Flood Hazard, Vulnerability and Risk Assessment for Different Land Use Classes Using a Flow Model

Muktarun Islam,Supria Paul,Md Abdullah Al Baky

doi:10.1007/s41748-019-00141-w

Muktarun Islam, Supria Paul + Show 1 more

Open Access

https://doi.org/10.1007/s41748-019-00141-w

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Abstract

This study is concerned with flood risk that can be assessed by integrating GIS, hydraulic modelling and required field information. A critical point in flood risk assessment is that while flood hazard is the same for a given area in terms of intensity, the risk could be different depending on a set of conditions (flood vulnerability). Clearly, risk is a function of hazard and vulnerability. This study aims to introducing a new approach of assessing flood risk, which successfully addresses this above-mentioned critical issue. The flood risk was assessed from flood hazard and vulnerability indices. Two-dimensional flood flow simulation was performed with Delft3D model to compute floodplain inundation depths for hazard assessment. For the purpose of flood vulnerability assessment, elements at risk and flood damage functions were identified and assessed, respectively. Then, finally flood risk was assessed first by combining replacement values assessed for the elements and then using the depth–damage function. Applying this approach, the study finds that areas with different levels of flood risk do not always increase with the increase in return period of flood. However, inundated areas with different levels of flood depth always increase with the increase in return period of flood. The approach for flood risk assessment adopted in this study successfully addresses the critical point in flood risk study, where flood risk can be varied even after there is no change in flood hazard intensity.

Highlights

This study is concerned with how we can assess flood risk in a given flood prone area
As risk is a combination of hazard, vulnerability and exposure (Skakun et al 2014), in the final step of risk assessment, the expected damage of the risk element was estimated first by combining replacement values assessed for the elements and following the
Area of inundation depth increases substantially with increasing return period, which has a considerable impact on the area of cropland and the area of settlements

Summary

Introduction

This study is concerned with how we can assess flood risk in a given flood prone area. Bangladesh is a deltaic country located at the lower part of the basins of the three mighty rivers—the Ganges, the Brahmaputra and the Meghna This unique geographical setting, surrounded by mountains on three sides, together with extremely flat and low-lying floodplain topography, a low-lying coastline, and an extreme climate variability has rendered the country highly prone to natural hazards such as flood (Chowdhury et al 1997; Hoque et al 2011; Islam et al 2010). About one-fifth to one-third of the country is annually flooded by overflowing rivers during pre-monsoon (April to May) and monsoon (June to September) periods These floods cause physical damages to agricultural crops, buildings and other infrastructure, social disruptions in vulnerable groups, livelihoods and local institutions, and direct and indirect economic losses (Baky et al 2012; Bhuiyan and Dutta 2012; Mirza 2011). The flood hazard problem in recent times is getting more and more frequent and acute due to growing population size and human interventions/socioeconomic activities in the floodplain at an ever-increasing scale (Bhuiyan and Baky 2014; Paul and Routray 2010)

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