Potential Flood Hazards in Wadi Dawqah Central Southwestern Saudi Arabia
Mohammed I. Al-Zahrani, Saad G. Al Harthi, Hussam A. Khiyami, Hashim M. Al-Hawsawy, Mohammed S. Theban, and Zekai Șen
Wadi Dawqah is located in the central southwestern Saudi Arabia, and lies between lat. 19°30′50″N. and 20°06′20″N., and long. 40°37′E. and 41°30′E. in the southern part of Jabal Ibrahim quadrangle and the Al Qunfudah quadrangle. The wadi’s headwater lies at an elevation of more than 2,000 m above the mean sea level (msl) in the Sarawat Mountain and runs toward the Red Sea coastal area reaching the sea. In this report two different approaches were suggested to estimate the possible flood magnitude in flood-prone areas. These are (a) the construction of synthetic unit hydrograph from the known characteristics and measurements of some physiographic parameters in the catchment area, (b) the control cross-section calculation method, which predicts the peak flood discharge and the future frequency of flood occurrences. The arid and semi-arid regions are most susceptible to potential flash flood occurrences, such as in the central southwestern part of the Kingdom of Saudi Arabia, where technological methods cannot possibly control the potential flood hazards. It is therefore imperative to prepare flood-risk maps. The availability of these maps is the key requirement in urban development such as the planning of future construction of dams, tunnels, highway, and bridges followed by the setting up of safety protocol based on sound scientific methods. A long-term study of hazardous hydrological events is necessary to maintain growth and development. In flood calculations, one of the main objectives is to show the inundation boundaries of each wadi catchment area on a digital elevation map (DEM), which was not available during this study and therefore inundation boundaries are presented as control cross-sections on a topographic contour map.
Al-Zahrani, M.I., Al-Harthi, S.G., Khiyami, H.A., Al-Hawsawy, H.M., Theban, M.S., and Sen, Z., 2008, Potential flood hazards in Wadi Dawqah central southwestern Saudi Arabia: Saudi Geological Survey Technical Report SGS-TR-2006-1, 28 p., 25 figs. 9 tables, 6 apps.