Author(s): Chih Ted Yang; Jungkyu Ahn; Paul M. Boyd; Daniel B. Pridal; John I. Remus
Linked Author(s):
Keywords: Drawdown flushing; Flushing efficiency; GSTARS computer model; Reservoir sedimentation; Sediment transport; Lewis and Clark Lake
Abstract: Lewis and Clark Lake, behind Gavins Point Dam near Yankton, South Dakota, U. S. A., is located on the main stream of the Missouri River. The Lewis and Clark Lake reach extends about 40 km from the Gavins Point dam. Large amount of sediment was supplied from a major tributary, the Niobrara River. Reservoir delta has been growing since the closure of Gavins Point dam in 1955 and has resulted in a 21% reduction of storage in 2007. Among several sediment management methods, flushing with water surface drop is a suitable management technique for the lake. The engineering viability of removing sediments deposited in the lake should be examined by numerical modeling before implementing a flushing. GSTARS4 (Yang and Ahn, 2011) was used for this study and calibrated with measured historic data from 1975 to 1995. Channel geometric changes and amount of flushed sediment were predicted with four hypothetical flow scenarios. The flushing efficiencies of all scenarios were estimated by comparing the ratios between water consumption and flushed sediment.
Year: 2013