Dhaka experiences extreme flooding due to its geographical location in the Ganges-Brahmaputra delta, which receives heavy monsoon rainfall, coupled with rapid urbanization and inadequate drainage infrastructure, exacerbating the floods. Climate change also increases the risk of extreme weather events and sea level rise, worsening the situation.
Dhaka is located in a very vulnerable spot, right in the heart of the delta formed by three major rivers: the Ganges, the Brahmaputra, and the Meghna. These waterways drain immense amounts of water from the Himalayas before reaching the ocean, so there's a strong flow in the area. As a result, the city is surrounded by this gigantic river system and sits on a very low plain, almost at the river level. Additionally, Dhaka is not far from sea level, which greatly facilitates flooding during heavy rains or floods. In short, as soon as it rains too much, residents quickly find themselves with their feet in the water.
With climate change, the monsoons are becoming more intense. Dhaka is experiencing heavy, unpredictable rains that are extremely concentrated over a short period. All of this causes the rivers surrounding the city—the Buriganga, the Turag, and the Balu—to overflow. Meanwhile, the global sea levels are rising slowly but surely, also increasing the levels of these rivers. As a result, water drainage becomes more complicated, and water ends up stagnating in the city. With these increasingly frequent weather situations, Dhaka is directly exposed to extreme flooding, which is becoming more problematic.
In Dhaka, the drainage system is severely outdated. Most of the existing sewers date from another era, unable to handle the enormous amounts of water during monsoon periods. The canals, already few in number, are often clogged with debris and poorly maintained, which greatly reduces their effectiveness. As if that weren't enough, the lack of clear urban planning means that new constructions spring up in the middle of drainage areas, disrupting their function. In short, without coherent urban management or serious modernization of infrastructure, the city literally struggles as soon as the rain becomes intense.
Dhaka is one of the fastest-growing cities in the world, with thousands of people arriving from the countryside every day in search of work or a better life. Behind this ultra-rapid urbanization lies a problematic consequence: the massive concreting of the soil. Where rain used to seep in naturally, it now runs off impermeable surfaces, exacerbating flooding. The massive influx of people also leads to the chaotic construction of precarious and unplanned housing, often near waterways or on low-lying land that is already vulnerable. As a result, the already fragile infrastructure quickly becomes overwhelmed by all this demographic pressure. More inhabitants also mean more waste, which, due to a lack of efficient collection, regularly clogs up drainage systems. All of this creates a perfect storm for Dhaka to find itself regularly submerged as soon as the monsoon arrives.
Around Dhaka, massive deforestation and the loss of wetlands have significantly increased the risk of flooding. Previously, trees and marshes naturally filtered rainwater, temporarily holding excess water. Today, with fewer green and wet areas available, water flows freely into the city. The soils become compacted, nothing absorbs the precipitation anymore, and as a result, it accumulates quickly, causing frequent and severe floods. Simply because the natural environments that acted as a buffer and hydraulic regulator are rapidly disappearing.
According to the World Bank, nearly 40% of the Dhaka metropolitan area floods every year during the monsoon season, severely disrupting the lives of residents and the local economy.
Historically, Dhaka was surrounded by a vast network of canals and wetlands that naturally served to absorb and regulate rainwater. However, these areas have been significantly reduced due to rapid and uncontrolled urbanization.
Bangladesh is traversed by three of the world's largest rivers (the Brahmaputra, the Ganges, and the Meghna), which makes it naturally vulnerable to flooding, particularly during the monsoon season and the melting of glaciers in the Himalayas.
More than 60% of the annual rainfall in Dhaka occurs between June and September, thereby concentrating the risks of flooding and increasing the difficulty for drainage systems to effectively manage rainwater.
Rapid population growth leads to significantly increased urbanization, pushing populations to settle in vulnerable areas. This reduces the surfaces capable of absorbing rainwater and increases the pressure on drainage infrastructure, making it insufficient to quickly evacuate water during heavy rainfall.
Indeed, several projects supported by the government of Bangladesh and the international community aim to improve the urban drainage system, preserve existing wetlands, and create stormwater retention infrastructure to reduce future flood risks.
Repeated flooding in Dhaka causes significant economic losses by damaging infrastructure and disrupting business activities. From a health perspective, it leads to increased risks of epidemics related to contaminated water, such as cholera, dengue, and dysentery.
The inhabitants of Dhaka adapt to flooding through various strategies, such as raising their homes, using temporary water storage systems, and frequently employing makeshift boats to navigate the flooded neighborhoods.
The period during which flooding in Dhaka is most frequent and extreme is generally the monsoon season, typically between June and September. The peak of heavy rainfall often occurs in July and August.
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