Browsing by Author "AL-Aloosi, Ahmed Natiq"
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Item FLOODS CAUSED BY THE FAILURE OF THE HIMREEN DAM IN THE NORTHEASTERN PART OF BAGHDAD, IRAQ USING HEC-RAS PROGRAM(2022-01-26) AL-Aloosi, Ahmed Natiq; Darama, Yakup; Al-Zaidi, Maha RashidCatastrophic flooding due to dam failures is a major concern for Nations because of the destructive damage to the surrounding environment and loss of lives. When dam failure occurs, a huge amount of water impounded in the dams reservoir discharges to a downstream valley causing damage to the properties, houses, agricultural areas and loss of lives of cattle and people living downstream of the failed dam. In this study, a hypothetical overtopping failure of the Himreen Dam in the Diayla River northeastern part of Baghdad is investigated by using HEC–RAS numerical model. In the study, the numerical model is calibrated to determine the value of average Manning’s roughness coefficient n=0.028 of the Diayla River bed. This value of Manning’s roughness coefficient is determined based on the comparison of flood levels calculated by the modelling study and previous observed flood levels during flooding events that occurred in the area. Sensivity analysis is performed by using three different n values 0.028, 0.030 and 0.035 of the Diayla riverbed in order to determine the effect of Manning’s roughness on the magnitude, depth velocity and arrival time of flood. Maximum flood discharge resulting from the failure of the Himreen Dam, flood elevations and water depths in the inundated areas, time of flood peak arrival to Baquba City (whose population is 400000 people) are calculated in each scenario. The failure of the dam will cause extensive damage to properties and lives of people downstream of the dam because of the severe flooding. The most damage will be in Baquba city because of the high population. A comparison of flood parameters showed that for n=0.035 (scenario 3) the maximum wave height of 35.77 m occurred downstream of the dam in Baquba City 12.61 m and in Nomania 5.64 m. In contrast to the water level and size of the inundation areas, the magnitude of the discharge and time of arrival of the flood wave in scenario 1 for n=0.028 are more critical. The results show that maximum discharge at Baquba City located downstream of the dam is 77201.8 m3 /sec and this value decreased to 131905.89 m3 /sec in Nomania, , and the arrival time of the flood wave to Baquba city is 17.15 hours and to Nomania is 105.45 hours. The results showed that the damage to the properties and the loss of lives will be maximum between the region near the dam and Baghdad city especially in Baquba (centre of Diayla state), because of its population. In comparison among the three scenarios, the worst scenario is 3, because of the highest wave and causing more damage and being more affected.