Estimating the Sediment Load Transported by the Valleys to Makhoul Dam Reservoir (Under Construction)

Abstract

The problem of sediments in dam reservoirs has negative effects on the life of dams and the associated financial costs for removing them from these reservoirs. This research is concerned with studying soil erosion in six valleys that flow into the Makhoul Dam reservoir and estimating the amount of sediment that will move into this reservoir annually. Three of these valleys (Al-Jirnaf, Umm Al-Shababit, and Al-Qasr) are located on the western (right) side of the reservoir, and the other three valleys (Al-Shook, Al-Rakhma, and Al-Fudha) are located on the left (eastern) bank of the reservoir. The sediments load expected to flow into the reservoir from these valleys were estimated by calculating the amount of soil erosion using the Universal Soil Loss Equation (USLE) and geographic information systems programs (GIS and Global Mapper) in addition to surfer program. Next, by figuring out the sediment delivery ratio (SDR), it was determined how much sediment load will be reached the reservoir from every valley. The results indicated that the total annual erosion of soil from these six valleys amounted to 1,010,677 tons, of which 249,175 tons are expected to reach the Makhul reservoir annually as a sediment load, divided as follows: Annual erosion from Al-Jarnaf valley is 518,700 tons, of which 121,467 tons reach the reservoir, at a rate of 48.7%. As for Al-Fudha valley, the annual erosion amounted to 232,198 tons, of which 54,692 tons reached to the reservoir, at a rate of 21.95%. The Umm al-Shababit valley occupied third place in terms of annual erosion 128,725 tons, of which 34,529 tons reached the reservoir at a rate of 13.85% of the total sediment load from the six valleys. Al-Shouk, Al-Rahma and Al-Qasr catchments came in fourth, fifth and sixth place, respectively. These catchments have annual erosion quantities of 52,299, 42,415, and 36,338 tons, and will contribute 14,901, 12,484, and 11,100 tons per year to the reservoir as a sediment load, which comes to 5.96%, 5.01%, and 4.45% for each of them, respectively.