Integrated Water Resources Analysis Using the Watershed Analyis Tool (HEC-WAT)

Current U.S. Army Corps of Engineers guidance stresses the need for integrated and systems types of analyses. ER 1105-2-100, the Planning Guidance Notebook, and more recently ER 1105-2-409, Planning in a Collaborative Environment, emphasize the need for a collaborative and coordinated decision making process that considers more than the traditional Corps' interests. In fact, the first point of the Corps' recently announced 12 Actions for Change is for the Corps to employ an integrated, comprehensive and systems based approach. Unfortunately at this time, a tool to perform a coordinated and collaborative analysis does not exist. This tool would have to accept input from multiple disciplines and for multiple purposes. Numerous agencies, consultants, NGO's, and other stakeholders who participate in these studies would have to have access to this tool. To address this need, the Corps' Hydrologic Engineering Center (HEC) has been developing an interface called the Watershed Analysis Tool (HEC-WAT or the WAT). The primary purpose of the WAT is to streamline and integrate a water resources study using software commonly applied by multi-disciplinary teams. By using a "plug-in" concept the WAT incorporates individual pieces of software such as our suite of software (HEC-RAS, HEC-HMS, HEC-ResSim, HEC-EFM, HEC-FIA, and HEC-FDA) and allows them to work together in a coordinated fashion so that water resources, economic, and environmental decisions can be made from the same interface. As the WAT matures, additional pieces of software will be incorporated into the WAT that will allow additional analyses and decisions to be made. The individual models use a shared schematic (representation of the physical system) that is developed by the Project Delivery Team. The shared schematic assures that the naming convention and project identification and location for the study is consistent throughout the modeling disciplines. The modeling files from the individual pieces of software will be stored in the WAT architecture so that the project files are located in a common site for easy retrieval and documentation. Output and alternative analysis comparisons from the models will be accessed directly from the WAT making the results and reporting from all the models much more accessible. These features and additional capabilities of the WAT will promote integrated water resources modeling and decision making and support the policy needs identified above. This paper will discuss the development, functionality, capabilities, benefits, requirements and application of the WAT to water resources studies.