Ground-water flow in the Central Valley, California
The agricultural productivity of the Central Valley is dependent on the availability of water from irrigation. About 7.3 million acres of cropland in the Central Valley receives about 22 million acre-feet of irrigation water annually. One half of this irrigation water is supplied by ground water, which amounts to about 20 percent of the Nation's ground-water pumpage. Ground water is important as a stable supply of irrigation water because of the high variability of surface-water supplies in the Central Valley. This large ground-water development during the past 100 years has had major impacts on the aquifer system, such as decline in water levels, land subsidence, depletion of the aquifer storage, and increase in recharge. The flow conditions before and during development were simulated on a regional scale using a three-dimensional finite-difference flow model. The concept presented in this report considers the entire thickness of the continental deposits as one aquifer system which has varying vertical leakance that depends on several factors, including amount of fine-grained sediments. The average horizontal hydraulic conductivity is about 6 feet per day, and the average thickness of the continental deposits is about 2,400 feet. The simulation results are shown on maps for comparison with observed hydrologic data. A description of the computer-tape file, which contains estimates of recharge/discharge, and the aquifer properties used in the simulation are included in appendix A and B, respectively. The theoretical basis of calculating borehole hydraulic conductance of multilayer wells which cause increases in vertical leakance during the post-development period is discussed in appendix C.
- OSTI ID:
- 6265446
- Journal Information:
- United States Geological Survey, Professional Paper; (USA), Journal Name: United States Geological Survey, Professional Paper; (USA) Vol. 1401-D; ISSN XGPPA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
540310 -- Environment
Aquatic-- Basic Studies-- (1990-)
58 GEOSCIENCES
580000* -- Geosciences
AGRICULTURE
AQUIFERS
CALIFORNIA
DATA
DIMENSIONS
DRAWDOWN
FEDERAL REGION IX
FINITE DIFFERENCE METHOD
FLOW MODELS
FLUID FLOW
GROUND SUBSIDENCE
GROUND WATER
HYDRAULIC CONDUCTIVITY
HYDROGEN COMPOUNDS
HYDROLOGY
INDUSTRY
INFORMATION
IRRIGATION
ITERATIVE METHODS
MAPS
MATHEMATICAL MODELS
NORTH AMERICA
NUMERICAL SOLUTION
OXYGEN COMPOUNDS
PERMEABILITY
PUMPING
RECHARGE
REGIONAL ANALYSIS
RESOURCE DEPLETION
ROCKS
SEDIMENTARY ROCKS
SEDIMENTS
SIMULATION
THICKNESS
THREE-DIMENSIONAL CALCULATIONS
USA
VALLEYS
WATER