Sediment Transport Capacity Calculations The hydraulic capacity of the stream to transport coarse sediments can be computed using a variety of equations. Sediment transport capacity can be computed at various downstream locations of interest for a range of stream flows or discharges. The required input data for the sediment transport equations include channel hydraulics and the sediment grain size. For each stream discharge of interest, the average cross-section hydraulics (depth, width, velocity, and energy slope) will have to be measured or computed using a hydraulic model or computed assuming normal depth. In order to compute the hydraulic capacity of the stream to transport reservoir sediment, use the grain size distribution representing the coarse reservoir sediments rather than the stream below the dam. Assume that the fine sediments, eroded from the reservoir, will be transported in suspension as wash load. There are many computer programs available to computer sediment transport capacity. The Bureau of Reclamation provides one such program (Huang and Bountry, 2009), which can be downloaded for free at: This program can compute sediment transport capacity using the equations listed in Table 6. Table 7. Sediment transport equations available in the SRH-Capacity program. Sand & Gravel Sediment Transport Equation Sand Gravel Mixture Engelund and Hansen (1972) √ Ackers and White (1973) √ Yang (1973) √ Yang (1979) √ Wilcock and Crowe (2003) √ √ Parker (1990) √ √ and Müller (1948) √ Yang (1984) √ Wu (2004) √ The U.S. Army of Engineers HEC-RAS (Bruner, 2016a and 2016b) can be used to compute the channel hydraulics parameters for various stream discharges of interest: The data required for the hydraulic model include the cross section coordinates of the stream channel and floodplains, estimates of channel roughness, and the downstream boundary water surface elevations associated with the stream discharges of interest.
Sediment Transport Capacity Calculations The hydraulic capacity of the stream to transport coarse sediments can be computed using a variety of equations. Sediment transport capacity can be computed at various downstream locations of interest for a range of stream flows or discharges. The required input data for the sediment transport equations include channel hydraulics and the sediment grain size. For each stream discharge of interest, the average cross-section hydraulics (depth, width, velocity, and energy slope) will have to be measured or computed using a hydraulic model or computed assuming normal depth. In order to compute the hydraulic capacity of the stream to transport reservoir sediment, use the grain size distribution representing the coarse reservoir sediments rather than the stream below the dam. Assume that the fine sediments, eroded from the reservoir, will be transported in suspension as wash load. There are many computer programs available to computer sediment transport capacity. The Bureau of Reclamation provides one such program (Huang and Bountry, 2009), which can be downloaded for free at: This program can compute sediment transport capacity using the equations listed in Table 6. Table 7. Sediment transport equations available in the SRH-Capacity program. Sediment Transport Equation Sand Gravel Sand & Gravel Mixture Engelund and Hansen (1972) √ Ackers and White (1973) √ Yang (1973) √ Yang (1979) √ Wilcock and Crowe (2003) √ √ Parker (1990) √ √ and Müller (1948) √ Yang (1984) √ Wu (2004) √ The U.S. Army of Engineers HEC-RAS (Bruner, 2016a and 2016b) can be used to compute the channel hydraulics parameters for various stream discharges of interest: The data required for the hydraulic model include the cross section coordinates of the stream channel and floodplains, estimates of channel roughness, and the downstream boundary water surface elevations associated with the stream discharges of interest.
dam_removal_analysis_guidelines_2016-12-14.docx