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Simulation of Temperature, Nutrients, Biochemical Oxygen Demand, and Dissolved Oxygen in the Catawba River, South Carolina, 1996-97

U.S. Geological Survey Water-Resources Investigation Report 03-4092, 123 pages (Published 2003)

By Toby D. Feaster, Paul A. Conrads, Wladmir B. Guimaraes, Curtis L. Sanders, Jr., and Jerad D. Bales

Prepared in cooperation with the Lancaster County Water and Sewer District

This report is available online in pdf format (13 MB): USGS WRIR 03-4092

ABSTRACT

Time-series plots of dissolved-oxygen concentrations were determined for various simulated hydrologic and point-source loading conditions along a free-flowing section of the Catawba River from Lake Wylie Dam to the headwaters of Fishing Creek Reservoir in South Carolina. The U.S. Geological Survey one-dimensional dynamic-flow model, BRANCH, was used to simulate hydrodynamic data for the Branched Lagrangian Transport Model. Waterquality data were used to calibrate the Branched Lagrangian Transport Model and included concentrations of nutrients, chlorophyll a, and biochemical oxygen demand in water samples collected during two synoptic sampling surveys at 10 sites along the main stem of the Catawba River and at 3 tributaries; and continuous water temperature and dissolved-oxygen concentrations measured at 5 locations along the main stem of the Catawba River.

A sensitivity analysis of the simulated dissolvedoxygen concentrations to model coefficients and data inputs indicated that the simulated dissolved-oxygen concentrations were most sensitive to watertemperature boundary data due to the effect of temperature on reaction kinetics and the solubility of dissolved oxygen. Of the model coefficients, the simulated dissolved-oxygen concentration was most sensitive to the biological oxidation rate of nitrite to nitrate.

To demonstrate the utility of the Branched Lagrangian Transport Model for the Catawba River, the model was used to simulate several water-quality scenarios to evaluate the effect on the 24-hour mean dissolved-oxygen concentrations at selected sites for August 24, 1996, as simulated during the model calibration period of August 23 – 27, 1996. The first scenario included three loading conditions of the major effluent discharges along the main stem of the Catawba River — (1) current load (as sampled in August 1996); (2) no load (all point-source loads were removed from the main stem of the Catawba River; loads from the main tributaries were not removed); and (3) fully loaded (in accordance with South Carolina Department of Health and Environmental Control National Discharge Elimination System permits). Results indicate that the 24-hour mean and minimum dissolved-oxygen concentrations for August 24, 1996, changed from the no-load condition within a range of - 0.33 to 0.02 milligram per liter and - 0.48 to 0.00 milligram per liter, respectively. Fully permitted loading conditions changed the 24-hour mean and minimum dissolved-oxygen concentrations from - 0.88 to 0.04 milligram per liter and - 1.04 to 0.00 milligram per liter, respectively. A second scenario included the addition of a point-source discharge of 25 million gallons per day to the August 1996 calibration conditions. The discharge was added at S.C. Highway 5 or at a location near Culp Island (about 4 miles downstream from S.C. Highway 5) and had no significant effect on the daily mean and minimum dissolved-oxygen concentration.

A third scenario evaluated the phosphorus loading into Fishing Creek Reservoir; four loading conditions of phosphorus into Catawba River were simulated. The four conditions included fully permitted and actual loading conditions, removal of all point sources from the Catawba River, and removal of all point and nonpoint sources from Sugar Creek. Removing the point-source inputs on the Catawba River and the point and nonpoint sources in Sugar Creek reduced the organic phosphorus and orthophosphate loadings to Fishing Creek Reservoir by 78 and 85 percent, respectively.

CONTENTS

Abstract

Introduction

Purpose and scope

Description of study area

Previous studies

Approach

Acknowledgments

Data-collection methods and data analysis

Continuous measurements of water level, streamflow, water temperature, and dissolved-oxygen concentration

Discrete measurements of discharge

Estimation of subbasin inflow hydrographs

Unit-flow method

Flow-simulation method

Time of travel

Reaeration rates

Water-quality data

Laboratory quality assurance and quility control

Summary statistics

Substrate and sediment oxygen demand data

Point-source flow and water-quality data

Meteorological data

Channel geometry

Water-quality model description

Water-quality model calibration and validation

Computational grid

Water level and streamflow

Mass transport

Water temperature

Water quality

Sensitivity analysis

Water-quality model applications

Variation in point-source loading

Addition of point-source load

Phosphorous loading

Summary

Selected references

REPORT AVAILABILITY

This report is available online in pdf format (13 MB): USGS WRIR 03-4092
To view the PDF document, you need the Adobe Acrobat® Reader installed on your computer. (A free copy of the Acrobat® Reader may be downloaded from Adobe Systems Incorporated.)

For more information, contact the South Carolina Publications Unit.

USGS South Carolina Publications South Carolina Water Science Center

 USGS South Carolina Publications • South Carolina Water Science Center