Long run optimization of landscape level irrigation through managed aquifer recharge or expanded surface reservoirs

Abstract

Decades of efforts to reduce groundwater overdraft through investment in irrigation efficiency has, in many cases, failed to reduce aquifer depletion. This is one reason for greater attention to water supply augmentation efforts through the capture of surface water during high flow events for managed aquifer recharge (MAR) or additional surface storage. We use a landscape level model to examine the optimal interaction among MAR, surface reservoir storage, crop choice, and groundwater conservation policies in Eastern Arkansas. We find the cost of MAR water must be less than half the average groundwater pumping cost to increase the aquifer level. Increases in irrigation intensive crops mean that only a fraction of the recharged water raises groundwater levels. We observe that policies to conserve groundwater, such as a pumping cap or tax, are more cost-effective for society with a lower cost of MAR water.