INTERPRETATION OF DRAWDOWN DATA AFFECTED BY INDUCED GROUNDWATER RECHARGE

This study employs drawdowns impacted by induced groundwater recharge to quantify the recharge rate and verify the transmissivity value of the aquifer. Calculation of recharge and transmissivity is based on the Cooper-Jacob method using the pumping rate corrected for recharge effects. Possible sources of recharge include surface-water bodies, leakage from other aquifers, and precipitation during pumping periods.

Calculation of recharge is demonstrated by an example using pumping test data published by other researchers. The data are obtained from a pumping test conducted in the city of Oakley, Kansas, USA. Recharge began 30 minutes after the start of pumping and continued to the end of the test. Recharge occurred at an increasing rate during the pumping period. The average recharge rate calculated for the entire period is 296.6 gpm.

To check the accuracy of the calculated recharge, the transmissivity of the aquifer is calculated using the equations developed in this study. The equations for calculation of recharge and transmissivity are interrelated. The obtained transmissivity value, 42,400 gpd/ft, is identical to that determined by the authors who conducted the pumping test.