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Source: https://erdc-library.erdc.dren.mil/jspui/ The Charleston Harbor model reproduced the Ashley, Cooper, and Wando Rivers, and a portion of the Atlantic Ocean. The model was of fixed-bed construction and was equipped with all the necessary appurtenances for accurate reproduction and measurement of tides, tidal currents, salinity intrusion, and other significant phenomena of the prototype. Construction of the Santee-Cooper power project in 1940-1942 included diversion of flow from the Santee River into the Cooper River watershed. Average freshwater flow into Cooper River was increased from 72 cfs to 15,000 cfs, and maintenance dredging in Charleston rapidly increased from about 180,000 cu yd per year up to 10,000,000 cu yd today. Prior studies led to the conclusion that rediversion of a major portion of the Santee River flow would result in a substantial reduction in maintenance dredging in Charleston Harbor. The amount of Santee River flow to leave diverted into Cooper River became a critical value with respect to power generation at Pinopolis, water quality in Charleston Harbor, and the prevention of saltwater intrusion into the Back River Reservoir constructed to supply freshwater for the Bushy Park industrial area and the City of Charleston. The results of previous studies indicated that a weekly average flow of 3000 cfs would be satisfactory with respect to reduced maintenance dredging. The power requirements could also be satisfactorily met with a minimum weekly average flow of 3000 cfs. A detailed study involving various weekly schedules for release of the 3000 cfs on conditions in the upper reaches of Cooper River and the Bushy Park Reservoir was considered necessary. Hydraulic and salinity tests were made for six weekly release schedules from the Pinopolis power plant. The first involved ·the continuous release of the existing weekly average freshwater discharge at the Pinopolis power generating station of 15,600 cfs, which is referred to as Schedule A. Schedules B, C, and D all involved release of the 3000-cfs weekly average flow; however, the respective daily flows were different. Schedule B had one day of 1325 cfs and six days of 3279 cfs; Schedule C had three days of zero flow and four days of 5250 cfs; and Schedule D has three days of 1200 cfs and four days of 4350 cfs. Schedule E reproduced a weekly average flow at Pinopolis of 3500 cfs, with 69 hours of zero flow, 3 hours of 28,500 cfs, and four days of 5250 cfs. Schedule BM also reproduced a weekly average flow at Pinopolis of 3500 cfs, but this schedule had one day of 1325 cfs and six days of 3860 cfs. The results of the six tests indicated that, due to rediversion, tide levels in the upper Cooper River, Back River Reservoir, and the East Branch of the Cooper River were lowered by amounts between about 0.3 ft and 2.0 ft. Tides at stations in lower Cooper River (below mile 20), the Wando River, and the Ashley River were reiatively unchanged. Surface and bottom ebb predominance was decreased drastically in the upper reaches of Cooper River, and was more nearly balanced throughout the length of Cooper River for rediversion conditions than for existing conditions. For existing conditions, the upstream limit of saltwater intrusion (100 ppm) was about Cooper River mile 25. For rediversion conditions, the upstream limit of saltwater intrusion was about mile 39 for Schedules B and D, mile 40.5 for Schedule C, and mile 36 for Schedules E and BM. The degree of salinity stratification was significantly reduced throughout the system for rediversion conditions._x000D_ _x000D_ NOTE: This file is very large. Allow your browser several minutes to download the file. |
