Riverbank Erosion
Riverbank erosion alone has rendered millions homeless and has become a severe social hazard. Structural interventions to provide protection against riverbank erosion are very costly. Bangladesh’s deltaic topography makes the country vulnerable to riverbank erosion forcing people to migrate or resettle. Millions of people have been rendered homeless by this disaster leading to migration in large urban and metropolitan towns and cities where they resort to informal settlements such as slums that lack minimum health and safety standards.
FOREWARN has been monitoring the water level forecasting of FFWC and GloFAS beside volunteers from our selected locations in Kurigram (Chilmari & Ulipur Upazila), Gaibandha (Fulchari & Sadar Upazila), Jamalpur (Sarishabari), and Sirajganj (Shahjadpur upazila) districts, from our database of potential HHs to be eroded.
Based on the analysis, FOREWARN experts suggestions and monitoring, the very systematic approach has been introduced with having a lead-time (as its very first kind) for Anticipatory Action on Riverbank erosion. Eventually, based on the riverbank erosion (RBE) EAP, there has been RBE threshold was met in Sirajganj to support the potential households which has been selected earlier.
Forecast
For 16 years, the Center for Environmental and Geographic Information Services (CEGIS) has predicted riverbank erosion along the Jamuna, Ganges, and Padma Rivers, funded by projects like JMREMP and EMIN of BWDB. Over the last decade, financial assistance from ADB and the Government of Netherlands has supported these efforts. CEGIS predicts riverbank erosion one year ahead and has developed tools for a two-year advance prediction for each river. Evaluation of recent predictions shows a reasonably good match with occurrences. Different approaches, including physical modelling, numerical modelling, and empirical modelling, are used for riverbank erosion prediction. CEGIS has updated tools for the Jamuna, Padma, and Ganges rivers using long-time series images and sedimentary features categorization. These methods have been successfully applied in various BWDB and WARPO projects, with erosion vulnerability assessed at 30%, 50%, and 70% probability.
Impact
Riverbank erosion in Bangladesh has significant implications, annually affecting millions in seventeen vulnerable districts. Impacting crops, livestock, houses, and public infrastructure, major rivers like Jamuna, Ganges, Padma, Lower Meghna, Arial Khan, and Teesta are erosion-prone (National Plan for Disaster Management, 2020). Erosion rates vary; for instance, Jamuna's rate decreased from 5,000 ha/year in the 1980s to 2,000 ha/year recently. Padma's erosion rate dropped from 2,300 ha/year in the 1990s to 1,200 ha/year in the 2000s (CEGIS, 2019). Between 2015 and 2019, 15,196 hectares were eroded. In 2019 alone, 460 ha were lost, impacting 21 ha of human settlements, along with 40 miles of Upazila road and 660 miles of rural road (CEGIS, 2020). The calculated risk index for riverbank erosion indicates very high impact in 4 (23.53%) districts, high impact in 3 (17.65%) districts, medium impact in 6 (35.29%) districts, and low impact in 4 (23.53%) districts.