The Modular Modeling System (MMS)—The Physical Process Modeling Component of a Database-Centered Decision Support System for Water and Ecosystem Management

Increasing demands for limited fresh-water supplies, and increasing complexity of water- management issues, present the water-resource manager with the difficult task of achieving an equitable balance of water allocation among a diverse group of water users. The Watershed and River System Management Program (WARSMP) is a cooperative effort between the U.S. Geological Survey (USGS) and the Bureau of Reclamation (BOR) to developed a database-centered, decision-support system to address these multi-objective, resource-management problems. The decision-support system couples the USGS Modular Modeling System (MMS) with the BOR RiverWare tools using a shared relational database. MMS is an integrated system of computer software that provides a research and operational framework to support the development and integration of a wide variety of hydrologic and ecosystem models, and their application to water- and ecosystem-resource management. RiverWare is an object- oriented reservoir and river-system modeling framework developed to provide tools for evaluating and applying water-allocation and management strategies.

The modeling capabilities of MMS and Riverware include simulating watershed runoff, reservoir inflows, and the impacts of resource-management decisions on municipal, agricultural, and industrial water users, environmental concerns, power generation, and recreational interests. Forecasts of future climatic conditions are a key component in the application of MMS models to resource-management decisions. Forecast methods applied in MMS include a modified version of the National Weather Service's Extended Streamflow Prediction Program (ESP) and statistical downscaling from atmospheric models. Enhancement, testing, and evaluation of these forecasting procedures are being conducted jointly with the development, testing, and application of the full decision- support system. These efforts are ongoing in the Gunnison River basin, Colorado; San Juan River basin in Colorado, New Mexico, Arizona, and Utah; Yakima River basin, Washington; and the Rio Grande basin, Colorado, New Mexico, and Texas.