Reservoir sediment routing and hydraulic flushing

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:220159

Hu, G ^[1]

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1. Univ. of California, Davis, CA (United States)

Dams for surface water impounding interrupt the natural process of sediment transport along the river channel. Sediment routing operation will recover this transport process to a certain extent. Another technique, hydraulic flushing, controls sediment accumulation by periodically removing sediments in the reservoir. The flushing funnel and the deep thalweg formed during flushing will maintain a low erosion datum in the reservoir, so that the development of deposition will stop at an earlier stage and a portion of the reservoir storage can be preserved as long-term storage capacity. Sediment releasing capacity of a reservoir consists of two parts: (1) sediment releasing capacity of dam structure or {open_quotes}dam capacity{close_quotes}, and (2) sediment carrying capacity of flow in the impounded region or {open_quotes}flow capacity{close_quotes}. Higher flow capacity is achieved by drawing down reservoir water level to decrease water depth and therefore increase flow velocity. However, dam capacity become smaller at lower water levels since hydraulic head on bottom outlets decreases. For a successful routing/flushing operation, dam capacity must not be smaller than flow capacity so that sediment carried into near-dam region can be released, without causing near-dam deposition and operational problems. Bed shear stress is an important flow parameter in routing or flushing design. Flow during sediment routing/flushing is highly unsteady and non-uniform. A method based on the principle of momentum conservation is introduced for bed shear calculation under such conditions.

• OSTI ID: 220159
• Report Number(s): CONF-9507190--
• Country of Publication: United States
• Language: English

Related Subjects

13 HYDRO ENERGY
DAMS
HYDROELECTRIC POWER PLANTS
REMOVAL
SEDIMENTATION
SHEAR PROPERTIES
WATER RESERVOIRS