Quantifying the Impact of Human activities on Water Sustainability and Crop Yields across the High Plains Aquifer using Process-Based Models
Dept. of Geological Sciences, Michigan State University
Water use for agriculture across the High Plains Aquifer (HPA) greatly expanded since the early to mid-1900s. There have also been significant advances in the efficiency of irrigation technologies over the last several decades from flood irrigation, to center pivot, then to Low Energy Precision Application (LEPA) systems. We present a synthesis of monitoring and modeling methods across the HPA region to investigate changes in water availability across this vast region that is dominated by agriculture. The integrated Landscape Hydrology Model (LHM) was used to quantify hydrologic fluxes including evapotranspiration and groundwater recharge across a range of observed climate conditions including the recent drought across the region. The LHM simulations are coupled to groundwater models to investigate the sustainability of recent water use practices and the quantify impacts of aquifer depletion on water levels and streamflows. Simulations are compared to measured water levels that have been synthesized across the region from presettlement to today, and with remotely sensed estimates from the GRACE satellite. We also present simulations that quantify the likely impacts of projected climate changes from the CMIP5 forecasts of global climate. Finally, we explore the likely impacts of projected changes in climate on crop yields under a range of agricultural management choices using the SALUS crop model.