Page - 950 - in Book of Full Papers - Symposium Hydro Engineering

Table 2 Emptying abilities of primary high concrete dams Projects Dam height (m) Storage capacity (×108m3) Residual head after emptying (m) Water head emptying ratio (%) Residual capacity after emptying (×108m3) Storage capacity emptying ratio (%) Emptying time (d) Goupitan 232.5 55.64 500.3 58.41 1.811 96.75 43 Longtan 216.5 272.7 297.6 48.76 16.9 93.80 123 Xiaowan 294.5 146 1090.0 51.81 10.61 92.73 58 Guangzhao 200.5 31.5 646.0 50.77 2.6 91.75 42.5 Wudongde 270 58.86 895.0 31.13 5.604 90.48 62 Laxiwa 250 10.06 2340.8 45.96 1.35 86.58 30 Huangdeng 203 15.49 1549.0 35.53 2.23 85.60 15 Jingping I 305 77.6 1758.9 40.37 14.23 81.66 70 Dagangshan 210 7.42 1051.6 38.24 1.4 81.13 3.7 Xiluodu 285.5 115.7 504.7 34.59 27.74 76.02 30 Ertan 240 57.9 1135.0 27.66 15.26 73.64 7.2 Baihetan 289 190.06 736.3 31.67 51.39 72.96 39 Three Gorges 181 393 145.0 17.54 171.5 56.36 10 The two tables above indicate that, most reservoirs can be discharged more than half water head and 70% capacity which are mainly affected by hydrologic conditions, reservoir topography, dam height and design of emptying facilities. Storage capacities emptying ratios of those reservoirs located in alpine and narrow valleys are usually larger, such as Shuibuya CFRD and Wudongde arch dam. On the other hand, water head emptying ratios of those reservoirs located in wide valleys are usually larger, such as Three Gorges and Bashan dam. Specially, storage capacities emptying ratios of some reservoirs with special topography can reach up to 95%, while water head emptying ratios of those are just about 60%, such as Pubugou, Tianshengqiao I. As most of high dams with 300m height are located in alpine and narrow valleys in southwestern China, it is difficult to emptying the water head of reservoirs. In addition, the emptying time cost varies a great deal for different reservoirs. KEY TECHNOLOGIES OF LOWER DISCHARGE FACILITIES The most effective measure to emptying reservoirs is via lower discharge facilities, the key technologies of which are an important breakthrough of emptying design, including enhance emptying ability, shorten emptying time, routine maintenance, hydraulic problems and downstream protection. 950