Submitted to: Nonpoint Source Water Quality Monitoring Results Workshop
Publication Type: Proceedings
Publication Acceptance Date: 8/27/2001
Publication Date: 8/27/2001
Citation: Suttles, J.B., Vellidis, G., Bosch, D.D., Lowrance, R.R., Usery, L. 2001. Use of the annagnps model for a watershed in the coastal plain of Georgia. In Proceedings of the 9th National Nonpoint Source Monitoring Workshop. Conservation Technology Information Center. Purdue University. August 27-30-2001. Interpretive Summary: Non-point source pollution from agricultural watersheds is a significant concern of rural communities. Much can be learned about the most effective management practices for controlling non-point source pollution by simulating watershed processes with dependable natural resource models. To gain confidence in these models and improve their applicability, the watershed models must be tested against observed data. A detailed study was conducted to verify the Annualized Agricultural Nonpoint Source Pollution (AnnAGNPS) model for Coastal Plain Conditions. Simulations of nitrogen, phosphorus, sediment, runoff and peak flow were made for a six-year period. Results from the simulation were compared to 4 years of monitoring data in 7 locations of varying drainage area. Significant differences were found between model simulations and observed data. These differences were attributed to a poor representation of the actual physical lprocesses in the watershed. These results indicate that further work is required to refine the model and incorporate the dominant hydrologic processes of Coastal Plain watersheds.
Technical Abstract: Natural resource models are useful for estimating non-point source water quality impacts of agriculture. Watershed scale models are particularly useful because of the natural complexity of watershed systems. Confidence in model results is built by making comparisons between model simulations and actual observations. Sediment and nutrient loadings in the Piscola Creek watershed in south central Georgia were modeled using the continuous simulation Annualized Agricultural Nonpoint Source Pollution (AnnAGNPS) model. Specifically, nitrogen, phosphorus, sediment, runoff, and peak flow were predicted over a six-year period. Land under cultivation makes up approximately one-third of the 390-km2 watershed. Livestock facilities are predominantly swine, dairy, dairy and beef cattle. Results from the simulation were compared to 4 years of monitoring data in 7 locations of varying drainage area throughout the watershed. Significant differences were found between model simulations and observed data. These differences were attributed to poor representation of the actual physical properties and processes in the watershed. Further work is required to develop improved estimates of the model parameters, refine the model, and incorporated the dominant hydrologic processes of Coastal Plain watersheds.