Forecasting landslide in the Western Ghats

Thiruvananthapuram, 
The Hindu,  January 3, 2016

A village-level early warning system based on rainfall threshold data and landslide records could be the most viable method for landslide risk management in the Western Ghats, according to a scientific paper presented at a workshop organised by the National Centre for Earth Science Studies here on Friday.

Presenting the paper, Pankaj Jaiswal from the Geological Survey of India said forecasting of the trigger, in this case the rainfall, could provide information on when landsliding would occur. This, in conjunction with landslide susceptibility maps, could be used to delineate potentially hazardous areas in the Western Ghats and provide early warning.

Dr. Jaiswal proposed the establishment of a threshold model for small river catchments or at the taluk level, along with installation of rain gauges at the village level, collection and dissemination of daily rainfall data and analysis of the data for threshold exceedance. The automated process could be implemented at the village level through panchayats. The paper also proposed public display of the threshold exceedance graph and susceptibility map to facilitate community-based response. Dr. Jaiswal explained how the GSI had modelled the rainfall threshold for the Nilgiri area using rainfall data and landslide records. The cost-effective model was successfully validated in November 2009 and deployed for village-level early warning.

Pointing out that high population density, unplanned settlements, unscientific slope cutting for infrastructure development, and transgress of population to hazardous areas posed a challenge for landslide risk management in areas like the Nilgiris, he said public awareness coupled with early warning could minimise the damage to life and property. Another paper by Kusala Rajendran from the Indian Institute of Science said the low-level seismic activity observed in parts of Kerala like the Wadakkancherry earthquake in 1993 and the couple of earthquakes that struck Pala in 2000 and 2001 were associated with the reactivation of shear zones.

Ms. Rajendran said a strong case of fluid-induced seismicity had been observed at the Idukki reservoir, noted for the low level activity that has decreased since the initial onset, but still persists and is in some ways related to the filling of the reservoir and rainfall in the catchment.