Evaluating the hydrologic response to irrigation and aquifer storage and recovery in the Republican River Basin

Irrigation increases crop production in the US and across the world. The primary source of irrigation in many regions is groundwater pumping, which causes significant water level declines in many agricultural areas. Improved water management strategies that are based on knowledge of the hydrologic responses to irrigation are needed to maintain crop production while moving toward sustainable groundwater irrigation practices. We use an integrated hydrologic model with an embedded irrigation module and newly-developed annual irrigation maps to quantify the recharge, transpiration, streamflow, and groundwater responses to irrigation. Irrigation enhances recharge via return flow across the region, mostly during the growing seasons from June to September. Aquifer Storage and Recovery (ASR) is a promising water management strategy that may improve water sustainability in intensive agricultural areas. Through ASR, surface water during moderate to high flow conditions could be stored in the adjacent aquifer and recovered for later use. A systematic method was developed to estimate the regional potential for ASR. Potential ASR sites are evaluated in the High Plains Aquifer, according to a newly-defined natural storage thickness and available water volume. Potential ASR sites are mainly located in the Republican River Basin (RRB) and the central to eastern portions of the Central High Plains.