Extreme Rainfall Pattern Analysis for Drought Prone Shali Reservoir Area in West Bengal of India

Abstract

Rainfall is one of the major sources of needed water. Rainfall amount also determines the agricultural and industrial activities in the region.  The present study has been conducted to examine the rainfall trend in the Shali reservoir area of the Gangajalghati block in Bankura district in West Bengal. The Shali reservoir was made to provide irrigation water in the Gangajalghati block. Water insufficiency is a habitual threat to the people of this area. Here the planting and production of crops highly depend on the constricted period of inconsistent rainfall. About 80-90 % of rainfall usually occurs in this area from June to September until the onset of heavy rains. Therefore, in this drought-prone area, the analysis of rain patterns is very vital to understand the change in rainfall at all times. The monthly and annual rainfall data have been taken from field surveys and secondary surveys for almost the last 40 years (1980 to 2020). The Mann Kendall (MK) and Sen’s Slope estimate (SSE) tests have been applied to recognize the standing trend and the SSE test has been used to discover the existing trend and extent of change in rainfall over time. The rainfall data has been taken from ten rain gauge stations surrounding the study area. The relevant maps were prepared using Remote Sensing and the rainfall distribution pattern was analyzed with the help of the kriging interpolation technique of GIS. The annual MK test shows a positive trend but the season-wise MK test is showing a negative trend during monsoon season. SPI result describes that the study area is not getting normal rainfall during the monsoon season, it may create harmful effects on agricultural productivity. The study suggests taking proper drought management programs to combat this situation.