Land use and climate change controls on recharge, northern High Plains aquifer, USA

Abstract

Understanding the controls of land use/land cover and climate change on diffuse recharge rates is critically important to develop appropriate management and sustainability plans for groundwater resources, particularly those in semiarid and arid regions. Much of the High Plains study area has been converted from natural rangeland to irrigated cropland cover. Field-based recharge rate estimates were implemented to quantify the differences in recharge rates beneath two rangeland and two irrigated com sites along an east-west transect in the Platte River Basin in central Nebraska. Historical climate data and the field-based estimates were used to calibrate HYDRUS-1D computer models. A total of 16 different global climate models (GCMs) and two global warming scenarios were used to project a 2050 climate relative to the baseline 1990 climate. The low-global-warming scenario (+1.0°C) projected no statistical differences between any future variables compared to the baseline variables. The high-global-warming scenario (+2.4°C) projected up to a 98% decrease in median annual recharge rate, and a 25% and 15% increase in median annual ET and irrigation, respectively. The high-global-warming scenario projections result in a bidirectional shift of climate gradients. Future northern High Plains temperatures will resemble current central High Plains temperatures and future recharge rates at the eastern study sites will resemble current recharge rates at the western study sites.