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LOUISIANA ENVIRONMENTAL MODELING SYSTEM FOR HYPOXIA RELATED ISSUES
Citation:
Carousel, R F. AND R C. Russo. LOUISIANA ENVIRONMENTAL MODELING SYSTEM FOR HYPOXIA RELATED ISSUES.
Impact/Purpose:
The objective of this research is to develop a state-of-the-art observation and forecasting system for the marine and coastal environments of the Gulf of Mexico's adjoining rivers, bays, shelf and waters. An integral component of the modeling system is the development of chemical and non chemical loadings from runoff in near and upland watersheds. This research has two subtasks1) Hypoxia in the Gulf of Mexico and 2) Development of real time predictive capability for environmental security assessments.
Subtask 1 Hypoxia in the Gulf of Mexico
Nutrients and sediments discharged into the Gulf of Mexico, largely from the Mississippi River Basin, are contributing to the formation of a zone of low dissolved oxygen (hypoxia) along the coast of Louisiana and Texas. The major vehicle for conducting an environmental assessment for the hypoxic zone is a modeling approach for characterizing and prioritizing sources of nutrient loadings initially within the Mississippi River basin.
To meet this objective, the following assessments/activities need to be developed: 1) determination of the relative nutrient contribution of all sources: atmospheric, nonpoint and point sources; 2) aggregation of the total nutrient loads to the receiving water body); 3) establishment of load/dose/response relationships.; 4) establish agreement of water quality criteria and biological targets for the Gulf; and 5) determination of total nutrient load targets that restore oxic conditions to the Gulf environment based upon model projections.
Subtask 2 Real time predictions for environmental security assessments.
Federal agencies and others have established programs for operational modeling and data collection in rivers, estuaries and coastal areas of the United States. These systems are designed to provide support for technological and natural disasters but are not sufficient to support the range of threats realized since the September 11th attacks primarily because of incomplete information about oceanographic conditions and restricted capability for modeling the transport and fate of certain pollution classes such as radiological agents.
To meet this goal, the following activities need to be developed: Identify exposure pathways, evaluate human health and ecological risks, develop remedial strategies for mitigation and provide for public outreach including dissemination of risk information and simulation results.
Description:
An environmental assessment tool to evaluate the impacts of nonpoint source (NPS) pollutants discharged from Mississippi River basins into the Gulf of Mexico and to assess their effects on receiving water quality will be described. This system (Louisiana Environmental Modeling System (LEMS) will build upon a joint effort by the U.S. Navy and EPA called the Northern Gulf Littoral Initiative (NGLI). This LEMS modeling system will expand on the state-of-the-art monitoring and coastal forecasting system developed for the Northern Gulf of Mexico. The modeling domain will be moved to the western side of Louisiana to encompass the hypoxic zone and the near coastal region. The modeling system will be linked to form a comprehensive modeling system for evaluating NPS discharges. The project should provide a technology that does not currently exist for the hypoxic zone, that combines a three-media model with an advanced coastal hydrodynamic and water quality model. This model to evaluate NPS discharges is important because of the impact on water quality including the formation of a hypoxic (dead) zone off the Louisiana coast line. The models mentioned above will be refined and coupled to produce the LEMS system, then applied to assess the water quality effects associated with NPS discharges on a larger scale in the Louisiana coastal regions of the Gulf of Mexico. Coupling the three-media model with the coastal hydrodynamic and water quality model will provide an innovative and useful approach to evaluate the impact of NPS discharges as they are transported and transformed through land runoff, surface stream networks, groundwater pathways and coastal tidal processes. The modeling system will help in defining the magnitude of reduction in NPS discharges to the Gulf of Mexico required to obtain a long-term decrease in the extent of hypoxia formation in the Gulf of Mexico.