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Flooding in Bangladesh: Understanding the Complex Drivers and Impacts
By Jasmine Andean and Siyao Li, on 3 September 2024
Floods all around the world have been increasingly mediatised in recent years, thanks to growing awareness of the impacts of climate change on the intensification of the global hydrological cycle and associated hydrometeorological hazards. This is true for Bangladesh, where the intense recent floods of 2020 and 2021 were fairly present in Western media outlets. Again, in June and July 2024, the heavy rainfall and consequent flooding in northern Bangladesh were discussed in British media including The Guardian and the BBC.
In many of these media accounts, climate change is seen as the primary cause of flooding in Bangladesh. This reflects wider narratives in development circles that climate change is the primary factor contributing to severe flooding in Bangladesh. It is unsurprising, then, that development funding in Bangladesh, too, is being increasingly earmarked for climate adaptation projects.
The notion of climate change as the primary cause of flooding in the country may be reductive and could have serious implications for the efficiency of development and adaptation projects and their impacts on communities.
The Bangladesh context
Bangladesh is situated in the downstream of three major rivers: the Brahmaputra (Jamuna), the Ganges (Padma) and the Meghna, flowing from neighbouring countries like India and China. The average annual combined discharge rate of these rivers into the Bay of Bengal is 100,000-140,000m3/s. Bangladesh’s weather system is dominated by the Indian monsoon, in which heavy rainfall during the summer monsoon months is typical and expected. Flooding is therefore normal in Bangladesh, and has occurred for centuries; in fact, in an average year, about 20-25% of the country’s area is expected to be flooded.
In a once-a-century event, the land affected can be up to and beyond 60% – this annual cycle of flooding also brings benefits to the ecology and economy of the country, with the fresh sediment deposited on river floodplains by floodwaters making the soil extremely fertile, promoting crop production.
Thus, previous programmes to stop flooding entirely have been ineffective and have, in some cases, brought negative consequences and environmental damages. For example, the government of Bangladesh and various international development actors such as the World Bank constructed coastal embankments (also known as polders), sometimes intending to entirely stop the inundation of land. This infrastructure has protected many communities in coastal Bangladesh from storm surges and inundation resulting from tropical cyclones, but created water-logging and challenges for agriculture and livelihoods, as the previously highly fertile floodplains became less fertile and conducive to crop cultivation due to the obstruction of the floodwaters depositing sedimentation to renew soil fertility and natural land development. The land surface elevation within these coastal embankments is much lower than its adjoining floodplains making them vulnerable to water-logging and poor drainage problems. Such initiatives that attempt to obstruct the natural ecology and hydrological processes in Bangladesh, actively working against nature, fail to address the true causes of flood damage and risk unintended harm to communities. Narratives that paint all flooding in Bangladesh as a consequence of climate change risk justifying or promoting such initiatives.
The fact that floods are natural and in some ways necessary in Bangladesh does not negate the fact that when combined with vulnerabilities, floods can also bring serious socioeconomic consequences and lead to a loss of life, livelihood and health in underprepared and vulnerable communities across Bangladesh.
Source A: Asian Development Bank (ADB). 2015. Capacity Building for Disaster Risk Finance in Bangladesh. Consultant’s report. Manila (TA 8144-BAN). Note: Economic losses are expressed in 2014 dollars to estimate the relative economic impact of events over the different years.
Source B: Annual Flood Report 2021. Flood Forecasting and Warning Centre (FFWC), Bangladesh Water Development Board (BWDB).As seen in Figure 1 (A), a statistically significant relationship is found between the area affected and the economic loss incurred nationally; the more land is affected, the more economic losses occur, and the more households face loss in their assets and livelihoods.
However, not all communities and demographics are equally affected by this economic loss, as some groups have fewer strategies for coping with the loss of income and assets. For example, during severe flash flooding in 2017 in the Haor wetland region in northeastern Bangladesh, a popular adaptation strategy for households facing income disruptions was to temporarily change their occupation, including working in neighbouring communities or nearby urban areas. However, women were less able to adopt this resilience strategy due to them not being allowed to work outside the home and beyond Haor communities. This made women and female-headed households face higher losses of income and most likely compromised their ability to recover from the floods. However, it is also important to note the majority of households who changed their income strategies also experienced a loss in daily income, and groups other than women were also particularly impacted by this loss. For example, the elderly and those whose livelihoods were highly reliant on natural resources also faced higher than average loss of income.
In some cases, coping strategies may also exacerbate economic loss and vulnerability. An example of this is seen in the char lands of Bangladesh. Char lands are riverine islands and sandbars that form due to the accumulation of sediments from major rivers and their tributaries) of Bangladesh. Approximately 6.5 million people live on these chars, with flood-induced temporary displacement occurring on average every 5 years. In a year of extreme flooding, a household may be displaced up to 3 times in a single year. Although temporary migration has at times been described as an adaptation strategy, this repeated setback of livelihoods inflicts chronic economic, social and psychological costs on char inhabitants, exacerbates the process of impoverishment and impedes development as the recurring losses exceed recovery capacity, preventing the accumulation and growth of assets. This creates a cycle of poverty that is challenging for the char inhabitants to escape. As floods are becoming more frequent and widespread as a result of climate change, living on char lands and river floodplains will inevitably increase exposure to flooding, and thus, flood risk cannot be reduced.
The drivers of vulnerability in Bangladesh are complex. For example, communities in the chars and flood-prone areas are so exposed to flooding because they have settled on floodplains, driven by extremely high population density. Bangladesh is approximately the size of the State of New York with more than half the population of the United States. As a result, land is scarce, and particularly poorer households find themselves settling on the precarious, yet highly fertile, land of the floodplains.
Although flooding is a prevalent feature of the Bangladesh landscape, much remains to be done to enhance the resilience and address the vulnerabilities of the country’s population. It should also be noted that although flooding is a natural process in Bangladesh and that development programmes should not rely on climate reductive narratives to aim to entirely obstruct them. Furthermore, climate change does seem to be having some impacts on flooding and rainfall variability during the monsoon season in Bangladesh. For example, the seasonality of monsoon rainfall seems to be undergoing some changes, with heavier rains being seen particularly in the pre-monsoon season and less rainfall during the peak (June) monsoon season; this could have considerable effects on agriculture and livelihoods in the country. Further changes are likely to materialise as climate change progresses. The proportion of annual flood-affected area also appears to be increasing, as seen in Figure 1 (B). Considering the correlation between economic loss and the percentage of the area affected, this underlines the urgent need to build resilience to flooding that should take into account of the spatial variability as ‘one size fits all solution’ may lead to maladaptation to climate change.
As it stands, considerable sections of the population of Bangladesh remain trapped in a vicious cycle of high exposure and vulnerability, flooding, and poverty, which in turn exacerbates exposure and vulnerability. To begin to truly address the social, economic, and developmental challenges brought by floods, underlying structures of poverty and inequality must be addressed. Any approach to flood mitigation in the country that fails to reckon with the flood risk framework – specifically vulnerability and exposure – will fall short of preventing flood damage to communities and economic losses.
MAPS Faculty summer interns, Jasmine Andean (Global Humanitarian Studies BSc alumna) and Siyao Li (Second-year Arts and Sciences BASc student) have been supervised by Dr Mohammad (Shams) Shamsudduha, UCL Department of Risk and Disaster Reduction.
The views expressed in this blog are those of the author(s).
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