Prepared in cooperation with the OKLAHOMA WATER RESOURCES BOARD Hydrogeology, water use, and simulation of flow in the High Plains aquifer in northwestern Oklahoma, southeastern Colorado, southwestern Kansas, northeastern New Mexico, and northwestern Texas Water-Resources Investigations Report 99–4104 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior U.S. Geological Survey Hydrogeology, water use, and simulation of flow in the High Plains aquifer in northwestern Oklahoma, southeastern Colorado, southwestern Kansas, northeastern New Mexico, and northwestern Texas By Richard R. Luckey and Mark F. Becker Water-Resources Investigations Report 99–4104 Prepared in cooperation with the OKLAHOMA WATER RESOURCES BOARD Luckey, R.R., and Becker, M.F.—Hydrogeology, water use, and simulation of flow in the High Plains aquifer in northwestern Oklahoma—USGS/WRIR 99–4104 Printed on recycled paper U.S. Department of the Interior BRUCE BABBITT, 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 U.S. Geological Survey. UNITED STATES GOVERNMENT PRINTING OFFICE: OKLAHOMA CITY 1999 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 Water-Resources Division Box 25286 202 NW 66 St., Bldg. 7 Federal Center Oklahoma City, OK 73116 Denver, CO 80225 Additional information about water resources in Oklahoma is available on the World Wide Web at http://ok.water.usgs.gov iii Contents Abstract. 1 Introduction . 2 Purpose and scope . 2 Description of study area . 2 Previous studies . 7 Geology . 7 Hydrology . 10 Base of aquifer . 11 Potentiometric surface . 11 Saturated thickness . 11 Water-level changes . 15 Hydraulic properties . 15 Recharge and discharge . 16 Water use . 20 Irrigation use . 21 Other use . 22 Total use . 23 Ground-water flow model . 24 Model design . 27 Predevelopment-period simulation . 30 Development-period simulation . 38 Model sensitivity . 46 Simulated response to future withdrawals . 50 Summary . 53 Selected references . 56 Appendix . 61 Summary of information required by Oklahoma water law . 63 Figures 1-2. Maps showing: 1. Location of study area (darker shade). Lighter shade is extent of High Plains aquifer outside the study area. .3 2. Geographic features within the study area. .4 3. Graph showing five-year moving-average annual precipitation for the Panhandle Climatic Division of Oklahoma. .5 4-10. Maps showing: 4. Major structural features and geologic units underlying the High Plains aquifer (modified from Hart and others, 1976, and Gutentag and others, 1984). .9 5. Altitude of the base of the High Plains aquifer in Oklahoma. 12 6. Altitude of January 1998 potentiometric surface of the High Plains aquifer in Oklahoma. 13 7. Generalized January 1998 saturated thickness of the High Plains aquifer in Oklahoma. 14 iv 8. Predevelopment to January 1998 water-level change of the High Plains aquifer in Oklahoma. 17 9. Hydraulic conductivity of the High Plains aquifer . 18 10. Specific yield of the High Plains aquifer . 19 11. Graph showing number of large-capacity wells tapping the High Plains aquifer in Oklahoma. 20 12. Diagram showing model cell with typical inflows and outflows. 26 13-16. Maps showing: 13. Boundary conditions for the model of the High Plains aquifer in Oklahoma. 28 14. Grid for the model of the High Plains aquifer in Oklahoma (only active cells are shown). 29 15. Areas where salt dissolution has occurred in Permian-age rocks underlying the High Plains aquifer (lightly shaded areas). 32 16. Mean 1961-90 precipitation and simulated greater-recharge areas. 33 17. Graph showing relation between simulated and observed water levels at observation wells in Oklahoma for the predevelopment-period model. 35 18. Map showing difference between simulated and observed predevelopment water levels. 36 19. Histogram showing difference between simulated and observed predevelopment water levels at model nodes. ..