Watershed Management Optimization Support Tool (WMOST) v3: Theoretical Documentation
Detenbeck, N., M. Tenbrink, A. Piscopo, A. Morrison, T. Stagnitta, R. Abele, J. Leclair, T. Garrigan, V. Zoltay, A. Brown, A. Le, J. Stein, AND I. Morin. Watershed Management Optimization Support Tool (WMOST) v3: Theoretical Documentation. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-17/220, 2018.
The Watershed Management Optimization Support Tool (WMOST) is a decision support tool that facilitates integrated water management by local communities or watershed management organizations. Integrated management involves consideration of management options across multiple programs (stormwater, wastewater, drinking water, land conservation) to find the most cost-effective solution given users' targets for water quantity and quality. WMOST v3 builds upon earlier versions of WMOST with additions of a water quality module, that allows users to specify goals for pollutant concentration or loads, and a Combined Sewer Overflows (CSO) module, that allows users to target reductions in the incidence of overflows from combined (sanitary + stormwater) sewers. The theoretical documentation describes the decision tool assumptions and underlying equations incorporated into the tool. A user guide for version 3 is being published as a separate report.
The Watershed Management Optimization Support Tool (WMOST) is a decision support tool that facilitates integrated water management at the local or small watershed scale. WMOST models the environmental effects and costs of management decisions in a watershed context, accounting for the direct and indirect effects of decisions. The model considers water flows and water quality. It is spatially lumped with options for a daily or monthly modeling time step. In this version (v3), management option cost optimization occurs through nonlinear programming. As a screening tool, WMOST contributes to an integrated watershed management process such as that described in EPA’s watershed planning handbook (EPA 2008). WMOST serves as a public-domain tool for local water resources managers and planners to screen a wide range of potential water resources management options across their jurisdiction for cost-effectiveness and environmental and economic sustainability (Zoltay et al., 2010). WMOST includes functions to evaluate various management practices, including projects related to stormwater (including green infrastructure [GI] and combined sewer overflow [CSO] systems), stream restoration, water supply, wastewater and land resources such as low-impact development (LID) and land conservation. WMOST can aid in evaluating LID and GI as alternative or complementary management options in projects proposed for grant funding. WMOST v3 builds on the optimization framework of WMOST v1 by incorporating two new optimization modules: The Water Quality module that allows consideration of water flows and loadings and the CSO module. The new version of WMOST also builds upon the modules added in WMOST v2: The Baseline Hydrology and Loadings and Stormwater Hydrology and Loadings modules. The Baseline Hydrology and Loadings and Stormwater Hydrology and Loadings modules assist users with input data acquisition and pre-processing. The CSO module allows evaluation of management options to minimize the number of CSO events. The Flood module allows the consideration of flood damages and their reduction in assessing the cost-effectiveness of management practices. The target user group for WMOST consists of local water resources managers, including municipal water works superintendents and their consultants.