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Application of GIS and Remote Sensing for Landslide Mitigation in the Rural Access Corridors

Sushil Chandra Tiwari
Engineer
DoLIDAR / MoLD, Nepal
tiwarisc@hotmail.com

Abstract :
In developing countries, the exploration of natural resources and construction related development activities are central to the process of development. However, in mountainous regions of countries like Nepal, landslides pose frequent hazards to both rural and urban communities and infrastructure, leading to economic disruption as fatality, injury, loss or damage of properties and infrastructure.
The threat posed by landslides is especially high along rural access corridors, where migratory patterns usually result in ad-hoc roadside development. Landslides and slope failures affect road users, road engineers, communities and farmers. Furthermore, in populated hilly or mountainous regions there is often a tendency to cultivate the marginal land because of the scarcity of land suitable for cultivation and road engineers also traditionally intend to locate roads through the more gentle parts of the terrain in order to ease construction and reduce construction cost. Rural access corridors therefore often contain both the engineering and agricultural land uses competing for land that is often of only marginal stability.
Engineering and land use practices relating to earthworks and drainage frequently impact adversely on slope stability and levels of risk from slope failures and landslides are frequently elevated. Furthermore, during the construction and operation of rural roads there is high migration in the road corridors, adding more pressure on the land and increasing potential risk of the landslides. Landslide hazards occurring in rural access corridors, therefore, pose both an engineering and socio-economic risk and thus the proper evaluation and planning for landslide mitigation is a critical element to minimize the landslide hazards and to ensure more sustainable rural road development.
Landslides are caused or triggered by many factors. Usually the slope or topography and the underlying geology are the most common casual factors for landslides and these are further triggered by other factors such as land use, rainfall or earthquakes and other human related activities. It is therefore important to map and evaluate all these factors to assess the susceptibility of landslides and the potential risk that might be posed by these. GIS and Remote Sensing, which are the modern tools to map and analyse relatively large volumes of spatial data, can thus be used effectively to map all these factors and analyse to assess landslide susceptibility, hazards or risk.

This paper illustrates the interface between the landslide problems and the common causal factors of the problems in rural access corridors. It is further explored how these factors can be interpreted, mapped or analysed with Remote Sensing and GIS. Besides, a suitable model for landslide susceptibility, hazard and risk assessment in a regional scale is also suggested, which can be used efficiently by the developers or planners at the local level for landslide mitigation.
For this paper, special reference is taken to the case studies carried out, as part of the Knowledge and Research program of DFID, UK on Landslide Risk Assessment in the Rural Access Sector by Scott Wilson in collaboration of the Department of Local Infrastructure Development and Agricultural Roads (DoLIDAR), Nepal.