Comprehensive assessment of flood exposure in arid regions: Integrating GIS techniques and multi-method approaches – A case study of downstream swat river, Pakistan

Abstract

Floods are among the most destructive natural disasters, causing extensive damage to human lives, property, and the environment. Pakistan is susceptible to natural calamities, such as the 2010 flood and the recent most 2022 flood, resulting in millions of people being impacted. The assessment of flood exposure is essential to plan effective mitigation and flood preparedness. Until now, an affective and inclusive method for calculating flood exposure in arid areas has not been developed. This paper proposes a new method in the selected area to calculate flood exposure in arid areas heavily affected by monsoons. This evaluates the exposure of settlements in the area based on four indicators: elevation of the area, slope and area topography, river density, and vegetation cover. Analytic Hierarchy Process (AHP) analysis was selected, and exposure maps were developed using ArcGIS. Due to heavy monsoon rains and climate change in the region, the risks of flood exposure become high. The results indicate low to high level exposure distribution in the area in terms of various social, economic, physical, and environmental factors. In the region, unexpected heavy precipitation during the monsoon season brings considerable losses to property and people exposed to floods due to river water overflow. In addition, the growing population and the unplanned construction of resident settlements in the floodplain is another threat. The analysis reveals that most riverside settlements have low elevation, with 55% of construction sites built in the floodplain indicating a high exposure rate ranging from 0.4 to 0.5. The study further discloses that numerous settlements have a high exposure to flood hazards increasing the likelihood of severe future impacts from flooding in the area. The local government must establish appropriate land use planning and zonation for construction in the area in light of these findings. Based on the results, the manuscript provides an inclusive analysis of the chosen indicators for the overall flood exposure of the area and results of low to high exposure, making this a valuable contribution to the field of exposure assessment. This study also provides thematic maps to the stakeholders for the effective management of exposure in the area to reduce the future flood susceptibility.