Bangladesh is divided in to several climatic regions. Each region is exposed to a different variety of climate hazards, and therefore, each region is differently vulnerable to climate variability and change. This section presents projections of the most prominent climate change impacts per region, with key maps from the assessment of Bangladesh‘s exposure to climate change
Central flood-prone area
The central flood-prone area is characterized by highly variable rainfall in the upstream region of the Himalayan river basins. Maximum precipitation occurs during monsoon, from west to east of the Hindu Kush Himalayan region. Mean annual precipitation ranges from 300 mm in Ladakh area (in India) in the west to 1400 mm in the center (Kathmandu) and 4000 mm in the east (Pasighat, India) in the Brahmaputra basin (ICIMOD, 2002).
The main climate change threat for Bangladesh is the potential increase in floods, notably flash floods, as a result of erratic precipitation, and the associated water scarcity issues during such events (e.g., Dhaka Tribune 2017; WHO-UNWater 2012). Flash floods cause surface water degradation, notably due to industrial effluents (e.g., Amin 2015) and the use of pesticides. Floods also cause sand deposition on banks and riverbeds, which decreases the water carrying capacity of large rivers. This results in the expansion of floodplains during monsoon, and thus, increasing riverbank erosion. Climate change is expected to increase rainfall intensity during the pre-monsoon and monsoon seasons, thereby increasing Bangladesh‘s exposure to river floods and flash floods in the future.
Flash floods and seasonal long-stay floods inundate an average of 26,000 km2 or 18% of the total area of Bangladesh annually (FFWC-GOB 2015). Monsoon floods affect lives, livelihoods, drinking water, sanitation, health, energy and infrastructure, including houses. However, livelihoods, since they are largely agrarian, are the most impacted. Floods, and the accompanying river erosion and sand deposition negatively impact crop production and yield, which tend to decrease every year. Cattle and poultry often die or are lost during such events, further affecting local communities relying on livestock and agricultural resources. People living in these areas, the char in particular, have to cope with river erosion by shifting their habitat and personal belongings after each flood. In addition, some people lose lives, while the elderly, children and women often get sick because of the lack of access to clean drinking water. Most of the existing tube wells get submerged during floods, along with roads, further exacerbating the lack of good communication and transport facilities in the area. Flood-related vulnerabilities are likely to worsen in this region because of climatic and socio-economic factors impacting the exposure and sensitivity of people and systems