IMPACT OF RAINFALL VARIABILITY ON GROUNDWATER STORAGE AND CROP PRODUCTION IN NEBRASKA

Climate change has impacted precipitation globally and will continue to do so in the future. In the Midwest from 1958 to 2016, there was a 29% increase in the amount of precipitation falling in the heaviest 1% of events. This trend is expected to continue. Changes in the variability of precipitation, with an increase in rainfall occurring during extreme precipitation events, may lead to changes in groundwater storage and crop production. Weather data files from locations across Nebraska were altered with an R script to reflect three scenarios: 16%, 29%, and 39% increases in the amount of precipitation falling in events above the 99th percentile. These altered files were then used in a DSSAT crop model to predict changes in crop production for corn and soybeans. Changes in crop yield were observed for each scenario, with corn yield generally decreasing in multiple locations and soybean yield increasing in multiple locations. Changes in groundwater storage due to changes in the timing of precipitation and the amount of precipitation becoming recharge were assessed using a MODFLOW model for a region of south-central Nebraska. Both changes in the timing of precipitation and the amount of precipitation becoming recharge affected groundwater storage. Changes in precipitation variability that may affect crop production and groundwater storage are of great importance to the continued sustainability of groundwater and to the agricultural industry, which is a major contributor to Nebraska’s economy.