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Feasibility of using a lined portion of the Los Angeles River for artificial recharge
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Feasibility of using a lined portion of the Los Angeles River for artificial recharge
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1
Feasibility of Using a Lined Portion of the Los Angeles River
for Artificial Recharge
by
Maryam Ghadiri
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(CIVIL ENGINEERING)
August 2015
Copyright 2015 Maryam Ghadiri
2
Acknowledgment
I would like to express the deepest appreciation to my Ph.D. Advisor, Professor Jiin-Jen
Lee, whose perpetual encouragement and advice motivated me to do this research during my
PhD. Without his insightful guidance and persistent help, this dissertation would not have been
accomplished. It was a true honor for me to have the opportunity to work under his supervision.
To me, he is not just an amazing advisor, but also an exceptionally kindhearted and caring role
model.
I would like to thank my committee members, Professor L. Carter Wellford, Professor
James E. Moore II, Professor Dennis Williams, and Professor Felipe de Barros for their
invaluable feedback, advice and support. My special thanks go to Professor Dennis Williams
(President of GEOSCIENCE Support Services, Inc.) who introduced me to a number of
outstanding engineers and researchers in his company and greatly helped the progress of research
work. I also would like to show my gratitude to Dr. Johnson Yeh (GEOSCIENCE Support
Services, Inc.) who generously provided his valuable insight and technical assistance on
numerous occasions during my Ph.D. study. Without his help this dissertation could not have
been accomplished.
I would also like to thank Dr. Iraj Nasseri (Chief Hydrologist, Los Angeles County) for
his invaluable time, advice and support and for providing the necessary data for the study area. I
have been always so grateful to have his help and support besides me. The assistance of many
individuals in different agencies in Los Angeles area was critical to the data collection.
3
I am grateful to Arthur Gotingco (County of Los Angeles Department of Public works),
Ted Johnson (Chief Hydrologist, Water Replenishment of Southern California), Miguel Osorio
(County of Los Angeles Department of Public works), and Diane Smith (Principal at
HydroSmith, PC) for facilitating access to the data that I needed during my dissertation, thereby,
expediting the completion of my dissertation.
Next, I turn to my family, first and the foremost, my dear husband, Hadi Meidani, who
selflessly and consistently helped me throughout my dissertation by giving me his infinite love,
support and more importantly hope. Hadi, I am indebted to you. During the last four years and a
half, there was so many times that I had no idea how to resume and remain hopeful and you
demonstrated to me that there is no problem without an answer in this world and I just needed to
be patient and persistent in my work and research. I am so grateful to have you standing beside
me. I also want to thank my little precious son, Arman Meidani, who has been very patient with
me, too, since he was born. I am also very much thankful to my parents, Shahin Monfared and
Modjtaba Ghadiri, for all the sacrifices that they have gladly made and all the pains that they
have taken to see that I always get the best.
Lastly, I want to dedicate this dissertation to the children who are suffering from water-
related diseases, due to lack of access to clean drinking water, which is the birthright of every
human being.
4
Contents
Acknowledgment ............................................................................................................................ 2
Abstract ......................................................................................................................................... 12
Chapter 1 ....................................................................................................................................... 14
Introduction ............................................................................................................................... 14
1.1. Conjunctive Use of Surface and Ground Water ......................................................... 16
1.2. Groundwater-Surface Water Interaction ........................................................................ 18
1.4. Research Objectives and Organization of this Dissertation ....................................... 18
Chapter 2 ....................................................................................................................................... 21
Technical Background............................................................................................................... 21
2.1. Governing Equations for Groundwater-Surface Water Interaction ............................ 21
2.2. Artificial Recharge .................................................................................................... 26
Chapter 3 ....................................................................................................................................... 30
Study Area ................................................................................................................................. 30
3.1. Introduction ............................................................................................................... 30
3.2. Description of Study Area .......................................................................................... 30
3.3. Aquifer Boundaries in the Model ............................................................................... 38
Chapter 4 ....................................................................................................................................... 44
Modeling Interaction between Surface Water and Groundwater .............................................. 44
4.1. Numerical Model ........................................................................................................ 44
5
4.2. Boundary Conditions .................................................................................................. 45
4.2.1. Recharge ...................................................................................................................... 48
4.3. Aquifer Parameters ..................................................................................................... 48
4.4. Aquifer Layer Elevations ............................................................................................ 51
4.5. Initial Water Level Elevations .................................................................................... 52
Chapter 5 ....................................................................................................................................... 64
Pumping Plan and Economic Analysis ..................................................................................... 64
5.1. Background ............................................................................................................... 64
5.2. Formulation of the Optimized Pumping Plan ............................................................ 66
5.3. The Optimization Problem ........................................................................................ 75
5.4. Cost-Benefit Analysis ................................................................................................ 84
5.5. Summary of Costs and Benefits ................................................................................. 92
Chapter 6 ....................................................................................................................................... 97
Summary, Findings and Recommendations .............................................................................. 97
6.1. Summary ....................................................................................................................... 97
6.2. Findings ...................................................................................................................... 98
6.3. Recommendations ...................................................................................................... 99
Bibliography ............................................................................................................................... 101
Abbreviations and Definitions ................................................................................................ 108
6
List of Figures
Figure 1. Surface water-groundwater interaction in gaining reach (taken from [15], [16]-
not to scale) .....................................................................................................................22
Figure 2. Surface water-groundwater interaction in losing reach (taken from [15]-not to
scale) ...............................................................................................................................22
Figure 3. Surface water-groundwater in losing-disconncted reach (taken from [15],-not to
scale) ...............................................................................................................................22
Figure 4. Henry Darcy’s experiment to model the flow rate in porous media [18] .......................23
Figure 5. Infiltration system and groundwater mound shape above a confined layer (taken
from [9]) ..........................................................................................................................28
Figure 6. Recharge mechanism and groundwater mound formation (image taken from [9]) .......28
Figure 7. Geology map of LA County [26] ...................................................................................36
Figure 8. Boundaries of Gaspur aquifer and LA River inside study area ......................................39
Figure 9. Boundaries of Exposition aquifer and LA River inside study area ................................40
Figure 10. Line location of geologic sections (modified from [33]) .............................................41
Figure 11. Aquifer types in geologic section A-A (modified from ‘Plate 6A’ [33] ) ....................42
Figure 12. Aquifer types in geologic section B-B (modified from ‘Plate 6E’ [33] ) .....................42
7
Figure 13. Gaspur aquifer boundary (modified from ‘Plate 26A’ [33]) ........................................46
Figure 14. Exposition aquifer boundary (modified from ‘Plate 26B’ [33]) ..................................46
Figure 15. Gardena and Gage aquifer boundary (modified from ‘Plate 26C’ [33]) ......................47
Figure 16. Hollydale aquifer boundary (modified from ‘Plate 26D’ [33]) ....................................47
Figure 17. Transmissivity Contours in ft^2pd/ft for the Gaspur Aquifer (modified from
‘Plate 26A’ [33]) .............................................................................................................49
Figure 18. Transmissivity Contours in ft^2pd/ft for the Exposition Aquifer (modified from
‘Plate 26B’ [33]) .............................................................................................................50
Figure 19. Transmissivity Contours in ft^2pd/ft for the Gardena/Gage Aquifer (modified
from ‘Plate 26C’ [33]) ....................................................................................................50
Figure 20. Transmissivity Contours in ft^2pd/ft for the Hollydale Aquifer (modified from
‘Plate 26D’ [33]) .............................................................................................................51
Figure 21. Water level contour lines for Gaspur aquifer (modified from ‘plate 26A’ [33]) .........52
Figure 22. Water level contour lines for Exposition aquifer (modified from ‘plate 26B’
[33]).................................................................................................................................53
Figure 23. Water level contour lines for Gardena/Gage aquifer (modified from ‘plate 26C’
[33]).................................................................................................................................54
Figure 24. Water level contour lines for Hollydale aquifer (modified from ‘plate 26D’
[33]).................................................................................................................................55
Figure 25. Locations of recharge in the numerical model-gray cells are 'no flow zones'-
light blue cells are 'recharge' zones .................................................................................56
8
Figure 26. Change in water elevation, ft in the Gaspur Aquifer after 10 years of recharging
for Scenario one (open channel) - purple cells are 'dry' zones- blue cells are
'initial input heads' cells ..................................................................................................58
Figure 27. Change in water elevation, ft in the Exposition aquifer after 10 years of
recharging for Scenario one (open channel) - purple cells are 'dry’ zones- blue
cells are 'initial input heads' zones ..................................................................................59
Figure 28. Change in water elevation, ft in the Gardena/Gage aquifer after 10 years of
recharging for Scenario one (open channel)- purple cells are 'dry' zones- blue
cells are 'initial input heads' cells ....................................................................................60
Figure 29. Change in water elevation, ft in the Hollydale aquifer after 10 years of
recharging for Scenario one (open channel)- purple cells are 'dry' zones- blue
cells are 'initial input heads' cells ....................................................................................61
Figure 30. Pumping well locations in the area of interest- greay cells are 'no flow' zones-
blue cells represents 'initial input head'...........................................................................69
Figure 31. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 1 ............70
Figure 32. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 2 ............70
Figure 33. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 3 ............71
Figure 34. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 4 ............71
Figure 35. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 5 ............72
Figure 36. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 6 ............72
Figure 37. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 7 ............73
9
Figure 38. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 8 ............73
Figure 39. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 9 ............74
Figure 40. Schematic of the drawdown at a pump location shown with the terms used in
the optimization ..............................................................................................................76
Figure 41. Groundwater level, ft in the Gaspur aquifer after opening the bottom of the
channel after 10 years- purple cells are 'dry' zones- blue cells are 'initial input
heads' ...............................................................................................................................78
Figure 42. Groundwater level, ft, in the Exposition aquifer after opening the bottom of the
channel after 10 years- purple cells are 'dry' zones- blue cells are 'initial input
heads' ...............................................................................................................................79
Figure 43. Groundwater level, ft in the Gardena/Gage aquifer after opening the bottom of
the channel after 10 years- purple cells are 'dry' zones- blue cells are 'initial input
heads' ...............................................................................................................................80
Figure 44. Groundwater level, ft in the Hollydale aquifer after opening the bottom of the
channel after 10 year- purple cells are 'dry' zones- blue cells are 'initial input
heads' cells ......................................................................................................................81
Figure 45. Different parts of a typical portable well (picture from [44]) ......................................85
Figure 46. 10-year cash flow diagram including total annual benefits and costs and the
initial costs for the optimal pumping plan ......................................................................95
10
List of Tables
Table 1. Summary of Hydrologic parameters of Central Basin .....................................................32
Table 2. Channel type categories for Los Angeles River [1] .........................................................33
Table 3. Daily flow statistics for the whole flow record [1] ..........................................................34
Table 4. Daily flow statistics for water years 2003-2008 [1] ........................................................34
Table 5. Daily average flow depth for five water years at five gage sites [1] ...............................35
Table 6. Principal aquifer/aquiclude in Central Basin region ........................................................38
Table 7. Change in storage open channel and closed channel condition after 10 yrs of
recharge for scenario one ................................................................................................62
Table 8. Stored volume of water in ten years ................................................................................62
Table 9. Walton’s well loss coefficients .......................................................................................77
Table 10. Calculated amount of optimal pumping rates in all wells through ten years
(scenario 1-infiltratin rate=3 ft/d) ...................................................................................82
Table 11. Calculated amount of optimal pumping rates in all wells through ten years
(scenario 2-infiltration rate=5 ft/d) .................................................................................82
Table 12. Calculated amount of optimal pumping rates in all wells through ten years
(scenario 3-infiltration rate=1.5 ft/d) ..............................................................................83
Table 13. All the associated costs with pumping provided by National Pump Company
and Bakersfield Well and Pump Company .....................................................................87
Table 14. Pump data for three types of pumps ..............................................................................88
11
Table 15. Present Worth of Net Benefit (PWNB) Calculation for all wells in 10 years with
infiltration rate=3 ft/d ......................................................................................................94
Table 16. Present Worth of Net Benefit (PWNB) Calculation for all wells in 10 years with
infiltration rate=5 ft/d ......................................................................................................94
Table 17. Present Worth of Net Benefit (PWNB) Calculation for all wells in 10 years with
infiltration rate=1.5 ft/d ...................................................................................................94
Table 18. Comparison of the amount of present Worth of Net Benefit in three different
scenarios ..........................................................................................................................96
12
Abstract
This dissertation investigates the feasibility of using artificial recharge derived from
surface water in a portion of the Los Angeles River north of the city of Los Angeles in Southern
California. Currently, the river channel in this area is concrete lined with no percolation
capability. The purpose of this study is to determine the technical and economic feasibility of
removing a portion of the lined channel to allow infiltration into aquifers of the Central Basin of
Los Angeles County (specifically, the forebay area). Water artificially recharged through a
breach in the lined channel will be banked for later use in dry seasons or when otherwise needed
to supplement water supply. The study includes removing a portion of the lined channel by
removing a portion of the concrete pavement and estimating the amount of artificial recharge that
could occur under various infiltration rates for different soils. In addition, the net benefit of
replenishing groundwater basin over a ten year study period will be evaluated. If the study period
is chosen too short, the project may not be economically feasible. Also, if the study period is
chosen too long, then the uncertainty in the parameters that were used for this study will be large.
This study is presented in stages with the first stage estimating the amount of surface water that
could be recharged into the aquifers using a distributed parameter ground water flow model. The
ground water model simulates the interaction between surface water and ground water and
quantifies the area and amounts of artificial recharge which could be achieved. As the project is
directly dependent on the amount of artificial recharge which could occur through the bottom
channel, streambed conductance (a model parameter incorporating stream width and
permeability), and sensitivity of this parameter to total net project benefits was evaluated using
13
the model. The second stage would be an economic feasibility of proposed alternatives
developed by enumerating costs associated with the optimal execution of the project as well as
potential benefits. In conjunction with this, an optimization pumping plan was formalized.
Specifically, well discharge rates were optimized in order to achieve maximum ground water
storage within the relevant geohydrological and land use constraints. Based on the optimal
pumping rates, pumping costs and value of extracted water was estimated which together, along
with construction costs, were analyzed in a comprehensive cost-benefit analysis. Three different
recharge scenarios were investigated as to potential variability. Subsequently, detail calculation
of upfront and annual costs and annual benefits for the optimal pumping plan, based on which
the total net benefit of the project, in present worth value, is calculated for a 10 year period for
three different recharge scenarios. Based on calculated net benefits, it was concluded that this
project is economically feasible and can be used as a conjunctive use measure for central basin
with unconfined aquifers through which the groundwater can be replenished easily.
14
Chapter 1
Introduction
Water is a renewable resource, albeit a limited one. Approximately, 96.5% of the water
on earth is in the oceans and only approximately 2.5% of the whole water resource is fresh water.
Among the sources of fresh water, approximately 68.6% are glaciers and ice caps, 30% is
groundwater and approximately 1.3% is surface water [1]. Clean drinking water is not accessible
to a large population on the planet. Based on the statistics presented by the Joint Monitoring
Programme for Water Supply and Sanitation, approximately 1.1 billion people lack access to
clean drinking water and approximately 2.6 billion people lack access to the most basic
sanitation facilities [2]. That is why every day thousands of people, mostly children and elderly,
die from water diseases while having access to clean water is taken for granted in the developed
countries Population growth, coupled with industrialization and urbanization, makes the water
crisis increasingly even more crucial all around the world. The new census data in the United
States revealed that population in cities grew 1.1% from 2010 to 2011 while the population
15
growth rate in suburbs was approximately 0.9% [3]. For example, in 2011 population growth in
Los Angeles has been doubled when comparing the average annual rate of the past decade [3].
Among the various sources of water, only one third of the earth’s fresh water source is
capable of being potable and from that groundwater supplies has a significant role in providing a
desirable amount of fresh water. Therefore, prudent planning and policy making are of great
importance to optimize the use of groundwater resources. This is particularly challenging in
arid/semi-arid regions that are characterized by water usage and demand. In these regions, due
to high temperatures, low precipitation and high evaporation rate, subsurface storage for banking
surface water seems a rational and efficient solution to overcome the water crisis; hence the
motivation for artificial recharge from surface streams.
This dissertation investigates the feasibility of artificial recharge in a portion of Los
Angeles County in Southern California as a representative semiarid area that has been highly
dependent on groundwater resources to meet water demand. Up until 1913, the Los Angeles
River’s main tributaries and groundwater supplies seemed sufficient for the city’s water demand.
Today, however, in order to respond to the increased population demand, other water resources
are being utilized and conjunctive use of surface and ground water has and is playing an
important part of the overall ground water basin management in most of Southern California. In
order to bring in water for direct as well as conjunctive use, a number of aqueducts have been
constructed. For example, a portion of the City of Los Angeles’ water supply comes from the
aqueducts originating in the Owens Valley and Mono Basin as well as other reservoirs located on
the eastern slopes of the Sierra Nevada. Water is also imported from the Colorado River and
Northern California via the State Water Project and contribute to the city’s water demand. The
urgency of maximizing use of all water supplies became evident in January 2014 when officials
16
announced that due to the severe drought in the State of California during the past three years,
the State Water Project may be unable to make any deliveries for the first time ever, except to
sustain public health and safety [4]. According to U.S. Drought Monitor, approximately 80% of
the state is under extreme drought condition and nearly 55% of the state is in the throes of an
exceptional drought [5]. Nonetheless, most water districts have groundwater and local storage
resources to diminish the stark effects of the severe drought [4]. Groundwater has always been
considered as a reliable resource to supply a portion of Californians’ demand. In normal years,
nearly 30% of California’s annual water demand is collected from groundwater. This amount
may even rise to approximately 60% of California’s water supply in drought years [6], which
emphasizes the role of the groundwater and the storage of surface water for societal well-being.
1.1. Conjunctive Use of Surface and Ground Water
Due to the growing population, the need for supplementary storage in times of water
surplus is crucial [7, 8, 9]. In view of the fact that the idea of building surface water storages may
raise economical and environmental issues, underground storage through artificial recharge of
water is considered to be a practical alternative [8, 9]. Therefore, in order to augment
groundwater resources for short or long term period, the recharge of groundwater was started in
early nineteenth century in Europe [10]. Conjunctive use is the practice of replenishing surface
water into groundwater basins and withdrawing the stored water in dry seasons or when there is a
necessity. The whole concept is to augment the yield of both groundwater and surface water
resources by optimizing the usage of these resources through a well-organized water
management system [11]. Conjunctive use is of great significance in California due to fluctuation
in hydrologic conditions precipitated by periods of floods and droughts [11]. According to the
report published by the Association of Groundwater Agencies in 2000, the total storage of water
17
in the State’s aquifers is approximately 850 million acre-ft which is roughly 20 times more than
the potential water storage behind all California’s dams [11]. However, not all of this amount
could be consumed due to the possibility of land subsidence, salt water intrusion that may take
place because of over pumping, water quality issues, high pumping cost, etc. [11]. Therefore, in
order to enhance water supply reliability and instead of merely depending on groundwater
supplies, storing the excess surface water in wet seasons and using it in dry seasons seems to be a
viable solution.
Groundwater basins in Coastal Plain of Los Angeles County, according to the water
replenishment district report, are divided into two regions: Central and West Coast Basins. In
1961, California Department of Water Resources divided the Central Basin into four areas: Los
Angeles Forebay, Montebello Forebay, Whittier area and pressure area [12]. Among these
basins, the first two Forebay areas are unconfined aquifers which are able to recharge water from
surface and replenish the basins, and Whittier and pressure areas are confined aquifers that are
unable to receive water from surface and water cannot penetrate into deeper layers of the
aquifers [12]. The Central Basin covers approximately 270 square miles [12]. West Coast Basin
aquifers are mainly confined aquifers which receives their recharge from nearby basins and also
from seawater intrusion from the Pacific Ocean [12]. The whole area of west coast basin covers
approximately 140 square miles [12].
To scientifically investigate the viability of augmenting this specific source of our water
supply (conjunctive use), we need the technical understanding of the interaction between surface
water and groundwater.
18
1.2. Groundwater-Surface Water Interaction
In general, groundwater (GW) and surface water (SW) are two associated constituents
with a complex interaction system. The relationship between GW-SW systems has seized the
attention of researchers since 1960 due to their concerns approximately “increase in the rate of
supply of organic matter in an ecosystem” [13] and acid rains [14]. Recently, other issues such as
interaction between lakes, wetlands and channels with groundwater have been subjects of
extensive research, as well [14]. The GW-SW interaction happens when the surface water
recharges the groundwater by infiltration through an unsaturated zone or when groundwater
recharges surface water through a saturated zone [14]. Saturated zone is the zone in which all of
the voids in soil are filled with water. The unsaturated zone, on the other hand, is the zone which
has both water and air among its voids. Thus, in order for the water to penetrate into the soil, it
has to go through the unsaturated zone first until it approaches the water table. Water table is the
upper surface of the saturated area with highly variable depths [15]. This upper surface can be
either very close to the land surface or hundreds or thousands of feet below the ground level [15].
The movement of groundwater depends on many factors such as topography, geology of the
area, distribution of hydraulic conductivity in different layers and also the climate conditions
[14]. A comprehensive discussion of groundwater movement is presented in the Chapter 2.
1.4. Research Objectives and Organization of this Dissertation
The objective of this research is to investigate the feasibility of the artificial recharge of
water from the Los Angeles River (LAR) into the ground for later use in dry seasons. To
implement this in practice would include making openings in the pavement of the LAR channel.
The removal of the channel’s pavement has been proposed in the past by park advocates and
environmental activists who believe in reinstating the wildlife and natural vegetation [16].
19
However, the feasibility and consequences of this proposal haven’t been studied systematically.
In this research, we aim to determine the potential net benefit of replenishing groundwater basin
by removing a section of LA River low flow channel.
First, in order to estimate the amount of surface water that can be recharged into the
ground, we need to create a numerical model of the interaction between the surface water and the
ground water in an idea area given the topology of the region and the municipal limitations.
Second, in order to investigate the economic feasibility of the proposed schemes, we need to
enumerate the costs associated with the execution of the project and the potential benefits that
can be earned from it.
The first phase (Chapters 3 and 4) of the proposed research concerns the simulation of the
interaction between surface water and ground water, based on which the storage can be
quantitatively estimated. These simulations are carried out given the actual site properties and
LA river water stream data and under three different recharge rates. To this end, the geology of
the region of interest is extracted. Then, the commercial GIS software ArcGIS was used to
digitize the LA county maps for different aquifer boundaries, groundwater elevation in aquifers
and the transmissivity data for each aquifer. Subsequently, all of these data as well as the site-
specific details are exploited in the finite difference model for the interaction behavior. Using
this model, one can then analyze the effects of recharge on water levels and calculate the
potential amount of water stored in the aquifers.
The second phase (Chapter 5) will concern the economic analysis of this specific
artificial recharge proposal. We will formalize an optimization problem for the pumping plan,
where the pumping rates are optimized to lead to maximum water storage given the relevant
constraints. Based on the optimal pumping rates, pumping costs and also the value of extracted
20
water is obtained which together with other construction costs are studied in a comprehensive
cost-benefit analysis. We consider three distinct scenarios to investigate the potential variability
in an important model parameter. Specifically, the streambed conductivity at the interface of
stream water and the ground is considered to take two other smaller and larger values. For these
two additional scenarios, we will repeat the pumping plan optimization and the associated cost-
benefit study. This will enrich the feasibility study by assessing the potential impact that this
parameter could impose on the total net benefit from the project.
21
Chapter 2
Technical Background
2.1. Governing Equations for Groundwater-Surface Water Interaction
In recent years there has been growing number of papers on the interaction between groundwater
and surface water. In general, there are two different modes of interaction depending on the
hydraulic head of groundwater and surface water [17]. If the groundwater level is higher than
surface water level, a gaining reach will take place. On the other hand, if the groundwater level is
lower than surface water level, a losing reach will occur [17, 10]. Figures 1-3 illustrate various
scenarios of flow regimes between surface water and groundwater:
22
Figure 2. Surface water-groundwater interaction in losing reach (taken from [15]-not to scale)
Figure 3. Surface water-groundwater interaction in losing-disconnected reach (taken from [15]-not to scale)
Figure 1 shows a gaining reach in which the head of groundwater is higher than the head of
stream and the channels receive water throughout its bed. Figure 2 shows the case in which flow
direction is from the stream to the groundwater. Figure 3 shows the scenario in which the flow
direction is still from the stream to the groundwater, but the water table is far below the stream
and a disconnected reach takes place.
In general, groundwater moves in three dimensional flow paths and forms a flow system
which depends on both the topography and hydrogeological characteristics of the porous medium
Figure 1. Surface water-groundwater in graining reach (taken from [15], [16]-not to scale)
23
[14, 15]. The flow path of groundwater is controlled by water table levels, distribution of the
hydraulic conductivity in the soil and climate effects such as precipitation [14].
The groundwater movement in the porous media is governed by the Darcy’s law, which
is the physics laws formulated by Henry Darcy originally based on his experimental results. In
essence, Darcy’s experiment (Figure 4) showed that the flow rate is proportional to the head loss
and at the same time is inversely proportional to the length of the flow path:
(1)
Where stands for flow rate, for the head loss and for length of the flow path. Let K denote
the hydraulic conductivity constant, indicating the permeability of the porous medium. Using this
constant, Darcy derived the following relationship [7]:
(2)
where A is the cross section of sample area.
Figure 4. Henry Darcy’s experiment to model the flow rate in porous media [18]
24
In the case of hydraulically connected stream-aquifer systems (Figure 1 and 2), the
concept of Darcy’s law can be generalized to estimate the flow rate between the river and aquifer
head, denoted by q, as follows [14, 19]:
(3)
where k denotes the streambed leakage which is the hydraulic conductivity of the semi-
impervious stratum divided by the thickness of streambed. in this equation is the difference
between the aquifer head and the river head. However, this linear behavior is considered to be
too simplistic for real applications. Thus, a combination of linear and non-linear relationship was
proposed by Rushton and Tomilson [20] to represent a more realistic behavior of the leakage
between aquifer and river, according to:
(4)
where
,
and
are constants. For a large head difference, the linear relationship dominates
whereas for a small head difference, the exponential part is the dominant term. Although, this
model is proved to capture more realistic behavior of aquifers, there are still limitations for
aquifer behavior analysis in this model, specifically for the complex flow patterns close to river
[20].
Analytical studies have also been conducted on the seepage from lined channels with
different geometries. For example, the author in [21] introduced an analytical solution to
quantify the seepage from polygon channels, which have been typically used in groundwater
artificial recharge. In [21], the seepage loss was quantified in irrigation problems and also
25
reservoir management by using an inverse hodograph and Schwarz-Christoffel transformation.
However, the analytical solution cannot be generalized to problems with different conditions
[21].
A different method to measure the water flux directly by using Bag-type seepage meters
was proposed by Lee for the first time in 1977 [17, 22]. This type of seepage meters consists of a
bottomless cylinder attached to a plastic bag which is positioned in the soil to collect
groundwater on its way to surface water. By measuring the volume of the cylinder and the filling
period, the seepage is calculated [17, 22]. Different types of automated seepage meters were
developed afterwards to overcome the inaccuracies involved in the first type of seepage meter.
Due to the rapid development in numerical modeling approaches in groundwater
modeling, starting from 1970’s, the computational modeling gradually gained the attention of
scientists and engineers in the groundwater research community. Groundwater models can be
categorized from different aspects. They can be one-dimensional, two dimensional or quasi-three
dimensional. Also, we may have different types of aquifers such as confined of unconfined or the
combination of both. Moreover, the models can be solved using finite element, finite difference
or a hybrid approach that is the combination of both [7].
One of the most popular computer programs for the simulation of the groundwater is
MODFLOW [7]. This program uses finite difference solution to solve the partial differential
equation for transient three dimensional groundwater flow [7]. The program has high capability
in modeling the groundwater in different types of aquifer, i.e. confined, unconfined, or
combination of both and also in various media, such as heterogeneous or anisotropic media. The
groundwater flow is governed by a three dimensional diffusion equation which establishes the
relationship between the rate of change in hydraulic head to the second order spatial derivatives
26
of the head in x, y and z directions. It is based on the numerical solution of the following partial
differential equation:
(5)
where
and
are hydraulic conductivities in three different coordinates system,
stands for volumetric flux per unit volume and
is the specific storage, ‘ is hydraulic head
and ‘ stands for time [7]. Among the available software packages, MODFLOW also has
capabilities in simulating the interaction between surface water and groundwater such as
recharge from river bed, pollutant transport, among others. Pollutant transport is one of the
important issues in the context of artificial recharge of groundwater.
2.2. Artificial Recharge
The artificial recharge mechanism depends on many factors such as soil properties and
infiltration rates [7, 8, 9]. Specifically, one needs to know how fast the water infiltrates into the
ground and what type of soils or aquifers with how much hydraulic conductivity are present in
the area of recharge. One also needs to know how deep the water can penetrate into the ground
and how much it contributes to the groundwater mound [8, 9]. Last but not least, one has to come
up with a groundwater management plan to evaluate when and for how long the water should be
pumped to meet the water demand and also to avoid surface flooding at the same time.
In general, artificial recharge consists of different methods some of which are discussed in here.
In “stream channel method”, as one of these methods, water is recharged to the ground through
the bed of natural channel by using the mechanism of increasing the time and the interface area
of water and soil [7]. In order to have an efficient infiltration system, soil has to be permeable
27
and the aquifers should be unconfined with sufficient transmissivity to ease the water movement
through the soil [9]. In another method, called the “basin method”, water is artificially recharged
by first diverting it into man-made basins, such as dams, where then infiltrating it into ground.
This method is one of the most favorable ones because of its space and cost efficiency and low
maintenance [9, 7]. Another method, called the “well method”, is used when we have at least one
of the following scenarios [9, 7]:
1- Adequate area for infiltration is not available.
2- The soil is not sufficiently permeable.
3- There are a number of confined aquifers in the region.
The water for injection wells usually should meet drinking water criteria to avoid clogging of the
wells and also contaminating the water in the aquifer especially in the regions where
groundwater is pumped for drinking water without extensive treatment procedures [9].
As mentioned earlier, one of the issues that need to be considered is the effect of recharge
on groundwater level. Numerous studies have been done to estimate the effects of the artificial
recharge on groundwater mounds. Rises in groundwater mounding depends on the hydraulic
conductivity of lower aquifers. If water hits layers with hydraulic conductivity (perching layer)
lower than the infiltration rate, water mound up above this layer. Bouwer et al. [9] showed that
by applying Darcy’s equation to the vertical flow, one could calculate the height of the
groundwater mound above this layer according to:
28
Figure 5. Infiltration system and groundwater mound shape above a confined layer (taken from [9])
(6)
where
is the height of mound,
, thickness of the confined (restricting) layer,
hydraulic
conductivity of soil,
hydraulic conductivity of confined layer and
downward infiltration
rate through soil [7, 9].
In the case of deep groundwater levels, Hantush equation developed by Hantush is used to
estimate the mounding rise as follows [7, 9, 23]:
Figure 6. Recharge mechanism and groundwater mound formation (image taken from [9])
29
} (7)
where
is the height of the water above the confined layer, is the original water level
above the impermeable layer, is the arrival rate at the water table, is the duration of
infiltration, is the fillable porosity, is the width of the area of recharge,
, and
is obtained through the following formula [7, 9, 23]:
(8)
where
and
. It should be noted that the values for are pre-
calculated and available in tables.
In 2010, USGS conducted a comparative study on simulating the groundwater mound
using the Hantush method and a finite difference scheme. The study focused on the groundwater
mounding formation beneath the structures designed to manage stormwater runoff [24]. To do
so, they developed a study on a 10 acre and 1 acre area. The characteristics of aquifer and
stormwater runoff were changed in different simulations to see which feature has the highest
effect on maximum height and the maximum extend of the groundwater mound [24].
Comparison of the results shows that the Hantush analytical method which only accounts for the
horizontal flow and does not include the vertical flow may underestimate the height of the
mound by approximately 15% [24]. The finite difference model, on the other hand, accounts for
the vertical component of the flow, and also incorporate the site specification, and thus produce
more accurate results compared to the analytical solution [24].
30
Chapter 3
Study Area
3.1. Introduction
The first phase of the proposed research as described in the introduction is to characterize
the groundwater flow system under a portion of the LAR in the Central basin. To demonstrate
this, a ground water model was used to investigate the possibility of replenishing the
groundwater basin by infiltration of LA river runoff into the aquifers. This chapter, first looks at
the characteristics within the area of interest (AOI) such as geology, hydrology and aquifer
parameters. This information is then used to generate a 3-dimensional ground water model
which considers all assumptions and limitations necessary to simulate the interaction between
surface water and groundwater.
3.2. Description of Study Area
The Los Angeles coastal plain basin consists of four groundwater basins: the Central
basin, the West Coast basin, the Santa Monica basin and the Hollywood basin [11].In the first
31
half of the 20
th
century, due to augmented groundwater development in Central and West Coast
basins in Los Angeles county area, the level of groundwater declined significantly and that led to
serious problems such as seawater intrusion [25]. Consequently, the Central and West coast
basin became adjudicated in early 1960s [25] which marked the beginning of groundwater
management system in these basins, which concerned buying and spreading the water on the
ground, pumping restriction and injection guidelines. However, Santa Monica and Hollywood
basins both remained non-adjudicated.
The California Department of Water Resources is the court delegated Watermaster to
ensure water allocation is launched based on the criteria that was established by court
adjudication or agreement by a qualified person [11, 25]. Furthermore, Water Replenishment
District of Southern California is the official groundwater level monitoring entity for Central and
West Cost Basins and it manages groundwater for approximately four million residents in
southern Los Angeles County area [26]. The area of interest in this investigation is located in
Central basin and it is not close to the area that has been affected by seawater intrusion.
Therefore, seawater intrusion is of no concern during this investigation. The hydrologic
parameters reported by Water Replenishment District of Southern California in 2006 are
tabulated in Table 1.
As stated in Table 1, the portion of unused storage available for storage is approximately
330,000 AF in Central Basin area. According to a personal communication with Water
Replenishment District of California [27] this estimated amount calculated with consideration of
recharging this amount of water all at once in Central Basin and the requirement was to raise the
groundwater level 75 feet or more below ground surface. Therefore, if we aim to replenish
32
groundwater in Central Basin the amount of allowable recharge should be less than or equal to
the amount of available storage in Central Basin.
Table 1. Summary of Hydrologic parameters of Central Basin
3.2.1. Los Angeles River
The Los Angeles river watershed covers the northern slope of the Santa Monica
Mountains, the Verdugo Hills, San Gabriel and Santa Susana Mountains which is approximately
830 mi
2
[28, 29]. The entire river is channelized from which approximately 75% of the river is
lined with concrete and the rest is natural bottom channel [28, 29]. Below table shows different
type of channels in LA river:
33
Table 2. Channel type categories for Los Angeles River [1]
As it’s shown in Table 1, approximately 60% of the channel is lined with concrete with
low flow channel. The trapezoidal channel has a top width between 400-600 ft, bottom width
between 200-400 ft and a depth between 20-35 feet [30]. Low flow channel is a rectangular
channel with a width of 12-20 ft and a range of depth between 1-3.2 ft [29].
Also, the daily flow rate analysis done by Tetra Tech and presented by United States
Environmental Protection Agency (EPA region IX) for five gage sites are shown in Table 2 and
3. The analysis has been done both for the entire flow record and also for five water years from
2003 to 2008. And, four of the five sites include the low flow channel.
34
Table 3. Daily flow statistics for the whole flow record [1]
Table 4. Daily flow statistics for water years 2003-2008 [1]
Approximately 72 % of the volume of LA River water is collected from the discharge
from three water reclamation plants (WRP) specifically Glendale WRP, Tillman WRP and
35
Burbank WRP [31]. Also, the daily average water depths for water years 2003-2008 in five gage
sites are tabulated in Table 5.
Table 5. Daily average flow depth for five water years at five gage sites [1]
3.2.2. Geology and Aquifer Systems
The section of LA River studied in the present research is located in Los Angeles
Forebay basin with unconfined aquifer system. The interest area is shown with a dashed line in
the following map:
36
Figure 7. Geology map of LA County [26]
37
As it can be seen, the northern part of central basin (Los Angeles Forebay) mostly
consists of Holocene sediments and Pleistocene deposits. Holocene sediments are mostly course
sand and gravel [32] and Pleistocene deposits are mostly consist of fine to medium sand with
minor sandy silt, clay and gravel lenses [33]. Pleistocene deposits consist of early (lower) and
late (upper) Pleistocene among which early deposits formed prior to the late deposits [25, 33].
Based on definitions reported by California Department of Water Resources, we have
four aquifer systems named as; Recent, Lakewood, San Pedro and Pico formations [33].
Recent Aquifers:
Aquifer systems formed by deposits in recent geological age (Holocene) such as Gaspur
and Semiperched are considered as ‘Recent aquifer systems’ [25].
Lakewood Formation:
The Lakewood formation, mainly consists of exposition, Bellflower, Gardena and Gage
aquifers which are formed mostly during late Pleistocene epoch [33].
Sand Pedro formation:
The San Pedro aquifer system consists of aquifers formed in early Pleistocene such as
Silverado, Lynwood and Sunnyside.
Pico Formation:
The Pico formation underlies all of the aforementioned aquifer systems. The lithology of
this formation is mainly clay, gravel and sand [33]. Although this aquifer system contains
permeable sediments but the information obtained from a number of wells points out that the
water quality is not suitable for use [33].
38
The Los Angeles Forebay and Montebello Forebay in Central Basin both consist of
relatively interconnected unconfined aquifers [33]. The depth of aquifers extends up to 1600 feet
in this region. And therefore, this area is considered as a practical region for the purpose of
recharging groundwater basins [33].
The most important aquifer (water-bearing zone)/aquiclude (impermeable body of rock or
sediments) systems in the central basin region are depicted in Table 6 [32, 25]:
Table 6. Principal aquifer/aquiclude in Central Basin region
The major part of groundwater mainly occurs in relatively recent deposits (Holocene) and
Pleistocene [33].
3.3. Aquifer Boundaries in the Model
The area selectes for purposes of this research is the seven mile by seven mile area shown
as a black rectangle in Figure 2. Three points were chosen to define the whole area displayed in
ArcGIS; intersection of Santa Monica Blvd/Western Ave, Western Ave/Slauson Ave and
Aquifer age Lithology Maximum thickness
Gaspur Holocene
Coarse Sand,
gravel
120
Semiperched Holocene Sand, gravel 60
Bellflower late Pleistocene calay, sandy clay 140
Exposition upper Pleistocene
gravel, sand,
clay
100
Gardena upper Pleistocene sand, gravel 160
Gage upper Pleistocene sand 120
Hollydale lower Pleistocene fluvial deposits
Jefferson lower Pleistocene fluvial deposits
Lynwood lower Pleistocene
Coarse Sand,
gravel
Silverado lower Pleistocene sandy gravel 300
Sunnyside lower Pleistocene 350
39
Atlantic Blvd/Slauson Ave. The fourth (last point) which is the upper right point was picked by
the software automatically. Boundaries of Gaspur and Exposition aquifers inside the study area
are shown below to show the exact street intersection.
Figure 8. Boundaries of Gaspur aquifer and LA River inside study area
40
Boundaries of Gaspur aquifer is illustrated with a gray shape and boundaries of LA river is
shown with blue color in the above map.
Moreover, Exposition aquifer and LA river boundaries are shown with yellow and blue
color in the following figure:
Figure 9. Boundaries of Exposition aquifer and LA River inside study area
41
In order to identify aquifer layers in study area, we need to get the information approximately the
geologic section in the area. Hence, two geologic sections were selected from the geologic maps
provided by Department of Water Resources [33]. Line locations of geologic sections are shown
with red lines in below picture.
Figure 10. Line location of geologic sections (modified from [33])
42
Figure 11. Aquifer types in geologic section A-A (modified from ‘Plate 6A’ [33] )
Figure 12. Aquifer types in geologic section B-B (modified from ‘Plate 6E’ [33] )
43
These sections were chosen to include the LAR in the area of interest of this dissertation. In both
sections, it can be seen that the Gaspur aquifer (recent aquifer system and highly permeable) and
other aquifers such as the Exposition, Gage and Gardena, Hollydale, Jefferson, Silverado and
Lynwood were formed at different epoch are lying underneath the recent formation.
In this study, the first four aquifers from the top; Gaspur, Exposition, Gardena/Gage and
Hollydale were analyzed for simulation of interaction between surface water and groundwater
out of approximately nine layer aquifers. The reason (as it is illustrated in geologic section A-A)
is due to presence of aquiclude formation underneath the Hollydale aquifer on the right side with
a thickness ranges between 60 and 120 ft. Aquiclude is a layer comprising sediments with low
permeability which confine the vertical groundwater movement [33]. Moreover, Jefferson
aquifer is also known as an aquifer with fine-grained sediments comprising sand, gravel and clay
lenses [33] with less permeably compare to the first four aquifers in the area of interest. Hence,
the first four layer of the geologic section is selected to be modeled for the purpose of this
research.
44
Chapter 4
Modeling Interaction between Surface Water
and Groundwater
4.1. Numerical Model
Before starting the model simulation, it is important to know the extent and characteristics and
quality of available data. The data required for aquifer boundaries, elevation contour lines,
transmissivity contour lines and water elevations are available in Bulletin No. 104, groundwater
geology provided by State of California Department of Water Resources. All of the data are
available in hard copy maps. Therefore, the first step would be digitizing these data in order to be
used as an input to our numerical model. As it’s mentioned before, ArcGIS was used to
georeference all of the available maps and then digitize all of the data regarding boundaries,
45
water elevation and transmissivity. The generated output files in ArcGIS are shapefiles that can
be imported to our model.
The software that was used to simulate the groundwater model in this research is
Groundwater Vistas which is a professional and graphical design system for Modflow and other
similar models [34]. GVistas is a model independent interface that using efficient graphical tools
creates an easy environment for building the models that are compatible with a wide variety of
groundwater codes. In this research, we used GWVistas to create a model which was then
simulated with MODFLOW 2000.
4.2. Boundary Conditions
The boundary condition is ‘No flow’ along the boundaries of each aquifer to indicate the
extent of Gaspur, Exposition, Gardena/Gage and Hollydale aquifers. Basically, the model was
generated in four layers representing Gaspur, Exposition, Gardena/Gage and Hollydale aquifers.
So, the boundary for each of the aquifers is introduced to the model separately. Following figures
show the boundary and transmissivity contour lines of all layers (aquifers).
Furthermore, the general head boundaries for each aquifer were chosen based on the water
elevation measurements provided in USGS report [25]. General head boundaries are defined at
the top and the bottom of each aquifer.
46
Figure 13. Gaspur aquifer boundary (modified from ‘Plate 26A’ [33])
Figure 14. Exposition aquifer boundary (modified from ‘Plate 26B’ [33])
47
Figure 15. Gardena and Gage aquifer boundary (modified from ‘Plate 26C’ [33])
Figure 16. Hollydale aquifer boundary (modified from ‘Plate 26D’ [33])
48
4.2.1. Recharge
Recharge is a form of constant flux boundary conditions that was assigned over approximately
one mile of Los Angeles River with the width of 16 ft in this research. Recharge is typically
distributed over large areas of the model and therefore is classified as a property in Groundwater
Vistas [35]. In this study, the recharge boundary condition has been used to specify the amount
of infiltrated water into the ground, based on which the interaction between surface water and
groundwater is simulated.
4.3. Aquifer Parameters
Aquifer hydraulic properties were defined for each aquifer system. Transmissivity data
was distributed spatially using ArcGIS based on available transmissivity maps provided by the
Department of Water Resources and imported into the model as shape files. Transmissivity is
defined as follows: where stands for hydraulic conductivity in and is the
saturated thickness.
The units of Transmissivity unit are
.
Following figures show transmissivity contour lines generated in GIS in Gaspur, Exposition,
Gardena/Gage and Hollydale aquifers respectively:
49
Figure 17. Transmissivity Contours in ft^2pd/ft for the Gaspur Aquifer (modified from ‘Plate 26A’ [33])
50
Figure 18. Transmissivity Contours in ft^2pd/ft for the Exposition Aquifer (modified from ‘Plate 26B’ [33])
Figure 19. Transmissivity Contours in ft^2pd/ft for the Gardena/Gage Aquifer (modified from ‘Plate 26C’ [33])
51
Figure 20. Transmissivity Contours in ft^2pd/ft for the Hollydale Aquifer (modified from ‘Plate 26D’ [33])
Moreover, vertical conductance between aquifers has to be put in the model. This value is
defined as the ratio of hydraulic conductivity to the thickness of the layer and the unit is per day.
The values that were taken for our study area is taken from USGS groundwater simulation report
in Los Angeles county area which are 0.55, 0.055 and 0.055 between layer one and two, two and
three and three and four respectively and the unit is per day [25].
4.4. Aquifer Layer Elevations
The top and bottom elevations for each aquifer is another property that is needed as input
to the model. Since the transmissivity data for each layer (aquifer) is available from the
52
Department of Water Resources (DWR), a unit thickness was calculated for each aquifer (i.e.
isopach). Thus, layer thickness rather than top and bottom elevation were used.
4.5. Initial Water Level Elevations
Another important property of the model is the starting ground water level or initial
heads. These were obtained from the average measured water level elevation data reported by the
Water Replenishment District (WRD) of Southern California report in 2013 and also well-
measurement data provided by Los Angeles County office during the last four years. The water
level contour lines then were drawn in ArcGIS and then imported to the model. Below figures
depict water level contour lines that are generated in ArcGIS.
Figure 21. Water level contour lines for Gaspur aquifer (modified from ‘plate 26A’ [33])
53
Figure 22. Water level contour lines for Exposition aquifer (modified from ‘plate 26B’ [33])
54
Figure 23. Water level contour lines for Gardena/Gage aquifer (modified from ‘plate 26C’ [33])
55
Figure 24. Water level contour lines for Hollydale aquifer (modified from ‘plate 26D’ [33])
56
Figure 25. Locations of recharge in the numerical model-gray cells are 'no flow zones'-light blue cells are 'recharge'
zones
The locations of recharge in the numerical model are shown in Figure 25 as square cells with
light blue color. Each cell width and length is about 900 ft in the numerical model. As can be
seen, approximately one mile of the lined Los Angeles low flow channel is considered to be
removed to replenish the groundwater basin.
57
4.7. Model Simulation
4.7.1 Baseline scenario
Before simulating artificial recharge scenarios, a baseline scenario was simulated which
assumed that the bottom of the LAR remained lined with no vertical infiltration. This scenario
serves as the reference against which project scenario results will be compared. This baseline
scenario is termed the “closed channel condition” scenario.
4.7.2 Predictive Scenarios
After assigning the properties and boundary conditions, the model was run to simulate
various predictive scenarios with different amounts of recharge in order to cover various types of
soils. We conduct this study first by setting a nominal amount of recharge equal to 3 ft/day as the
base infiltration rate. To account for the other possibilities, i.e. other types of permeability at the
interface of the stream and the ground, we considered two other values for the recharge value,
equal to 5 ft/day and 1.5 ft/day and we refer to these as second and third scenarios. Then we
solved the pumping optimization problem and conducted the economic study for these two
values, as well. By this sensitivity study, we manage to quantify the impact of the change in the
rate of recharge on the groundwater conditions and consequently on the net benefit of
replenishing the groundwater basin.
The predictive scenarios simulate “open channel conditions” whereby 0.8 mile length of the
channel bottom is removed to allow for infiltration. After running both baseline and predictive
runs, results were compared as shown in Figures 26-29. As can be seen in the figures, contour
lines of ground water level change showed no significant change in water level in the first layer
(Gaspur aquifer) and purple color cells show dry cells.
58
Figure 26. Change in water elevation, ft in the Gaspur Aquifer after 10 years of recharging for Scenario one (open
channel) - purple cells are 'dry' zones- blue cells are 'initial input heads' cells
59
Figure 27. Change in water elevation, ft in the Exposition aquifer after 10 years of recharging for Scenario one (open
channel) - purple cells are 'dry’ zones- blue cells are 'initial input heads' zones
60
Figure 28. Change in water elevation, ft in the Gardena/Gage aquifer after 10 years of recharging for Scenario one
(open channel)- purple cells are 'dry' zones- blue cells are 'initial input heads' cells
61
Figure 29. Change in water elevation, ft in the Hollydale aquifer after 10 years of recharging for Scenario one (open
channel)- purple cells are 'dry' zones- blue cells are 'initial input heads' cells
As it can be seen, the difference between water levels is higher in regions closer to the river and
as we go farther the value of water level change gets smaller. By looking at the output files in
opened channel and closed channel condition, we can tell how much change in storage we would
have and how much water (in acre-ft/year) we can store. The results obtained from both models
are summarized in Tables 7 and 8.
62
Table 7. Change in storage open channel and closed channel condition after 10 yrs of recharge for scenario one
Open channel
scenario
closed channel
scenario
Subsurface inflow from upgradient 5.53E+09 5.72E+09
Subsurface outflow from downgradient 4.72E+09 4.47E+09
Recharge 9.45E+08 0
Difference of inflow plus recharge & outflow 1756290000 1244800000
Table 8. Stored volume of water in ten years
Stored Volume in 10 yrs in acre-ft 11742.19467
Stored Volume in 1 yr in acre-feet 1174.219467
For the open channel condition in which the bottom of the channel was removed, the summation
of all the inflows including the subsurface inflow from upgradient and the recharge from river
has been calculated. Then the outflow which is the subsurface outflow to downgradient has been
subtracted from the inflows. The difference as it is tabulated in Table 8 is 1.7E+9 ft
3
. This
amount is obtained for a ten year period in our simulation and then is converted to approximately
1.2E+03 acre-ft/yr.
Therefore, by running both models, the change of storage and consequently the value of
water level change after 10 years can be predicted. The aforementioned results show that
removing the pavement of LA River seems a potentially feasible way to replenish groundwater
in this area and probably in similar areas along LA River.
63
Considering the abundant stored water, in order to thoroughly investigate the feasibility
of this artificial recharge idea, the next step would be conducting a comprehensive cost benefit
analysis. To do so, we need to enumerate and aggregate the costs associated with the pumping
operation. Also, we need to calculate how much water can be feasibly collected from the
aquifers. To this end, we conduct the pumping optimization to find the maximum pumping rate
which is translated to the highest feasible volume of extracted water. This is achieved by
minimizing the pumping costs while satisfying the constraints. In the next chapter, we first
describe the groundwater management models that have been developed during the last couple of
decades to optimizing the pumping plan. Furthermore, the pumping plan and optimization
framework developed in this study is discussed.
64
Chapter 5
Pumping Plan and Economic Analysis
5.1. Background
Groundwater management and design systems have been a crucial topic during the last
four decades. Optimization methods are crucial tools to optimize a sustained-yield groundwater
withdrawal [36, 37]. Optimization is a tool exploiting linear or nonlinear formulations to find the
most logical answer that generates the best results for a prescribed objective function [38]. Large
body of literature have been focused on different optimization methods to model groundwater
management problems among which several methods have proven to be reliable and useful for
designing groundwater operation systems. In general, groundwater management models can be
categorized into two groups [36]:
1- Hydraulic management models
2- Policy making and water allocation models
65
The objective of hydraulic management models is to facilitate optimization of pumping
plan/operation and location of wells. Many efforts have been made by researchers to achieve
specified objectives while satisfying a given set of constraints among which ‘embedding method’
and a ‘response matrix approach’ are two techniques that incorporate porous media flow
equations as constraints in optimization model. The embedding approach, first presented by
Aguado and Remson (1974), considered groundwater variables as decision variables in a linear
programming (LP) management models [39]. The capabilities of this approach were tested by
solving simple cases of confined, unconfined, transient, steady state, one and two-dimensional
flow examples [39]. The objective functions and constraints in these examples were proposed to
evaluate the feasibility of this method and weren’t designed to solve any specific hydrologic or
economic problems [39].
In 1976, Alley et al. [40] conducted research on aquifer management under transient and steady-
state condition using the embedding approach. The purpose of their study was to approximate the
equations of transient and steady-state flow in two dimensional aquifers. To do so, finite
difference form of the two dimensional governing equation of confined/unconfined aquifers was
used as constraints in the linear program [36, 40]. The objective of the optimization problem was
to maintain the sum of groundwater heads at maximum level while obtaining a specified flow
rate during a given time. In order to consider the transient behavior, a consecutive management
model for each time step was created and the optimal solution for each time step was set as the
initial condition of the next step.
Response matrix approach is another technique for groundwater hydraulic management models
in which an external groundwater simulation model is employed to develop unit responses [36].
In 1958, for the first time the incorporation of response matrix approach into linear programming
66
was proposed by Lee and Aronofsky in the petroleum engineering literature [36, 41]. The
objective of their work was maximizing the profits from oil production [36, 41].
On the other hand, the main focus of policy making models is on the effect of institutional
policies such as taxes on regional groundwater usage.
In this research, the main focus of economic and cost studies chapter is the first category
(hydraulic management models) in which our decision variables are location of wells, pumping
rates, well diameters, etc. The most essential objectives of these models are minimization of
operating cost and/or maximization of the pumping rate subject to the model’s constraints [42,
43].
Therefore, in order to justify the feasibility of the proposed artificial recharge for construction, a
cost-benefit analysis of different components of this project is required. Such analysis will
provide undisputable explanation to launch this proposal. Specifically, the total cost estimate of
the project will be compared with the present or projected value of water to investigate the
economic feasibility of this study.
5.2. Formulation of the Optimized Pumping Plan
For this portion of the study, the pumping plan was optimized such that the net benefit of
the extracted water is maximized. To do so, an objective function was characterized to determine
the potential net benefit of replenishing groundwater basin by removing a section of LA River.
In the most general case, the decision variables include the number of pumps, pumping
rates and pump locations. However, in this study, we only considered the pumping rates as the
decision variables and predetermined the number of pumps together with their locations. In
subsequent sections, the approach for the selection of the pump locations will be explained.
67
The objective function for the pumping plan optimization is defined as the product of
pumping rate of wells and the present or projected price (value) of water minus dollar value of
the total cost. Total cost includes constant cost, denoted by C, which includes rate-invariant costs
such as installation and operational costs for each pump, the maintenance, etc. and also variable
cost, denoted by C', which is the cost that varies with changes in pumping rate. Thus, we can
write the following objective:
(9)
We aim to maximize this objecting, satisfying the relevant constraints that assure the feasibility
of the optimal solution. The following constraints are considered for our optimization problem:
Constraint 1. The maximum pumping from the area should be less than the amount of
safe yield of the central basin, which is approximately 218,000 AFY.
Constraint 2. The groundwater hydraulic head at each well must be nonnegative, so the
wells don’t go dry during pumping.
5.2.1. Selection of the Number and Locations of Pumping Wells
As previously discussed the number and locations of production wells was selected
before conducting the optimization step. To do so, the model was run with no pumping wells
operating for ten one-year periods. Also, locations were selected for the pumps in the region
where the calculated groundwater hydraulic heads in the model with no pumps had relatively the
highest values. To identify this region, ten monitoring wells were placed in the area of our
interest at relative distances of approximately half a mile. Since, the upper part of the area of our
interest is located in central business district of downtown Los Angeles, we avoided positioning
68
wells in that area. After adding the monitoring wells to the model, the groundwater head at every
location and time periods was calculated.
Furthermore, as described earlier under Constraint 2, the hydraulic head should be non-negative
for the duration of pumping in all wells. As illustrated in the Figures 31-39, groundwater
hydraulic head increases as time passes during the ten year period in different wells. This means
that Constraint 2 will become less strict as time passes because the higher the hydraulic head, the
more one can pump the water. Thus, if a single optimization problem is considered for every
period, the hydraulic head calculate at the beginning of the periods for every well is the
governing head. In order to calculate the hydraulic head at the beginning of recharge, the first
period (first year) is divided into 15 time steps and the remaining nine periods is divided into six
time steps each. Doing so, the groundwater hydraulic head in the first few days of the recharge
will be considered to be the head calculated at the first sub-period based on which the pumping
rate is optimized.
Afterwards, considering the quantity of head at the beginning and at the end of ten year stress
period, nine wells among the ten monitoring wells that have higher hydraulic heads were
selected to run as pumping wells. Figure 30 shows the location of fourteen wells/pumps in the
area (in red color).
69
Figure 30. Pumping well locations in the area of interest- greay cells are 'no flow' zones-blue cells represents 'initial
input head'
Pumping/monitoring wells
70
Figure 31. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 1
Figure 32. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 2
71
Figure 33. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 3
Figure 34. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 4
72
Figure 35. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 5
Figure 36. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 6
73
Figure 37. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 7
Figure 38. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 8
74
Figure 39. Hydraulic head (ft) vs. time (days) during the ten years of recharge at well 9
5.2.2. Well Interactions
The effect of pumping of each well on other wells (i.e. well interactions) was determined
in order to design a multi-pumping operation. As discussed in Chapter 2, the groundwater flow
is calculated using the numerically solving the following partial differential equation:
(10)
where
and
are hydraulic conductivities in three different coordinates system,
stands for volumetric flux per unit volume and is the specific storage, is hydraulic head.
This equation is in fact a linear relationship between the hydraulic head and fluxes. Thus, to
quantify the impact of pumping flux at one well on the water level at other wells, we need to
estimate the linear relationship between the head at the impacted well versus the pumping rate at
the reference well. To do so for each pair of reference and target wells, we need to data points.
Thus, we run the model two times with two different pumping rates at the reference well. We
75
identified these linear interactions for all the pair combinations. Based on the calculated linear
relationship, it was concluded that the interacting effect between wells should be included in our
optimization problem.
5.3. The Optimization Problem
As discussed in the model approach, first the objective function is formed as follows
(11a)
Subject to:
Q
i
≤ 218,000 acre ft/yr (11b)
h
i
≥0 (11c)
where P stands for the present value of water in US Dollar, i is the index of a well in the area, Q
is the pumping flow rate in gallon per minute (GPM), C
constant
is the constant cost (cost for
drilling a well, cost of pumps, etc.) and C´(Q
i
) is variable cost at different pumping rates. The
variable pumping cost itself is a function of Q
i
at nine different wells, according to
) (12)
Variable cost at each well expresses the production of a constant coefficient, c, pumping rate at
each running well, Q
i
, and pumping head in each well,
which is a function of Q
i
itself, as
shown in Figure 40.
76
Figure 40. Schematic of the drawdown at a pump location shown with the terms used in the optimization
The constant coefficient is calculated by converting mechanical horse power to electrical horse
power and multiplying that by the amount of power rate in Los Angeles area which is
approximately $0.22/KWh. To calculate the mechanical power, the total head for pumping is
required which includes the drawdown resulted from pumping and the drawdown because of
well loss (CQ
i
2
). Jacob first in 1947 described the constituents of drawdown in a pumping well
[7] which consist of aquifer loss, the linear part of drawdown (BQ), and well loss (CQ
i
n
):
s wi (Q i b ij Q j +CQ i
2
(12)
The first term in this equation denotes the total aquifer loss, which is calculated by Modflow
88/96, including the interactions between all the wells as described earlier in Section 5.2.2. The
second term of a drawdown at a well is the well loss (CQ
n
), where n is a constant greater than
one. Well loss is associated with turbulent flow and is described as energy losses due to flow
during well screen and flow inside of the well to the pump intake [7, 19, 44]. There is not a
77
precise value for ‘n’ due to variation in wells, however Jacob [45] recommended that the value
n=2 can be a reasonable assumption. Furthermore, the well loss coefficient, C, was calculated
based on Walton’s table [44] ith an atypical unit of (T
2
/L
5
):
Table 9. Walton’s well loss coefficients
Nonlinear well loss coefficient C
Well Deterioration sec ²/ft⁵ sec ²/m⁵
Mild 5 to 10 1900-3800
Severe ˃10 ˃3800
The well deterioration is assumed to be mild in this study where C is the coefficient determined
in pumping cost calculation with the unit of min.$/ft
5
which is equal to 6.7*10
(-10)
day
2
/ft
5
. The
groundwater level in each layer can be plotted. Figures 41-44 illustrate the groundwater level in
our model after opening the bottom of the canal and before installing any pumps in the area. The
purple cells denote dry areas.
78
Figure 41. Groundwater level, ft in the Gaspur aquifer after opening the bottom of the channel after 10 years- purple
cells are 'dry' zones- blue cells are 'initial input heads'
79
Figure 42. Groundwater level, ft, in the Exposition aquifer after opening the bottom of the channel after 10 years-
purple cells are 'dry' zones- blue cells are 'initial input heads'
80
Figure 43. Groundwater level, ft in the Gardena/Gage aquifer after opening the bottom of the channel after 10 years-
purple cells are 'dry' zones- blue cells are 'initial input heads'
81
Figure 44. Groundwater level, ft in the Hollydale aquifer after opening the bottom of the channel after 10 year-
purple cells are 'dry' zones- blue cells are 'initial input heads' cells
5.3.1. Solution of the optimization problem
The optimization problem (Equation 11) consists of a non-linear cubic objective function
and a non-linear (quadratic) inequality constraint and a linear equality constraint can be solved.
To solve this nonlinear optimization problem, we used the numerical technique called “interior
point algorithm”. Table 11-13 tabulates the calculated results for the pumping rate at each well
considering all the limitation and constraints for three different scenarios.
82
Table 10. Calculated amount of optimal pumping rates in all wells through ten years (scenario 1-infiltratin rate=3
ft/d)
Table 11. Calculated amount of optimal pumping rates in all wells through ten years (scenario 2-infiltration rate=5
ft/d)
pumping rate well 1 well 2 well 3 well 4 well 5 well 6 well 7 well8 well 9
1
2 2.01E+05 2.78E+04
3 1.94E+05 1.51E+05 1.40E+05 1.12E+05 9.37E+04 1.05E+05 7.75E+04 3.96E+04 1.86E+04
4 1.94E+05 1.51E+05 1.40E+05 1.12E+05 9.37E+04 1.05E+05 7.75E+04 3.96E+04 1.86E+04
5 1.95E+05 1.57E+05 1.50E+05 1.26E+05 1.10E+05 1.21E+05 9.57E+04 6.94E+04 5.87E+04
6 1.95E+05 1.57E+05 1.50E+05 1.26E+05 1.10E+05 1.21E+05 9.57E+04 6.94E+04 5.87E+04
7 1.95E+05 1.57E+05 1.50E+05 1.26E+05 1.10E+05 1.21E+05 9.57E+04 6.94E+04 5.87E+04
8 1.95E+05 1.57E+05 1.50E+05 1.26E+05 1.10E+05 1.21E+05 9.57E+04 6.94E+04 5.87E+04
9 1.95E+05 1.57E+05 1.50E+05 1.26E+05 1.10E+05 1.21E+05 9.57E+04 6.94E+04 5.87E+04
10 1.95E+05 1.57E+05 1.50E+05 1.26E+05 1.10E+05 1.21E+05 9.57E+04 6.94E+04 5.87E+04
pumping rate well 1 well 2 well 3 well 4 well 5 well 6 well 7 well8 well9
1
2 1.98E+05 2.89E+04
3 1.92E+05 1.55E+05 1.45E+05 1.23E+05 1.05E+05 1.10E+05 7.59E+04 3.73E+04 1.68E+04
4 1.92E+05 1.55E+05 1.45E+05 1.23E+05 1.05E+05 1.10E+05 7.59E+04 3.73E+04 1.68E+04
5 1.94E+05 1.62E+05 1.55E+05 1.37E+05 1.22E+05 1.27E+05 9.42E+04 6.76E+04 5.76E+04
6 1.94E+05 1.62E+05 1.55E+05 1.37E+05 1.22E+05 1.27E+05 9.42E+04 6.76E+04 5.76E+04
7 1.94E+05 1.62E+05 1.55E+05 1.37E+05 1.22E+05 1.27E+05 9.42E+04 6.76E+04 5.76E+04
8 1.94E+05 1.62E+05 1.55E+05 1.37E+05 1.22E+05 1.27E+05 9.42E+04 6.76E+04 5.76E+04
9 1.94E+05 1.62E+05 1.55E+05 1.37E+05 1.22E+05 1.27E+05 9.42E+04 6.76E+04 5.76E+04
10 1.94E+05 1.62E+05 1.55E+05 1.37E+05 1.22E+05 1.27E+05 9.42E+04 6.76E+04 5.76E+04
83
Table 12. Calculated amount of optimal pumping rates in all wells through ten years (scenario 3-infiltration rate=1.5
ft/d)
As can be seen in Table 10, it is optimal that no pumping is planned for the first year, in all three
scenarios. In second year, Well 1 and 2 are active, in two of the scenarios. Beginning from the
third year, all of the nine wells will be extracting water for all the scenarios. Therefore,
assuming the first scenario to hold true, the first two pumping wells will be installed in the upper
part of the recharge area (Figure 30) by the end of the first year. The rest of the wells will be
installed at the end of the second year in the locations that are shown in Figure 30. The
calculated pumping rate is bigger in the wells closer to the recharge area and as the location of
the wells gets farther from the recharge area, the amount of optimal pumping rate gets smaller.
Comparing scenarios 1 and 2, one can notice that the quantity of optimal pumping rates do not
change significantly except for wells 3, 4 and 5 in which the pumping rates are slightly higher.
Lastly, for the third scenario (infiltration rate=1.5 ft/d), nine wells with will be installed at the
same location as scenarios 1 and 2, at the end of the second year and will be running afterwards
until the end of the tenth year.
pumping rate well 1 well 2 well 3 well 4 well 5 well 6 well 7 well8 well9
1
2
3 1.94E+05 1.50E+05 1.39E+05 1.10E+05 9.16E+04 1.03E+05 7.63E+04 3.55E+04 1.30E+04
4 1.94E+05 1.50E+05 1.39E+05 1.10E+05 9.16E+04 1.03E+05 7.63E+04 3.55E+04 1.30E+04
5 1.95E+05 1.57E+05 1.49E+05 1.25E+05 1.09E+05 1.20E+05 9.47E+04 6.83E+04 5.75E+04
6 1.95E+05 1.57E+05 1.49E+05 1.25E+05 1.09E+05 1.20E+05 9.47E+04 6.83E+04 5.75E+04
7 1.95E+05 1.57E+05 1.49E+05 1.25E+05 1.09E+05 1.20E+05 9.47E+04 6.83E+04 5.75E+04
8 1.95E+05 1.57E+05 1.49E+05 1.25E+05 1.09E+05 1.20E+05 9.47E+04 6.83E+04 5.75E+04
9 1.95E+05 1.57E+05 1.49E+05 1.25E+05 1.09E+05 1.20E+05 9.47E+04 6.83E+04 5.75E+04
10 1.95E+05 1.57E+05 1.49E+05 1.25E+05 1.09E+05 1.20E+05 9.47E+04 6.83E+04 5.75E+04
84
5.4. Cost-Benefit Analysis
To evaluate the profitability of the project, we calculate the present worth values
corresponding to the incurred costs and earned benefits throughout the life of the project for
three different scenarios (see section 5.1.).
Specifically, considering the time value of money, we formed the cash flow diagram and
calculated the associated present worth was determined for all fourteen wells during the ten year
period. Specifically, for a benefit earned at the end of the n-th year, denoted by B
n
, and a cost
incurred in that same year, denoted by C
n
, using the compound interest calculation, the
corresponding present worth values, PWB and PWC respectively, can be calculated according to:
PWB
(15)
PWC
(16)
And the present worth of the net benefit PWNB is given by
PWNB
(17)
where i is the minimum attractive rate of return. If the sum of the calculated PWNB for all the
annual costs and benefits is found to be positive, it means that the project is economically
feasible since it earns more than the minimum attractive rate of return. In what follows, we
briefly describe the various types of cost associate with this project.
5.4.1. Construction Cost
The cost of construction in this research consists of the cost of digging wells and the cost of
removing the concrete of the LA River low flow channel.
85
Water well material and dimensions were designed based on the typical well design criteria
published in the Technical Bulletin by Water replenishment district of Southern California
(WRD) [46]. The cost for drilling a new well depends on many factors such as well use (if it’s
for irrigation or potable), depth of well, casing diameter and material, etc [46].
Figure 45. Different parts of a typical portable well (picture from [44])
86
The characteristics of the wells considered for this study are as follows. The borehole diameter is
26" the casing diameter is 16", with stainless steel as the casing material. The range for the well
depth is 150-210 ft, the screen is 400’ stainless steel louvered, the filter pack is silica sand. The
cost for a well with above characteristics for agricultural and irrigation purposes was estimated
approximately $250,000 based on the Technical Bulletin published by Water Replenishment
District of Southern California in Fall 2005 [46].
This estimated cost also includes the drilling contractor’s labor, equipment, and materials, well
design and construction monitoring by a consultant, water storage and treatment facilities (if
needed) [46].
5.4.2. Capital Costs of Pumping Equipment
Cost of pumps includes the cost of purchasing a pump, freight to USA domestic jobsite, start up
services, maintenance cost per year and also the cost of installing a pump into a well. The
detailed quantity of all the aforementioned costs in this study is tabulated in Table 19. Pump
selections were made according to depth to both the upper water level and to the lowest water
level in different wells and consequently three pumps with the information included in Table 11.
87
Table 13. All the associated costs with pumping provided by National Pump Company and Bakersfield Well and
Pump Company
Detailed Cost
estimates
Comments
Cost for
9 wells
pump pricing
$57,000 per
pump
X 9 pumps
513000
Freight to
domestic
USA jobsite
estimated at
$3,000 per
truckload,
two truckloads
required
6000
Start up
services
Allow $1,500
per day, one
day per pump
plus one day at
same rate for
travel
13500
Variable
Frequency
Drive
Estimated at
$9,000 to
$12,000
9000
cost of
installing
the pump into
a well
$53,066.55/pump 477594
Total=$ 1019094
88
Table 14. Pump data for three types of pumps
5.4.4. Risk Analysis Costs
As part of the cost analysis, we also consider the cost of risks associated with different potential
future events in this project. Risk, by definition, is the product of the probably of a hazardous
event and a measure (e.g. the cost) of its consequences. For the purpose of this study, earthquake
and flood occurrence were considered as the relevant hazardous events in Los Angeles area and
the potential impact of these events on the proposed research are briefly discussed in here.
5.4.4.1 Cost Impacts from Earthquakes
Based on input from several drilling contractors in southern California, the effects of the
earthquakes on water wells during past earthquake events in Los Angeles area were very minor
and negligible. The one well where damage could reasonably be tied to earthquake activity was
flow
(US gpm)
Head
(ft)
Speed
(rpm)
Efficiency (%) Power
(hp)
flow
(US gpm)
Head
(ft)
Speed
(rpm)
Efficiency (%) Power
(hp)
flow
(US gpm)
Head
(ft)
Speed
(rpm)
Efficiency (%) Power
(hp)
1560 175 1770 77.9 88.3 1872 158 1770 68.5 109 1560 180 1770 78.3 90.1
1300 216 1770 83.2 84.9 1560 223 1770 81.1 108 1300 220 1770 83.2 86.6
1040 244 1770 81.2 78.7 1248 267 1770 82.9 101 1040 248 1770 81 80.2
780 264 1770 72.8 71.3 936 296 1770 76.5 91.3 780 268 1770 72.5 72.6
520 279 1770 57.25 64.1 624 317 1770 60.9 81.2 520 283 1770 56.9 65.3
pump type 1 pump type 2 pump type 3
flow
(US gpm)
Head
(ft)
Speed
(rpm)
Efficiency (%) Power
(hp)
flow
(US gpm)
Head
(ft)
Speed
(rpm)
Efficiency (%) Power
(hp)
flow
(US gpm)
Head
(ft)
Speed
(rpm)
Efficiency (%) Power
(hp)
1560 175 1770 77.9 88.3 1872 158 1770 68.5 109 1560 180 1770 78.3 90.1
1300 216 1770 83.2 84.9 1560 223 1770 81.1 108 1300 220 1770 83.2 86.6
1040 244 1770 81.2 78.7 1248 267 1770 82.9 101 1040 248 1770 81 80.2
780 264 1770 72.8 71.3 936 296 1770 76.5 91.3 780 268 1770 72.5 72.6
520 279 1770 57.25 64.1 624 317 1770 60.9 81.2 520 283 1770 56.9 65.3
pump type 1 pump type 2 pump type 3
flow
(US gpm)
Head
(ft)
Speed
(rpm)
Efficiency (%) Power
(hp)
flow
(US gpm)
Head
(ft)
Speed
(rpm)
Efficiency (%) Power
(hp)
flow
(US gpm)
Head
(ft)
Speed
(rpm)
Efficiency (%) Power
(hp)
1560 175 1770 77.9 88.3 1872 158 1770 68.5 109 1560 180 1770 78.3 90.1
1300 216 1770 83.2 84.9 1560 223 1770 81.1 108 1300 220 1770 83.2 86.6
1040 244 1770 81.2 78.7 1248 267 1770 82.9 101 1040 248 1770 81 80.2
780 264 1770 72.8 71.3 936 296 1770 76.5 91.3 780 268 1770 72.5 72.6
520 279 1770 57.25 64.1 624 317 1770 60.9 81.2 520 283 1770 56.9 65.3
pump type 1 pump type 2 pump type 3
89
located very close to the epicenter. As a result, the wells are not typically insured for seismic
events.
5.4.4.2 Flood risks
Los Angeles River line channelization began in 1938 as a solution to control the flood in the city.
Before then, flooding along the channel caused lots of loss of property and casualties especially
during 1914, 1934 and 1938 [16]. Since the beginning of 21
st
century many proposals have been
submitted to remove the channel lining to make it more natural [16]. However, since flooding
has been a crucial issue, especially in 20
th
century, the flood control analysis has been an active
research to investigate the effects of removing the lining of channel when the flooding occurs.
Our potential proposal is to remove just the lining of the low flow channel and not the
channel itself. This way, one can reduce the risk of flooding significantly. To quantify the risk
associated with the flood events, we need to calculate the occurrence probability of the extreme
event multiplied with the cost associated with its disastrous consequences. A detailed study of
the flood risk is outside the scope of this dissertation. In what follows, we roughly evaluate the
potential impact.
U.S. Army Corps of Engineers performed series of improvements along Rio Hondo
Channel, Los Angeles River, and Compton Creek as Los Angeles County Drainage Area
(LACDA) project. LACDA project is a multi-use project partly aimed to increase flood control
capacity of the lower Los Angeles River, Rio Hondo, and lower portion of Compton Creek [47]
in order to alleviate the potential severe overflow. As part of the project, a risk analysis was
conducted through which the LA River level of flood protection was enhanced to 133-year
90
recurrence interval or the probability of exceedance equal to 1/133 ((P = 0.0075). Thus, for the
purpose of this study, the likelihood of having a flood during our ten-year study would be 7.5%.
To quantify the impact of a flood event, we consider a change in the roughness parameter
of the streambed and consider a composite formula, which consider a streambed composed of
concrete and natural channel, which is the realistic representation of the channel conditions in
our project. The composite formula is given by
(18)
where P
i
is the wetted perimeter of the portion with material type i with Manning roughness
coefficient n
i
., and P is the total wetted perimeter. Based on the modified roughness coefficient,
using the Manning equation, the flow rate was calculated to be 7% smaller than the flow rate
when the concrete pavement is intact. These rough estimates provide a ballpark estimate of how
small the potential impact of the project will be on the flood event and how small is the risk of
the flood itself. As mentioned earlier, a thorough study should be conducted to fully determine
the two way interaction between the artificial recharge project and a flood event.
5.4.5. Real Estate Costs
In this study, we assumed that in order to drill and install a well in the area of our interest we can
get easement to property which is the right to enter/use a property without possessing it. Also, if
we work with the City of LA or Vernon, we could use their land as a part of the deal. Therefore,
there was no consideration for the cost of Real Estate in this study.
91
5.4.6 Insurance Costs
Typically the cost of the contractor’s insurance policies is included in the mobilization line item
or as one of the fixed price items. It is in the form of a percentage of the cost of the entire work.
Based on estimation by a contractor in Los Angeles area, the amount for insurance is
approximately 0.5% to 0.75% of the total contract value.
5.4.5. Value/Cost of Water
According to a communication with the Los Angeles County office [48] the “cost/value” of the
water is the amount per acre-foot of water delivered, and it varies based upon factors such as
source (local runoff, imported, and recycled), and level of treatment (untreated, tertiary treated,
advanced treated, etc.). Here is a representative list of costs of water per acre-foot:
(1) Local runoff from rainfall event: $0
(2) Recycled water (tertiary treated): $250
(3) Recycled water (advanced treated): $1,000
(4) Imported water (untreated): $593
(5) Imported water (treated): $890
The water replenished to the ground from LA River is considered as imported water (untreated).
Therefore, the value of water in this study is considered to be $593/AF.
92
5.5. Summary of Costs and Benefits
In this section, we present in detail, the calculation of upfront and annual costs and annual
benefits for the optimal pumping plan, based on which the total net benefit of the project, in
present worth value, is calculated for a 10 year period. As discussed earlier, 9 pumping wells will
be constructed at the locations described in Section 5.2. In what follows, first the calculation of
annual benefits and annual and upfront costs for each well during the 10 year period is explained.
Based on these well-specific results, in the subsequent section, the total Present Worth of Net
Benefit for this project is calculated.
5.5.1. Well-specific Costs and Benefits
A cost-benefit analysis is conducted for each one of the 9 wells for the three scenarios with
different infiltration rate. In this section, we include the results of the cost-benefit analysis for
the 9 wells corresponding to all three scenarios (with infiltration rate=3ft/d, 5 ft/d and 1.5 ft/d) in
Tables 15-17. For each well, four types of costs are incurred: (1) variable costs (annual), (2)
initial cost, (3) pumping fee costs (annual) and (4) pump maintenance costs (annual). In what
follows, a detailed explanation of the cost and benefit calculations for well #1 (tabulated in Table
12) is presented.
In Table 15, the first column shows the year at the end of which costs and benefits are calculated.
The second column corresponds to the calculated variable costs of all nine wells during 10 years
period. The third column includes the initial (start-up) costs which consist of all the construction
costs and pump purchase cost. The entries on this column for all the years are zero except at the
end of the first and second year for the first and second scenario and second and third year for
the third scenario.
93
The forth column shows the annual fees for pumping per acre-feet charges that are paid to WRD
for all of the pumps in ten years. The fifth column includes the pump maintenance costs for all
wells which for each well begin to incur right after the beginning of the project during the first
year, but the total annual values are considered to incur at the end of each year. In Table 15,
sixth column is the total costs which is the summation of the four cost amounts in the previous
four columns, and the seventh column include the translation of the total cost values at the end of
different years to the Present Worth values according to the compound interest calculation
(Equation (16)).
The benefits that are earned throughout a given year are considered as a lump-sum at the end of
that year. It is calculated based on the total amount of water extracted from the wells during 10
years multiplied by the dollar value of water. These annual benefit values are also translated into
the Present Worth value using the compound interest calculation (Equation (15)). The final
column includes the PWNB earned by the operation of all wells over a period of 10 years.
Given the values in Table 15-17, total annual benefits and annual costs can be calculated for the
whole project. Figure 46shows the cash flow diagram created based on these annual values. The
x-axis shows the time in the unit of years, and the y-axis is the dollar value of the benefits or
costs. The upward arrows in the positive direction show the earned annual benefits at different
years and the downward arrows indicate the incurred annual or upfront costs. Cash flow
diagrams are not typically drawn to the scale, but higher costs or benefits are highlighted by
relatively longer arrows.
94
Table 15. Present Worth of Net Benefit (PWNB) Calculation for all wells in 10 years with infiltration rate=3 ft/d
Table 16. Present Worth of Net Benefit (PWNB) Calculation for all wells in 10 years with infiltration rate=5 ft/d
Table 17. Present Worth of Net Benefit (PWNB) Calculation for all wells in 10 years with infiltration rate=1.5 ft/d
year
variable cost
($)
initial
cost ($)
Fee for
pumping per
acre-ft charges
by WRD=$268
Pump
maintenance
($)
Total cost PWC Benefit PWB
Present Worth of
Net Benefit (PWNB)
1 0 623352 0 $0.00 $623,352.00 $623,352.00 0 0 -623352
2 1.00E+05 1750000 512656.7447 3000 $2,365,926.74 2230112.871 1.13E+06 1069186.54 -1160926.331
3 4.13E+05 0 2049549.073 13500 $2,476,519.07 2266365.773 4.63E+06 4234543.486 1968177.713
4 4.13E+05 0 2049549.073 13500 $2,476,519.07 2200355.12 4.63E+06 4111207.268 1910852.148
5 4.80E+05 0 2297355.248 13500 $2,791,125.25 2407649.157 5.37E+06 4636349.694 2228700.537
6 4.80E+05 0 2297355.248 13500 $2,791,125.25 2337523.454 5.37E+06 4501310.383 2163786.929
7 4.80E+05 0 2297355.248 13500 $2,791,125.25 2269440.246 5.37E+06 4370204.255 2100764.009
8 4.80E+05 0 2297355.248 13500 $2,791,125.25 2203340.045 5.37E+06 4242916.753 2039576.708
9 4.80E+05 0 2297355.248 13500 $2,791,125.25 2139165.092 5.37E+06 4119336.653 1980171.561
10 4.80E+05 0 2297355.248 13500 $2,791,125.25 2076859.313 5.37E+06 3999355.974 1922496.661
14106994.92
year
variable cost
($)
initial
cost ($)
Fee for
pumping per
acre-ft charges
by WRD=$268
Pump
maintenance
($)
Total cost PWC Benefit PWB
Present Worth of
Net Benefit (PWNB)
1 0 623352 0 $0.00 $623,352.00 $623,352.00 0 0 -623352
2 9.95E+04 1750000 509288.2874 3000 $2,361,805.29 2226228.002 1.13E+06 1062211.33 -1164016.672
3 1.23E+02 0 2069310.689 13500 $2,082,934.15 1906179.813 4.63E+06 4237746.482 2331566.669
4 1.23E+02 0 2115278.903 13500 $2,128,902.36 1891502.175 4.63E+06 4114316.973 2222814.797
5 4.96E+05 0 2379590.519 13500 $2,889,160.52 2492215.243 5.55E+06 4788858.927 2296643.684
6 4.96E+05 0 2379590.519 13500 $2,889,160.52 2419626.45 5.55E+06 4649377.599 2229751.15
7 4.96E+05 0
2379590.519
13500 $2,889,160.52 2349151.893 5.55E+06 4513958.834 2164806.942
8 4.96E+05 0 2379590.519 13500 $2,889,160.52 2280729.993 5.55E+06 4382484.305 2101754.312
9 4.96E+05 0 2379590.519 13500 $2,889,160.52 2214300.964 5.55E+06 4254839.131 2040538.167
10 4.96E+05 0 2379590.519 13500 $2,889,160.52 2149806.761 5.55E+06 4130911.778 1981105.017
15581612.07
year
variable cost
($)
initial
cost ($)
Fee for
pumping per
acre-ft charges
by WRD=$268
Pump
maintenance
($)
Total cost PWC Benefit PWB
Present Worth of
Net Benefit (PWNB)
1 0 0 0 $0.00 $0.00 $0.00 0 0 0
2 0.00E+00 2373352 0 0 $2,373,352.00 2373352 0.00E+00 0 -2373352
3 4.05E+05 0 1970053.48 13500 $2,388,823.48 2186111.884 4.54E+06 4150533.482 1964421.598
4 4.05E+05 0 2020490.514 13500 $2,439,260.51 2167251.373 4.54E+06 4029644.157 1862392.784
5 4.78E+05 0 2415588.099 13500 $2,906,688.10 2507334.688 5.34E+06 4610557.692 2103223.004
6 4.78E+05 0 2415588.099 13500 $2,906,688.10 2434305.522 5.34E+06 4476269.604 2041964.081
7 4.78E+05 0 2415588.099 13500 $2,906,688.10 2363403.42 5.34E+06 4345892.819 1982489.399
8 4.78E+05 0 2415588.099 13500 $2,906,688.10 2294566.427 5.34E+06 4219313.416 1924746.99
9 4.78E+05 0 2415588.099 13500 $2,906,688.10 2227734.395 5.34E+06 4096420.793 1868686.398
10 477600 0 2415588.099 13500 2906688.099 2162848.927 5344901 3977108.31 1814259.383
13188831.64
95
Figure 46. 10-year cash flow diagram including total annual benefits and costs and the initial costs for the optimal
pumping plan
96
Table 18. Comparison of the amount of present Worth of Net Benefit in three different scenarios
Scenario one
(infiltration rate 3 ft/d)
$12,776,478
Scenario two
(infiltration rate 5 ft/d)
$14,246,845
Scenario three
(infiltration rate 1.5 ft/d)
$10,050,950
Table 18 tabulates the PWNB corresponding to the three considered scenarios. In addition to the
values in Tables 15-17, the two other cost values that are subtracted from the total PWNB are the
cost associated with pumping (Table 13) and the cost of insurance which is calculated to be 0.5%
of the total present worth cost of project. As can be seen, due to the increase in the value of the
infiltration rate, the amount of stored water in the ground increases and consequently the
pumping flow rate can be increased leading to larger profits.
As it’s tabulated in Table 18, the amount of net benefit does not change significantly by
changing the value of the infiltration rate of the soil.
97
Chapter 6
Summary, Findings and Recommendations
6.1. Summary
The purpose of this study was to determine the technical and economic feasibility
of removing a portion of the lined Los Angeles channel to allow infiltration into aquifers of the
Central Basin of Los Angeles County (specifically, the Forebay area). Therefore, first the
amount of surface water that could be recharged into the aquifers was estimated using a
distributed parameter groundwater flow model. Afterwards, the economic feasibility of the
proposed schemes was investigated by enumerating the costs associated with the optimal
execution of the project and the potential benefits that can be earned from it. Three distinct
scenarios were considered to investigate the potential variability in the infiltration rate of the soil
in the recharge area. Based on the calculated net benefits, it is concluded that this project is
economically feasible.
98
6.2. Findings
As a result of the investigation carried out in this dissertation, the following summarizes
significant findings:
1- By removing the pavement of Los Angeles River canal for half a mile in the area located
in Los Angele Forebay Basin with unconfined aquifer system, in ten years we could
recharge approximately 11,742 AF water into the ground instead of disposing it into the
ocean and we could significantly enhance water supply reliability. Approximately 62%
of the LA River channel is lined channel in Southern California (Table 2) which could
benefit the underlying ground water basins by allowing infiltration in a portion of the
channels.
2- The amount of stored water during 10 year of recharge would be 11,742 AF, 19,171AF
and 6063 AF for the three different scenarios respectively.
3- Sensitivity analysis of the infiltration rate parameter to total net project benefits was
evaluated and it showed that considering all the costs and constraints, the potential net
benefit of replenishing groundwater basin by removing a section of LA River and
pumping the stored water in ten years is approximately $ 12,776,478, $ 14,246,845and $
10,050,950 in three different scenarios (infiltration rate 3 ft/d, 5 ft/d and 1.5 ft/d
respectively).
4- The groundwater level after ten years of constant recharging and pumping is
approximately 180 ft to 213 ft below the ground surface which satisfies the assumption
99
made by WRD in Table 1. However, this study does not include potential water quality
impacts from contaminated sites in the basin and a detailed study regarding water quality
issues is recommended.
5- Although, by conducting this research, the amount of pumping rate could be increased,
the Central Groundwater Basin is adjudicated and therefore the pumping rights are fixed.
Hence, pumping could not increase unless a court action takes effect to allow the
increase.
6- Another possibility is to pump the replenished water as “Stored Water”, and it could be
used to help fill up the accumulated overdraft to better drought-proof the region [27]. A
partnership can be established with a groundwater provider so that they could claim this
Stored Water as theirs, and then they could pump it later. This way, it will not be
considered as part of their adjudicated pumping right. But, that would have to be
approved by the Storage Panel in the Central Basin – a group of pumpers and WRD
Board members who evaluate any new groundwater storage project [27].
6.3. Recommendations
The preliminary results obtained by the developed model in this research show that in regions
with unconfined aquifers especially with high permeability deposits/soils, there is a potential to
replenish groundwater by opening the bottom section of the LA River channel. Since a big
portion of LA river water is treated water which people usually are not willing to directly
consume, sending this water into ground may be a reasonable and potential plan to increase the
groundwater supply. Such groundwater supply will be a valuable source of water in LA area. In
what follows, I will describe the plans for future research
100
6.3.1. Pilot Testing
Before starting this project, pilot testing can be conducted to evaluate the time, cost and
feasibility of this proposal in a small-scale trial. For instance, we could simply open ¼ mi x 16 ft
of the channel and run for a long enough period to represent the variations of seasonal flows in
the river. Subsequently, our results can be calibrated to actual data and used to predict larger-
scale projects.
6.3.2. Flood analysis
As mentioned in the previous chapter, a detailed study should be carried out to fully
determine the two way interaction between the artificial recharge project and a flood event. In
the previous chapter, we previously estimated how likely it is to experience a flood event, and
what impact the removal of the pavement play in changing the flow rate, which could increase
the chance of a flood. Based on the modified roughness coefficient, using the Manning equation,
the flow rate was calculated to be 7% smaller than the flow rate when the concrete pavement is
intact.
6.3.3. Liquefaction
The impact of the proposed artificial recharge may have an impact on the liquefaction
potential in the study area. Liquefaction is the process through which saturated fine deposits,
such as sand and silt, can behave like liquids during and after earthquakes [49]. Groundwater rise
can increase the possibility of ground failure when shaken by earthquake. Therefore, a study will
be performed order to investigate the possible impacts of the artificial charge on the liquefaction.
101
Bibliography
[1] U.S. Geological Survey, “Where is Earth's water located?,” 2012.
[2] World Health Organization and UNICEF, “Water for life: Making it happen,” 2005.
[3] D. Lee, “U.S. population in cities growing faster than in suburbs,” Los Angeles Times,
2012.
[4] B. Boxall, “California drought could force key water system to cut deliveris,” Los Angeles
Times Magazine, 2014.
[5] “U.S. Drought Monitor,” Nov 2014. [Online]. Available:
http://droughtmonitor.unl.edu/Home/StateDroughtMonitor.aspx?CA.
[6] Water Education Foundation, “Where does my water come from?,” 2006.
[7] D. K. Todd and L. W. Mays, Groundwater Hydrology, Wiley.
[8] H. Bouwer, J. T. Back and J. M. Oliver, “PREDICTING INFILTRATION AND GROUND-
WATER MOUNDS FOR,” JOURNAL OF HYDROLOGIC ENGINEERING, pp. 350-357,
1999.
102
[9] H. Bouwer, “Artificial recharge of groundwater: hydrogeology and engineering,”
Hydrogeology Journal, vol. 10, p. 121–142, 2002.
[10] P. Brunner, P. G. Cook and C. T. Simmons, “Disconnected Surface Water and
Groundwater: From Theory to Practice,” Groundwater, vol. 49, no. 4, pp. 460-467, 2011.
[11] W. E. F. Montgomery Watson America, “Groundwater and Surface Water in Southern
Califonia, A Guid to Conjunctive Use,” Association of Ground Water Agencies, 2000.
[12] C. H. Ted Johnson, “An introduction to the Central and West Coast Basin,” water
replenishment distcrict of southern california, 2005.
[13] S. Nixon, Coastal marine eutrophication, 1995.
[14] M. Sophocleous, “Interactions between groundwater and surface water:,” 2002.
[15] T. Winter, J. Harvey, L. Franke and W. Alley, “groundwater and surface water, A single
source,” 2010.
[16] U.S. Geological Survey, “Geological, Hydrological, and Biological Issues Related to the
Proposed Development of a Park at the Confluence of the,” 2004.
[17] E. Kalbus, F. Reinstorf and M. Schirmer, “Measuring methods for groundwater – surface
103
water interactions: A reveiw,” Hydrology and earth system sciences, vol. 10, pp. 873-887,
2006.
[18] “Darcy's Law Basics and More,” [Online]. Available:
http://biosystems.okstate.edu/darcy/LaLoi/basics.htm.
[19] W. Walton, Groundwater resource evaluation, 1970.
[20] L. Tomilson and K. Rushton, “Possible mechanisms for leakage between aquifers and
rivers,” Journal of Hydrology, vol. 40, pp. 49-65, 1979.
[21] B. R. Chahar1, “Analysis of Seepage from Polygon Channels,” JOURNAL OF
HYDRAULIC ENGINEERING, pp. 451-460, 2007.
[22] D. R. Lee, “ Device for Measuring Seepage Flux in Lakes and Estuaries,,” vol. 22, pp. 140-
147.
[23] M. S. Hantush, “Growth and decay of groundwater-mounds in response to uniform
percolation,” Water resources research, pp. 227-234, 1967.
[24] G. B. Carleton, “Simulation of Groundwater Mounding Beneath Hypothetical Stormwater
Infiltration Basins,” U.S. Geological Survey, 2010.
104
[25] E. G. Reichard, M. Land, S. M. Crawford, T. Johnson, R. R. Everett, T. V. Kulshan, D. J.
Ponti, K. J. Halfored, T. A. Johnson, K. S. Paybins and T. Nishikawa, “Geohydrology,
Geochemistry, and Ground-Water Simulation-Optimization of the Central and West Coast
Basins, Los Angeles County, California, Everett, Trayle V. Kulshan, Daniel J. Ponti, Keith
J. Halford, Theodore A. Johnson, Katherine S. Paybins, and Tracy,” USGS, 2003.
[26] “Water Replenishment District of Southern California,” December 2014. [Online].
Available: www.wrd.org.
[27] T. Johnson, Interviewee, Chief Hydrologist. [Interview]. Nov 2014.
[28] C. Conkle, J. Moyer, B. Willardson, I. Nasseri and A. Walden, “Hydrology Manual,” Los
Angeles County Department of Public Works, 2006.
[29] UNITED STATES ENVIRONMENTAL PROTECTION AGENCY, REGION IX, “Special
Case Evaluation Regarding Status of The Los Angeles River,” 2010.
[30] T. T. Inc, “Los Angeles River Analysis,” 2009.
[31] D. Ackerman, K. C. Schiff, H. Trim and M. Mullin, “Characterization of water quality in
the,” SCCWRP Annual Report 2001-02, 2003.
[32] “Coastal Plain of Los Angeles Groundwater Basin, Central Subbasin,” California's
105
Groundwater Bulletin 118, 2004.
[33] State of California Department of Water Resources, “Planned Utilization of The
Groundwater Basins of the Coastal Plain of Los Angeles County, Bulletin 104, Appendix
A,” 1961.
[34] “Groundwater Vistas,” Environmental Simulations, Inc, [Online]. Available:
http://www.groundwatermodels.com/.
[35] J. O. Rumbaugh and D. B. Rumbaugh, “Guide to Using Groundwater Vistas,”
Environmental Simulations Inc..
[36] S. M. Gorelick, “A review of distributed parameter groundwater management modeling
methods,” Water Resources Research, vol. 19, pp. 305-319, 1983.
[37] R. Peralta, H. Azarmina and S. Takahashi, “Embedding and Response matrix Techniques
for Maximizing Steady-State Groundwater Extraction: Computational Camparison,”
Groundwater, vol. 29, pp. 357-364, 1991.
[38] A. Singh, “An overview of the optimization modelling applications,” Journal of Hydrology,
Vols. 466-467, pp. 167-182, 2012.
[39] E. Aguado and I. Remson, “Groundwater Hydraulics in Aquifer Management,” Journal of
106
the Hydraulics, vol. 100, pp. 103-118, 1974.
[40] M. Alley, E. Aguado and I. Remson, “Aquifer Management Under Transient and Steady-
State Conditions,” vol. 12, pp. 963-972, 1976.
[41] A. S. Lee and J. Aronofsky, “A Linear Programming Model for Scheduling Crude Oil
Production,” Journal of Petroleum Technology, vol. 10, 1958.
[42] D. C. McKinney and M.-D. Lin, “Genetic algorithm solution of groundwater management
models,” Water Resources Research, vol. 30, pp. 1897-1906, 1994.
[43] M. Pulido-Velázquez, J. Andreu and A. Sahuquillo, “Economic Optimization of
Conjunctive Use of Surface Water and Groundwater at the Basin Scale,” Journal of Water
Resources Planning and Management, vol. 132, pp. 454-467, 2006.
[44] W. Walton, "Selected analytical methods for well and aquifer evaluation, Illinois State
Water Survey Bulletin 49," Urbana, Illinois, 1962.
[45] C. Jacob, "Drawdown test to determine effective radius of artesian well," Society of Civil
Engrs, vol. 112, pp. 1047-1064, 1947.
[46] M. Sellers, B. Chong and N. Matsumoto, “Installing a Water Supply Well in the Central and
West Coast Basins – Issues and Costs,” Water Replenishment District of Southern
107
California, 2005.
[47] “LOS ANGELES COUNTY DRAINAGE AREA (LACDA) PROJECT,” Los Angeles
Department of Water and Power, [Online]. Available:
http://ladpw.org/wmd/watershed/LA/LACDA_Drainage.cfm.
[48] P. E. Eric Batman, Value/Cost of water, LA county, Department of public work, 2014.
[49] “About Liquefaction,” USGS, [Online]. Available:
http://geomaps.wr.usgs.gov/sfgeo/liquefaction/aboutliq.html.
[50] ASTM standards: Standard guid for application of a groundwater flow model to a Site-
Specific Problem, American Society for Testing and Materials, 1993.
[51] D. E. Prudic, L. F. Konikow and E. R. Banta, “A NEW STREAMFLOW-ROUTING
(SFR1) PACKAGE TO SIMULATE STREAM-AQUIFER INTERACTION WITH
MODFLOW-2000,” U.S Geological Survey, 2004.
[52] M. Sellers, B. Chong and N. Matsumoto, “Installing a Water Supply Well in the Central and
West Coast Basins – Issues and Costs,” Water Replenishment District of Southern
California, 2005.
108
Abbreviations and Definitions
AC acre
Acre-ft or AF acre-foot
acre-ft/yr or AFY acre-feet per year
Alluvial A geologic term describing beds of sand, gravel, silt, and clay deposited
by flowing water.
Aquifer A geologic formation or group of formations which store, transmit, and
yield significant quantities of water to wells and springs.
Basin Paso Robles Groundwater Basin
Basin Watershed The surrounding watershed which is tributary to the Paso Robles
Groundwater Basin.
Drawdown The change in hydraulic head or water level relative to a background
condition.
DWR California Department of Water Resources
Formation A geologic term that designates a body of rock or rock/sediment strata of
similar lithologic type or combination of types.
ft feet, foot
ft/day feet per day
GEOSCIENCE Geoscience Support Service, Inc.
GIS Geographic Information System
gpm gallons per minute
Groundwater Water contained in interconnected pores located below the water table
in an unconfined aquifer or located in a confined aquifer.
GW groundwater
Groundwater Storage Groundwater which becomes part of an aquifer system until it is
removed (either naturally or anthropologically).
Head Energy, produced by elevation, pressure, or velocity, contained in a
water mass.
109
Abbreviations and Definitions (cont.)
Hydraulic Conductivity The measure of the ability of the soil to transmit water, dependent upon
both the properties of the soil and those of the fluid.
in. inch
in/yr inch per year
K See Hydraulic Conductivity
MCWRA Monterey County Water Resources Agency
MODFLOW 96/88 A modular finite-difference flow model developed by the United States
Geologic Survey (USGS) to solve the groundwater flow equation.
Permeability The capability of soil or other geologic formations to transmit water. The
term is used to separate the effects of the medium from those of the
fluid on the hydraulic conductivity.
Specific Yield The ratio of the volume of water that a saturated rock or soil will yield by
gravity to the total volume of the rock or soil.
Stress Period Represents a period of time during which all model stresses remain
constant.
Transient Model calibration process for which the groundwater rate and flow
direction vary with time.
USGS United States Geological Survey
Watershed An area of land that drains all the streams and rainfall to a common
outlet.
Water Year or WY Term used in hydrology to describe a time period of 12 months for which
precipitation totals are measured.
Abstract (if available)
Abstract
This dissertation investigates the feasibility of using artificial recharge derived from surface water in a portion of the Los Angeles River north of the city of Los Angeles in Southern California. Currently, the river channel in this area is concrete lined with no percolation capability. The purpose of this study is to determine the technical and economic feasibility of removing a portion of the lined channel to allow infiltration into aquifers of the Central Basin of Los Angeles County (specifically, the forebay area). Water artificially recharged through a breach in the lined channel will be banked for later use in dry seasons or when otherwise needed to supplement water supply. The study includes removing a portion of the lined channel by removing a portion of the concrete pavement and estimating the amount of artificial recharge that could occur under various infiltration rates for different soils. In addition, the net benefit of replenishing groundwater basin over a ten year study period will be evaluated. If the study period is chosen too short, the project may not be economically feasible. Also, if the study period is chosen too long, then the uncertainty in the parameters that were used for this study will be large. This study is presented in stages with the first stage estimating the amount of surface water that could be recharged into the aquifers using a distributed parameter ground water flow model. The second stage would be an economic feasibility of proposed alternatives developed by enumerating costs associated with the optimal execution of the project as well as potential benefits. In conjunction with this, an optimization pumping plan was formalized. Specifically, well discharge rates were optimized in order to achieve maximum ground water storage within the relevant geohydrological and land use constraints. Based on the optimal pumping rates, pumping costs and value of extracted water was estimated which together, along with construction costs, were analyzed in a comprehensive cost-benefit analysis.
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Ghadiri, Maryam
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Core Title
Feasibility of using a lined portion of the Los Angeles River for artificial recharge
School
Viterbi School of Engineering
Degree
Doctor of Philosophy
Degree Program
Civil Engineering (Environmental Engineering)
Publication Date
07/24/2015
Defense Date
01/23/2015
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