Spatial and Temporal Analysis of Rainfall and Temperature Trends of Bangladesh during 1989 to 2019 and the Possible Impacts of Rainfall and Temperature Changes

This paper analyzed the temperature and rainfall data series of 35 meteorological stations distributed throughout Bangladesh over 30 years (1989 to 2019) to present the trend and time series analysis of these climatic variables. Also, the possible impacts of temperature and rainfall changes on different sectors are discussed here. Statistical methods like the Mann Kendall test and Sen's slope test were used to detect trend variation in temperature and rainfall patterns. Maps were generated using Geographical Information System (GIS) to visually represent the magnitude of change observed in the study. The result shows a change of mean temperature in Bangladesh with an upward trend (0.25 °C per decade) in the pre-monsoon season. The southern, south central and southeastern areas like, Patuakhali (0.47°C per decade), Sandwip (1.0°C per decade), Khepupara (0.73°C per decade), Syedpur (1.1°C per decade), Faridpur (0.8°C per decade), Teknaf (0.8°C per decade), Hatia (1.12°C per decade) and Chandpur (0.47°C per decade) are found to be prone to increase of maximum temperature in all seasons. The highest upward trend in minimum temperature is observed in the northwestern, northeastern, central and southern parts of Bangladesh like, Chittagong (0.65°C per decade), Barisal (0.4°C per decade), Srimangal (1.05°C per decade), Dhaka (0.54°C per decade) and Bogra (0.42°C per decade). Southern areas like Sandwip (34 mm/year) and Chittagong (24 mm/year) has faced maximum increase in rainfall amount in monsoon and pre monsoon seasons. Decrement of rainfall is mostly faced by central regions, like Madaripur (-17.55 mm/year) and Faridpur (-12.28 mm/year) throughout monsoon and winter seasons. But in post monsoon season, these two stations have faced an exceptionally higher increment of rainfall which is almost 32.75 mm/year and 32.38 mm/year respectively.