Potential Flood Hazard in Wadi Damad, Southwest Saudi Arabia

SGS-TR-2007-8 Saad G. Al-Harthi, Mohammed I. Al-Zahrani, Faisal A. Al-Ammawi, Hussam A. Khiyami, and Zekai Şen
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ABSTRACT

 

Floods are one of the most dangerous natural disasters in the world, and are known for the damage they cause to human life and property. This harm is bigger especially in the regions that are subject to erosion. The main causes of floods are: (1) the rainfall type and intensity, (2) drainage-area surface features, and (3) subsurface soil and geological composition. It is noted that the drainage area properties can be changed by humans. Flash floods develop suddenly and mostly in the places having arid or semi-arid climates. At present, various methodologies and applications have been carried out to prevent damages regionally.  This report presents the procedure for the preparation of flood inundation maps and its application in Wadi Damad. It is clear that this wadi has occasional high-flood potential because of the high standard deviations of rainfall, which are bigger than the monthly averages. It is also seen from figures 1-7 that the wadi is subject to large damage by flash floods.  The report explains clearly the required precautions to prevent damage from floods in Wadi Damad. These precautions were achieved with the following steps:

  1. Topographic map contours were used in the calculations since digital elevation maps were not available in the region.
  2. The regional rainfall risk maps at various risk levels were plotted for Wadi Damad.
  3. Three places for the control-cross-section area were selected and their parameters (Manning coefficient, bed slope, cross-section area and hydraulic radius) were calculated.
  4. The peak values of discharge at various cross-section depths were found.
  5. Three infiltration tests were performed in places on the selected cross-sections. Therefore, the effective rainfall amount and duration were calculated
  6. The inundation surface maps and boundaries in each cross-section were formed and the mathematical relationships were given.
  7. The general and specific conclusions obtained from the study and the recommendations that would help the region’s community in the future were implied.

As a result, this technical report is appropriate due to the sufficient and factual processes.

 

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Al-Harthi, S.G., Zahrani, M.I., Ammawi, F.A., Khiyami, H.A., and Şen, Z., 2009, Potential flood hazard in Wadi Damad, Southwest Saudi Arabia: Saudi Geological Survey Technical Report SGS-TR-2007-8, 37 p., 32 figs., 9 tables, 7 apps.