INTEGRATING HYDROLOGIC MODELS AND SPATIAL DATA IN A DISTRIBUTED INTERNET APPLICATION

Planning and assessment in landand water-resource management are evolving from simple, local-scale problems toward complex, spatially explicit regional ones. Such problems have to be addressed with distributed models that can compute runoff and erosion at different spatial and temporal scales. In addition, to evaluate management practices and their impacts on water quality, land and resource managers need to describe and simulate the impacts of land use and best management practices (BMPs) on watershed response. The extensive data requirements and the difficult task of building input parameter files have long represented an obstacle to the timely and cost-effective use of such complex models by resource managers. To address this problem an Internet-based hydrologic modeling tool, DotAGWA, is being developed. This paper will review the DotAGWA design and features. Introduction Effective watershed decision-making requires the integration of knowledge, data, simulation models, and expert judgment to solve practical problems and provide a scientific basis for decision-making at the watershed scale (NRC 1999). User-friendly decision support tools are needed to help different stakeholder groups develop, understand, evaluate and share alternative watershed management strategies. The tools should integrate a suite of components consisting of database management systems, geographic information systems, simulation models, decision models, and user-friendly interfaces that could then be available to different stakeholder groups. The Internet provides a great opportunity for sharing information and applications with decisionmakers. The Automated Geospatial Watershed Assessment tool (AGWA, see: http://www.tucson.ars.ag.gov/agwa) was developed jointly by the USDA Agricultural Research Service, the U.S. Environmental Protection Agency, the University of Arizona, and the Univ. of Wyoming to conduct hydrologic modeling and watershed assessments at multiple time and space scales (Miller et al., 2002; Goodrich et al., 2006). AGWA is a standalone, desktop application that uses widely available standardized spatial datasets. The required data sets include topography (DEM data), soils, and land-cover data. These data are used to develop input parameter files for two USDA-ARS watershed runoff and erosion models: the Kinematic Runoff and Erosion Model (KINEROS2) (Smith et al., 1995; http://www.tucson.ars.ag.gov/kineros) and the Soil and Water Assessment Tool (SWAT) (Arnold et al., 1994; http://www.brc.tamus.edu/swat/). AGWA is currently being used nationally and internationally. International applications include projects in Israel, Kenya, and Mexico. In 2004, AGWA was added to the EPA BASINS toolbox (BASINS 3.1 – www.epa.gov/OST/BASINS/), a multipurpose environmental analysis system to support environmental assessments. AGWA is also recognized by NASA (i.e. “Coin Chart” , http://wec.gsfc.nasa.gov/index.html) as an environmental modeling tool and decision support system. The development and subsequent support of AGWA has illustrated that the application is useful to many stakeholders and organizations. However, not all of these people have access to the geospatial data or software required to process the geospatial data. While some people recognized the value of the application, they did not have adequate scientific training to understand the inner-workings of the hydrologic models, nor had access to other tools such as geographic information systems. Recognizing these issues lead to the initial development of DotAGWA, an Internet version of the AGWA tool (Miller et al. 2003). This paper will review the current status and design characteristics of DotAGWA. DotAGWA was designed as a shared application used to assist in the decision-making processes and to offset the software and data requirements typically required in a desktop application (Figure 2). The features available in DotAGWA help users share and visualize data. Different stakeholder groups can also interact with the application to help facilitate the communication and decision making processes. Users access the application through an Internet browser interface. Application servers connect the user-interface to the database servers (both spatial and nonspatial). The application servers also connect the user and the data to the hydrologic models. Users can define management scenarios, attach models to a plan and have the application parameterize and run the models for the defined management plan. The user can specify different output formats (i.e., XML, Word doc, HTML) for the resulting simulation output. Finally, the DotAGWA architecture provides access to some of the individual components of the application. For example, the Web Services component of Figure 1 shows a watershed delineator (WShedDelin). The delineator has been implemented as a web service, which makes it available for consumption by other applications over the Internet. Consequently, other application developers could extend these components. W e b S er ve r Web Client response Application Server response requests requests ArcIMS Spatial Server Application Logic ArcSDE Oracle 9i Database ResultsProc Simulate