Abstract
In arid regions, flash floods often occur as a consequence of excessive rainfall. Occasionally causing major loss of property and life, floods are large events of relatively short duration. Western Saudi Arabia is an extremely arid region where rainfall is characterized by extremely high spatial and temporal variability. This area is subject to environmental hazards such as flood risks because most of the infrastructure is located on wadis and flood plains. In this paper, an integrated approach was adopted in which geographic information system and rainfall-frequency analysis using annual maximum 24-h rainfall were utilized to identify, assess and mitigate hydrological and environmental flood hazards in the study area. The study shows that the prediction of annual maximum 24-h duration rainfall along with prediction of 25-, 50-, 100- and 200-year return periods for the best fit of Gumbel pdfs. In addition, probable maximum precipitation was also estimated for 50- and 100-year return periods, which will aid decision-making for future project designs and flood protection studies.