2.1 Study area description
Bangladesh, positioned in subtropics has a hot and warm sub-humid
climate which is mostly triggered by the monsoonal system, modulating
topography, and complex hydrogeologic setting (Fig. 1). Most parts of
the country are floodplain, excluding for few hilly regions in the
southeastern and eastern areas (Rahman and Islam, 2019). The daily
temperature in the country ranged between 18 °C and 32 °C with a mean of
26°C whereas the mean annual rainfall was 2400 mm (Islam et al. 2020a).
The climate of the country is predominated by four seasons such as
pre-monsoon hot monsoon (March–May), rainy and moist monsoon period
(June-August), and post-monsoon (September- November) and dry winter
(December–February) seasons (Islam et al. 2020a). The region is
characterized by Hot and humid monsoon with high rainfall and dry and
mild cold winter. Seasonal variations in temperature and rainfall are
distinct features. Outlines of seasonal wind integrated with local
geographic features create an irregular rainfall pattern over
Bangladesh. The wind is normally light which varies its direction and
intensity based on monsoonal circulation. The sunshine hour duration is
elevated because of its position near to the equatorial belt.