Estimating the Probable Maximum Precipitation in the Bakhtiari Dam Basin Using the Statistical and Synoptical Methods

The two main approaches for estimating PMP are the synoptic and statistical techniques that their results are often different and selection of the appropriate option is difficult. In the most previous researches the frequency factor in the statistical method has been considered equal to 15 which this is the ultimate limit of frequency factor and the corresponding PMP is became too large. In the present research the PMP for 1 to 7 days durations in the Bakhtiari Dam basin was calculated using statistical and synoptic techniques, and the frequency factors in Statistical technique were properly determined. Results showed that the appropriate factor frequency in statistical technique for this area is about 6.1 which in this case, its results are almost the same as synoptic techniques. Based on the results of synoptical PMP and statistical PMP with factor frequency 6.1 at different durations, about 55 percent of the PMP have been observed, while for factor frequency 15, less than 30% of statistical PMP has been observed.