Flood Assessment and Identification of Emergency Evacuation Routes in Seti River Basin, Nepal

Bhabana Thapa,Teiji Watanabe,Dhananjay Regmi

doi:10.3390/land11010082

Bhabana Thapa, Teiji Watanabe + Show 1 more

Open Access

https://doi.org/10.3390/land11010082

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Journal: Land	Publication Date: Jan 5, 2022
Citations: 9	License type: CC BY 4.0

Affiliation: Hokkaido University, Himalayan Rescue Association

Abstract

Sudden floods frequently occur in the Himalayas under changing climates. Rapid glacial melt has resulted in the formation of glacial lakes and associated hazards. This research aimed to (1) identify flood-prone houses, (2) determine pedestrian emergency evacuation routes, and (3) analyze their relationships to socioeconomic status in the Seti River Basin. Detailed hazard maps were created using field survey results from unmanned aerial vehicle photogrammetry and the Hydrologic Engineering Center River Analysis System. Questionnaire, focus-group, and key-informant surveys helped identify the socioeconomic situation. Inundation maps revealed that most residents are exposed to future flooding hazards without proper evacuation routes. Highly impoverished and immigrant households were at the highest risk in terms of income inequality and migration rate (p < 0.001) and were located on the riverside. The locations of 455 laborers’ houses were significantly correlated with inundation hazards (p < 0.001). Governmental and associated agencies must develop adequate plans to relocate low-income households. Group discussions revealed the need for stronger adaptive capacity-building strategies for future risk management. Pokhara requires better systematic and scientific land-use planning strategies to address this issue efficiently. A similar approach that combines flood modeling, proper evacuation route access, and socioeconomic survey is suggested for this river basin.

Highlights

Climate change has increased the threat of global flooding hazards, as indicated by the rising frequency and greater spatial coverage during the last decade compared with those observed in previous decades [1]
We suggest that nine new evacuation routes be created, three of which can be connected suggest that nine new evacuation routes be created, three of which can be connected with with the existing routes
We identified and suggested detailed evacuation routes and a safe evacuation system, which only became possible with the combined approach applied here

Summary

Introduction

Climate change has increased the threat of global flooding hazards, as indicated by the rising frequency and greater spatial coverage during the last decade compared with those observed in previous decades [1]. Global warming is generally expected to increase the magnitude and frequency of extreme rainfall events, potentially impacting riverine hazards [2]. Floods often cause enormous damage to lives, property, crops, and infrastructure, and the number of casualties by floods can increase in the future [4,5,6]. Monsoonal floods are a common hazard in Nepal, where glacial lake outburst floods (GLOFs) threaten human safety and wellbeing [5]. GLOFs can cause catastrophic flooding in downstream areas, severely damaging property in addition to causing loss of life [7]. One-fifth of the world’s population depends on water derived from the

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Conclusion