Modeling the High Plains Aquifer's Response to Land Use and Climate Change

Abstract

The High Plains Aquifer is extremely important to the economic life of Kansas and the surrounding states, but water is being withdrawn from the aquifer much faster than it is being recharged. Due to the importance of irrigated agriculture to the multi-state region, the imbalance in water-use threatens long-term economic stability. In order for water resource engineers to plan for responsible and sustainable-use of the aquifer, they must be able to predict future water demand with predicted changes in climate and land-use. Seven target counties overlying the High Plains Aquifer were chosen to develop a method of predicting water-use based on land-use and weather records. A water budget model was created to predict irrigation withdrawals from the High Plains Aquifer based on crop-specific evapotranspiration, and the model was validated based on historic reported water-use, weather data, and land-use. In the seven target counties, predicted water use matched historic reported water use with a slope of 1.015. This new model could be used to predict future irrigation demand under different land-use and climate conditions. Additionally, the link between withdrawals and groundwater levels was examined for the seven target counties. In some counties, the change in water surface elevation was correlated with water-use, but in others, the amount of water withdrawn from the aquifer had no impact on the water table. In order to model the impact of future irrigation demand on the aquifer, physical groundwater models such as SWAT and MODFLOW should be utilized.