River erosion is a dangerous disaster which can be referred to as “a silent killer”. It occurs all over the world. Sometimes its consequence is so severe that, the misery of the people is beyond imagination. According to the geologist, riverbank erosion is river erodes away the bed and the banks of its channel. Lateral river erosion that widens the river channel and vertical river erosion which deepens the river channel. Now the question is, how does it work? Mainly river flow causes erosion of the river banks. River erosion also occurs due to rain, waves, wind, flood, human activity, and some other similar natural phenomenon. The river erodes the bank in four ways and those are hydraulic action, abrasion, attrition, and solution.
Bangladesh is a small country in Southern Asia, located on the Bay of Bengal and covered by India on all sides except for a small border with Burma. The most important resource of this country is river as she is braided together by more than 700 rivers including tributaries. Thus it is called a riverine country. The main rivers in Bangladesh are the Padma, the Meghna, the Jamuna, the Karnafuly, the Buriganga, the Sitalakshya, the Dhaleswari, and the Madhumati, etc. Most of the rivers originate from the Himalayan region and fall into the Bay of Bangle. Bangladesh has many trans-boundary rivers flowing through the country thus she is known as “Sap of Asia” to some extent. As for being a riverine country, the river bank erosion phenomenon has a great impact on this country.
Nowadays we can see that riverbank erosion has become an enzootic and recurrent natural hazard in Bangladesh. When rivers join to the mature stage they become sluggish and meander (like three mighty rivers, Brahmaputra, Ganges, and Meghna) thus they create massive oscillations. These oscillations cause riverbank erosion. Some researchers have estimated that about 5% of the total floodplain of Bangladesh is affected by erosion. They also reported that 94 out of 489 upazilas of Bangladesh are spontaneously affected by river erosion. The erosion monitoring report done by the Centre for Environmental and Geographic Information Services (CEGIS) has speculated 22 vulnerable locations for the year 2018. Bangladesh is destined to lose about 2,270 hectors of land in 2018. Erosion mainly occurs along the banks of the major rivers which are Kurigram, Gaibandha, Bogra, Sirajganj, Tangail, Manikganj, Rajbari, Rajshahi, Faridpur, Shariatpur, and Madaripur.
At Durgapur Upazila under Netrokona, river erosion has turned in a devastating way as Someshwary and other rivers became full to their brim due to heavy rain. At least 300 houses and over 500 acres of cropland at Dakumara, Kamarkhali and Ranikong villages under Durgapur upazila have been sucked up by river leaving 1000 people shelterless. At Lalmonirhat, At least 150 families at four villages of Sadar, Aditmari upazilas became homeless after being devoured by the rivers Teesta and Dharla. Again at Kurigram villages like Gamburyan, Majhipara and Modonchar are being squashed by the river Brahmaputra. Jamuneshwari River by taking a ruffle turn made about 200 family homeless at Rangpur district. Kajipur upazila of Sirajganj is affected by Jamuna River. The largest river the Padma has made 700 families of Naria thana of Shariatpur district lost their homestead in the erosion.
At present, Padma river erosion is the most common topics people talk about. We have to work in order to prevent erosion. Hydrology expert Dr. Ainun Nishat said,” The Padma flows according to her own will. Her characteristics can’t be understood by mathematics or science. Erosion is a natural course which may continue for two years at a place. In order to prevent Padma, we have to understand the scale of Padma. The Centre for Environmental and Geographic Information Services (CEGIS) is working to update the morphology for Padma Bridge which is essential to protect riverbanks and continuous erosion. Some various methods like concrete block revetments, stone gabion mattress, sack revetment, concrete counterfort wall systems can be provided along the bank of Padma. The most important thing, the contribution from the government side should be conducted for the embankment to prevent Padma river erosion.
Bangladesh is a country which is affected by a major natural disaster known as riverbank erosion almost every year. Dr. Maminul Haque Sarker, deputy executive director of CEGIS said, “We have been implementing the erosion divination report for the agencies accountable for river management. Actually, this is some sort of divination for the authorities, which they can utilize for the authorities to design and plan the riverbank indemnity measures.” So, it’s a major issue for a developing country like Bangladesh.
Last but not least, we have to increase public awareness. We should create some volunteers who will act on the field to develop consciousness among the illiterate people. We have to broadcast news about the act how will we effort to prevent erosion across the country.
References:
1) Islam, M. and A. Islam (1985). A Brief Account of Bank Erosion, Model Studies and Bank Protective Works in Bangladesh. REIS Newsletter 2: 11–13.
2) Flood Plan Coordination Organization (FPCO) (1995) Bangladesh Water and Flood Management Strategy.
3) Chowdury. M. (2000). An Assessment of Flood Forecasting in Bangladesh: The Experience of the 1998 Flood. Natural Hazard. 22: 139–63.
Author:
Abu Tawhid Shohan
Chittagong University of engineering and technology
Dept. of Water Resources Engineering
Email: [email protected]