Simulation of Ground-Water Flow in the Mojave River Basin, California By CHRISTINA L. STAMOS, PETER MARTIN, TRACY NISHIKAWA, and BRETT F. COX U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 01-4002 Version 3 Prepared in cooperation with the MOJAVE WATER AGENCY 7208-20 Sacramento, California 2001 U.S. DEPARTMENT OF THE INTERIOR GALE A. NORTON, Secretary U.S. GEOLOGICAL SURVEY Charles G. Groat, Director The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the United States Government. For additional information write to: Copies of this report can be purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Information Services Placer Hall, Suite 2012 Box 25286 6000 J Street Federal Center Sacramento, CA 95819-6129 Denver, CO 80225 CONTENTS Abstract.................................................................................................................................................................................. 1 Introduction .......................................................................................................................................................................... 2 Purpose and Scope ...................................................................................................................................................... 3 Description of Study Area .......................................................................................................................................... 3 Acknowledgments ...................................................................................................................................................... 5 Surface-Water Hydrology ..................................................................................................................................................... 6 The Mojave River ....................................................................................................................................................... 6 Ungaged Tributary Streams ........................................................................................................................................ 15 Ground-Water Hydrology ..................................................................................................................................................... 16 Geologic Setting ......................................................................................................................................................... 17 Stratigraphic Units....................................................................................................................................................... 19 Definition of Aquifers ................................................................................................................................................. 24 Effects of Faulting on Ground-Water Flow ................................................................................................................ 24 Ground-Water Recharge and Discharge ..................................................................................................................... 28 Recharge ........................................................................................................................................................... 28 The Mojave River ................................................................................................................................... 28 Mountain-Front Recharge ....................................................................................................................... 30 Artificial Recharge .................................................................................................................................. 31 Irrigation-Return Flow .................................................................................................................. 31 Fish Hatchery Discharge ............................................................................................................... 32 Treated Sewage Effluent ............................................................................................................... 32 Septic Systems .............................................................................................................................. 36 Imported Water ............................................................................................................................. 38 Discharge .......................................................................................................................................................... 38 Pumpage ................................................................................................................................................. 38 Evapotranspiration .................................................................................................................................. 42 Transpiration by Phreatophytes and Hydrophytes ........................................................................ 42 Bare-Soil Evaporation from Dry Lakes ........................................................................................ 44 Free-Surface Evaporation ............................................................................................................. 44 Underflow at Afton Canyon .................................................................................................................... 44 Ground-Water Flow Model ................................................................................................................................................... 44 Model Grid ................................................................................................................................................................. 45 Model Boundary Conditions ....................................................................................................................................... 48 Aquifer Properties ............................................................................................................................................. 49 Transmissivity ......................................................................................................................................... 49 Storage Coefficient ................................................................................................................................. 49 Vertical Leakance ................................................................................................................................... 53 Stream-Aquifer Interactions ....................................................................................................................................... 53 Simulation of Recharge .............................................................................................................................................. 58 Mountain-Front Recharge ................................................................................................................................. 58 Artificial Recharge ............................................................................................................................................ 59 Irrigation-Return Flow ............................................................................................................................ 59 Fish Hatchery Discharge and Imported Water ........................................................................................ 59 Treated Sewage Effluent ......................................................................................................................... 59 Septic Systems ........................................................................................................................................ 60 Simulation of Discharge ............................................................................................................................................. 60 Pumpage ........................................................................................................................................................... 60 Recreational Lakes in the Baja Model Subarea ................................................................................................ 61 Contents III Transpiration by Phreatophytes and Bare-Soil Evaporation ............................................................................ 62 Dry Lakes ......................................................................................................................................................... 63 Model Calibration ...................................................................................................................................................... 63 Simulation of Steady-State Conditions ............................................................................................................ 64 Simulation of Transient-State Conditions ........................................................................................................ 66 Simulation Results ..................................................................................................................................................... 75 Steady-State Ground-Water Flow Directions and Travel Times ............................................................................... 86 Evaluation of Effects of Regional-Scale