Emergency spillway design for Wangfuzhou hydroproject

The emergency spillway for Wangfuzhou hydroproject is constructed on the earth and rockfill dam crossing the main river channel and blocked with a 12 m high sand gravel dam. The river bed is composed of sand and gravel. The emergency spillway is 415.6 m wide, with maximum discharge of 4 960 m3/s. The dynamite chambers are reserved in the blockage and it will be exploded for emergency flood diversion. The upstream water level should be controlled during flood diversion and the adjacent structures along the sides of the spillway should be protected. The exploded blockage will be reconstructed after flood season. The main problems to be solved in the design include the site selection of emergency spillway, dam structure, seepage prevention mode, scour prevention measures etc.