بررسي تغييرات مكاني حداكثر بارش محتمل 24 ساعته در حوضه آبريز قره قوم

Spatial distribution of Probable maximum precipitation for 24 h duration over Ghareh Ghum watershed

One of the most important problems in Hydrometeorology is the estimation of reliable Probable Maximum Precipitation (PMP) for different durations that are expected to occur over a point or an area. A statistical method for estimating PMP values was developed by Hershfield based on frequency equation. Many researches had been done on frequency factor in this method but all of them lead to high estimation of PMP. In this paper the frequency factor of Hershfield method is analyzed based on local data in Ghareh Ghum watershed with 44491 km area. Using L-Moment method confirms the homogeneity of 57 stations in investigated watershed. Based on this procedure, the frequency factor of Hershfield equation was found to be 7.63. The approximated frequency factor is in accordance with corresponding researches in Atrak watershed and Malaysia. Finally a generalized map was prepared for showing the spatial distribution of 24 h Probable maximum precipitation.