Revised estimates of one-day probable maximum precipitation (PMP) for India

Abstract

Design floods for major dams throughout the world are based on the probable maximum flood (PMF) which results from the probable maximum precipitation (PMP). Estimates of PMP can be made using a number of methods, the most favoured being the hydrometeorological method involving maximisation and transposition of historic storms. In this paper the in situ maximisation and storm transposition approach has been used for estimating PMP for a one-day duration for different locations in India. Based on these PMP values a generalised map of one-day PMP was produced. It was found that one-day PMP over the Indian region varied from 70 cm to 170 cm, with high values in the mountainous areas of the Western Ghats and in some locations in the north-eastern parts. These results are considerably higher than those obtained using statistical analysis of daily rainfall records using Hershfield's method and they have serious implications for dam safety over much of India.