Recent landslides in Uttarakhand: nature's fury or human folly

Abstract

Hill slopes in the Himalaya are known for their instability due to ongoing tectonic activity. However, increasing anthropogenic intervention in the recent times appears to be contributing to terrain instability in addition to natural factors, as observed by increasing frequency and magnitude of landslides since 1970. During August and September 2010, Uttarakhand Himalaya witnessed largescale slope destabilization, particularly along the roads where widening work was in progress (Figure 1). The landslides killed about 220 people in the entire rainy season of 2010, while 65 lives were lost, 6 persons went missing, 21 people were injured, 84 livestock died, 534 houses were fully damaged and 2138 houses were partially damaged due to heavy precipitation within 4 days from 18 to 21 September, which virtually brought the state to a grinding halt for several days. The cause of regional-scale landslides has been attributed to exceptionally high rainfall in the region during September. When the average rainfall for the month of August and September from 2000 to 2009 is compared with rainfall data of the same period of 2010, it was found that in September 2010, 336% higher rainfall was received by the area (Figure 2). However, the question that arises is: was it unusual rainfall-induced calamity or a result of human intervention? Here we present our preliminary observations along Rishikesh–Mana National Highway (NH-58) that runs along the Ganga–Alaknanda Valley (Figure 1). Our observations suggest that inadequate consideration of geology and geomorphology during the road alignment and poor, faulty engineering techniques were major factors responsible for the recent landslides. Experts hold the view that while tampering with the Himalayan slopes, one needs to be extra careful as the slopes which have evolved by exogenic and endogenic processes are precariously balanced. It would be unjust to say that our planners and policy makers are not aware of the sensitivity of the Himalayan ranges, but it seems that the awareness is masked by the pressure of utilizing the Himalayan resources for national growth Figure 1. Map of the Upper Ganga and Alaknanda valley. Red dotted circles show the areas that suffered maximum damage during August and September 2010. MCT, Main Central Thrust; AF, Alaknanda Fault; NAT, North Almora Thrust; ST, Saknidhar Thrust.