CCHE2D-Sed Model

Sediment transport is a process that sediment or soil particles are mobilized and carried by water flows from one place to the next. Sediment entrainment and deposition are closely related to the flow conditions and sediment properties. Sediment transport is the major forcing changing the earth landscape and causing problems in watersheds, rivers, reservoirs, lakes, and coasts.

Key capabilities of CCHE2D Sediment Transport Model

  1. Unsteady flow
  2. Non-uniform sediment (multiple sizes)
  3. Non-equilibrium bed load sediment transport
  4. Suspended sediment transport
  5. Morphological change of beds
  6. Bank erosion process includes bank surface erosion, toe erosion and mass failure

The Bonnet Carré Spillway delivered a plume of thick sediment to Louisiana’s Lake Pontchartrain in mid-May 2011.

Sediment Pollution in the Lake Pontchartrain, LA

Flood release from the Mississippi River to the Lake Pontchartrain, LA, is operated once in few years to reduce flood threat to the New Orleans City. A large amount of sediments in the Mississippi River is brought into the Lake with the flood water downgrading the water quality. It takes many days for the sediment to deposit and to be transported out of the Lake. CCHE2D-SED has been applied to simulate the sediment transport process.

Comparisons of the CCHE2D simulated sediment transport process in the Lake Pontchartrain, LA, after the 1997 flood release from the Mississippi River are shown. The simulated distributions of suspended sediment are very close to those observed with satellite imagery.

Bank Erosion of ChuoShui Creek, Taiwan

Chuoshui Creek is a mountain river in Taiwan. Characterized by a steep slope, an abundant supply of sediment and a high rate of precipitation in Typhoon seasons. The studied river reach has a braided channel pattern with rapidly changing sub-channels. Both bed erosion and bank erosion are significant particularly during the typhoon seasons, resulting in fast channel changes and a severe farmland loss along banks. CCHE2D sediment transport and bank erosion model were applied to simulate the sediment transport and morpho-dynamic process in one reach of the river.

Bank erosion and channel bed erosion are simulated at the same time.

Typhoon induced flow and sediment conditions are used as boundary conditions.

Kerr reservoir is a big reservoir in Virginia, its area is about 200km2. Continuous two years of sediment transport process in the Kerr Reservoir were simulated using CCHE2D-Sed. Majority of sediments came with the major flood incidents.

Because the reservoir is very large, the sediments from upstream tributaries travel slowly and it took a long time (~16 days) to reach the dam of the reservoir. Some of the sediments came into the channels of side tributaries. When the reservoir becomes wider, large flow circulations are developed due to the highly irregular shape of the reservoir. The shape of the sediment plume indicated the transport process and the complex flow field.