Figure - Old River

Old River

The goals of the sedimentation investigation were as follows:

  • Summarize the geomorphology and chronology of the various construction works.
  • Evaluate long term sedimentation trends of the Mississippi River and Old River Control complex.
  • Evaluate various operational combinations of the control structures to alleviate the tendency for sediment deposition in the Mississippi River and the ORCC, and improve sediment transport/diversion into the Atchafalaya.
  • Evaluate various design alternatives in the main channel of the Mississippi River to both improve the navigation channel and improve sediment transport/diversion into the Atchafalaya.
  • Evaluate the general effects of dredging the inflow and outflow channels. This would involve the examination of both the bathymetric trends as well as the time associated with the return of dredged sediment associated with each design alternative. Determine long term trends of Low Sill operation by itself with no other structures in place.
  • Approximate the time it takes for sediment to fill back in the Low Sill and Auxiliary Structure inflow and outflow channels dredged to -10 feet elevation (“as built” condition).
  • Evaluate the feasibility of operation to maintain the required flow and sediment split (Flow: 70% through the Mississippi River and 30% to the Atchafalaya River; Sediment: 35% through the Mississippi River and 65% through the ORCC; as called for in the Old River Complex Authorization (Flood Control Act of 1945)).