Flood Hazard Evaluation in Wadi Hali and Wadi Yibah, Kingdom of Saudi Arabia
Hossam A. Khiyami, Zekai Z. Şen, Saad G. Al-Harthy, Faisal A. Al-Ammawi, Ali B. Al-Balkhi, Mohammed I. Al-Zahrani and Hashim M. Al-Hawsawy
Wadi Hali and Wadi Yibah lie about 360 – 420 km south of Jeddah city near Al-Qunfudah town, on the Tihamat Asir region originating their floods along the coastal area.
In this report, we suggested two different approaches to estimate the possible magnitude of the flood in this flood-prone area.
The first approach is the construction of synthetic unit hydrograph from the known characteristics and measurements of some physiographic parameters in the catchments area.
The second approach is the control section calculation method, which predicts the flood discharge peaks and the future frequency of flood events occurrence.
Arid and semi arid regions are most susciptible for potential flash flood occurrences, such as in the southwestern part of the Kingdom of Saudi Arabia, where it is not possible to control the potential flood hazards by using of technological methods that forewarn us of its occurrence or imminence.
Therefore, it would be better to prepare flood risk maps.
The availability of these maps is the key requirement of any urban development that entails construction of dams, tunnels, highways, and bridges for sustainable future.
This is followed by the provision of protection according to sound scientific methods.
In order to maintain this growth and development, it is necessary to conduct continuous maintenance work against hazardous hydrological events.
Unavailability of digital elevation models (DEM) of each wadi catchment, in order to show the inundation bounderies on it, is one of the main objectives after all flood calculations.
Instead classical topographic map contours around some representative cross-sections are presented as inundation bounderies.
Khiyami, H.A., Şen, Z.Z., Al-Harthy, S.G., Al-Ammawi, F.A., Al-Balkhi, A.B., Al-Zahrani, M.I., and Al-Hawsawy, H.M., 2005, Flood hazard evaluation in Wadi Hali and Wadi Yibah, Kingdom of Saudi Arabia: Saudi Geological Survey Technical Report SGS-TR-2004-6, 48 p., 50 figs. 14 tables, 6 apps.