Identification Of A Suitable Probability Distribution For Rainfall Analysis Of Bankura District In West Bengal

Abstract

The daily rainfall data of 22 years (1992 to 1993 and 1997 to 2016) of Bankura district in West Bengal were collected from the Indian Meteorological Department (IMD), Kolkata. The data was then processed to identify the maximum rainfall received on any one day (24 hrs duration), in any week (7 days), in a month (4 weeks), in a monsoon season (4 months), pre-monsoon (4 months), post-monsoon(4 months) and in a year (365 days). The data were analysed to find out the standard deviation and coefficient of variation during all the six periods of study. The data showed that the annual daily maximum rainfall received at any time ranged between 58.7mm (minimum) to 258.8mm (maximum) indicating a large range of fluctuation during the period of study. These data were analysed using Anderson-Darling (AD) statistical goodness of fit teston the basis of probability plot to identify the best fit probability distribution for all the six period of study and the trend has been presented in this study. The lognormal distribution was found as the best fit probability distribution for the annual and monsoon period of study. The weibull (3P) was found as the best fit distribution for pre-monsoon and post-monsoon period of study. Weibull (3P), gamma (2P), lognormal, exponential and largest extreme value were observed in most of the weekly period of study as best fit probability distributions. The scientific results clearly established that the analytical procedure devised and tested in this study may be suitably applied for the identification of the best fit probability distribution of rainfall data.