Why frequent landslides in Himalayas?

Unscientific constructions in the ecologically fragile Himalayas, depleting forest cover and structures near streams blocking the flow of water are causing frequent landslides in Himachal Pradesh, say experts.

Extensive cutting of hill slopes for construction and widening of roads, blasting for tunnels, and hydro projects are the main reasons behind increase in slides, said geological expert Prof Virender Singh Dhar. Dhar further said that vertical cutting of mountains for road construction has been witnessed in Himachal with just 5-10 feet retaining walls. According to experts, slopes in Himachal have become highly vulnerable to landslides due to cutting of rocks at the foothills and the lack of proper drainage system, and high intensity rainfall is making the things worse for the state. The rain intensity has increased and high temperatures coupled with heavy rains lead to landslides due to loosening of the strata in places which have undergone cutting downstream on the foothills, Scientist (climate change) Suresh Attre had earlier said.

Himachal Pradesh receives about 730 mm of rains on an average during the whole monsoon season from June to September, but according to the Met department the state has received 742 mm rainfall this year till date. As per the state emergency operation centre, Himachal witnessed 113 landslides in 55 days since the onset of monsoon.

The Public Works Department (PWD) has suffered a loss of Rs 2,491 crore and the National Highways Authority of India (NHAI) about 1,000 crore, officials told PTI. According to data compiled by the disaster management department, an alarming six-time increase had been witnessed in incidents of major landslides in 2022 which saw 117 major landslides as compared to 16 in 2020.

There are 17,120 landslide-prone sites in the state out of which 675 are near critical infrastructure and habitations, according to the data. The maximum of such prioritized sites are in Chamba (133) followed by Mandi (110), Kangra (102), Lahaul and Spiti (91), Una (63), Kullu (55), Shimla (50), Solan (44), Bilaspur (37), Sirmaur (21) and Kinnaur (15). The increased human activity and exploitation of natural resources for development pose a serious threat to ecology which is on the threshold of peril, said a former bureaucrat.

The major active landslides/sinking sites in the state included Jhandota and Kakroti villages, and Sapdoth Panchayat in Chamba; Mcleodganj Hill and Bariara village in Kangra; Baridhar to Kalyan Ghati Road; Mansar near Salogra; Jabalpatwar village in Solan; and Kotrupi, Doada Hanogi, and Mile 5, 6 and 7 near Pandoh and Nagani village in Mandi district. The other sites include Urni Dhank, Batsari, Nesang, Purbani Julha in Kinnaur besides Nigulsari, where 28 persons were killed and 13 were injured in a major landslide on August 11, 2021. Ten such sites have been identified in Shimla district. As per the Landslide Atlas of India prepared by the National Remote Sensing Centre, ISRO, Hyderabad, all 12 districts of Himachal are susceptible to landslides. The landslide exposure analysis of the mountainous areas covering 147 districts in 17 states put Himachal’s Mandi district at 16th place, followed by Hamirpur at 25, Bilaspur at 30, Chamba (32), Solan (37), Kinnaur (46), Kullu (57) Shimla (61), Kangra (62), Una (70), Sirmaur (88) and Lahaul and Spiti (126) in socio-economic parameter risk exposure map. NHAI Regional Officer in Himachal Pradesh Abdul Basit said rains had saturated the mountains and cloudburst and landslide have caused extensive damage to roads. The most affected stretches include Shimla-Kalka, Shimla-Matour, Manali-Chandigarh and Mandi-Pathankot, he said. Slides and road cave-ins have also been witnessed where there was no rock cutting, he said, adding tunnel is the only solution to ensure uninterrupted connectivity. Sixty-eight tunnels have been proposed for Himachal Pradesh, out of which 11 have been constructed, 27 are under construction and 30 are in the stage of preparation of a detailed project report.