Citation:

Carousel, R F. SELECTION OF CANDIDATE EUTROPHICATION MODELS FOR TOTAL MAXIMUM DAILY LOADS ANALYSES. Presented at Eighth International Symposium on Fish Physiology, Toxicology, and Water Quality, Chonqing, China, October 12-14, 2004.

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:

A tiered approach was developed to evaluate candidate eutrophication models to select a common suite of models that could be used for Total Maximum Daily Loads (TMDL) analyses in estuaries, rivers, and lakes/reservoirs. Consideration for linkage to watershed models and ecological endpoints were to be included in the assessment. Four tiers including 1) identification of candidate models; 2) developing a series of minimum requirements including well developed representations for sediment, nutrients, and some plankton species; internally or successfully coupled to a hydrodynamic model, documentation of algorithms; 3) documentation including operational instructions and flow of execution, have had at least 3 applications during the last 10 years with one other than the developer; and 4) source code analysis including non-proprietary nature, must be a one-time purchase without a run-time license, PC-compatible platform is required and for reservoir and estuary models, multi-dimensional capability. A comprehensive review was undertaken and over 250 models were identified as possible candidates. From the initial review a total of 7 contained the minimum requirements for TDML analyses.

Record Details: