Spatiotemporal trends in the frequency of daily rainfall in Bangladesh during 1975–2017

Bangladesh is greatly susceptible to the impacts of climate change. Climate change has enhanced the frequency and intensity of extreme events in Bangladesh, thus resulting in loss of biodiversity and agricultural crop production. However, trend studies in the frequency of climatic variables like rainfall at the micro-scale are less explored in the previous literature. Therefore, this study aims to explore the spatiotemporal trends in the frequency of daily rainfall using different statistical models based on 23 station data from 1975 to 2017 in Bangladesh. The statistical results show that the frequency of rainfall ranges of < 5 mm, > 10 to ≤ 15 mm, > 15 to ≤20 mm, and > 25 to ≤ 30 mm exhibited an increasing trend while rainfall ranges of > 5 to ≤ 10 mm, > 20 to ≤ 25 mm, > 30 to ≤ 35 mm, and > 35 mm displayed a decreasing trend ( p > 0.10). The jump test results indicate that only one jump occurred in the average rainfall ranges of > 15 to ≤ 20 mm ( p < 0.10). The changes in temporal trends of different rainfall frequency ranges show an irregular pattern during the study period. The spatial map of trends among various rainfall ranges over sub-climatic regions is heterogeneous nature which varies from region wise and station wise. The probability density function (PDFs) of rainfall frequency ranges will move upward in the future and broaden with an increase in the forthcoming period. To adapt to climate change, the findings highlight the need for the advancement of water resource management and reallocation of agricultural adaptation plans in Bangladesh.