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EUTROPHICATION MODELING CAPABILITIES FOR WATER QUALITY AND INTEGRATION TOWARDS ECOLOGICAL ENDPOINTS
Russo, R C. AND R F. Carousel. EUTROPHICATION MODELING CAPABILITIES FOR WATER QUALITY AND INTEGRATION TOWARDS ECOLOGICAL ENDPOINTS. Presented at Sixth International Symposium on Fish Physiology, Toxicology, and Water Quality, La Paz, B.C.S., Mexico, January 22-26, 2001.
Develop, test, and refine models to evaluate sub-basins to determine whether local water quality problems due to excessive nutrient loading exist, and if so, to characterize them and determine their relationships to nutrient loading. Develop models to simulate overland flow and non-point source pollutant loads to track and assess nutrient loadings across watersheds and provide approaches for estimating nutrient budgets within sub-basins and for predicting changes in nutrient budgets in response to changes in watershed activities/land use/land cover. Demonstrate the application of the recommended approach/models for predicting changes in nutrient budgets in response to changes in proposed watershed activities/land use/land cover, resulting in specific recommendations for reducing the nutrient loads to a basin. For coherence, cooperation, and economics, these models will be housed in a unified, consistent, computational environment for environmental analyses that allows teaching (i.e., technology transfer) to multiple users (users concentrate on problem, not model input/output); that appeals to multi-disciplinary groups for distribution and use as a consistent assessment methodology (includes models, tools, modular design and facilitated updates of science/engineering); that includes resident visualization, animation tools, documentation and tutorials on-line, hooks to GIS and environmental databases; and is executable on UNIX, personal computers, and HPC resources.
Objective # 2.2 Conserve and enhance nation's waters: By 2005, conserve and enhance the ecological health of the nation's (state, interstate, and tribal) waters and aquatic ecosystems-rivers and streams, lakes, wetlands, estuaries, coastal areas, oceans, and groundwater-so that 75% of waters will support healthy aquatic communities.
A primary environmental focus for the use of mathematical models is for characterization of sources of nutrients and sediments and their relative loadings from large river basins, and the impact of land uses from smaller sub-basins on water quality in rivers, lakes, and estuaries for excessive algal blooms, low dissolved oxygen (hypoxia), and related fish kills. For such a comprehensive evaluation a linked modeling system is required consisting of models that will simulate constituents and processes necessary to evaluate nutrient budgets and cycles on land and in the aquatic environment. Modeled processes include hydrodynamics, sediment erosion and transport, water temperature, oxygen and BOD dynamics, inorganic and organic nutrients, growth/respiration of algae, specified species within each trophic level, and toxicity of pollutants to modeled organisms, indirect effects produced by changes in grazing and predation pressures, changes in decay rates and detritus and nutrient cycling, and dissolved oxygen. A pilot study conducted in the Tensas watershed, located in the northeast corner of the State of Louisiana, will be described. Water quality models were evaluated that provide full capabilities for simulating eutrophication, can be linked to watershed loading models for nutrients, and provide output that can be used to determine indications of ecological impairment with fish-health as an endpoint. A total of 80 water quality models were evaluated from which seven water quality models were identified as candidates for use in linking to watershed loading models for evaluating the impact of nutrients and sediment on water quality. An overview of the necessary processes for moving towards an ecological endpoint will be presented.