Landslides in Nilgiris: Causal Factors and Remedial Measures

TLDR: In this article, the authors gave an over view of the various causal factors involved in triggering of landslides in Nilgiris and suggested that cutting of slope at toe, heavy loading on slope at crest, blocking of surface drainage system and choking of weep holes in retaining structures, improper planning and design/implementation of remedial measures, vegetation removal and dumping are possibly the main causal factors for most of the landslides during heavy rainfall.

Abstract: Landslide is a major natural hazard which affects 15% land area of the country. Himalayas and Nilgiris are most affected locations due to landslides in India. Rainfall is the major triggering factor for landslides in Nilgiris, whereas some of the Himalayan regions experienced landslides due to combination of rainfall and earthquake. Though the rainfall is a major triggering factor, some of the other causative factors are also responsible for triggering of landslides in Nilgiris. The present study gives an over view of the various causal factors involved in triggering of landslides in Nilgiris. It is found that, cutting of slope at toe, heavy loading on slope at crest, blocking of surface drainage system and choking of weep holes in retaining structures, improper planning and design/implementation of remedial measures, vegetation removal and dumping are possibly the main causal factors for most of the landslides in Nilgiris during heavy rainfall. The study also suggest, though the retaining walls are commonly adopted as remedial measures, cost effective subsurface drainage systems together with slope reinforcement might be effective solution to control the landslides in many locations. Present study also gives an over view on the use of numerical analysis pertaining to landslides in Nilgiris together with on-going detailed site specific geotechnical investigation.