Shop – California Water Library

Page

Showing
351-361 of 1126

Per Page

Sort By

Geohydrology of Recharge and Seawater Intrusion in the Pajaro Valley, Santa Cruz and Monterey Counties, California

U.S. Geological Survey (USGS) | August 14th, 2003

Summary

The U.S. Geological Survey (USGS) in cooperation with the Pajaro Valley Water Management Agency (PVWMA), has completed the collection and analyses of geologic, hydrologic

View Document Download Now Email

Geohydrology, Geochemistry, and Ground-Water Simulation-Optimization of the Central and West Coast Basins, Los Angeles County, California By

U.S. Geological Survey (USGS) | January 3rd, 2003

Summary

Historical ground-water development of the Central and West Coast Basins in Los Angeles County, California through the first half of the 20th century caused large water-l

Historical ground-water development of the Central and West Coast Basins in Los Angeles County, California through the first half of the 20th century caused large water-level declines and induced seawater intrusion. Because of this, the basins were adjudicated and numerous groundwater management activities were implemented, including increased water spreading, construction of injection barriers, increased delivery of imported water, and increased use of reclaimed water. In order to improve the scientific basis for these water management activities, an extensive data collection program was undertaken, geohydrological and geochemical analyses were conducted, and ground-water flow simulation and optimization models were developed. In this project, extensive hydraulic, geologic, and chemical data were collected from new multiple-well monitoring sites. On the basis of these data and data compiled and collected from existing wells, the regional geohydrologic framework was characterized. For the purposes of modeling, the three-dimensional aquifer system was divided into four aquifer systems—the Recent, Lakewood, Upper San Pedro, and Lower San Pedro aquifer systems. Most pumpage in the two basins is from the Upper San Pedro aquifer system. Assessment of the three-dimensional geochemical data provides insight into the sources of recharge and the movement and age of ground water in the study area. Major-ion data indicate the chemical character of water containing less than 500 mg/L dissolved solids generally grades from calcium-bicarbonate/sulfate to sodium bicarbonate. Sodium-chloride water, high in dissolved solids, is present in wells near the coast. Stable isotopes of oxygen and hydrogen provide information on sources of recharge to the basin, including imported water and water originating in the San Fernando Valley, San Gabriel Valley, and the coastal plain and surrounding hills. Tritium and carbon-14 data provide information on relative ground-water ages. Water with abundant tritium (greater than 8 tritium units) is found in and downgradient from the Montebello Forebay and near the seawater barrier projects, indicating recent recharge. Water with less than measurable tritium is present in, and downgradient from, the Los Angeles Forebay and in most wells in the West Coast Basin. Water from several deep wells was analyzed for carbon-14. Uncorrected estimates of age for these samples range from 600 to more than 20,000 years before present. Chemical and isotopic data are combined to evaluate changes in chemical character along flow paths emanating from the Montebello and Los Angeles Forebays.

View Document Download Now Email

Geohydrology, Geochemistry, and Groundwater Simulation (1992–2011) and Analysis of Potential Water-Supply Management Options, 2010–60, of the Langford Basin, California

U.S. Geological Survey (USGS) | October 30th, 2013

Summary

Groundwater withdrawals began in 1992 from the Langford Basin within the Fort Irwin National Training Center (NTC), California. From April 1992 to December 2010

Groundwater withdrawals began in 1992 from the Langford Basin within the Fort Irwin National Training Center (NTC), California. From April 1992 to December 2010, approximately 12,300 acre-feet of water (averaging about 650 acre-feet per year) has been withdrawn from the basin and transported to the adjacent Irwin Basin. Since withdrawals began, water levels in the basin have declined by as much as 40 feet, and the quality of the groundwater withdrawn from the basin has deteriorated. The U.S. Geological Survey collected geohydrologic data from Langford Basin during 1992–2011 to determine the quantity and quality of groundwater available in the basin. Geophysical surveys, including gravity, seismic refraction, and time-domain electromagnetic induction surveys, were conducted to determine the depth and shape of the basin, to delineate depths to the Quaternary-Tertiary interface, and to map the depth to the water table and changes in water quality. Data were collected from existing wells and test holes, as well as 11 monitor wells that were installed at 5 sites as part of this study . Water-quality samples collected from wells in the basin were used to determine the groundwater chemistry within the basin and to delineate potential sources of poor-quality groundwater. Analysis of stable isotopes of oxygen and hydrogen in groundwater indicates that present-day precipitation is not a major source of recharge to the basin. Tritium and carbon-14 data indicate that most of the basin was recharged prior to 1952, and the groundwater in the basin has an apparent age of 12,500 to 30,000 years. Recharge to the basin, estimated to be less than 50 acre-feet per year, has not been suffcient to replenish the water that is being withdrawn from the basin. year of natural recharge derived from precipitation runoff and as much as 40 acre-feet per year of underfow from the Irwin Basin. Between April 1992 and December 2010, an average of about 650 acre-feet per year of water was withdrawn from the Langford Basin. Groundwater withdrawals in excess of natural recharge resulted in a net loss of 11,670 acre-feet of groundwater storage within the basin for the simulation period. A numerical groundwater-fow model was developed for the Langford Basin to better understand the aquifer system used by the Fort Irwin NTC as part of its water supply, and to provide a tool to help manage groundwater resources at the NTC. Measured groundwater-level declines since the initiation of withdrawals (1992–2011) were used to calibrate the groundwater-fow model. The simulated recharge was about 46 acre-feet per year, including approximately 6 acre-feet per year of natural recharge derived from precipitation runoff and as much as 40 acre-feet per year of underflow from the Irwin Basin. Between April 1992 and December 2010, an average of about 650 acre-feet per year of water was withdrawn from the Langford Basin. Groundwater withdrawals in excess of natural recharge resulted in a net loss of 11,670 acre-feet of groundwater storage within the basin for the simulation period. The Fort Irwin NTC is considering various groundwater-management options to address the limited water resources in the Langford Basin. The calibrated Langford Basin groundwater-flow model was used to evaluate the hydrologic effects of four groundwater-withdrawal scenarios being considered by the Fort Irwin NTC over the next 50 years (January 2011 through December 2060). Continuation of the 2010 withdrawal rate in the three existing production wells will result in 70 feet of additional drawdown in the central part of the basin. Redistributing the 2010 withdrawal rate equally to the three existing wells and two proposed new wells in the northern and southern parts of the basin would result in about 10 feet less drawdown in the central part of the basin but about 100 feet of additional drawdown in the new well in the northern part of the basin and about 50 feet of additional drawdown in the new well in the southern part of the basin. Reducing the withdrawals from the three existing production wells in the central part of the basin from about 45,000 acre-feet to about 32,720 acre-feet would result in about 40 feet of additional drawdown in the central basin near the pumping wells, about 25 feet less than if withdrawals were not reduced. The combination of reducing and redistributing the cumulative withdrawals to the three existing and two proposed new wells results in about 40 feet of additional drawdown in the central and southern parts of the basin and about 70 feet in the northern part of the basin. These results show that reducing and redistributing the groundwater withdrawals would maintain the upper aquifer at greater than 50 percent of its predevelopment saturated thickness throughout the groundwater basin. The scenarios simulated for this study demonstrate how the calibrated model can be utilized to evaluate the hydrologic effects of different water-management strategies.

View Document Download Now Email

Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin, Fort Irwin National Training Center, California

U.S. Geological Survey (USGS) | July 19th, 2018

Summary

Groundwater pumping from Bicycle Groundwater Basin (referred to as Bicycle Basin) in the Fort Irwin National Training Center, California, began in 1967. From 1967 to Dece

Groundwater pumping from Bicycle Groundwater Basin (referred to as Bicycle Basin) in the Fort Irwin National Training Center, California, began in 1967. From 1967 to December 2010, about 46,000 acre-feet of water had been pumped from the basin and transported to the Irwin Basin. During this time, not only did water levels in the basin decline by as much as 100 feet, the quality of the groundwater pumped from the basin also deteriorated in some wells. The U.S. Geological Survey collected geohydrologic data from existing wells, test holes, and 16 additional monitoring wells installed at 6 sites in Bicycle Basin during 1992–2011 to determine the quantity and quality of groundwater available in the basin. Geophysical surveys, including electrical, gravity, and seismic refraction surveys, were completed to help determine the geometry of the structural basin, delineate depths to the interface between Quaternary and Tertiary rocks, map the depth to the water table, and used to develop a geohydrologic framework and groundwater-flow model for Bicycle Basin. Water samples were used to determine the groundwater quality in the basin and to delineate potential sources of poor-quality groundwater. Analysis of stable isotopes of oxygen and hydrogen in groundwater indicated that present-day precipitation is not a major source of recharge to the basin. Tritium and carbon-14 data indicated that most of the groundwater in the basin was recharged prior to 1952 and had an apparent age of 15,625–39,350 years. Natural recharge to the basin was not sufficient to replenish the groundwater pumped from the basin. Interferograms from synthetic aperture radar data (InSAR), analyzed to evaluate land-surface subsidence between 1993 and 2010, showed 0.23 to 1.1 feet of subsidence during this period near one production well north of Bicycle Lake (dry) playa. A groundwater-flow model of Bicycle Basin was developed and calibrated using groundwater levels for 1964–2010, and a subsidence model using land-surface deformation data for 1993–2010. Between January 1967 and December 2010, the simulated total recharge from precipitation runoff and underflow from adjacent basins was about 5,100 acre-feet and pumpage from the Bicycle Basin was about 47,000 acre-feet of water. Total outflows exceeded natural recharge during this period, resulting in a net loss of about 42,100 acre-feet of groundwater storage in the basin. The Fort Irwin National Training Center is considering various groundwater-management options in the Bicycle Basin. The groundwater-flow model was used to (1) evaluate changes in groundwater levels and subsidence with the addition of capture and recharge of simulated runoff in retention basins (scenario 1) for predevelopment through 2010; (2) simulate a base case (scenario 2) for reference; and (3) compare projections of alternative future pumping strategies for 2011–60 (scenarios 3–5). Model results from the runoff-capture simulation (scenario 1) indicated that total recharge, including runoff captured using retention basins, locally increased water levels, which partially offset, but did not mitigate, groundwater depletion associated with pumping. Groundwater-storage depletion in scenario 1 was about 14 percent less than without runoff capture. Simulated-drawdown results in model layer 1 in the eastern part of the basin indicated that, because of the captured runoff, simulated heads were as much as 100 feet higher in December 2010 than prior to the onset of development in 1967. In contrast, simulated drawdown for model without runoff capture indicated that, without captured runoff, simulated heads for December 2010 in this area were 80–90 feet lower than during the predevelopment period. Subsidence was mitigated slightly in scenario 1 compared to without runoff capture; the largest decrease in subsidence at observation sites was about 0.07 feet. Scenario 2 results indicated that simulated drawdown in model layer 6 at the end of 2060 ranged from about 46 to 135 feet. Subsidence at observation sites at the end of 2060 ranged from 0.83 to 2.8 feet. Reducing the base case pumping rate by 25 percent in the existing production well in the subsidence area and redistributing the pumpage to the other two production wells (scenario 3) resulted in a reduction of drawdown in the subsidence area compared with the base case (scenario 2). The difference in subsidence at the end of 2060 between scenario 3 and the base case was small (less than 0.07 feet) for all observation locations. Repeating the simulation scenario 3 but additionally reducing the basin-wide pumpage by 3 percent per year from 2011 through 2020 (scenario 4) resulted in about 60 feet less drawdown in the subsidence area than for the base case. Subsidence at observation sites ranged from 0.12 to 0.43 feet less than for the base case. Reducing the pumpage in the existing production well in the subsidence area to zero, while continuing the base case pumping rate in the other two existing production wells (scenario 5), resulted in more than 100 feet less drawdown in the subsidence area than in the base case. The simulated subsidence at the end of 2060 ranged from about 0.19 to about 1.16 feet less than in the base case, indicating that the discontinuation of pumpage at well 14N/3E-14P1 would result in substantially reduced subsidence. Overall, continued water-table declines dewatered the more productive upper layers of the aquifer, causing more groundwater to be withdrawn from deeper, lower yielding layers and resulting in faster declines in the water table and greater vertical gradients in the future. If the water table declines into the perforated intervals of wells, increased maintenance costs and altered well-water quality could potentially result. Water-management scenario 1 indicated that adding managed recharge resulted in a modest decrease (4–5 percent) in the rate of subsidence compared with historical conditions. The reduction of pumpage in the area of subsidence and redistribution of the amount of reduced pumpage to wells in other parts of the basin (scenario 3) resulted in modest decreases (5–6 percent) in the rate of subsidence compared with continuation of historical pumpage. Including either a basin-wide reduction of pumpage of 3 percent annually (cumulatively, a 24 percent decrease) as well as redistribution of the pumpage (scenario 4) or discontinuing pumping in the area of greatest subsidence (scenario 5), however, demonstrated that subsidence could be reduced substantially (22–26 percent for scenario 4 and 62–68 percent for scenario 5) compared with subsidence for continuing historical pumpage.

View Document Download Now Email

Geohydrology, Simulation of Regional Groundwater Flow, and Assessment of Water-Management Strategies, Twentynine Palms Area, California

U.S. Geological Survey (USGS) | June 28th, 2011

Summary

The Marine Corps Air Ground Combat Center (MCAGCC) Twentynine Palms, California, overlies the Surprise Spring, Deadman, Mesquite, and Mainside subbasins of the Morongo gr

The Marine Corps Air Ground Combat Center (MCAGCC) Twentynine Palms, California, overlies the Surprise Spring, Deadman, Mesquite, and Mainside subbasins of the Morongo groundwater basin in the southern Mojave Desert. Historically, the MCAGCC has relied on groundwater pumped from the Surprise Spring subbasin to provide all of its potable water supply. Groundwater pumpage in the Surprise Spring subbasin has caused groundwater levels in the subbasin to decline by as much as 190 feet (ft) from 1953 through 2007. Groundwater from the other subbasins contains relatively high concentrations of fluoride, arsenic, and (or) dissolved solids, making it unsuitable for potable uses without treatment. The potable groundwater supply in Surprise Spring subbasin is diminishing because of pumping-induced overdraft and because of more restrictive Federal drinking-water standards on arsenic concentrations. The U.S. Geological Survey, in cooperation with the MCAGCC, completed this study to better understand groundwater resources in the area and to help establish a long-term strategy for regional water-resource development. The Surprise Spring, Deadman, Mesquite, and Mainside subbasins are filled with sedimentary deposits of Tertiary age, alluvial fan deposits of Quaternary-Tertiary age, and younger alluvial and playa deposits of Quaternary age. Combined, this sedimentary sequence reaches a maximum thickness of more than 16,000 ft in the Deadman and Mesquite subbasins. The sedimentary deposits of Tertiary age yield a small amount of water to wells, and this water commonly contains high concentrations of fluoride, arsenic, and dissolved solids. The alluvial fan deposits form the principal water-bearing unit in the study area and have a combined thickness of 250 to more than 1,000 ft. The younger alluvial and playa deposits are unsaturated throughout most of the study area. Lithologic and downhole geophysical logs were used to divide the Quaternary/ Tertiary alluvial fan deposits into two aquifers (referred to as the upper and the middle aquifers) and the Tertiary sedimentary deposits into a single aquifer (referred to as the lower aquifer). In general, wells perforated in the upper aquifer yield more water than wells perforated in the middle and lower aquifers. The study area is dominated by extensive faulting and moderate to intense folding that has displaced or deformed the pre-Tertiary basement complex as well as the overlying Tertiary and Quaternary deposits. Many of these faults act as barriers to the lateral movement of groundwater flow and form many of the boundaries of the groundwater subbasins. The principal recharge to the study area is groundwater underflow across the western and southern boundaries that originates as runoff in the surrounding mountains. Groundwater discharges naturally from the study area as spring flow, as groundwater underflow to downstream basins, and as water vapor to the atmosphere by transpiration of phreatophytes and direct evaporation from moist soil. The annual volume of water that naturally recharged to or discharged from the groundwater flow system in the study area during predevelopment conditions was estimated to be 1,010 acre-feet per year (acre-ft/yr). About 90 percent of this recharge originated as runoff from the Little San Bernardino and the Pinto Mountains to the south, and the remainder originated as runoff from the San Bernardino Mountains to the west. Evapotranspiration by phreatophytes near Mesquite Lake (dry) was the primary form of predevelopment groundwater discharge. From 1953 through 2007, approximately 139,400 acre-feet (acre-ft) of groundwater was pumped by the MCAGCC from the Surprise Spring subbasin. A regional-scale numerical groundwater flow model was developed using MODFLOW–2000 for the Surprise Spring, Deadman, Mesquite, and Mainside subbasins. The aquifer system was simulated by using three model layers representing the upper, middle, and lower aquifers. Measured groundwater levels for predevelopment conditions (before 1953) and for the period 1953 through 2007 were used to calibrate the groundwater- flow model. The simulated steady-state (predevelopment) recharge was about 980 acre-ft/yr; about 90 percent of the recharge was in the Mesquite subbasin. Most of the simulated steady-state discharge occurred as evapotranspiration at the Mesquite Lake (dry). A total of about 145,450 acre-ft of groundwater was simulated as being pumped from the model domain during the transient simulation period (1953–2007); about 139,400 acre-ft of the total was extracted from the Surprise Spring subbasin. The transient simulation indicates that almost all of the groundwater pumped in the Surprise Spring subbasin comes from groundwater storage, which is consistent with the measured long-term declines in groundwater levels. The calibrated groundwater model was used to evaluate the potential effects on water levels and aquifer conditions in the Surprise Spring, Deadman, Mesquite, and Mainside subbasins for water-management strategies being considered by the MCAGCC to meet the projected water demand at the base for 2008–2017. One of the main objectives of the water-management strategies is to reduce pumpage from the Surprise Spring subbasin. Reducing groundwater pumpage in the Surprise Spring subbasin by about 38 percent (about 1,345 acre-ft/yr) substantially decreased or reversed simulated hydraulic-head declines in the subbasin. Redistributing about 15 percent of the 2007 groundwater pumpage (about 550 acre-ft/yr) from the Surprise Spring to the Mainside subbasin resulted in more than 60 ft of simulated declines in hydraulic head in the Mainside subbasin by 2017; however, redistributing about 22 percent of the 2007 pumpage (about 800 acre-ft/yr) from the Surprise Spring subbasin to the Deadman subbasin resulted in 5–10 ft of simulated hydraulic-head decline in the Deadman subbasin. The water-management scenarios simulated for this study demonstrate how the calibrated regional model can be utilized to evaluate the hydrologic effects of a water-management strategy.

View Document Download Now Email

Geohydrology, Water Quality, and Estimation of Ground-Water Recharge In San Francisco, California, 1987-92

U.S. Geological Survey (USGS) | January 14th, 1993

Summary

The city of San Francisco is considering further development of local ground-water resources as a supplemental source of water for potable or non-potable use. By the y

The city of San Francisco is considering further development of local ground-water resources as a supplemental source of water for potable or non-potable use. By the year 2010, further water demand is projected to exceed the delivery capacity of the existing supply system, from which San Francisco draws most of its water. The existing system is fed by surfacewater sources; thus, supplies are susceptible to drought conditions and damage to conveyance lines by earthquakes. The primary purpose of this study is to describe local geohydrology and water quality, and to estimate ground-water recharge in the area of the city of San Francisco. Seven ground-water basins were identified in San Francisco on the basis of geologic and geophysical data. Basins on the east side of the city are relatively thin and contain a greater percentage of fine-grained sediments than those on the west side. The relatively small capacity of the basins and greater potential for contamination from sewer sources may limit the potential for ground-water development on the east side. Basins on the west side of the city have a relatively large capacity and low density sewer network. Water-level data indicate that the southern part of the largest basin on the west side of the city (Westside basin) probably cannot accommodate additional ground-water development without adversely affecting water levels and water quality in Lake Merced; however, the remainder of the basin, which is largely undeveloped, could be developed further. A hydrologic routing model was developed for estimating ground-water recharge throughout San Francisco. The model takes into account climatic factors, land and water use, irrigation, leakage from underground pipes, rainfall runoff, evapotranspiration, and other factors associated with an urban environment. Results indicate that areal recharge rates for water years 1987-88 for the seven ground-water basins range from 0.32 to 0.78 foot per year. Recharge for the Westside basin was estimated at 0.51 foot per year. Average annual ground-water recharge represents the maximum annual long-term yield of the basin. Attainable yield may be less than the volume of ground-water recharge because interception of all discharge from the basin may not be feasible without inducing seawater intrusion or causing other undesirable effects.

View Document Download Now Email

Geologic Analysis, Ventura River Watershed

Daniel B. Stephens & Associates, Inc. (DBS&A) | March 3rd, 2020

Summary

This memorandum summarizes geologic analysis performed for the Ventura River Watershed (VRW) by Daniel B. Stephens & Associates, Inc. (DBS&A) in support of nume

View Document Download Now Email

Geologic Influences on the Quality of Groundwater Used for Domestic Supply in the Northern Sierra Nevada Foothills

U.S. Geological Survey (USGS) | May 25th, 2021

Summary

Approximately 2 million California residents depend on groundwater from domestic wells for their drinking-water supply. The State of California, in collaboration with the

View Document Download Now Email

Geologic Map and Borehole Stratigraphy of Hinkley Valley and Vicinity, San Bernardino County, California

U.S. Geological Survey (USGS) | December 17th, 2020

Summary

Hinkley Valley, in the central to western Mojave Desert of southeastern California, has a long historical record owing to its position as a crossroads for rail and road t

View Document Download Now Email

Geologic Setting, Geohydrology, and Ground-Water Quality near the Helendale Fault in the Mojave River Basin, San Bernardino County, California

U.S. Geological Survey (USGS) | July 15th, 2003

Summary

The proximity of the Moja ve River groundwater basin to the highly urbanized Los Angeles region has resulted in rapid population growth and, consequently, an increase in

View Document Download Now Email

← Prev

Page : 36

Geohydrology of Recharge and Seawater Intrusion in the Pajaro Valley, Santa Cruz and Monterey Counties, California

Geohydrology, Geochemistry, and Ground-Water Simulation-Optimization of the Central and West Coast Basins, Los Angeles County, California By

Geohydrology, Geochemistry, and Groundwater Simulation (1992–2011) and Analysis of Potential Water-Supply Management Options, 2010–60, of the Langford Basin, California

Geohydrology, Geochemistry, and Numerical Simulation of Groundwater Flow and Land Subsidence in the Bicycle Basin, Fort Irwin National Training Center, California

Geohydrology, Simulation of Regional Groundwater Flow, and Assessment of Water-Management Strategies, Twentynine Palms Area, California

Geohydrology, Water Quality, and Estimation of Ground-Water Recharge In San Francisco, California, 1987-92

Geologic Analysis, Ventura River Watershed

Geologic Influences on the Quality of Groundwater Used for Domestic Supply in the Northern Sierra Nevada Foothills

Geologic Map and Borehole Stratigraphy of Hinkley Valley and Vicinity, San Bernardino County, California

Geologic Setting, Geohydrology, and Ground-Water Quality near the Helendale Fault in the Mojave River Basin, San Bernardino County, California

Filter Results

Type

Topic

Keywords

Publisher

Basin

Hydrological Region

Search for:

Search the California Water Library

Type

Topic

Keywords

Hydrological Region

Basin