Modeling Effects of Agricultural Expansion on Groundwater Recharge and Surface Water Runoff in Central Nebraska

Historical increases in agriculture have altered the natural processes of groundwater recharge and surface water runoff in agriculturally dominated landscapes.  The objective of this research is to use the best available data and modeling tools to quantify the historical effects of agriculture expansion on watershed processes in central Nebraska.  The study implements an innovative approach to develop spatial datasets of agricultural land use from the mid-20th century to the present.  The datasets are used as an input for CropSim modeling which utilizes soils, climate, and land use data to simulate crop responses and pumping, recharge, and runoff watershed processes.  Natural conditions are also modeled through time to develop a baseline of recharge and runoff in the absence of anthropogenic activity.  The natural conditions vs. historic conditions results are compared to evaluate the cumulative effects of agricultural expansion on recharge and runoff.  This research leads to a better understanding of the interaction between ground and surface water in response to anthropogenic activity, so that more informed decisions can be made in the future to minimize impacts of expanding agriculture.