Dez dam is one of the key dams in Iran. It is 203 m high with a reservoir of2.3 BCM volume. This double arch dam has been constructed in a narrow gorge in1962, southern west of Iran. It has three irrigation outlets at level of 222.7 m asl, twopower intakes at elevation of 270 m asl. No bottom outlet have been designed andinstalled for Dez dam and consequently the sediment-entering reservoir cannot beevacuated easily. Considering an annual 15.8 million cubic meter sediment inflowinto the reservoir, the bed level is increasing about 1.2 meter per year and therefore itis very necessary to take an appropriate measure saving dam reservoir.One of existing method to save dam reservoir is to flush the sediment out throughexisting bottom outlets.In this study, the feasibility and efficiency of pressure and free flow sediment flushingtechniques have been studied and some good points are presented. The results ofpresent study shows that the flushing method cannot resolve the sedimentationproblem of Dez dam and it must be applied jointly by other methods to save thereservoir from being decommissioned.
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