Flood risk assessment in bangladesh and people`s adjustment scenarios: A case study in Brahmaputra-jamuna floodplain

Abstract

Bangladesh is certainly one of the most impressive floodplain and delta areas in the world. The interaction between the rapidly increasing population, the intensity of agricultural production, the extreme variability of precipitation, and the unusual dynamics of the river systems makes flood management in Bangladesh a truly challenging task. We are well aware of the fact that a large number of highly qualified institutions and authors have tackled issues concerning monsoonal floods in Bangladesh, not only from the natural and social science point of view but also from the technical and engineering science side. The riverine country Bangladesh has been experiencing floods more frequently than ever before in the recent years. The present study undertakes a detailed assessment of flood risks of the Brahmaputra-Jamuna Floodplain (Map 6.3), the study area for this research. An attempt has been undertaken in this research to develop a GIS model using ArcGIS 10 Modelbuilder option. The underlying objective was to contribute to the flood management system in the country. The model involved the analysis of the hydrologic, topographic and the local resident’s coping capacity variables. Combining the weight of the above variables throughout the study area the model was able to demarcate flood risk zones of various intensity. Uniform flood risk was not found into the whole area. Some parts of the area are identified as high risk zones, some are moderate risk zones and others are risk free or low risk zones. Flood intensity and duration of the area is controlled mainly by the hydrological and topographical characteristics of the catchment area. The effect of river morphology and dynamics and precipitation trends of the area were found fluctuating with season. Coping strategies and options of the local residents were found to be poor and inadequate and are mainly based on indigenous knowledge. Almost all of the peoples found were not afraid of flood and they take it as a routine problem that happens almost every year. No unusual measures are taken to survive during the flood period except storing and preserving dry foods and medicine after a flood warning is received. A Hazard Intensity Surface Index has been prepared for the area combining all the variables that contribute to the overall hazard potential of the study area. Thus the study area has been categorized into several belts with different hazard potentials (Map 4.9). In the case of human adjustment, people themselves take measures that save and reduce the loss and damage. The help received from government sources were found to be very inadequate and untimely. Also, the most poor are the ones who are deprived due to the relief distribution system at the local level. Notwithstanding the need for greater sophistication, it is likely that, the flood protection, mitigation and risk assessment model have been developed and expected to acknowledge the problem and considered here to successfully deal the flood problems of the study area. Moreover, the suggested models to analyze the risk of flood should be considered rudimentary, and are presented solely to illustrate the concept.