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Sediment transport and deposition in Lakes Marion and Moultrie, South Carolina, 1942-85

Water-Resources Investigations Report 95-4236
By: , , and 
https://doi.org/10.3133/wri954236

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Abstract

Lakes Marion and Moultrie, two large reservoirs in the South Carolina Coastal Plain, receive large inflows of sediment from the Santee River. The average rate of sediment deposition for both lakes during the period 1942-85 was about 0.06 inch per year, or about 800 acre-feet per year. The rate during 1983-85 was about 0.037 inch per year, or about 490 acre-feet per year, reflecting the decreasing trend in sediment inflow. This is a reversal of a trend toward increasing suspended- sediment concentrations in streams that were caused by farming practices in the southern Piedmont from about 1800 to about 1920. Only a small part of the eroded sediment has been carried out of the Piedmont, but the remaining sediment is becoming less available for transport. Sediment deposition is concentrated in several areas of upper Lake Marion where the velocity of the incoming water decreases significantly. Beds of aquatic macrophytes appear to encourage deposition which, in turn, creates favorable habitat for the plants. The rate of sediment accumulation in Lakes Marion and Moultrie averaged 650,000 tons per year during 1983-85, reflecting a trap efficiency of 79 percent of the total sediment inflow of 825,000 tons per year. Thickness of post-impoundment sediment varies from about 11 feet near the mouth of the Santee River in Lake Marion to 0 feet in Lake Moultrie near Bonneau. Sediments in Lake Marion tend to have finer texture and higher contents of organic matter, nutrients, and trace metals than those in Lake Moultrie.

Suggested Citation

Patterson, G.G., Cooney, T., and Harvey, R., 1996, Sediment transport and deposition in Lakes Marion and Moultrie, South Carolina, 1942-85: U.S. Geological Survey Water-Resources Investigations Report 95-4236, v, 73 p., https://doi.org/10.3133/wri954236.

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title Sediment transport and deposition in Lakes Marion and Moultrie, South Carolina, 1942-85
Series title Water-Resources Investigations Report
Series number 95-4236
DOI 10.3133/wri954236
Year Published 1996
Language English
Publisher U.S. Geological Survey
Contributing office(s) South Atlantic Water Science Center
Description v, 73 p.
Country United States
State North Carolina, South Carolina
Other Geospatial Cooper River Basin, Lake Marion, Lake Moultrie, Santee River Basin
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