Changes in rainfall and its relationship with the vegetative environment in the central-coastal region of Bangladesh

The present study is aimed at examining the rainfall changes and their relationship to vegetation dynamics in the central-coastal region of Bangladesh. Different statistical tests were used in the study to investigate the rainfall changes, such as the Mann-Kendall test and Sen’s slope estimation. The normalized difference vegetation index (NDVI) time series were collected from Google Earth Engine and processed in R programming to examine the level and extent of vegetation coverage. A correlation analysis was used to determine the association between the total rainfall (June–September) and mean NDVI (October–November). Results depict that annual rainfall decreased in all the stations, with the highest values in Senbag (Z = -5.16 and Q = 55.24). The post-monsoon variability exhibited an increasing trend in the majority of the stations, whereas other seasons showed a decreasing trend with the highest values in Feni (pre-monsoon Z = -2.37 and monsoon Z = -2.49). The relationship between rainfall and vegetation dynamics (NDVI) was observed, which was a moderate to strong positive lag correlation throughout the region. It was also noticed that the locations with higher rainfall fluctuations have a weaker association with the NDVI. Reduced rainfall can reduce vegetation productivity by disrupting growth seasons, lowering soil water content, and increasing salinity in the area. It is expected that the findings will contribute to a better understanding of the impacts of climate change induced rainfall variability and the response of the vegetative environment to it.