Rainfall statistics change in West Bengal (India) from period 1901-2000

Abstract

The study aims to investigate rainfall trends in West Bengal, India. The paper deals with monthly, seasonal and annual general rainfall trends. The study is carried out to understanding the underlying feature for the purpose of forecasting and in identifying the changes and impact that are very crucial for an agro-based economy like the one of West Bengal, India. Here we studied using monthly data series of last 100 years (1901-2000). The methodology has been adapts various statistical approaches in order to detect the possible precipitation changes in annual, monthly and seasonal basis; including both the non-parametric tests for monotonies trend (Mann-Kendall test, Sequential version of Mann-Kendall test and Sen's estimator of slope). Maximum of the districts showed an increasing trend in annual rainfall, but only one district (South 24 Pargana), this trend was statistically significant. In case of Monsoon months (June to September) maximum number of districts shows the increasing trend but it is not statistically significant. Only three districts (Midnapur west, North 24-Parganas and South 24-Parganas) of them are statistically significant. The majority of districts show very slight change in rainfall in nonmonsoon months.