Improving flood control capacity of High Aswan Dam and elevation of flooding

摘要

High floods brought considerable damages with them. Sometimes not only the fields but erosion occurred in the riverbanks and beds. The important navigation on the Nile was seriously hampered. Various schemes for flood protection have been proposed from time to time, but it was limited, because the water passing down the river to the sea exceeded the safe margin. Reached to 162-milliard m~3, of which 41-milliard m~3 specified as flood control capacity, between elev. 175, 182 m U.S. the Dam. If several high floods occur in sequence, the reservoir water level becomes comparatively high. According to instruction of operation for. The High Dam, the flood control capacity must be emptied down to level 175m, before the arrival of the following. Flood, this will result in releasing high discharges, that may reach 350-400 million-m~3/day. In this case, further degradation is expected. This may affect the riverbed, downstream the control structures existing on the river; the canal intakes and water pumping station. To avoid this, it was decided to make use of one of the western valleys (khor Toshka), connecting a huge depression (Toshka Depression) on the western desert to the reservoir, to act as additional spillway named as Toshka Spillway. When the live storage of the lake reached to the max. level (175 m). In spite of this case, the High Dam had been controlled by passing discharges through Toshka Spillway (total 12.60 billion m~3) beside, additional limited discharges D.S. Also the next flood (1999/2000) was high. Max. lake water level reached to (181.60m), which is less than the designed level by only 0.40m. This high flood was also been controlled by passing (14.1 milliard m~3) through Toshka Spillway. Flood of years (2000/2001) and (2001/2002) were above average and high, they had been controlled by passing (8.3, 5.7 milliard m~3) through the spillway. It would cause significant damages. So, Toshka Spillway improved flood control capacity and in conjunction with High Aswan Dam had played an important part in controlling and floods.