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CONTENTS <br /> Page Page <br /> Foreword ----------------------------------------III Ground-water development—Continued <br /> Abstract -----------------------------------------Al Effects of ground-water withdrawal on the Central Valley <br /> Introduction--------------------------------------- 1 aquifer system—Continued <br /> Purpose and scope------------------------------- 2 Changes to the ground-water flow system----------- 23 <br /> Basin environment------------------------------- 2 Changes in aquifer storage---------------------- 26 <br /> Previous investigations---------------------------- 7 Land subsidence----------------------------- 27 <br /> Well-numbering system--------------------------- 7 Mechanics of land subsidence----------------- 30 <br /> Hydrogeology ------------------------------------- 7 Areal extent and effects -------------------- 32 <br /> Geologic setting--------------------------------- 8 Quality of ground water------------------------------ 34 <br /> Water-bearing characteristics of the aquifer system Base of freshwater------------------------------- 34 <br /> (post-Eocene continental deposits)--------------- 12 Dissolved solids--------------------------------- 36 <br /> Storage coefficient---------------------------- 12 Hydrochemical facies----------------------------- 36 <br /> Hydraulic conductivity------------------------- 14 Sacramento Valley---------------------------- 37 <br /> Ground-water flow system ---------------------------- 15 San Joaquin Valley --------------------------- 37 <br /> Regional flow ---------------------------------- 15 Problem compounds------------------------------ 39 <br /> Ground water in storage--------------------------- 21 Chloride----------------------------------- 39 <br /> Ground-water development---------------------------- 22 Boron------------------------------------- 39 <br /> History of development --------------------------- 22 Nitrate------------------------------------ 40 <br /> Depth and yield of wells--------------------------- 22 Effects of human activities------------------------- 40 <br /> Effects of ground-water withdrawal on the Central Valley Selected references --------------------------------- 41 <br /> aquifer system----------------------------- 23 <br /> ILLUSTRATIONS <br /> Page <br /> FIGURE 1. Maps showing location of study area----------------------------------------------------------------A3 <br /> 2. Photograph of Sutter Buttes --------------------------------------------------------------------- 5 <br /> 3. Graphs showing precipitation in the Sierra Nevada and runoff in the Central Valley ----------------------------- 5 <br /> 4. Graphs showing mean annual precipitation and cumulative departure of precipitation from mean value, 1860 to 1980, at four <br /> Central Valley stations------------------------------------------------------------------------ 6 <br /> 5. Diagram showing well-numbering system------------------------------------------------------------ 7 <br /> 6. Generalized oblique view of part of Central Valley structural trough----------------------------------------- 9 <br /> 7. Map showing approximate areas of marine deposition during the Tertiary------------------------------------- 10 <br /> 8. Map showing thickness of Central Valley aquifer system ------------------------------------------------- 11 <br /> 9. Geologic and hydrologic units and equivalent layers in digital flow model-------------------------------------- 13 <br /> 10. Diagrams showing concepts of Central Valley aquifer system---------------------------------------------- 16 <br /> 11. Map showing estimated predevelopment water table ---------------------------------------------------- 18 <br /> 12. Representative hydrographs showing long-term changes in ground-water levels in the Central Valley----------------- 19 <br /> 13. Map showing water table in 1976------------------------------------------------------------------ 20 <br /> 14. Generalized sections showing predevelopment and current ground-water flow conditions in the San Joaquin Valley ------- 21 <br /> 15. Maps showing ground-water pumpage in the Central Valley----------------------------------------------- 24 <br /> 16. Diagrams showing change in regional ground-water flow system due to development----------------------------- 26 <br /> 17. Diagrams showing change in effective vertical conductance of Central Valley aquifer system due to development--------- 26 <br /> 18. Map showing estimated change in hydraulic head in lower pumped zone from 1860 to 1961------------------------- 28 <br /> 19. Map showing areal extent of land subsidence in the Central Valley------------------------------------------ 29 <br /> 20. Graph showing relation of ground-water storage to hydraulic head in a compacting aquifer system------------------- 30 <br /> 21. Diagrams showing influence of hydrogeology and well construction on potential for land subsidence ------------------ 31 <br /> 22. Graphs showing changes in hydraulic head and compaction at two wells in subsiding areas of San Joaquin Valley, 1960-80-- 32 <br /> 23. Photograph showing magnitude of subsidence at a site 10 miles southwest of Mendota in the San Joaquin Valley--------- 33 <br /> 24. Map showing distribution of dissolved-solids concentrations in ground water of the Central Valley ------------------- 35 <br /> 25. Map showing chemical types of ground water in the Central Valley ----------------------------------------- 38 <br /> v <br />