Landslide Susceptibility Assessment using Open-Source Data in the Far Western Nepal Himalaya: Case Studies from Selected Local Level Units

Abstract

This paper explores openly available geo-spatial and earth observatory data to understand landslide risk in data scarce rural areas of Nepal. It attempts to explore the application of open-source data and analytical models to inform future landslide research. The first step of this procedure starts from the review of global open datasets, literatures and case studies relevant to landslide research. The second step is followed by the case study in one of the mountainous municipalities of Nepal where we tested the identified open-source data and models to produce landslide susceptibility maps. Past studies and experiences show that the major potential sites of landslide in Nepal are highly concentrated in a geologically weak area such as the active fault regions, shear zones, axis of folds and unfavorable setting of lithology. Triggering factors like concentrated precipitation, frequent earthquake phenomenon and haphazard infrastructural development activities in the marginally stable mountain slopes have posed serious issues of landslides mostly through the geologically weak regions. In this context, openly available geo-spatial datasets can provide baseline information for exploring the landslide hazard scenario in the data scarce areas of Nepal. This research has used the available open-source data to produce a landslide susceptibility map of the Bithadchir Rural Municipality in Bajhang District and Budiganga Municipality in Bajura District of the Sudurpaschim Province of Nepal. We used qualitative analysis to evaluate the parameters and assess the susceptibility of landslide; the result was classified into five susceptibility zones: Very High, High, Moderate, Low, and Very Low. Slope and Aspect were identified to be the major determinants for the assessment. This approach is applicable, specifically, for the preliminary investigation in the data scarce region using open data sources. Furthermore, the result can be used to plan and prioritize effective disaster risk reduction strategies.

Landslide susceptibility analysis using frequency ratio and weight of evidence approaches along the Lakhandehi Khola watershed in the Sarlahi District, southern Nepal

“…This map exhibits the present landslide susceptibility zones and the probability of future occurrences of landslides which is useful to all the stakeholders for land use planning and developing mitigation strategies against the consequences of increasing landslides in the Siwalik Hills of Nepal Himalaya. The results of the susceptibility mapping can be used to plan and prioritize effective disaster risk reduction strategies (Paudyal et al 2021).…”

Landslide susceptibility assessment in the Rangun Khola watershed of far western Nepal

“…According to the data published by MoHA in Nepal Disaster Report (MoHA, 2019), a total of 483 landslide events were recorded causing 161 fatalities and affecting 1083 households with an estimated loss of $2 million during 2017/18. Apart from these many small-scale landslides go unreported; losing productive lands unless and until they involve the loss of life and properties or cause the blockage of the road (Dahal, 2012, Paudyal et al, 2021. The current study area, Rangun Khola watershed is regarded as prone to landslides and erosion events historically and now facing the development of urban features and other linear infrastructures (Dhakal, 2014b;Bhandari et al, 2021).…”

“…There are multiple studies in Nepal Himalaya focused on landslide susceptibility mapping using various approaches (Dhital et al, 1991;Pantha et al, 2008;Devkota et al, 2012;Regmi et al, 2014;Paudyal et al,2021). These studies focus on to access physical properties of the landslides, geological settings, and associated loss of life and property, and study of the relationship between landslide occurrences and landslide conditioning factor needed to be studied for susceptibility mapping.…”