Landslide disaster and application possibility of landslide early warning system (lews) in lam dong province, southern Vietnam

Abstract

Landslide disasters have occurred and caused many houses cracked, collapsed and lives in many countries. Bao Loc city belongs to Lam Dong Province, southern Vietnam, locates on Di Linh - Bao Loc plateau about 800 - 1000m elevation with complex mountainous terrain. Residents living there have to evacuate to temporary areas supported by local government. In order to reduce damages of assets and costs of lives, mechanism of landslide hazard need to be investigated and assessed. The main cause was soil extraction activities at toe of slope, which lost the counterweight berm, associated with the moisture increase of soil due to heavy rainfall in rainy season. The 1.2-hectare landslide area was investigated with reduced shear strength of slope materials. The analysis results from GeoStudio software show that the slope is stable in dry season with the minimum factor of safety (FS) is 1.474, in rainy season the slope is unstable with minimum factor of safety (FS) is 0.896 commensurate with groundwater present model. The analysis results from Band Stability and Toe Erosion also show that the slope is unstable with the minimum factor of safety (FS) is 0.73. The results of the micro tremor observation also show the study area is potentially very high landslide. The extensometer was also installed to record the extension of the cracks in the hazard zone. The results showed that some cracks have been developed especially in the rainy season. The unmanned aerial vehicle (UAV) was also used to monitor and investigate the small and large landslide areas. A landslide early warning system (LEWS) for predicting landslide disasters using global navigational satellite system (GNSS) has been also developed. The preliminary results showed that the landslide early warning can be applied in the area but it depended on many installed factors and infrastructure of the local telecommunication system.