The effect of operation of Mosul dam on sediment transport in its reservoir

摘要

Mosul dam is the biggest hydraulic structure in Iraq located on the River Tigris 50 Km northwest of Mosul city. Itsstorage capacity is 11.1 × 109 m3 and it had been in operation since 1986. A physical distorted model with movable bedhaving a vertical scale 1:100 and a horizontal scale 1:1000 was used to conduct the experiments relating the waterlevel at the reservoir with the bed load transport rate. The model represents the first 15 km of most northern part ofMosul dam reservoir. The construction of the model was based on bathymetric survey conducted in 2009. Twenty-fourexperiments were executed using four different discharges (500, 1000, 1500 and 2000 m3/s respectively) whichrepresent the average discharges in the flood period of River Tigris. At each individual discharge six operations wereassumed where the reservoirs water level was 305,307,309,310, 312, 315m above sea level (m.a.s.l) respectively. In allthe experiments conducted, bedload transport rate was decreasing when the water level within the reservoir wasincreasing. It was also evident that bedload transport rate dramatically decreased at level 310 onward. This is due tothe fact that at this level represent the effect of backwater which was noticeable on the river cross section.