EFFECT OF RAPID DRAWDOWN WATER IN UPSTREAM AL-WAND DAM BY USING GOE-STUDIO SOFTWARE

The rapid drawdown effects directly on the stability of upstream slope of earth dams, where the seepage direction will be in the reverse direction due to emergency emptiness, which causes flow from downstream to upstream through the dam body, such flow may be not considered in design. In this research two cases of rapid drawdown are adopted, in the first case, the reservoir is empty from service canal (outlet flow) where the discharge of this canal is 200 m3 /sec. In the second case, the reservoir is empty by spillway canal with discharge capacity equal to 2750 m3/sec. The results show that the discharge from spillway takes a few hours which threaten the dam stability compering with allowable factor of safety while discharge from outlet flow service takes a few days and the threaten was nominal, both of them under rapid drawdown condition .