5. Final Remarks Information and the GIS package developed will be used to evaluate the effectiveness of implemented watershed management practices in decreasing the selected water-quality constituents such as nutrients, pesticides, and suspended sediment into the Cheney reservoir. They may be transferable to other watersheds in Kansas and the Nation with similar hydrologic and land-use characteristics. The future task for the integrated database is to store and manipulate all data within GIS environment and automate the steps for preparing field data as AnnAGNPS input format. 1. Introduction Annualized Agricultural Non Point Source (AnnAGNPS) is a useful tool to assess drainage behavior and sediment yield. The integrated GIS system was develop to handle and provide the large amounts of detailed input data. Moreover, this linkage enables managers to identify sensitive or critical areas of non point source pollution and to perform and evaluate various “what-if” scenarios in the decision-making process related to watershed management and specific water-quality management. In this study, we examined the utility of this newly implemented linkage by modeling the runoff, sediments, and nutrient loadings of Cheney Lake and its associated watershed in south-central Kansas. 2. GIS Interface and Data Management A GIS interface AnnAGNPS-ArcView interface, Spatial AnnAGNPS Extension (SAE), is being developed at the Kansas Geological Survey (KGS) (Tsou et al., 2001). The ArcView interface has the capability of providing maps of various soil properties and nutrient distribution useful for predicting areas with the potential for contributing to total maximum daily load (TMDL). Because of the complexity of input data to AnnAGNPS, a database using ACCESS was developed to store and manage the data. Figure 4. Dominant soil in each cell within Redrock Creek watershed. Figure 5. Land use is predominately agricultural and consists mainly of pasture and cropland. Crops produced in the watershed include corn, grain sorghum, soybeans, and wheat. Figure 1. Relationship between cell ID and field data in the database. Figure 2. Tables of field data 3. Application to Cheney Reservoir Watershed, Kansas Cheney Reservoir has a contributing drainage area of about 933 square miles in five south-central Kansas counties. The contributing drainage area includes the North Fork Ninnescah River and associated tributaries. Cheney Reservoir, constructed by the Bureau of Reclamation, U.S. Department of the Interior, between 1962 and 1965 serves as a water-supply source, flood control, and venue for recreational activities such as boating and fishing. The reservoir has a conservation-pool storage of 151,800 acre-feet, with an additional flood- control-pool capacity of 80,860 acre-feet. The City of Wichita, Kansas, a major metropolitan area, acquires much of its daily water supply from Cheney Reservoir. Figure 7. Mean annual phosphorus yields. Figure 6. Sampling locations in Cheney Reservoir watershed. Figure 9. Comparison between modeling and observation Abstract Sediment yield and water quality are inherently affected by the spatial and temporal variations of a watershed. Hence, distributed-parameter models are often applied to watershed assessment. Annualized Agricultural Non Point Source (AnnAGNPS) is a cell-based continuous-simulation model used widely to investigate surface runoff and non point source pollution. This model requires over 400 separate input parameters of 34 data categories (e.g., climate, land characterization, field operations, chemical characteristics, and feedlot operations). Because of the complexity of data requirements, a user-friendly interface was developed to directly link with a Geographic Information System (GIS, ESRI ArcView) and a database- management system (Microsoft Access) to facilitate data preparation, manipulation, and analysis as well as output display and interpolation. The interface was built as an ArcView Extension so that it can be easily adopted by state and regional watershed/lake managers and others. This customized linkage provides a powerful assessment tool that allows managers to visually evaluate surface runoff and water quality that AnnAGNPS can stimulate. More importantly, this linkage enables managers to identify sensitive or critical areas of non point source pollution and to perform and evaluate various “what-if” scenarios in the decision-making process related to watershed management and specific water-quality management. In this study, we examined the utility of this newly implemented linkage by modeling the runoff, sediments, and nutrient loadings of Cheney Lake and its associated watershed in south- central Kansas. Acknowledgments Appreciation is expressed to Dr. Kyle Mankin, Dr. Samar J. Bhuyan, Dr. Philip Barnes and Qianhong Tang at Kansas State University for sharing their experience in AGNPS and AnnAGNPS. This project was partly funded through the project entitled, “An Integrated Modeling Approach to Predict the Effects of Watershed Management on the Eutrophication of Reservoirs in the Central Plains”, which was supported by United States Environmental Protection Agency. References Milligan, C.R., and Pope, L.M., Occurrence of phosphorus, nitrate, and suspended solids in streams of the Cheney Reservoir Watershed, south-central Kansas, : U.S. Geological Survey Water-Resources Water-Resources Investigations Report , 18 p. Pope, L.M., and Milligan, C.R., Preliminary assessment of phosphorus transport in the Cheney Reservoir Watershed, south-central Kansas : U.S. Geological Survey, Water-resources Investigations Report , 29 p. Tsou, M.-S. and Whittemore, D.O., A user interface for ground-water modeling, an ArcView extension: Journal of Hydrological Engineering, ASCE, v. 6, no. 3, p Tsou, M.-S., Zhan, X., Misgna, G., Wang, S.H., Huggins, D.G., Liu, S., and Volkman, C., Modeling procedures for using AnnAGNPS ArcView extension: Kansas Geological Survey, Open-file Report Integrative Watershed Management Assessment Based on an AnnAGNPS, GIS and Database Management System Linkage Lyle Frees and Chad Volkman, Natural Resources Conservation Service, Salina, KS Ming-Shu Tsou, Girmay Misgna, and Xiaoyong Zhan, Kansas Geological Survey, Lawrence Kansas Shih-Hsien Wang and Donald G. Huggins, Kansas Biological Survey, Lawrence, Kansas Figure 3. Schematic diagram of planned and implemented tasks for the GIS interface. Figure 8. Areas of focus for Phosphorus transport concerns produced with AnnAGNPS results from 1997 land use and land management conditions. Runoff Sediment Phosphorus 4. Result Modeling results are compared with observation of six long-term sampling sites to quantify modeling output for water-quality constituent concentrations and loading characteristics in selected subbasins within the watershed and into and out of Cheney Reservoir.