Rainfall and Temperature Characteristics in the Coastal Zones of Bangladesh and West Bengal, India

Abstract

Climate is one of the most important factors in agricultural production and livelihoods of the coastal zone of Bangladesh and the bay of West Bengal, India. In this study, nearly 40 years (1970 - 2017) of historical rainfall and temperature data from six weather stations located in the coastal zone were analysed to assess their key characteristics influencing crop growth and yield. The results revealed that the rainfall in the coastal zone varied both spatially and seasonally. The total annual rainfall generally increased from the west to east and from north to south, resulting in rainfall difference up to 1000 mm year^-1. In addition to spatial variations, the rainfall varied seasonally, with the wettest 25% of days during the wet season contributing to more than 70% of the annual total precipitation. Heavy rainfall (> 40 mm day^-1) was found to occur in the dry season (from December to February), including around the sowing time of rabi crops, resulting in a risk of waterlogging. Daily temperature and rainfall were also investigated to detect linear trends over the 40-year period. Maximum temperature was found to have increased at five weather stations with an average rate of 0.04°C year^-1 except at Canning, West Bengal showing that the coastal zone has been experiencing hotter and longer summers. The rainfall behaviour was more varied, although it exhibited a general increase in the recent decade.