Assessment of flash flood “April 2018” and its effect on Wadi Degla and Wadi el-Halazouni-east Cairo-Egypt

الملخص EN

Integrated Geographic Information System and Remote Sensing technology with an improved Soil Conservation Service curve number model were applied to analyze and assess the characteristics and impacts of the rainfall storm occurred at April 2018 in East Cairo.

In addition, evaluating the effects of land use changes and urbanization on surface runoff is one of the main objectives in this study.

Wadi Degla (195 km²) and Wadi El-Halazouni (48 km²), were selected for this study.

The morphometric analysis revealedthat, Wadi Degla and Wadi El-Halazouni have elongated shape and lower peak runoff of longer duration over its area.

The return period calculations revealed that the storm of April 2018 may be happened only every 67 years.

The HEC-HMSsoftware is applied to estimate the peak discharge and runoff volume for two different cases (rural case at 1984 and urban case at 2018).

The results revealed that the runoff volume of Wadi El-Halazouni attains about 252.3 x 10³ m³and 416.7 x 10³ m³for rural case and urban case, respectively.

For Wadi Degla the runoff volume in rural case was estimated as 1434.6 x 10³ m³, while in urban case it is reached about 1570.4 x 10³ m³indicating more runoff volume of urban case than the rural case. It is recommended, in Wadi El-Halazouni catchment, to construct a rainwater drainage system to collect the rainfall water and use it for irrigation.

In Wadi Degla, construction of storage dams along its main trunk is necessary to protect the urban area in the Delta of the wadi from the occasionally flash flood risk.