REDUCING DAMAGES
CAUSED BY FLOOD IN
AGRICULTURE
Background of floods in Bangladesh
◦ Floods have always been one of the major natural calamities of Bangladesh from the beginning. There are 230 rivers which occupy about 7% of the total land
area of Bangladesh. Most part of the country is low lying and 80% of the landmass is flood plain. At least one- third of the country is vulnerable to flooding. Floods
accounted for 40% of the total number of natural disasters that occurred between 1985 and 2009 and with massive destruction. Recent data show that during past 50
years, at least 7 major floods have strike Bangladesh. 34% of its land area goes under water for about five to seven months in every year.
◦ Causes of floods in Bangladesh includes: Geographic Location of Bangladesh(Lying under the GBM basin), High Cross-Boundary Flow, Local Rainfall, Siltation,
Unstable and Migratory Rivers, Deforestation beside the banks etc.
◦ Not to mention the floods causes severe damage to the economy and to the people. A diagrams below show flood affected area of Bangladesh foe the past years and
the effects:
◦ Flood impact on economy and harvests. Bangladesh is expected to incur losses equivalent to 1.5% of gross domestic product (GDP) - $2.2 billion in 2014 dollars on average
per year due to floods. In the recent decades, Bangladesh has experienced several devastating floods in 1987, 1988, 1998 and 2004. The floods of 1988 and 1998 were
particularly catastrophic, each affected over 60% of Bangladesh and caused losses equivalent to more than 8% of GDP (over $12 billion in 2014 dollars).Bangladesh
agriculture comprises about 18.6% of the country's GDP and employs around 45% of the total labor forces. Majority of the poor in this country live in areas of high risk to
floods and landslides and are more reliant on local natural resources. A special type of rain fed rice “Aman” grown in Bangladesh is highly susceptible to river floods and has
been affected in all years of flooding. During the Bangladesh 1998 floods, 69% of Aus rice production, 82% of deep-water Aman and 91% of transplanted Aman were lost.
◦ Floods in Bangladesh:
◦ Bangladesh generally experiences four types of flood and they include: Flash Flood , Rain fed Flood , River Flood , Flood due to Cyclonic Storm Surges.We intend to focus on
preventing the rain fed flood and river flood damages over the country.
Figure : Floods in Bangladesh
Figure : Flash Flood
◦
Possible solutions!
#There are some existing and effective solutions to our flood problems but sadly they lack proper implementation . Some of them are discussed below:
1. Dredging: Continuous dredging of the rivers and channels and dispersion of the dredged sediments on the delta plain will not only increase elevation of the land but will also
increase the capacity of the rivers. Adequate sediment supply, accumulation and dispersion are primary requirements for accelerated growth of the Ganges-Brahmaputra delta at
a rate that is sufficient to keep pace with the rising sea level. Proper and regular dredging is to be ensured. It might be a bit costly to dredge the rivers regularly but the effort is
worth it considering the damages we are reducing.
2. Flood preparedness : An understanding of when a flood might occur helps a lot for the farmers to harvest the crops on the eleventh hour. The Flood Forecasting
and Warning Center (FFWC) under the Bangladesh Water Development Board (BWDB) have mainly taken the responsibility of the flood prediction, early warning
and also flood management. The flood management works is done by the Bangladesh Water Development Board (BWDB). Proper management of this
organization is to be ensured.
3.Forestation and bank elevation : Ensuring proper forestation in the country can reduce river erosion , help to reduce wave impacts and much more. Mangrove trees are to be
planted on the bank of the rivers. They stabilize coastlines by trapping sediment in their roots and reducing wave impacts with their dense roots. Also elevating the banks somewhat
through dredging can benefit this process highly. People and Government should ensure this practice. More importantly, it costs almost nothing compared to other methods.
4. The Dutch Solution: The Dutch have found a way to manage flood waters. They say: “Don’t fight the water, live with it.” What it means is that they have considered a vast
amount of their lands to be used as artificial river ways so that the water can pass causing no harm to the remaining land but at the same time they can use that water for various
other purposes. It is definitely hard to implement such a method in Bangladesh with such limited land areas and people being not so open minded when it comes to donating lands
for the overall betterment of the country but as the generations are changing it is now worth a shot.
◦ 5.Embarkment : Embarkment is a great structural way of stopping overflow of the rivers and river erosion. But it lacks implementation in Bangladesh . Flood walls are also
effective methos of containing waters(not implemented). We have implemented it somehow but it needs more attention.
◦
Figure : Flood walls
◦ 6.Creating flood bypass like Japan: Though the initial costs are higher but starting the implementation of the flood bypass like Japan can create a big difference in the county.
This process can solve the infrastructure problem of the roads while creating water bypass.
#Other than these solutions we can implement some innovative ideas throughout the country tha can help to reduces the flood damages to the country. Some of the ideas are
discussed below:
1.Creating overhead reservoirs:
The idea is to build flyway like water containers above the roads. Using proper structural design we can materialize this idea in our country as we are already building flyovers.
This method will help us reserve the rainfall water to a significant amount and use it afterwards according to our needs as this method can also reduce the scarcity of water during
dry seasons. This methos is favourable for our country as it requires no extra lands, as they will be built over road. Also the will be used as storages. The schematic idea is shown
below:
2.Creating long underground dams:
The idea is to build dams not inside the rivers but outside the river , on the lands. This process will have several benefits. Firstly , it will not reduce the river capacity as normal
river dams do. It will also be used as a water reservoir for the country to use where the country lacks fresh water. It will have a much higher quantity of water to hold as it will be
dug deep and will take up little space to do so. The building will be within our range and sometimes it can create eye catching beauty. The idea is shown below:
Figure: Underground water reservoir and their usage
3.Under highway water tunnel and reservoir:
Here, we think of the idea of building tunnels down the roads that could occupy water and be used as a reservoir as well. We see that during the floods the roads get destroyed and
repair is necessary but what if we used the roads themselves to prevent the effects of the flood by building long under ground tunnels. It will allow the water to be stored down the
roads and the can be used afterwards. Well if you say about what about the primary infrastructure cost?? Well were are saving a huge portion of the economy what if more that
enough to overcome the costs of this infrastructure. Also the fact that it requires no additional land because we can build it with the roads , we have no worries about that as well.
The idea is shown below schematically:
Summary: We tried to prevent damages caused by the rainfall related floods in Bangladesh . Succeeding in doing
these will help the economy grow immensely and reduce the losses caused.
References:
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2. Jongman, B. (2018). Effective Adaptation to Rising Flood Risk. Nat Commun 9, 1986 .
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4. Sommer et al. (2001). California’s Yolo Bypass: Evidence that flood control can be compatible with fisheries, wetlands, wildlife, and agriculture.(Yolo
fisheries).
5. Bhattacharya, A. K. (2019). An Analysis of Flood Control in astern South Asia.
6. Mochizuki, T., Ueda, T. (2003). Flood Control Works in Japan : Achievements To Date and Future Outlook.
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Generation Infrastructure. Washington, DC: World Bank and World Resources Institute. © World Bank and World Resources Institute.
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University of Engineering and Technology.
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