EPA/600/F-18/054 science in ACTION INNOVATIVE RESEARCH FOR A SUSTAINABLE FUTURE Watershed Management Optimization Support Tool (WMOST) WMOST is a software application designed to facilitate integrated water resources management across wet and dry climate regions. The tool allows water resources managers and planners to screen a wide range of practices. Example objectives include: meeting projected water demand, maintaining minimum in-stream flow targets, reducing flooding, meeting water quality criteria or loading targets for Total Maximum Daily Loads, and reducing combined sewer overflows across their watershed or jurisdiction for cost-effectiveness and environmental and economic sustainability. Uses WMOST screens management practices for water and water-related resources within a watershed context for an optimal mix, while accounting for the direct and indirect cost and performance of each practice (Figure 1). It can be used to (1) identify the most cost-effective mix of management practices to meet projected human demand, in-stream flow standards, water quality standards, and target pollutant loads, (2) understand trade-offs between meeting management goals and total annual costs, and (3) characterize the sensitivity of the solution to input data and parameters (e.g., effects of climate variability and resulting changes in runoff and recharge rates on the mix of least- cost practices; the robustness of the recommended mix of practices to a range of cost assumptions). Cost savings associated with reducing the probability of flooding damage are incorporated using outputs of FEMA's HAZUS tool (a tool that contains models for estimating potential losses from earthquakes, floods and hurricanes), using publically available data from Flood Insurance Studies. Features ~ Implementation in Microsoft Excel 2016©, allowing development of input files that can be submitted to an online server with optimization programs, eliminating the need for specialized software on the user's computer. Inclusion of over twenty potential management practices and goals related to the following: - Stormwater and agricultural best management practices: Up to fifteen best management practices (BMPs, structural and nonstructural), including traditional grey infrastructure, riparian buffers, green infrastructure and other low impact development practices - Water supply: Demand management practices, surface and groundwater pumping, surface water storage, water treatment plant, and drinking water distribution system leak repair. - Wastewater: Septic systems, wastewater treatment plant, and infiltration repair in wastewater collection systems (combined or separate sewers). - Nonpotable water reuse: Wastewater reuse facility and nonpotable distribution systems. - Others: Aquifer storage and recharge, transfer of water and wastewater between drainage basins, land conservation, minimum human demand, and minimum and maximum in-stream flow targets, maximum combined sewer overflow events, maximum water quality concentrations or loads. ~ Spatially lumped models representing one basin and one reach, but with flexibility in the number of hydrologic response units (land-use/soil combinations). ~ Modeling time step of a day or month without a limit on the length of the modeling period. ~ Consideration of baseflow, peak water flows, and water quality (concentration and pollutant loads). ~ Automated import of runoff and groundwater recharge rate time series and pollutant loads from existing hydrology/water quality models and estimated performance of proposed BMPs. Page 1 of 2 ------- Source Water Treated Water Component without storage Flow jump between 1 Private GW and 5W withdrawals and discharges are water flows only; see water quality flows in Figure 2. 2 Up to 9 stonmwaler management options may be modeled representing traditional, green infrastructure or low impact development practices or combination of practices. 3 This flow represents the fraction of municipal water use that is routed directly to the storm sewer (e.g ., hydrant flushing) Figure 1. Watershed and human water system components represented in WMOST. Process WMOST calculates the optimal solution based on user inputs of, human water system characteristics, watershed characteristics, management practices, and management goals (Figure 2). Input Data •Human water system characteristics •Watershed characteristics •Management practices (costs and effectiveness) •Management goals Optimization • Objective: Minimize annual management costs • Subjectto management goals and physical constraints of the watershed and water system Results • Mix of least cost management practices (number of units, costs) • Graphs of modeled, measured, and target instreamflowsand pollutant loads or concentrations Figure 2. WMOST modeling process from user inputs to results used to derive optimal solutions. Contacts Naomi Detenbeck, EPA's Office of Research and Development | detenbeck.naomi@epa.gov Model Download WMOST Versions 2 and 3: www.epa.gov/exposure-assessment-models/wmost Page 2 of 2 ------- |