Probabilistic landslide hazard assessment using homogeneous susceptible units (HSU) along a national highway corridor in the northern Himalayas, India

Landslides (Impact Factor: 2.81). 09/2011; 8(3):293-308. DOI: 10.1007/s10346-011-0257-9

ABSTRACT The increased socio-economic significance of landslides has resulted in the application of statistical methods to assess their
hazard, particularly at medium scales. These models evaluate where, when and what size landslides are expected. The method presented in this study evaluates the landslide hazard on the basis of homogenous susceptible
units (HSU). HSU are derived from a landslide susceptibility map that is a combination of landslide occurrences and geo-environmental
factors, using an automated segmentation procedure. To divide the landslide susceptibility map into HSU, we apply a region-growing
segmentation algorithm that results in segments with statistically independent spatial probability values. Independence is
tested using Moran’s I and a weighted variance method. For each HSU, we obtain the landslide frequency from the multi-temporal data. Temporal and
size probabilities are calculated using a Poisson model and an inverse-gamma model, respectively. The methodology is tested
in a landslide-prone national highway corridor in the northern Himalayas, India. Our study demonstrates that HSU can replace
the commonly used terrain mapping units for combining three probabilities for landslide hazard assessment. A quantitative
estimate of landslide hazard is obtained as a joint probability of landslide size, of landslide temporal occurrence for each
HSU for different time periods and for different sizes.


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    ABSTRACT: Abstract: Landslides are the most common natural disaster in hilly terrain which causes changes in landscape and damage to life and property. The main objective of the present study was to carry out landslide hazard zonation mapping on 1:50,000 scale along ghat road section of Kolli hills using a Landslide Hazard Evaluation Factor (LHEF) rating scheme. The landslide hazard zonation map has been prepared by overlaying the terrain evaluation maps with facet map of the study area. The terrain evaluation maps include lithology, structure, slope morphometry, relative relief, land use and land cover and hydrogeological condition. The LHEF rating scheme and the Total Estimated Hazard (TEHD) were calculated as per the Bureau of Indian Standard (BIS) guidelines (IS:14496 (Part-2) 1998) for the purpose of preparation of Landslide Hazard Zonation (LHZ) map in mountainous terrains. The correction due to triggering factors such as seismicity, rainfall and anthropogenic activities were also incorporated with Total Estimated Hazard to get final corrected TEHD. The landslide hazard zonation map was classified as the high, moderate and low hazard zones along the ghat road section based on corrected TEHD.
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May 30, 2014