TREND ANALYSIS OF RAINFALL PATTERN OF FIVE SELECTED REGIONS IN BANGLADESH

Abstract

Every year, Bangladesh experiences an abundant amount of rainfall due to its geographic location. Majority of the country’s economy depends on agricultural sector which is dependent of seasonal rainfall to some extent. So, rainfall trend plays a vital role in country like Bangladesh. Data used in this study have been collected from Bangladesh Water Development Board (BWDB).These data represent daily rainfall data from January 2007 to December 2017 of Dhaka, Chattagram (Chittagong), Sylhet, Rajshahi and cox’sbazar regions. Dhaka has four stations, Chattagram and Rajshahi have six stations each, Cox’sBazar and Sylhet has two stations each. So, data obtained from total twenty rainfall stations have been analyzed in Microsoft Excel. Especially intensity of total rainfall over past ten years, rainfall trends in four characteristics seasons of the selective regions, month of maximum rainfall over the past ten years and annual rainfall intensity trend have been analyzed. For seasonal trend analysis we have considered four seasons. Dry season, Pre-monsoon, Monsoon and Post monsoon. Dry season consists of months November to February, Pre-monsoon starts from March to May, Monsoon continues through June to August and post monsoon lasts from September to October. After data analysis we have found that Chattagram region experienced 75% more rainfall than any other selected regions over the last 10 years. In dry season rainfall varies from 0 mm to 2500 mm around the five regions. In pre monsoon season rainfall ranges 1000 mm to 8500 mm. Rise of rainfall from dry season is about 70%. In monsoon all the regions had maximum rainfall varying from 5000 mm to about 35000 mm. It is almost 90% more than that of in dry season. In post monsoon season, rainfall resides in between 1500 mm to 13000 mm which represents 80% more rainfall than dry season. Month of maximum rainfall has shifted from monsoon to post monsoon season. So, we are having unexpected rain now-a-days which may affect our agricultural sectors as well as economic sectors. Rajshahi division having less rainfall is facing droughts frequently. Chattagram having abundant rainfall is experiencing landslides killing mass people and destroying homes and other domestic animals. Unpredictable behavior of rainfall pattern is making difficulties to design a fix irrigation schedule. Abrupt rainfall and storms are getting earlier than expected time, creating frequent floods in Bangladesh in the past few years consecutively.