Evaluation of the APEX Model to Simulate Runoff, Sediment, and Phosphorus Loss from Agricultural Fields in Northeast Wisconsin
Author: Forrest Stephen Kalk
Publisher:
Published: 2018
Total Pages: 236
ISBN-13:
DOWNLOAD EBOOKDue to the negative consequences of elevated nutrients in surface water, research in the Lower Fox River Watershed in northeastern Wisconsin has focused on monitoring, quantifying, and defining techniques to reduce nutrient and sediment runoff. To support these efforts, the United States Geological Service and University of Wisconsin – Green Bay have been collecting data during runoff events at edge of field locations for several years. My research uses these critical data to parameterize an Agricultural Policy/Environmental eXtender (APEX) model to predict runoff, nutrient loads, and sediment loads from cropland. Data from three sites were used to both manually and automatically calibrate the model, and six additional sites were used in the validation of the model. I attempted to improve model predictions during snowmelt periods and for estimates of dissolved phosphorus (DP). Results show that the manually calibrated model out-performed the automatically calibrated model in nearly all comparisons. Runoff, sediment, total phosphorus (TP), and dissolved phosphorus (DP) were all successfully calibrated by the manual model. The automatic model only had reasonable estimates for runoff volumes. Validation of both models were poor overall, although several locations produced acceptable results both statistically and when visualized graphically. Generally, estimates of runoff were most successful during model validation, with slightly weaker estimates of sediment, TP, and DP. Simulation of snowmelt periods remained poor. The fraction of TP that's in the soluble form was simulated more realistically in comparison to previous research.
