The Atchafalaya River Delta. Report 12: Two-Dimensional Modeling of Alternative Plans and Impacts on the Atchafalaya Bay and Terrebonne Marshes

• Main Authors: Donnell, Barbara Park, Letter, Joseph V. Jr.
• Other Authors: United States. Army. Corps of Engineers. New Orleans District.
• Format: Report
• Language: English
• Published: U.S. Army Engineer Research and Development Center (ERDC) 1992
• Subjects: Ingenieurwissenschaften (620); Atchafalaya River; Atchafalaya River Delta; Atchafalaya Basin; Louisiana; Terrebonne Marshes; Hydrodynamics; Wax Lake Outlet; Delta evolution; Delta growth; TABS-2; Computer program; Numerical model; Mathematical model; Sediment transport; Sedimentation; Deposition; Salinity; Saltwater encroachment; Geomorphology; Verification; Subsidence; Beer Island
• Online Access: https://hdl.handle.net/20.500.11970/111966

Source: https://erdc-library.erdc.dren.mil/jspui/ The Wax Lake Outlet and Atchafalaya River deltas in Louisiana have grown dramatically, and concern over the impact of this growth has led the US Army Corps of Engineers to conduct an investigation to predict how the deltas will evolve over the next 50 years. An additional task was to determine the impacts of that growth on navigation, flood control, salinity, and sedimentation in the bay area. The technical approach for this investigation builds upon the TABS-2 finite element numerical modeling system and is fully described in Report 11 of this series. Comparisons of the existing condition results with various alternatives are presented. In summary, the extension of the Avoca Island Levee to Beer Island (Reach 2) resulted in an approximate 8 percent increase in the predicted size of the 50-year delta evolution regardless of other constraints tested. For all alternatives tested, the size of the 50-year subaerial delta fell within the bounds of 56 to 144 square miles. The most extreme delta evolution simulation tested was the condition without the Wax Lake Outlet flow control project, no navigation channel dredging, and no levee extension. For all delta evolution simulations tested, the water surface elevations within areas east of the levee increased from 3.4 to 6.0 ft by year 2030. In each case tested, the Avoca Island Levee Extension to Reach 2 decreased the backwater effect of the 50-year delta by approximately 2 ft.