The modular modelling system (MMS): a toolbox for water and environmental resources management

Abstract

INTRODUCTION Increasing demands for limited fresh-water supplies, and increasing complexity of environmental resource-management issues, present resource managers with the difficult task of achieving an equitable balance of resource allocation among a diverse group of users. Achieving such a balance is most difficult in arid and semi-arid regions. Hydrological and ecosystem models are often the tools being employed to address these resource-allocation issues. The inter-disciplinary nature of water- and environmental-resource problems requires the use of modelling approaches that can incorporate knowledge from a broad range of scientific disciplines. Selection and application of appropriate models and tools is a function of a number of evaluation criteria, including problem objectives, data constraints, and spatial and temporal scales of application. The US Geological Survey (USGS) Modular Modelling System (MMS) (Leavesley et al ., 1996b) 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 environmental-resources management. MMS supports the integration of models and tools at a variety of levels of modular design. These include individual process models, tightly coupled models, loosely coupled models, and fully integrated decision-support systems. A geographic information system (GIS) interface, the GIS Weasel, has been integrated with MMS to enable spatial delineation and characterization of basin and ecosystem features, and to provide objective parameter-estimation methods for selected models using available digital data coverages.