Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Shindala, Adnan

Committee Member

Huddleston, David H.

Committee Member

Truax, Dennis D.

Committee Member

Zitta, Victor L.

Committee Member

Warsi, Zahir U.

Date of Degree

5-12-2001

Document Type

Dissertation - Open Access

Major

Civil Engineering

Degree Name

Doctor of Philosophy

College

College of Engineering

Department

Department of Civil Engineering

Abstract

In the development of the watershed, hydrodynamic, and water quality models for St. Louis Bay in Mississippi, the Better Assessment Science Integrating Point and Nonpoint Sources (BASINS 2.0) - Nonpoint Source Model (NPSM) was selected as the watershed model and the Environmental Fluid Dynamics Code (EFDC) which includes hydrodynamic and water quality models was selected as the Bay model. Watershed model calibration was initially accomplished utilizing historical data collected by the U.S. Geological Survey (USGS), U.S. Environmental Protection Agency (USEPA), Mississippi Department of Environmental Quality (MDEQ), and Gulf Coast Research Laboratory (GCRL). The watershed model simulated nonpoint source flow and pollutant loadings for all sub-watersheds, routed flow and water quality, and accounted for all major point source discharges in the St Louis Bay watershed. The model was executed for the period of time spanning from 1965 through 1999 in order to quantify flow and pollutant loadings under a variety of hydrologic conditions. Time varying output from the watershed model was applied directly to the St. Louis Bay model. The Bay model, in turn, simulated hydrodynamics and water quality, including water depth, velocities, salinity, temperature, and fecal coliforms. Final Bay model calibration was performed utilizing a set of site specific data acquired on St. Louis Bay during the period July 14-18, 1998. Model verification was conducted against another set of field data taken in the Bay, during April 18-27, 1999. Fecal coliform was modeled in each of the 750 segments of a three-dimensional system. Comparisons of the predicted and observed data are made qualitatively by using spatial and temporal comparisons. The response of model prediction calculations is consistent with trends of the observed data ranges. The applicability of the mathematical models is also demonstrated for the development of Total Maximum Daily Load (TMDL) for fecal coliform in the St. Louis Bay. The calibrated/verified model will be used as a planning tool to assess the water quality in the Watershed and the Bay as well as for calculating TMDL and Waste Load Allocation (WLA).

URI

https://hdl.handle.net/11668/18335

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