Influence of hydro-climatic factors on future coastal land susceptibility to erosion in Bangladesh: a geospatial modelling approach

Asib Ahmed,Clare Woulds,Rizwan Nawaz,Frances Drake

doi:10.1007/s41651-020-00050-x

Abstract

This study envisaged the likely impacts of future hydro-climatic changes on the susceptibility of coastal land to erosion through the development of raster-based geographical information system (GIS) model called land susceptibility to coastal erosion (LSCE). The model was applied to the coastal area of Bangladesh to assess future erosion susceptibility under four greenhouse gas (GHG) concentration trajectories: A1B, RCP2.6, RCP4.5 and RCP8.5. The results indicate considerable changes in future scenarios of coastal land susceptibility to erosion in the area compared to current baseline conditions. The current area of 276.33 km2 (0.61%) high and very high susceptible lands would be substantially increased to 1019.13 km2 (2.25% of land), 799.16 km2 (1.77%), 1181.38 km2 (2.61%) and 4040.71 km2 (8.96%) by 2080 under A1B, RCP2.6, RCP4.5 and RCP8.5 scenarios, respectively. Spatially, the western and eastern coastal zones would have low to moderate susceptibility to erosion, whereas the central coastal zone would have moderate to high/very high susceptibility to erosion. Seasonally, the model predicted the high erosion susceptibility during the monsoon seasons and very low erosion susceptibility during the winter seasons in the future. The model outputs were enhanced by integrating experts’ judgements through fuzzy cognitive mapping (FCM) approach. The LSCE model might be indispensable for coastal researchers in generating future scenarios of physical susceptibility to erosion for highly dynamic coastal areas around the world.

Highlights

Along with a number of coastal hazards such as tidal surge, cyclone, flooding, the excessive rate of coastal erosion considerably increases coastal vulnerability at national, regional and global levels (Ramieri et al 2011)
Considering the mentioned situations, the current study focused on the research question: how levels of future erosion susceptibility in the coastal area of Bangladesh will undergo changes due to likely changes in hydro-climatic triggering factors? This study aimed to generate future scenarios for erosion susceptibility in the coastal area by applying the land susceptibility to coastal erosion (LSCE) model (Ahmed et al 2018b) under the four greenhouse gas emission trajectories: A1B, RCP2.6, RCP4.5 and RCP8.5 for the three timeslices (i.e. 2020, 2050 and 2080)
The general assessment was carried-out by averaging the parameter values and applied for the entire coastal area followed by the equal interval method

Summary

Introduction

Along with a number of coastal hazards such as tidal surge, cyclone, flooding, the excessive rate of coastal erosion considerably increases coastal vulnerability at national, regional and global levels (Ramieri et al 2011). Along with a number of predispositions and preparatory factors, a range of triggering factors such as heavy rainfall, sea level rise, prevailing winds and discharge of water govern the likelihood and severity of susceptibility to erosion (Saunders and Glassey 2007; MPI 2017). These triggering factors are closely associated with changes in climatic conditions. The likely changes in future climate might have substantial influences on triggering factors (MPI 2017), the consequent results of which would convert a considerable amount of coastal lands into high erosion susceptibility. Future scenarios of sea level rise might change the horizontal configuration of all coastlines

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