Flood Dynamics, River Erosion, and Vulnerability in the Catchment of Dharla and Dudhkumar Rivers in Bangladesh

Abstract

AbstractBangladesh is a land of rivers, and the major part of the country consists of deltaic landform by three large river systems, the Ganges, the Brahmaputra, and the Meghna. The livelihood of the people and environmental settings are mainly dependent on the hydrological characteristics of the rivers and associated resources in the catchment area. However, in the riverine areas of the country, flood is a common phenomenon that causes severe impact on people and properties. The effect of flood brings enormous sufferings to the inhabitants and causes riverbank erosion and loss and devastation to the resources and constructions. The alterations in river morphology as a result of flood have been related with bank line shifting, river widening, and extensive erosion of river bank. This chapter illustrates and analyzes the hydro-geomorphological conditions of the catchment of Dharla and Dudhkumar, which are the two perennial rivers in the north-western part of Bangladesh, and also provides a detailed understanding of inundation patterns and dynamics of floods in these catchments. This chapter further discusses and analyzes the causes and impact of floods, particularly on hydro-geomorphology, riverbank erosion, resource and live, and livelihood. Moreover, a flood vulnerability index was assessed considering the criteria for physical vulnerability, social vulnerability, and coping capacity indices. Finally, a management perspective approach and policy issues were drawn and discussed based on the findings. To fulfill the objectives, necessary data were collected and analyzed. Inundation data for the years 1954, 1974, 1988, 1998, 2004, and 2020 were used and analyzed for flood dynamics. Water level and discharge data of the two rivers were analyzed for hydrological conditions, and on the other hand, Landsat satellite data were analyzed to find out the geomorphological characteristics, river dynamics, and riverbank erosion. Flood vulnerability was assessed considering the IPCC vulnerability framework and GIS-aided multi-criteria analysis (GIS-MCA) modeling techniques. SRTM digital elevation model was used and analyzed for elevation and slope of the catchment area. Detail flood inundation and river dynamics, hydro-geomorphological characteristics, and erosion status of the Dharla and Dudhkumar Rivers were assessed and discussed in this chapter. Moreover, flood vulnerability assessment highlights the vulnerable areas with different magnitudes. Finally, this chapter concludes by discussing some management issues and policy implications for mitigating the adverse effects of such events, floods. The outcome of this work will be helpful to decisions and policymakers to minimize the exposure and vulnerability of floods. The overall approach discussed in this chapter can also help in achieving disaster risk reduction and ensure the safety of livelihood in the river floodplains.KeywordsFloodsRiver bank erosionFlood vulnerabilityRemote sensingGIS-MCAFlood management