659 -114 -800
16 3,923 212 195 -154
17 4,779 688 364 -228
18 4,728 985 -650 453
19 3,207 5 -737 815
20 4,155 988 -1,053 780
21 4,466 1,779 -1,385 1,220
22 3,016 1,754 -1,194 1,310
23 4,008 1,440 -1,048 1,169
24 3,938 1,162 -756 900
25 4,300 833 -901 1,244
26 4,874 686 -1,233 943
27 5,299 500 -1,213 673
28 5,176 435 -965 251
29 4,932 184 -1,135 380
30 4,433 211 -1,135 423
31 4,695 0 -1,004 331
32 4,865 -41 -869 392
33 4,490 -187 -924 699
34 4,305 -262 -666 525
35 3,381 503 -624 247
36 2,512 800 -1,210 823
37 2,117 764 -845 681
38 2,501 75 -647 762
Total 199,655 3,682 -30,257 -31,241

139

San Clemente (North) Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
39 6,171 -1,843 192 883
40 2,390 -867 530 -434
41 2,800 -492 426 -491
42 2,614 136 479 -401
43 4,704 84 504 -1,092
44 5,288 248 -6 -83
45 5,904 205 -80 -116
46 5,516 377 -437 202
47 4,904 718 -239 177
48 1,544 88 53 25
49 1,229 -446 320 -18
50 1,290 -650 719 -611
51 1,539 -934 774 -466
52 1,744 -899 665 -491
53 2,367 -541 398 -82
54 2,262 191 -324 233
55 1,993 782 -623 222
56 1,377 802 -331 197
57 840 369 -196 221
58 740 -143 140 -48
59 3,706 -1,870 1,595 -679
60 4,740 -2,085 1,073 -731
61 3,753 -745 295 -605
62 2,356 533 -202 242
63 1,272 985 -518 345
64 985 807 -309 308
65 896 509 -90 113
66 904 205 77 160
67 1,020 193 31 257
68 746 263 -174 85
69 1,207 447 -3 -122
70 1,109 -436 957 -436
71 1,705 -419 903 -531
72 2,772 -936 1,086 -904
73 3,169 -583 317 -338
74 3,697 -387 -419 69
75 4,340 -274 -709 -114
Total 95,593 -6,608 6,874 -5,054

140

San Clemente (South) Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
76 4,450 496 -479 909
77 4,021 -349 -342 755
78 3,878 74 -354 651
79 4,186 -172 -87 934
80 4,487 99 -220 492
81 4,417 -200 -37 38
82 5,097 -1,384 721 171
83 3,128 -1,074 437 -37
84 2,648 -1,108 69 446
85 2,761 -1,165 -144 410
86 3,030 -1,132 228 214
87 3,801 -1,296 433 223
88 3,798 -1,185 230 297
89 3,110 -962 -10 378
90 3,149 -812 326 253
91 4,476 -598 -231 293
92 4,041 -457 -566 380
93 3,438 47 -162 203
94 3,015 -292 565 -210
95 2,829 -1,143 1,319 -716
96 2,519 -1,270 955 -1,498
97 2,136 -993 716 -2,154
98 2,338 -1,109 218 -1,808
99 3,017 -1,061 118 -1,487
100 2,879 -1,065 203 -1,277
101 2,487 -1,480 811 -1,162
102 2,659 -1,683 1,249 -1,066
103 3,399 -1,726 1,084 -1,768
104 3,432 -2,228 1,179 -1,454
105 3,702 -2,515 1,049 -545
106 9,655 -4,937 1,990 -625
107 9,794 -2,023 1,460 790
108 3,511 -787 1,391 -133
109 3,725 -1,374 1,198 -46
110 4,081 -1,041 -526 686
111 2,650 2,034 -683 824
112 1,961 2,488 -16 321
113 2,548 2,508 -34 284
Total 140,253 -30,875 14,058 -6,034

141

Trestles to San Onofre (SONGS) Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
114 4,088 3,222 -231 475
115 5,305 1,789 -328 409
116 4,691 1,020 -110 242
117 7,232 1,000 31 267
118 4,890 50 770 280
119 4,173 -6 1,115 -175
120 3,038 -573 1,139 -646
121 2,224 -1,600 1,555 -961
122 3,010 -1,809 1,604 -1,145
123 4,056 -1,323 1,161 -1,090
124 2,079 86 346 -172
125 3,278 437 226 -50
126 3,633 -269 338 -138
127 4,969 -203 -41 -184
128 4,240 -66 107 -185
129 3,188 -95 146 28
130 3,200 -73 -142 135
131 3,266 -487 -276 610
132 10,830 -1,827 -2,379 3,070
133 5,018 -351 -1,098 496
134 17,711 -6,274 1,731 -5,592
135 4,682 -460 -353 -848
136 3,842 901 -1,760 140
137 2,926 1,537 -1,980 544
138 3,094 1,754 -1,918 1,039
139 3,313 1,618 -1,612 1,209
140 4,111 836 -1,136 1,010
141 3,342 249 -5 -61
142 2,657 -601 771 -825
143 5,559 -1,476 1,682 -1,287
144 6,601 174 672 -361
145 6,523 912 97 542
146 6,829 692 -102 466
147 5,486 223 416 -128
148 3,558 -913 1,051 -692
149 2,244 -1,036 1,597 -1,001
150 2,367 -1,302 1,969 -934
151 2,519 -1,324 1,541 -966
Total 173,772 -5,568 6,594 -6,479

142

San Onofre State Beach to Camp Pendelton MCB (North) Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
152 1,713 -889 222 191
153 1,604 -118 553 -423
154 768 119 257 -217
155 575 2 56 -26
156 522 -27 50 -43
157 817 77 -42 -6
158 3,744 575 -1,016 -1,030
159 3,799 -464 -704 -702
160 3,332 -127 -686 -282
161 2,654 -104 143 -308
162 2,324 144 -190 464
163 2,357 -189 -393 471
164 2,493 -706 110 -307
165 2,662 -790 -437 55
166 2,612 -1,034 -233 14
167 3,489 -342 -140 -311
168 2,384 2,070 -1,267 552
169 1,330 1,191 -382 122
170 2,818 750 -215 -279
171 2,814 -166 299 -1,246
172 3,125 -1,693 1,119 -1,464
173 3,156 -520 840 -676
174 2,251 -713 537 -518
175 2,207 -923 447 -577
176 2,193 -549 -158 -224
177 1,887 -19 -906 363
178 1,732 38 -1,039 387
179 1,929 587 -932 315
180 1,985 197 -60 193
181 2,180 -219 215 -81
182 2,352 -270 71 -616
183 2,350 -271 197 -101
184 2,205 -53 54 80
185 2,283 -96 -16 -255
186 2,345 -93 311 -300
187 2,110 228 278 -305
188 1,832 573 -86 120
189 1,800 -237 356 -614
190 1,690 -1,202 611 -516
191 1,577 -945 414 -135
Total 88,000 -6,208 -1,762 -8,235

143

San Onofre State Beach/Camp Pendelton MCB (Central) Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
192 1,742 -394 -84 -144
193 1,836 -459 -288 -131
194 1,511 -841 22 -206
195 1,701 -289 -414 -225
196 1,976 -334 -384 -498
197 2,382 -887 160 -917
198 3,310 -560 -149 -590
199 3,737 -140 -702 -109
200 4,103 -255 -370 -13
201 4,149 -21 -256 -261
202 3,794 -443 141 -477
203 4,984 -619 456 -911
204 5,730 -683 86 -469
205 4,752 -315 -180 -267
206 5,415 -98 -263 -304
207 5,803 88 -390 -75
208 6,097 201 -595 276
209 6,106 203 -387 365
210 5,855 93 -42 221
211 6,209 93 83 500
212 5,887 143 65 756
213 5,672 -143 398 867
214 5,738 -507 871 509
215 5,202 -389 716 71
216 4,973 -207 457 307
217 4,127 22 2 262
218 4,376 -52 -160 207
219 4,063 -100 136 -55
220 4,257 -272 456 -308
221 3,669 -261 559 -219
222 3,295 -200 331 -238
223 2,960 -706 782 -343
224 3,289 -734 925 -262
225 3,390 -788 759 -128
226 3,622 -566 438 18
227 3,864 -477 415 214
228 3,721 -425 520 172
229 3,642 20 252 -117
230 3,916 245 416 -201
231 4,065 25 593 -29
Total 164,920 -11,032 5,375 -2,752

144

San Onofre State Beach/Camp Pendelton MCB (South) Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
232 4,199 -446 619 -145
233 4,557 -578 552 -376
234 5,556 -469 -92 -172
235 4,317 -658 -36 -288
236 4,146 -785 -87 -191
237 4,043 -557 -307 -167
238 4,129 -844 -564 105
239 4,364 -866 -324 38
240 5,109 -590 -285 55
241 5,442 -216 -717 138
242 5,314 -173 -625 -66
243 5,518 -292 -225 -420
244 5,382 -709 386 -786
245 5,514 -796 722 -924
246 5,502 -525 579 -309
247 5,070 -719 683 -312
248 4,963 -1,051 1,058 -169
249 5,248 -827 825 123
250 5,368 -781 665 177
251 5,380 -1,059 1,055 64
252 5,501 -704 918 -32
253 6,083 -656 767 -12
254 5,950 -612 758 92
255 6,152 -632 673 10
256 5,844 -698 629 -79
257 6,045 -729 557 -877
258 10,342 -1,238 668 18
259 6,433 -663 151 54
260 6,304 -373 185 -278
261 5,744 -232 171 -220
262 5,682 -326 297 -764
263 5,871 -615 825 -1,305
264 5,794 -463 514 -411
265 5,996 -160 -39 198
266 5,585 -69 -187 176
267 5,659 -81 -62 -302
268 5,511 -431 412 -413
269 8,301 -1,033 632 -15
270 8,540 -811 514 189
271 7,701 -654 349 348
272 6,208 -708 375 -125
Total 234,367 -24,829 12,989 -7,373

145

Camp Pendelton MCB (South) to Santa Margarita Marsh Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
314 9,376 -1,047 936 140
315 8,784 -1,205 1,124 448
316 8,686 -945 1,292 159
317 9,470 -1,097 1,335 166
318 9,220 -1,241 1,428 408
319 8,213 -1,407 1,562 -396
320 8,306 -2,767 5,844 -663
321 8,003 -6,948 19,640 -504
322 8,332 -4,867 28,427 -430
323 8,851 -4,341 32,168 -342
324 8,559 -5,120 33,732 -169
325 8,525 -4,578 30,764 -114
326 8,481 -3,758 29,211 -114
327 8,712 -5,473 26,605 -78
328 8,970 -7,298 13,264 -961
329 6,548 -2,634 2,892 -2,038
330 8,286 -1,995 734 -326
331 9,169 -1,970 684 -213
332 9,558 -2,156 792 -206
333 9,933 -2,272 1,037 -72
334 9,938 -2,058 1,099 -119
335 10,228 -2,659 1,834 -748
336 10,102 -2,771 1,192 -1,193
337 9,805 -2,833 968 -999
338 9,394 -2,322 1,237 -827
339 9,658 -2,477 1,317 -659
340 9,765 -2,238 1,016 -873
341 9,956 -2,261 503 -816
342 10,329 -2,303 984 -947
343 10,932 -2,846 1,004 -1,106
344 11,189 -3,953 1,719 -1,577
345 11,382 -2,330 1,492 -666
346 11,790 -2,427 1,159 -703
347 12,320 -1,848 1,047 436
348 13,058 -1,892 874 -336
349 14,414 -1,432 858 -659
350 16,071 -1,302 544 -390
351 17,412 -1,570 866 255
352 17,442 -1,814 964 1,131
353 17,613 -2,439 1,558 -87
354 17,780 -3,337 1,470 236
Total 434,560 -112,231 257,176 -15,952

146

Santa Margarita Marsh to Oceanside Harbor Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
355 17,692 3,355 6,507 336
356 17,551 -4,866 -1,157 6,191
357 17,111 -2,137 -3,893 -588
358 16,578 -1,788 702 -15,868
359 14,666 -1,576 665 -1,570
360 14,433 -1,543 621 123
361 16,364 -1,915 907 429
362 16,421 -1,979 681 777
363 16,131 -1,907 -23 1,194
364 15,298 -2,005 -298 1,362
365 14,647 -2,277 42 1,446
366 13,416 -2,310 275 1,559
367 11,950 -2,629 415 1,755
368 11,438 -2,042 1,466 1,329
369 11,248 -1,334 1,384 743
370 11,098 -711 909 1,002
371 10,374 145 895 793
372 10,170 467 936 713
373 10,177 826 593 1,044
374 10,586 1,290 -41 1,024
375 8,781 1,943 -64 1,147
376 19,867 -917 -767 436
377 18,053 435 -862 496
378 13,933 -655 -24 144
379 14,474 -428 -353 226
380 5,064 -193 -167 -11
381 8,956 -1,019 1,004 -802
382 11,934 -1,504 215 -930
383 11,845 -1,030 -402 -1,302
384 11,403 -593 -1,110 -256
385 10,139 -604 -1,033 -120
386 17,632 -940 -789 -238
387 12,431 -2,774 3,429 -3,298
388 8,924 -2,075 994 -1,088
Total 450,785 -35,290 11,657 -1,802

147

Oceanside City Beach Sediment Net Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
389 1,760 -1,777 857 -726
390 4,537 -2,028 577 -2,904
391 5,571 -1,610 -509 -822
392 5,981 -1,298 -969 785
393 6,248 -622 -1,398 563
394 6,383 300 -2,552 436
395 6,272 72 -1,891 113
396 6,419 -957 -955 -91
397 5,844 -1,122 -284 -356
398 4,738 -642 -610 -545
399 5,700 -1,404 -128 -451
400 5,304 -1,050 -894 -869
401 5,085 -1,897 -1,048 -1,316
402 4,433 -1,548 42 -586
403 3,206 -1,387 672 -790
404 2,765 -1,690 646 343
405 2,885 No data No data No data
406 2,364 No data No data No data
407 1,635 No data No data No data
408 1,588 No data No data No data
409 1,824 No data No data No data
410 1,066 No data No data No data
411 1,455 No data No data No data
412 1,868 No data No data No data
413 2,693 -2,152 -329 -163
414 2,410 -1,778 217 -340
415 3,129 -1,832 -254 -413
416 2,811 -1,840 430 -750
417 2,620 -2,010 729 -966
418 2,213 -1,869 813 -1,064
419 1,954 -2,205 1,358 -898
420 1,761 -1,961 1,501 -1,245
421 1,176 -1,050 738 -374
422 2,861 -815 1,420 -1,403
423 1,793 -1,179 676 -994
424 1,512 -769 523 -536
425 1,456 -398 197 -145
426 1,539 -435 173 -83
427 1,485 -499 285 -189
428 1,057 -195 -14 -54
429 718 -412 101 -188
Total 128,119 -21,399 8,564 -9,805

148

Carlsbad North to Carlsbad State Beach (Agua Hedionda Lagoon) Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
430 717 -261 81 -97
431 869 -93 -122 12
432 1,643 -742 -129 157
433 1,940 -1,154 -206 -58
434 1,069 -606 -33 -3
435 1,256 -872 -250 -158
436 1,490 -1,037 -559 -326
437 1,655 -1,432 8 -839
438 1,832 -1,258 292 -1,212
439 4,734 -1,770 628 -1,484
440 3,386 -1,607 1,212 -1,649
441 2,950 -1,128 748 -1,326
442 2,985 -1,507 1,033 -1,064
443 2,210 -1,586 1,240 -1,398
444 2,633 -1,848 1,384 -961
445 3,488 -2,283 1,629 -901
446 3,433 -2,290 1,441 -1,399
447 2,974 -1,756 1,104 -852
448 2,961 -1,899 1,020 -370
449 3,030 -2,145 1,167 -750
450 3,466 -2,635 1,318 -947
451 4,399 -2,144 905 -1,079
452 4,488 -2,151 1,259 -908
453 4,422 -325 711 -583
454 4,310 42 508 46
455 5,684 71 572 -1,084
456 5,695 968 -437 -135
457 4,431 1,348 95 60
458 4,764 442 54 -335
459 4,856 233 204 -214
460 4,563 1,195 1 -638
461 4,403 1,529 -235 -350
462 2,752 2,611 -281 111
463 1,360 1,575 -146 -35
464 1,308 -784 266 -51
465 2,135 -843 971 -681
466 3,019 172 -60 -332
467 3,424 872 -456 -562
468 3,871 799 -19 -1,066
469 4,068 1,144 4 -1,535
Total 124,673 -23,155 16,922 -24,996

149

Carlsbad State Beach (Agua Hedionda Lagoon) to Carlsbad State Beach (South) Net Sediment
Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
470 7,297 -1,336 2,219 -1,518
471 4,897 -42 -40 -482
472 2,601 -289 283 -954
473 1,984 -528 364 -643
474 2,042 -366 345 -524
475 2,334 -415 384 -627
476 1,515 -10 70 -189
477 1,120 -61 -172 34
478 1,227 -56 -207 63
479 633 37 -47 -5
480 631 45 -107 51
481 670 78 -185 75
482 1,230 -125 126 -189
483 951 179 -175 123
484 1,188 376 -276 -145
485 1,508 428 -307 -336
486 1,486 1,130 -375 -319
487 1,783 1,459 -425 -151
488 5,865 -1,425 -2,390 607
489 2,385 -1,180 -659 315
490 1,882 -514 -572 270
491 1,699 -411 -384 223
492 1,584 -571 46 -23
493 1,594 -528 -84 210
494 1,855 -583 -55 -73
495 2,073 -793 61 -443
496 2,092 -645 35 -437
497 2,139 -270 94 -628
498 2,051 -552 225 -177
499 2,369 -685 276 -578
500 2,629 -516 239 -652
501 2,504 -459 69 -424
502 2,426 -507 163 -687
503 2,613 -909 266 -520
504 2,111 -805 392 -584
505 2,282 -663 92 -771
506 1,956 -591 -106 -174
507 1,972 -470 -154 -125
508 2,302 -76 -52 -284
509 2,126 220 -58 -243
Total 85,606 -12,429 -1,081 -10,934

150

Carlsbad State Beach (South) to Encinitas (North) Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
510 1,824 -355 56 289
511 2,155 -1,018 -202 -84
512 2,523 -414 -367 64
513 2,356 -16 -125 -23
514 1,538 -454 32 -23
515 2,657 -866 51 -834
516 2,892 -1,496 -57 -415
517 2,505 -1,534 25 -435
518 2,364 -1,233 -247 -365
519 2,328 -1,077 -647 134
520 2,358 -450 -639 -430
521 2,254 106 -587 -261
522 2,483 -260 -916 437
523 2,897 -235 -356 -417
524 3,196 -739 165 -437
525 3,370 -1,541 332 -707
526 3,823 -1,690 124 -1,226
527 5,976 -4 -208 -884
528 7,062 2,984 -76 -1,118
529 7,659 3,280 20 -833
530 7,417 -2,651 969 -1,537
531 7,265 1,524 596 -298
532 7,836 254 849 -1,163
533 5,225 -2,406 1,124 -1,560
534 2,601 -1,521 666 -1,077
535 1,605 -1,430 257 -544
536 1,674 -1,217 395 -668
537 2,156 -831 43 -412
538 2,082 -44 -2 -379
539 1,690 395 84 -304
540 1,459 351 236 -288
541 1,252 264 403 -530
542 1,559 -142 345 -359
543 2,013 -88 161 -269
544 1,463 316 93 -154
545 1,536 -70 243 -240
546 1,560 26 84 -248
547 1,254 208 30 -207
548 1,234 55 245 -299
549 1,137 -211 320 -444
Total 118,238 -14,230 3,519 -18,548

151

Encinitas (North) to Encinitas (South) Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
550 1,619 -145 305 -582
551 1,401 -502 284 -523
552 1,789 -539 71 -295
553 975 -498 47 -225
554 2,803 -1,126 -226 -1,038
555 3,114 -480 -116 -1,051
556 2,859 -243 -178 -755
557 2,563 -903 -241 -711
558 2,362 -695 -718 -738
559 2,105 -853 -1,410 -242
560 1,727 -482 -612 -240
561 1,996 -923 -621 -464
562 2,367 -1,168 -488 -354
563 2,151 -272 -532 -114
564 2,184 -344 -651 -104
565 2,185 -322 -863 -22
566 2,614 252 -1,138 -197
567 2,823 -2 -917 -61
568 2,608 400 -352 -496
569 2,746 -45 -16 4
570 2,400 -300 278 -153
571 2,958 -665 247 -365
572 3,452 -1,220 296 -446
573 3,188 -1,399 837 -404
574 3,702 -1,806 1,305 -233
575 7,251 -1,676 772 -950
576 3,370 -2,224 1,889 -1,271
577 2,934 -1,436 1,958 -1,539
578 2,707 -1,763 2,107 -1,360
579 2,565 -745 1,837 -1,361
580 2,220 550 1,472 -922
581 1,892 1,300 1,095 -245
582 1,999 2,212 1,263 -374
583 2,052 2,255 652 265
584 1,071 2,088 -350 815
585 962 3,067 -805 163
586 848 909 251 145
587 1,962 51 464 293
588 1,669 266 64 201
589 1,085 343 -81 -20
590 1,538 531 -185 159
591 1,713 641 186 234
Total 98,529 -7,911 7,180 -15,576

152

Encinitas (South) to Cardiff State Beach Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
592 2,576 -599 1,221 -116
593 2,143 -1,116 1,094 -64
594 1,818 -684 738 96
595 1,388 3 112 248
596 1,165 134 -54 156
597 1,204 120 167 98
598 1,798 71 142 14
599 1,666 20 167 -175
600 2,327 -952 538 -184
601 2,526 -1,415 248 -91
602 2,386 -1,525 229 -31
603 1,922 -1,610 756 -520
604 2,085 -1,060 82 -377
605 2,534 -629 -60 -60
606 2,144 -448 51 -200
607 2,129 -396 289 -286
608 2,132 -837 81 -265
609 2,408 -970 142 -314
610 2,091 -1,265 688 -902
611 1,985 -1,263 1,107 -1,337
612 1,880 -574 637 -1,023
613 4,978 1,995 -1,562 -1,148
614 4,525 -422 -264 -830
615 3,513 -972 237 -2,612
616 2,810 -1,726 -7 -1,237
617 3,668 -1,550 -542 -477
618 3,229 -1,245 -163 -633
619 3,281 -1,276 269 -831
620 3,156 -1,489 869 -1,797
621 3,033 -1,730 1,259 -1,691
622 2,638 -1,358 856 -963
623 2,395 -1,253 964 -2,125
624 2,152 -970 789 -1,454
625 2,852 -525 835 -889
626 5,247 -151 113 -1,092
627 4,060 -1,660 1,293 -538
628 2,296 539 -68 -355
629 2,478 -689 694 -692
630 1,578 -372 427 -497
Total 100,196 -29,849 14,374 -25,194

153

Cardiff State Beach to Del Mar Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
631 1,842 527 130 -668
632 528 384 -79 -62
633 868 -4 380 -109
634 220 144 -13 -10
635 681 -878 380 -20
636 724 -542 80 125
637 440 -47 -16 -231
638 492 180 -21 -145
639 328 -142 34 -44
640 2,101 -664 -41 -404
641 1,571 -398 -103 -459
642 602 -378 -69 -22
643 802 -505 244 -239
644 829 -250 -321 -199
645 1,268 -647 354 -1,054
646 1,651 -784 810 -1,277
647 1,682 -197 601 -789
648 2,179 -304 404 -608
649 2,308 -364 227 -464
650 1,515 347 -109 -157
651 1,800 -31 217 -628
652 1,074 -297 323 -351
653 1,136 -495 534 -419
654 558 16 -25 -190
655 504 -186 19 -151
656 1,436 -3,399 -207 -45
657 14,431 183 -351 -454
658 1,796 -1,140 438 -774
659 1,392 -1,093 636 -1,245
660 1,400 -1,182 1,003 -1,771
661 1,455 -1,248 1,091 -1,444
662 1,500 -1,468 1,207 -1,143
663 2,711 -1,787 804 -2,135
664 3,436 -1,945 690 -2,786
665 3,058 -1,657 988 -3,209
666 3,472 -1,606 1,266 -1,858
667 3,569 -1,463 957 -1,947
668 2,826 -1,115 1,086 -1,861
669 3,523 -804 1,035 -1,202
Total 73,708 -25,239 14,583 -30,449

154

Del Mar to Los Penasquitos Marsh Sediment Net Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
670 3,745 -732 1,265 -1,331
671 3,875 -1,014 1,444 -1,722
672 3,158 -487 1,209 -1,322
673 2,841 143 1,143 -1,737
674 3,254 186 507 -489
675 2,829 252 446 -402
676 1,992 336 396 -402
677 1,581 283 456 -359
678 1,661 404 122 -232
679 1,319 255 76 24
680 1,808 358 75 304
681 1,887 -126 168 20
682 1,637 -655 393 -436
683 1,599 -213 -155 -45
684 1,480 -338 145 -209
685 1,968 4 -454 209
686 2,510 185 -851 250
687 3,168 -162 -1,490 1,042
688 2,748 -1,193 -1,169 501
689 2,979 -1,318 -464 -629
690 3,372 -1,298 -616 -662
691 3,927 -1,258 -770 -1,143
692 3,747 -1,279 149 -1,228
693 4,518 -838 362 -2,141
694 5,102 -175 -252 -2,263
695 4,367 -1,357 500 -2,454
696 4,497 -853 197 -2,153
697 4,591 -641 248 -2,131
698 5,404 -629 -130 -2,981
699 5,739 -1,177 -266 -2,316
700 4,785 -1,224 -1,137 85
701 4,549 -1,413 -605 19
702 4,666 -302 -725 787
703 1,858 -321 -208 372
704 2,663 -1,933 1,263 -1,816
705 3,647 -1,997 1,044 -2,978
706 3,237 -2,156 1,813 -2,843
707 2,542 -1,999 1,640 -2,162
708 2,777 -1,831 1,485 -2,012
709 2,772 -1,640 999 -1,660
Total 126,799 -28,153 8,253 -38,645

155

Los Penasquitos Marsh to Torrey Pines State Reserve Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
710 7,283 -4,780 3,738 -6,028
711 3,161 -2,060 1,548 -2,389
712 3,035 -1,691 1,168 -1,789
713 2,888 -1,607 1,417 -1,508
714 2,964 -1,215 1,470 -2,029
715 3,330 -560 1,261 -2,425
716 3,281 -626 1,438 -2,750
717 2,716 -797 803 -1,304
718 2,289 -16 314 -1,164
719 2,551 -196 477 -1,034
720 1,379 -371 414 -508
721 1,380 -104 221 -213
722 2,235 -154 9 -186
723 2,401 -168 14 -350
724 1,937 -152 262 -18
725 1,967 46 -524 710
726 2,160 103 -453 569
727 2,959 7,194 -46 319
728 2,648 -1,741 1,180 -75
729 2,948 -1,723 398 33
730 3,830 -2,228 370 -67
731 3,769 -2,192 392 -149
732 3,025 -1,897 98 193
733 2,678 -1,370 -204 128
734 5,530 -2,090 417 -1,351
735 5,655 -1,841 847 -1,882
736 14,094 -3,274 1,039 -6,089
737 9,926 -2,051 846 -4,061
738 9,849 -1,842 897 -3,935
739 9,741 -2,108 1,781 -3,893
740 8,785 -2,349 2,334 -3,866
741 9,316 -2,426 2,658 -3,674
742 8,874 -2,539 2,833 -3,646
743 8,516 -2,618 2,828 -3,538
744 8,536 -3,049 2,602 -3,861
745 7,961 -2,902 2,836 -3,344
746 7,539 -2,954 3,102 -3,720
747 6,152 -2,702 3,111 -4,251
748 5,731 -2,947 2,997 -3,866
749 6,480 -2,758 2,887 -3,417
Total 201,499 -58,755 49,780 -80,428

156

Torrey Pines State Reserve to La Jolla Shores Beach Net Sediment Volume Change
Shore
Segment ID
Area
(m
2
)
Sediment Volume Change (m
3
)
06-07 El Niño winter Summer 07 07-08 La Niña winter
750 6,499 -2,961 2,784 -2,873
751 6,103 -3,201 2,592 -2,369
752 6,765 -3,439 2,660 -2,614
753 6,557 -3,664 2,796 -2,987
754 6,757 -3,707 2,586 -2,763
755 6,103 -3,277 2,446 -2,295
756 5,014 -2,946 2,105 -2,256
757 4,922 -3,699 1,526 -2,511
758 6,553 -4,679 2,437 -2,646
759 4,330 -3,329 1,813 -2,399
760 4,446 -3,347 2,531 -2,069
761 3,766 -2,779 2,025 -1,174
762 2,906 -2,253 1,439 -345
763 2,526 -1,722 1,289 6
764 2,728 -1,805 1,356 -809
765 2,694 -1,204 928 -740
766 2,618 -2,093 891 460
767 2,533 -1,907 670 462
768 2,281 -1,749 569 519
769 1,496 -856 108 449
770 3,802 -496 -740 572
771 1,272 119 -288 128
772 1,344 879 -886 521
773 1,287 7,994 -2,145 808
774 979 -504 -79 204
775 2,538 -1,853 785 -584
776 2,538 -1,730 687 -605
777 2,952 -1,933 182 -252
778 3,472 -2,011 300 -340
779 2,638 -1,811 1,213 -945
780 2,487 -1,909 1,406 -939
781 2,126 -1,748 1,411 -774
782 2,259 -1,436 1,262 -928
783 7,430 -4,025 2,981 -3,426
784 6,184 -3,114 1,677 -524
785 3,941 -1,774 851 168
786 3,267 -1,467 796 93
787 3,113 -1,348 812 -207
788 2,439 -865 544 -303
789 1,937 -776 618 -564
790 2,237 -906 691 -712
791 2,479 2,319 686 -118
792 2,710 792 296 44
Total 153,028 -72,220 48,611 -37,637

Abstract (if available)

Abstract Light Detection and Ranging (LiDAR) technology combined with high-resolution differential Global Positioning Systems (dGPS) provide the ability to measure coastal elevation with high precision. This study investigates the use of LiDAR data and GIS to conduct time-series analyses of coastal sediment volume shifts during the 2006-2007 El Niño winter, Summer of 2007 and following 2007-2008 La Niña winter in the Oceanside Littoral Cell (OLC). The OLC, located in Southern California, spans from Dana Point to La Jolla and includes over 84 km of coastline. The ability to quantify sediment volume changes contributes to the scientific understanding of the role El Niño storms play in the OLC sand budget. This study provides a method to analyze LiDAR data to evaluate coastal geomorphologic changes over time. Additionally, identifying specific areas of coastal beach erosion associated with historical El Niño events can aid beach managers, planners, and scientists in protecting the valuable coastline. LiDAR datasets were prepared and formatted which included ground classifying millions of elevation points. Formatted datasets were inputted into an Empirical Bayesian Kriging (EBK) model, creating high-resolution, 1-meter grid cell, Digital Elevation Models (DEMs). The EBK model also incorporated uncertainty into the workflow by producing prediction error surfaces. LiDAR-derived DEMs were used to calculate sediment volume changes through a technique called DEM differencing. Results were visualized through a series of maps and tables. Overall results show that there was a higher rate of beach sediment erosion during the 2006-2007 El Niño winter than the 2007-2008 La Niña winter. Sediment accretion was evident during the intermediary Summer of 2007. Future applications of this study include incorporating bathymetric datasets to understand near-shore sediment transport, evaluating sediment contribution through cliff erosion, and conducting decadal scale studies to evaluate long-term trends with sea level rise scenarios.

Linked assets

University of Southern California Dissertations and Theses

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Asset Metadata

Creator Grubbs, Melodie (author)

Core Title Beach morphodynamic change detection using LiDAR during El Niño periods in Southern California

School College of Letters, Arts and Sciences

Degree Master of Science

Degree Program Geographic Information Science and Technology

Publication Date 02/10/2017

Defense Date 01/13/2017

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag Beach erosion,El Niño,LiDAR,OAI-PMH Harvest,Oceanside Littoral Cell,remote sensing,sand budget,sediment transport

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Kemp, Karen (committee chair), Lee, Su Jin (committee member), Swift, Jennifer (committee member)

Creator Email melodie.grubbs@gmail.com,mgrubbs@usc.edu

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c40-333587

Unique identifier UC11255941

Identifier etd-GrubbsMelo-5036.pdf (filename),usctheses-c40-333587 (legacy record id)

Legacy Identifier etd-GrubbsMelo-5036.pdf

Dmrecord 333587

Document Type Thesis

Rights Grubbs, Melodie

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the a...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus MC 2810, 3434 South Grand Avenue, 2nd Floor, Los Angeles, California 90089-2810, USA