Analysis of Spatio-Temporal Rainfall Variability over Bangladesh

Rainfall is one of the most important climatic components for Bangladesh. This study is an attempt to evaluate the spatial and temporal changing pattern of rainfall in all over the country. The analysis is based on the rainfall variations over 27 meteorological stations of Bangladesh Meteorological Department (BMD). Time series statistical tests were applied to examine the annual and seasonal trends for rainfall during the period of 1975-2013 respectively. The nonparametric Mann Kendall test was used to determine whether there was a positive or negative trend in rainfall data with their statistical significance and the Theil-Sen estimator was used to determine the trend magnitude. Overall the rainfall pattern showed a declining trend both annually and seasonally. Apart from the post-monsoon, rainfall had been decreased in all other seasons in most parts of the country. Comparatively the declining trend is higher in the north and northeastern regions. Increase of rainfall had only been observed in southeastern part of the country.