Bangladesh is located in South Asia and shares a border with India.
Located on the coast of the Indian Ocean’s warm waters, Bangladesh is prone to tropical storms and consequent floods. These storms significantly impact the country in terms of occurrence and intensity. The causes of flooding in Bangladesh can be identified as fluvial flooding and cyclonic flooding.
The primary cause of flooding is the fluvial snowmelt in the high Himalayas. This, along with monsoon rain, leads to a considerable rise in the flow of three major rivers. Moreover, heavy rainfall on the hills and flood plains of Bangladesh during non-monsoon season can have comparable impacts as monsoon rain. Interestingly, this can be more devastating despite lower levels of flooding due to people being less prepared outside of the monsoon season.
The primary reasons for flash floods are intense precipitation and the overflow of nearby rivers. Deforestation in the region has worsened these factors. Additionally, cyclones and hurricanes entering the Bay of Bengal can cause storm surge floods, further contributing to flooding.
The immense storm surges cause devastation as they ravage everything in their trajectory. Attempts to safeguard against these storm surges have been made through the construction of embankments. However, this measure has inadvertently led to drainage congestion. The embankments, while preventing floodwater from flowing back into the river, have also contributed to the heightened accumulation of sediment in channels. Consequently, this has exacerbated the severity of flooding.
Despite causing devastation, floods in Bangladesh have undeniable benefits. The floodwaters play a crucial role in replenishing the ground water reserves, preventing a shortage of drinking water. Additionally, these waters bring along nutrient-rich sediment that greatly enhances farming production.
The sediment in the waters helps support the growth of vegetables in challenging conditions, while also providing a suitable habitat for fish to live and thrive. This is particularly significant in Bangladesh, where fish serves as a primary food source, making it economically vital as it contributes to 10% of the annual export earnings.
The aftermath of floods creates ideal circumstances for the growth of algae, which is beneficial for fertilizers. The floodwaters effectively purify the area by removing pollutants from residential areas. Nevertheless, even though flooding brings advantages, it poses a significant risk to human life. As a result, a Flood Action Plan was put into effect to handle and alleviate the consequences of flooding. It is widely acknowledged that completely preventing flooding is an impossible endeavor; hence, the primary aim of the plan is to manage and reduce the impacts of flooding.
The most effective way to achieve control is by constructing embankments along the main rivers. However, these embankments are not designed to withstand significant flooding events, such as the flooding in 1991. Instead, they aim to prevent expected annual flooding and provide some degree of control to establish a more consistent pattern.
While the seasonal floods will be stopped, ensuring safety for the people, there remains a possibility of flooding. Sluices are employed on the embankments to manage the river’s flow and velocity in order to prevent erosion. Additionally, the embankments were constructed at a distance from the river to protect them from erosion and maintain their durability.
This solution is both affordable and accessible to countries such as Bangladesh. Moreover, it allows for the utilization of floodwater in the flourishing shrimp industry while enabling the cultivation of land between the river and embankment.
The flood action plan has faced objections due to several reasons. Firstly, when the embankments are breached, the resulting damage is expected to be significantly greater due to the sudden discharge. In contrast, natural flooding would cause less damage as it follows a more natural course. Additionally, the effectiveness of the sluices has been a major point of contention, with many arguing that they are inadequate and unable to function efficiently.
The use of the sluices is a topic of debate among people, as their decisions have an impact on those downstream. Additionally, sudden breaches of the embankments can result in the deposition of infertile river sand, significantly reducing fertility. This also affects the naturally produced algae, leading to the removal of natural fertilizers. Moreover, embankments prolong the duration of flooding by preventing backflow into the rivers.
The lack of flushing pollutants prevents a large portion of agrochemicals from entering the food chain as they stay on the land. Moreover, stagnant water formed by embankments might contribute to disease outbreaks. The drying up of wetlands leads to reduced biodiversity, negatively impacting the environment. Ultimately, the absence of floods results in a notable decline in groundwater levels.
People will need to be relocated in order to build the embankments. The plan appears to prioritize protecting and ensuring the safety of the people. However, the negative impacts on the economy and society outweigh these concerns. The plan creates numerous problems that affect the environment, economy, and society in relation to fluvial flooding safety. While the embankments protect people from flooding, the ongoing risk of disastrous flooding still persists. Therefore, the progress achieved is somewhat limited.
The installation of flood defences on Kutubdia Island, located in the Bay of Bengal in Bangladesh, has been both effective and crucial. These defences include sea walls constructed along the island’s coastline to successfully reduce storm surges and safeguard the land.
Recent advancements have made it increasingly feasible to grow crops along the coast without concern for storm surges causing damage. Numerous embankment sites, such as the depicted one in the image, have been created across the island. These embankments have a dual function of protecting the area behind them and maintaining communication systems. Furthermore, reinforced concrete storm shelters have been built to guarantee residents’ safety during storms. Situated at an elevation of 25 feet above sea level, these shelters provide exceptional protection.
Despite the 1991 flooding, there has been significant reconstruction on the island of Kutubdia. Prior to the flooding, many poorly constructed houses were washed away. As part of the reconstruction process, reinforced concrete was used to build new structures, such as the market town depicted in this picture. These concrete buildings provide safer accommodations for the residents.
The defenses demonstrate that there is currently a level of safety for people residing on the island. However, aside from the evacuation of coastal lowlands and residing at an elevation of over 5m, there are no strategies available that can entirely eliminate the possibility of flooding. Additional details include a video highlighting the events of 29th April 1991 when a Tropical Cyclone struck the east coast resulting in the loss of 140,000 lives.
1 in 3 people drowned in this low lying area, which is prone to flooding. The high density population lives near the coast on low land, but an earth wall provides some level of protection.
Most of Bangladesh is situated below 15m sea level, which leaves it vulnerable to frequent tropical storms fueled by warm waters above 27°C. To protect people from rising floodwaters, cyclone bunkers were constructed on stilts. Warnings were issued, alerting local residents about the approaching storm.
Surge caused the embankment to break, leaving people who hadn’t gone to shelters exposed. These individuals reside in a vulnerable area due to the prevalence of fishing along the coast, which is necessary for them to earn sufficient income. Farming is also practiced to a certain extent.
Prawn farming is advantageous in areas with saltwater, providing livelihoods for many people. It also generates numerous jobs through the crucial processes of fish and prawn packing and exporting, which hold significant importance for Bangladesh. The substantial economic activity resulting from this industry contributes to wages that are twice the national average. Additionally, there are plans for future improvements such as tree planting programs, aimed at stabilizing soil conditions and protecting villages and embankments.
Earth embankments are being used as cyclone shelters, with each shelter costing �80,000. There is a focus on promoting public awareness about these shelters.
