Assessment of flood risk in madaripur sadar upazila under climate change using an integrated approach

Abstract

In Bangladesh, flood usually inundates around 20% of its terrain in a normal flood and this inundation extent may rise to 65% during an extreme flood, which is likely to be further worsened by climate change. Moreover, in coming years, the changes in sensitivity, adaptive capacity, and exposure of the elements at risk would make it more complex for the decision makers to prepare flood risk mitigation plans. Though there is a wide array of literature available on flood risk assessment, most studies could not follow the recent IPCC approach of risk, and some did not incorporate the climate change scenarios in their hazard analyses. The overwhelming majority of studies used future hazard scenarios superimposed on current socioeconomic conditions by making the implicit assumption that the drivers of risk other than hazard would remain constant. In this study, flood risk has been investigated from an integrated approach by considering both the physical hazard indicators such as flood depth, duration, and extent along with the selected socio-economic vulnerability and exposure indicators of the affected area. Results showed an increasing trend of flood depth, duration, and flooded areas from baseline to 2080s. The percentage areas under different hazard zones for the RCP 2.6 and RCP 8.5 scenarios have been analyzed. The analysis clearly suggests that the flood hazard would increase with time due to climate change. Analysis of socio-economic vulnerability and exposure indicates a decreasing trend with time, which reflects that the adaptive capacity of the study area could improve in future. Assessment of exposure for the present and future time regimes indicates significant shifts of a few unions from lower exposure zone to medium and high exposure zones. Outcomes of the risk assessment shows that the lower risk zone of the total study area would get lowered from 60% to 90% as we move from baseline to 2080s, in both climate scenarios. The study also identified several flood mitigation strategies through literature review and key informant interviews which include introduction of early warning system and efficient dissemination of information along with minor structural improvements. This study findings provide useful information about the flood hazard and flood risk areas in the Madaripur Sadar upazila, a part of the Arial Khan floodplain. The generated hazard and risk maps can be useful for the concerned authorities, planners, and policy makers in identifying the hazard and risk zones of the particular river flood and thereby incorporating in plan a more suitable, economical and sustainable flood management strategies along the river.