T176 Assessing Groundwater Availability and Sustainability (Posters)

Tuesday, 2 November 2010
8:00 AM - 6:00 PM
Hall D

GROUNDWATER LEVEL, STORAGE-VOLUME CHANGE, AND SUSTAINABILITY IN THE EQUUS BEDS AQUIFER, KANSAS, 1940-2010

Paper number: T176-5
Program: Technical Sessions
Time: 8:00 AM – 6:00 PM

Authors

Abstract

A part of the Equus Beds aquifer northwest of Wichita, Kansas, which is in an approximately 165-square mile study area in Harvey and Sedgwick Counties, was developed to supply water to residents of Wichita and other surrounding cities and for irrigation in south-central Kansas. Groundwater pumping for city and agricultural use caused water levels to decline, reaching record low water-levels and maximum loss of aquifer storage volume in this part of the Equus Beds aquifer in October 1992. January 1993 to January 2010 was a period of water-level rises and recovery of aquifer storage volume associated with city pumpage from the aquifer that decreased from about 60 percent (38,600 acre-feet) to about 30 percent (18,600 acre-feet) of Wichita’s water usage and precipitation that averaged 1.89 inches more than the long-term (1940-2009) average of 31.52 inches in the study area. An important factor in the decreased city pumpage was increased use of water from Cheney Reservoir by Wichita. Irrigation pumpage in this period showed no trend in usage but generally was more than city pumpage. In 2007, Wichita implemented Phase 1 of the Equus Beds Aquifer Storage and Recovery project for large-scale artificial recharge of the aquifer. Artificial recharge during 2007-2009 was only about 2550 acre-feet, or equivalent to about 4.4 percent of city pumpage during this period, but is planned to be greater in the future.

The direction of ground-water flow in the Equus Beds aquifer from predevelopment (1940) through January 2010 was generally from west to east. Water-level changes from October 1992 to January 2010 in the Equus Beds aquifer ranged from declines of less than 2 feet to rises of more than 30 feet. Aquifer storage volume in the study area from August 1940 to January 2010 decreased by about 100,000 acre-feet, represented a recovery of about 65 percent of the 283,000 acre-feet of storage volume previously lost from August 1940 to October 1992, and was the largest recovery since October 1992.

Sustainable yield for the Equus Beds aquifer in the study area was estimated to be about 58,000 acre-feet per year using 2 different methods. The sum of permitted annual irrigation (about 45,600 acre-feet) and city (about 31,400 acre-feet) pumpage of 77,000 acre-feet per year greatly exceeds the estimated sustainable yield without artificial recharge.