THE EFFECT OF IRRIGATION ON PREMONSOON SEASON PRECIPITATION OVER SOUTH-WEST BENGAL, INDIA

The present work is on the modification of climatic variables, such as rainfall, as a result of change in land use during the premonsoon per iod over the southern part of West Bengal, India. Data analysis suppor ts a decreasing tendency in rainfall during the recent years. As a pos sible factor behind such change, a significant increase in agricultura l activity during recent years in coastal and inland regions has been stressed. The increase in soil moisture as a result of irrigation hind ers the development and intensity of the sea-breeze circulation. The l ow-level moisture supply also decreases, which is an essential criteri on for the formation of premonsoon thunderstorms, that is, northwester s. So, the increased vegetation or soil moisture is not always likely to increase rainfall activity: rather, mesoscale effects may be more i mportant in some specific areas.