Environmental Informatics Archives, Volume 2 (2004), 838-845 EIA04-001 ISEIS Publication #002 © 2004 ISEIS - International Society for Environmental Information Sciences
An Online WebGIS-based Hierarchical Watershed Decision Support System for United States Yi Shi1*, Jeremiah Asher1, Jon Bartholic1, Jin-Yong Choi2, Bernie Engel2, Rick Farnsworth3 1. Institute of Water Research, Michigan State University, 115 Manly Miles Bldg. East Lansing, MI 48823 2.Department of Agriculture Engineering, Purdue University 3. Department of Forestry and Natural Resources, Purdue University
Abstract. The web-based Digital Watershed and Understanding your watershed programs created by Institute of Water Research of Michigan State University established a hierarchical watershed decision support system framework that could be expanded to the whole United States. The Digital Watershed website is designed to provide both a centralized information repository and a computing center for watersheds in the United States. This site is based on the comprehensive database of 8-digit watersheds for the whole continent of the United States, which is included in the EPA BASINS system. The database contains all regulated facilities, river network, DEM, state soil and other data layers. The digital watershed site is interconnected with Michigan's local level watershed decision support system called Understanding your watershed by the scaling function. Understanding Your Watershed is an interactive web-based mapping program utilizing the capabilities of a Web Geographic Information System (WebGIS). The program enables a user to select a Michigan 12-digit watershed and display various features within that watershed such as streets, water bodies, elevation, risk areas, wetlands and other information available across the state. The scaling function provides the seamless transition between two systems. This framework is being used to create and integrate local level watershed information systems for other states in EPA region 5. In the meantime, the decision support tools such as online watershed delineation and L-THIA (Long Term Hydrological Impact Assessment) developed by Purdue University are being integrated into the framework under the online spatial decision support systems interoperability project funded by EPA region 5. This paper describes the design principles and strategies behind the framework, illustrates the system functionality and reports the progress made for the ongoing interoperability project. Keywords: WebGIS, Digital Watershed, Watershed Decision Support System, Scaling Function, L-THIA
1. Introduction In 1991, the U.S. Environmental Protection Agency (USEPA) adopted a watershed management approach for achieving the nation’s environmental, natural resource, human health and economic development goals. The basic decision unit for planning and implementation is a watershed, an area of land where surface water flows to a common point such as a stream, lake or marsh. For each hydrologically defined unit or watershed, stakeholders (individuals and groups who control activities and those impacted by activities occurring in a watershed) employ a problem-solving, science-based process to identify their primary problems, develop and implement least-cost solutions, assess progress, and make necessary modifications to ensure the achievement of their mutually supported ecologic, economic, and social objectives.
*Corresponding author:
[email protected]
Environmental Informatics Archives, Volume 2 (2004), 838-845
In its definitive review of watershed management, the National Research Council (1999) concluded the approach, though promising for integrating human and natural systems and developing workable strategies, required the development of a critical body of integrated physical, biological and economic research and an effective interface for incorporating the science into real-time management. The Council recommended interdisciplinary, problemsolving research and model development to fill the research gap. For an effective interface, they recommended the development of user-friendly decision support systems that assist resource managers, agencies and watershed groups in selecting and implementing science-based strategies. A watershed decision support system encompasses “…a suite of computer programs with components consisting of databases, simulation models, decision models, and user interfaces that assist a decision maker in evaluating the economic and environmental impacts of competing watershed management alternatives” (National Research Council, 1999). In other areas of the report, the Council pointed to the importance of incorporating geographic information systems, using new information technologies and the worldwide web, blending ecosystem management and other approaches with watershed management, and incorporating smart growth, low impact development and other emerging concepts. A little more than a decade after its introduction and almost five years after the National Research Council’s report, USEPA remains committed to watershed management (Mehan III 2003) and its role in environmental and resource policy from planning and resource policy to distribution of state and federal water quality and conservation funds. Significant advancements have been made along several fronts. The information/knowledge base for watershed management is extensive and available through traditional and web-based communication channels. Watershed groups and resource professionals can typically obtain information and educational materials developed by experts within their own state, the Federal government and environmental organizations. Furthermore, state and federal agencies, universities, and organizations typically provide expertise via the web and/or technical support to watershed groups by serving on technical committees, facilitating the writing of planning documents, conducting watershed analysis, contributing to the implementation of the plans, and attracting funds. A second major advancement is the wide availability of the geographical, ecologic, economic and social data that is required as part of a successful watershed management effort and its access via the web and geographic information systems (GIS). Watershed groups and the professionals who support the groups can download critical data at “data clearinghouse” site managed by state and federal agencies, organizations and commercial firms. In addition to providing data, some of these entities now serve the data using web-based interactive GISs. Users of these online systems can quickly access the available data to obtain a better understanding of their watersheds, conduct partial inventories of available resources, create maps for use in their meetings and documents, and conduct first tier analyses such as estimating the area of an impacted area, looking for land use and resource conflicts, measuring distances and creating buffers. A third major advancement is within the GIS software industry. With the rapid advancing of distributed computing technologies and high-speed growth of the Internet, we have now entered a new Internet-driven online computing era. The software industry is moving towards the Internet platform while the new distributed technologies like XML and Web services provide the solid foundation for such a crucial shift. Over the past few years, major GIS software vendors have realized this important change in technologies. So they re-engineered their GIS software products for the Internet platform. This new generation of GIS software products enables us to share not only spatial datasets but also advanced geoprocessing functions across the Internet. Finally, we are beginning to see the development of some components of a user-friendly online watershed decision support system. In 2002, EPA Region 5 held a conference with Michigan State University and Purdue University to highlight advancements in this area. They followed up this conference with the creation of the Midwest Spatial Decision Support System Partnership at http://www.epa.gov/waterspace/. Visitors of this site can learn of new data and tools for use in watershed management. Particularly promising are the tools such as Michigan State University’s Digital Watershed (http://www.iwr.msu.edu/dw), Understanding your watershed and Online RUSLE, Purdue University’s L-THIA (http://www.ecn.purdue.edu/runoff), the Watershed Delineation Tool (http://pasture.ecn.purdue.edu/~watergen), the Impervious Surface calculator etc. These tools require limited inputting of data and perform reasonably well as a means of identifying and comparing likely resource impacts under different land use changes. With all these advancements, the authors believe that the time has matured for us to integrate existing systems built by both Michigan State University and Purdue University and further develop a full-fledged nation wide watershed decision support system. The online spatial decision support systems interoperability project funded by EPA region 5 is our first step towards this goal. The major tasks of this project are to integrate Michigan State University’s Digital Watershed and Understanding your watershed systems and Purdue University’s Online Watershed Delineation Tool and L-THIA across the web.
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2. Design Principles and Goals Watershed systems are very complex systems. We need holistic approach that involves the coordination among different organizations and decision-making based upon sufficient information from different sources to deal with such complicated systems and achieve the goal of optimizing the use of land, water and vegetation in a watershed to alleviate drought, moderate floods, prevent soil erosion, and improve water quality and agricultural production on a sustained basis. There is also an urgent need to educate the general public on watershed problems and actions needed to meet these problems. In reality, watershed systems are integrated systems and constantly shaped by various natural processes at different spatial and time scales and human activities. Our current understanding of watershed and its relationship with human society is highly fragmented. Our watershed knowledge is scattered in different organizations and research publications. Users must discover duplicate information and filter out extraneous information. So, the question we asked ourselves when we designed the system is “could we build an integrated watershed decision support system that can break both organizational and disciplinary boundaries to integrate our watershed knowledge from different sources and make data and models at different scales available to decision makers and other users in a user-friendly way?” The answer to this question helped us define the following goals: o Our system should be able to integrate watershed knowledge from different sources. Different organizations and disciplines may have different partial information about a watershed. Our system should allow them pool information together in a systematic way. o Data must be made more readily available and in a user-friendly format for immediate use by watershed groups and the public. Data clearinghouses primarily server the experienced GIS analyst rather than the committee. Separate online interactive GISs displaying different layers are a step in the right direction. They should, however, be combined to improve efficiency, minimize the learning curve of constituents, and improve analysis capabilities. Tools also need to be developed that automate repetitive tasks and analyses such as resource inventories. These online interactive GISs must allow watershed groups to add and save local data to existing data layers as well as new data layers. Finally, a routine needs to be developed that exports the maps created by watershed groups directly to their on-line and printed documents. o Models must be made more readily available and in a user-friendly way for immediate use by watershed groups. We have realized that making complicated models online in a user-friendly way is a very difficult task. But the recent advancements in Server-based GIS have made task more approachable. o Scale must be taken into consideration when we build the system. Most of us have an intuitive appreciation for the implications of observing a system at different scales. Spatial relationships, and especially spatial patterns, are discernible only on a particular scale of reference. Models themselves are often scale dependent too. We use different models at different scales with data in different scales. o Currently available decision support tools need to be modified to work across regions and be made more user-friendly. As a general rule, watershed groups should be able to generate results in 3 to 6 mouse clicks. This keeps committees focused on their primary tasks of making timely decisions based on the best available science-based information and research. o A significant, interdisciplinary and regional effort needs to be undertaken to complete the development of a functional watershed decision support system. The system should be modular and allow users to access the supporting data, models and tools from a central or remote system. 3. System Functionality Bearing the above design goals in mind, we tried to integrate the Michigan State University’s Digital Watershed, Understanding Your Watershed and Purdue University’s Online Watershed Delineation and L-THIA programs into one interoperable watershed decision support system. The Digital Watershed website (http://www.iwr.msu.edu/dw) is designed to provide both a centralized information repository and a computing center for watersheds in the United States. This site is based on the comprehensive database of 8-digit watersheds for the whole continent of the United States, which is included in the EPA BASINS system. The database contains all regulated facilities, river network, DEM, state soil and other data layers. The Digital Watershed system provides users with two forms of access to an online interactive GIS for a specific 8-digit watershed. The address-based entry allows users to locate their watersheds by street addresses (figure 1). The map-based entry allows users to locate their watersheds on regional maps (figure 2). Once the users get into their specific watersheds, they can use an interactive GIS to map the watershed dataset (figure 3). The interactive GIS provide basic GIS functions such as zoom, pan and identify
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functions. The hyperlink function allows user to access EPA’s surf your watershed information for that 8-digit watershed. The visualization function allows users generate a 3-D view of the 8-digit watershed. The modeling function allows users to run an erosion and deposition model called USPED. The Understanding Your Watershed system offers the similar functionality but the system was based on more detailed dataset for Michigan and it’s only available for Michigan. The program enables a user to select a Michigan 12-digit watershed and display various features within that watershed such as streets, water bodies, elevation, risk areas, wetlands and other information available across the state. To meet the above mentioned scale goal, we developed the scaling function to interconnect Digital Watershed and Understanding Your Watershed systems. In Digital Watershed, you can use the down arrow icon to scale down to 12-digit watershed that your click point is in (figure 4). In Understanding Your Watershed, you can use the up arrow icon to scale up to 8-digit watershed that the 12-digit watershed is part of. Purdue University’s Online Watershed Delineation Tool (http://pasture.ecn.purdue.edu/~watergen), (which is also the entry point for the Web GIS version of L-THIA) can delineate watershed areas down to less than 100 acres, offers a complete regional database and meshes with many other tools (Choi et al, 2003). L-THIA, Long-term Hydrologic Impact Assessment, is designed to help these people to quantify the impact of land use change on the quantity and quality of their water (Engel et al., 2003).
Figure 1 Address-based Entry for Digital Watershed
This tool uses the land use and a soil characteristic from the user along with thirty years of precipitation data to determine the average impact that a particular land use change or set of changes will have on both the annual runoff and the average amount of several non-point source pollutants. The L-THIA model was developed as an accessible online tool to assess the water quality impacts of land use change. As a quick and easy-to-use approach, L-THIA’s results can be used to generate community awareness of potential long-term problems and to support planning aimed at minimizing disturbance of critical areas. L-THIA is an ideal tool to assist in the evaluation of potential effects of land use change and to identify the best location of a particular land use so as to have minimum impact on a community’s natural environment.
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Figure 2 Map-based Entry for Digital Watershed
Figure 3 Interactive GIS for an 8-digit watershed But the Online Watershed Delineation tool and L-THIA do not have the scaling capability or address entry functions. Integrating Digital Watershed and Online Watershed Delineation tool (available through the delineate watershed icon) and L-THIA could make Digital Watershed scaling capability more generally available and provide Online Watershed Delineation tool and L-THIA a user-friendly interface and a nation-wide search engine for watershed delineation and L-THIA modeling via both street address and map-based entries. In order to integrate the Online Watershed Delineation tool into Digital Watershed, we developed an additional tool that allows users to delineate a local watershed above any point in an 8-digit watershed. The tool actually sends the user click point
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information from Digital Watershed site to Online Watershed Delineation tool site. The Online Watershed Delineation tool site takes in the point information and generates the local watershed above that point (figure 5). It also clips the data for the local watershed and makes them available to download. You can also bring up an interactive GIS to view the result, calculate the percentage of impervious area for the local watershed and run LTHIA model. 4. Conclusions The work done so far for the integration of Digital Watershed and the Online Watershed Delineation tool illustrated the great benefits we can get by combining online tools developed by separate organizations. With the advancements in distributed computing and server-based GIS, we believe this is the future direction for online watershed decision support systems.
Figure 4 Scaling Down From 8-digit System to 12-digit System
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Figure 5 Watershed Delineation Result
References B. A. Engel, J-Y Choi, S. Pandey, J. Harbor, 2003, Web-Based DSS for Hydrologic Impact Evaluation of Small Watershed Land Use Changes, Computers and Electronics in Agriculture, Vol. 39, 241-249.
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Choi J. Y., B. A. Engel, L. Theller and J. Harbor, 2003, Internet Based SDSS for Watershed Management using Web-GIS Capability, Proc. of ASAE Annual Meeting Presentation, Las Vegas, NV, Paper. No. 033033, American Society for Agricultural Engineers, St. Joseph, Michigan. National Research Council. 1999. New Strategies for America's Watersheds. Washington, D. C.: National Academy Press. G. Tracy Mehan, III, 2003 Challenges and Opportunities of Source Water Protection, Plenary Address to the National Source Water Protection Conference.
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