Modeling the Impact of Climate Change and Land-Use Change on Kansas Reservoirs

The water quality in Kansas reservoirs is closely linked to local land-use, and it is very important to be able to assess the degree to which future changes in land-use might improve or impair human use of these vital water resources. This analysis was designed to test the applicability and suitability of EUTROMOD for quantitative water quality prediction in Kansas reservoirs. EUTROMOD is a spreadsheet model that can be used to predict reservoir water quality from watershed land-use, local soil characteristics, and other key variables. Thirty Kansas reservoirs were modeled using data from the Kansas Department of Health and Environment (KDHE) and the National Resources Conservation Service. Predicted water quality outputs from the model (concentrations of total phosphorus, total nitrogen and chlorophyll a) were then plotted against actual measured values obtained from a long-term water quality database developed by the KDHE. Predictions of total phosphorus and chlorophyll a concentrations were improved with the use of the Canfield-Bachman phosphorus loading model, and a regional chlorophyll a predictive model developed by Jack Jones and others. The results of this initial modeling assessment will be used in conjunction with the Soil and Water Assessment Tool (SWAT), a process-based watershed model, to forecast the watershed response to detailed climate and land-use change. We will then be able to analyze the impacts of farmers’ land-use choices on reservoir water quality, for example, as they switch from food production to cultivating biofuel crops, or as they implement new land management practices.