River Erosion in Bangladesh: The Complaint-free Crying Sound of People on the Coast (Part -3, Final)
In the previous articles of Part-01 and Part-02, we had discussed the several causes of river erosion and the impact of river erosion, various natural and human-made causes of river erosion, and how river erosion affects society, communication, economy, education, health care, and politics.
Today, we will discuss the control measure of river erosion. We try to discuss some signification methods of river erosion mitigation.
While river erosion significantly impacts a region’s demography, geography, and community standard, we should know how we can prevent river erosions.
Sometimes we cannot wholly protect this event, but we can reduce river erosion and minimize this natural hazard’s harmful effect by several initiatives. Several methods exist to control riverbank erosion.
In an international journal (JES), a study of “Riverbank erosion and sustainable protection strategies” describes the erosion protection measures are categorized on three forms.
There are three different erosion control categories: structural protection measures, non-structural protection measures, and biological protection measures.
Here we describe different types of measures are in short as follows.
(a) Structural measures:
Structural measures are used for the long-term protection of riverbank. As it can give long-term riverbank protection, this method is expensive and time-consuming.
Usually, people use two major types of structural measures. One is hard material protection, and another is a barrier across the river.
Hard material protection:
Hard material protection is also called the “Resistive bank stabilization method.” This mechanism is to fight back with the force of water flow.
This method mainly protects the riverbank by using stone boulders/ blocks/geo bags dumping and placing at and on the erosion banks; These hard materials resist eroded riverbank from erosion.
This protection technique is appropriate for continuous riverbank erosion. There are some examples of hard material protections; revetment, guide bunds, boulders/brick mattresses.
Barrier across the river:
The river’s barrier is called the ‘Redirection bank stabilization method.’ The mechanism is to flow forwards, and the energy of water flows away from eroding bank.
In this method, appropriate measures of the barrier flow velocity are maintained, and riverbank erosion decreases. Some examples set up the barriers across the river: Groynes, Spurs, Vanes, Submerged bend way weirs.
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Non-structural measures
Non-structural measures are used for short-term riverbank protection. Some examples of non-structural measures; are flow area increase by dredging, flow diversion at the upstream of the problem area by channelization, and geo-bag dumping.
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Biological protections
Biological protections are traditional approaches that are experienced all over the world. This mechanism is also called “Bioengineering practice.” There are some biological protections; bank vegetation, wooden piling, willow posts, brandlings, crisscross porcupines and log hardpoints.
According to the International Strategy for Disaster Reduction (ISDR), “a coping method means how people use the available resources and their ability to face and manage adverse circumstances.”
Additional mitigation measures:
Riverbank erosion cannot be completely prevented as a natural hazard. To minimize the negative effect of river erosion, we should take some precautions. Then we can control the damage to land, house, and the education system.
According to River Research Institute (2000), a correct mechanism can ensure the damage in human life and geography.
Hazard Zoning Map:
To identify the most vulnerable and susceptible areas, we should make a hazard zoning map. There are three types of resistivity along the riverbank: relatively erosion-resistant bank line, moderately erosion-resistant bank line, and highly erodible bank line. This map should be superimposed with a geomorphic map of a country.
Suitable Shelter Options:
A sustainable guideline for appropriate shelter options besides the riverbank should be prepared considering the predicted zoning based on vulnerability towards riverbank erosion.
Even the typology of rural houses varied based on geographical, social, climatic, and other relevant factors. Thus, a comprehensive field investigation has helped to make broad categories of shelters or rural houses beside the riverbank areas.
Many people are straggling against several natural disasters. They are losing a home, crop field, workplace, education, etc. So it is very important to develop an appropriate plan for them.
Therefore, they can handle these natural hazards. A proper plan and sustainable solutions can increase the adopting capacity and desire of the local community to decrease their vulnerabilities.
Within three articles, we tried to detail the discussion of riverbank erosion. It can help understand the cause of erosion, the impact of erosion, and the protection measure.
We hope it will be helpful for many people who are in a vulnerable condition. Government should take the initiative for control measures and awareness buildup in the riverbank community. Next time we will discuss another important topic with you. Stay with the green page.
