干旱区生态环境知识资源中心

Defining the characteristics of rainfall distribution is the key for many engineering applications such as road design, flood damage mitigation measures, and planning and management of water resources. Since Makkah Al-Mukarramah area is of utmost importance in Saudi Arabia, studying the characteristics of rainfall distribution is necessary. This research aims at investigating rainfall data to define the best rainfall distributions and its characteristics in the study area via rainfall frequency analysis. Different statistical analyses such as log-normal distribution, normal distribution, extreme value type I distribution, Pearson type III distribution, and log-Pearson type III distribution were preformed on more than 20 stations having annual rainfall data over ten years. The results showed the best probability distributions, and rainfall predictions at various return periods for the study area. 36% of rainfall stations follow three parameters log-normal distribution, 27% of stations follow log-Pearson type III distribution, 14% of stations follow Pearson type III distribution, 9% of stations follow GEV distribution, 9% of stations follow two parameters log-normal distribution and 5% follow Gumbel Type I.