Estimation of Probable Maximum Precipitation by using Synoptic Method (Case Study: Ajichai Basin)

Estimation of probable maximum precipitation (PMP) is recognized as practical researches in which is taking into consideration by hydrologists in relation to designing the great structures of hydraulic in particular dams. In this study, synoptic method is used in order to estimate probable maximum precipitation in the Ajichai catchment. The meteorological data related from 40 synoptic and climatology stations have been used during the period of 30 years. The date was obtained from Meteorological Organization and Tamab Company, then the missing values was estimated. Also the pressure date of 850-hpa and 500-hpa was collected from National Centers for Environmental Prediction and National Center for Atmospheric Research belong to the Meteorological Organization of the United State of America. In this paper, the researchers used the 500-hpa temperature and pressure data as a representative for atmosphere middle-levels; moisture and streams flow of 850-hpa for analyzing the system’s humidity. Isohyets maps, in continued, produced by GIS for the selected storms and determined Depth-Area-Duration curves for each storms. In the end, the amounts of PMP estimated for 24-48-72 hours durations related to the selected storms. So that PMP was estimated for 24 hour in Ajichai catchment during period 50 and 100 years respectively, 68/1 and 75/1 mm, PMP for 48 hour respectively, 84/5 and 103/9, PMP for 72 hour, respectively, 103/9 and 128/7 mm.