The Development of an Integrated Watershed Model for Understanding the Impacts of Sediments on Aquatic Life

In response to fish decline, many federal and state agencies (e.g., National Marine Fisheries Service (NMFS), United States Department of Agriculture (USDA), United States Bureau Reclamation (USBR), United States Forest Service (USFS), Department of Fish and Wildlife (DFW), United States Department of Energy and United States Army Corps of Engineers (USACE)) have employed management plans in the last twenty to thirty years to augment fish populations and other aquatic organisms by improving stream habitats. Most of the restoration efforts have focused on the enhancement of the stream corridors to restore habitat quality variables (e.g., pool-riffle sequence, depth, shade) and river geomorphologic characteristics (e.g., sinuosity and slope) within a stream corridor (microscale), believed to be important for fish, without considering the overall effects of watershed (macroscale) parameters on the instream parameters over time. Lack of understanding of the complex interaction between watershed parameters with instream parameters and the effects of scale on fish and aquatic species has caused, in some cases, the unsuccessful implementation of TMDLs and failure of these management plans. The long-term objective of this research will be the development of an integrated model that facilitates a rapid and versatile prediction of sediment transport within a watershed based on sound theory and the usage of robust models. This integrated model should account for the interaction between instream and watershed-wide parameters. It will incorporate an interactive suite of numerical models providing the capability to simulate hydrologic, hydrodynamic, and sediment transport/storage phenomena at multiple spatial and temporal scales. The paper presents the vision of the blueprint watershed integrative methodology.