AVALANCHE RISK ASSESSMENT A CASE STUDY OF GYONG SECTOR SIACHEN PAKISTAN

Abstract

Avalanches are natural hazard that could damage infrastructures and threaten lives in high altitude mountainous terrains. A massive ice avalanche struck a Pakistani military base at Gayari sector, Saltoro Valley on 7 April 2012 and buried/killed 135 soldiers and civilians. Keeping in view the catastrophe a study was designed with the objectives to (a) study avalanche types, trigger mechanics, snow force distribution and their potential associated risk using Alpha Beta glacier model & simulation techniques and (b) assess the current camp sites suitability analysis and/or propose alternative camp sites in Gyong Sector Siachen. Using expert knowledge from known avalanche paths, terrain parameters that are most likely to contribute to avalanche activity were documented and statistically evaluated for key factors. ArcGIS model builder was used to model the avalanche starting zones with terrain modeling by utilizing a digital elevation model (DEM). Terrain analysis such as slope, aspect and curvature along with terrain roughness was used to extract possible triggering zones. Using alpha beta statistical model runouts of critical avalanches in the area were calculated. Release zone modeling of the slopes over the present camp site revealed that the ground has very high probability of triggering and the site was declared to be the most dangerous. Linear regression analysis of five known avalanche paths in Goma sector yielded 𝛼=0.94𝛽−0.81 as model equation for the area. The β angle for present camp site was 19.13°, α angle was 17.17° and maximum runout was 3910 m down the slope of the release point which was well over the present camp site of Pakistan army. Complete analysis of the area was carried out and alternate camp site was proposed in the area. The study contributed to the body of knowledge through an investigation of release zones and runout in Gyong sector. Similar methodology could be used to carry out site suitability analysis of other camp sites in the Siachen area to facilitate Pakistan army.