Tunneling, landslides on NH-44, and the fragile Himalayas

The Himalayas in Asia are some of the youngest mountains on Earth; formed 50 Ma ago due to the closure of the neo-Tethys sea and the subsequent collision of the Eurasian and Indian plates this mountain chain is still undergoing orogeny, the process of mountain formation caused by the movement and collision of tectonic plates. These mountains are not particularly stable since the rock mass is not very robust. Because of the highly deformable anisotropic rock mass and the considerable variation in geological parameters even within a relatively small local area, the geological stability of this particular area is especially precarious owing to the forces emerging from plate tectonics. Most of the Himalayas are subjected to significant summer rainfall, which can either amplify the pace of surface runoff or permeate into the ground, eventually leading to mass slides or flows.

Demands and Challenges of Development in the Himalayas

The construction and development of tunnels, motorways, water conveyance facilities, irrigation systems, and hydropower plants are in great demand close to the Himalayan mountain range because of the region’s high population density. Large, permanent rivers are common in the Himalayas since much of the mountain range is at altitudes of more than 4000 m when snowfall is the norm and some regions even see permafrost. Many hydroelectric projects are built with tunnels stretching hundreds of kilometers in order to harness the energy of these rivers. Also, the Himalayan areas are distinguished by their widely dispersed urban and rural habitation zones. The passage between these zones frequently entails the extensive mountainous belts that need to be carved in order to prepare the way for the passage of people and commodities. One of the reasons these areas are prone to landslides is that roads have been built in these transition zones, which destabilizes the mountain slopes. 

Landslides on NH44: Impact on Lives and Economy

Due to landslides on this section of the National Highway-44 (NH-44), the whole Kashmir valley as well as the UT of Leh and Ladakh experience negative repercussions on an annual basis in the form of the loss of human life as well as harm to the economy. Between the years 2000 and 2010, this route was the scene of about 8000 incidents and was responsible for 2,000 deaths. In addition, the Kashmir Traders and Manufacturers Fund (KTMF) estimates that the prolonged obstruction of the National Highway has resulted in economic losses for the Kashmir valley that approach roughly 50 million rupees. The Kashmir valley is connected to the rest of India through the arterial National Highway (NH-1A, which is 270 kilometers in length. In 2010, NH-1A became known as NH 44. On this road lies the Jawahar Tunnel, which traverses the Pir Panjal Range and connects Jammu with Kashmir. In the past, various proposals for newly constructed tunnels were considered along the route. Among these, the Chenani-Nashri Tunnel as well as the new Banihal Double Road Tunnel have been put into existence. There are stretches of the route that passed over terrain that was quite hazardous. As a result, the congestion in NH has developed into a pattern that has persisted over the course of many years.

Although there have been instances of landslide events in the past along NH44, the frequency of such occurrences has increased significantly after the route was widened and tunneled throughout the stretch. The majority of the landslides occur in the areas of Ramsoo, Maroog, Anokhifal, Panthyal, Battery Cheshma, Nashri, and Kheri along the Bichleri stream in the districts of Ramban and Udhampur. Between the years 2004 and 2016, India remained one of the nations that was most severely affected by landslides that were brought on by human activity. As a result, India was responsible for 18% of all casualties that were brought on by such landslides worldwide. The number of construction-related landslide incidents that occurred in India was 28%, followed by China (9%) and Pakistan (6%).

Tunneling and Landslides: Understanding the Risks

In the Himalayas, where people’s lives are dependent on the occurrence of landslides, it is highly crucial to have an understanding of the mechanisms that initiate landslides. It is a well-known fact that landslides can be caused by tunneling that has not been properly anticipated or carried out.  This is especially prevalent when the tunnel traverses an old landslide, which happens more often because of the fact that the characteristics of the active but now inactive mass movement were not detected during the ground research stage. The excavation of a tunnel can in fact lead to a quick progression of landslides, which can have a significant influence not only on the surrounding environment but also on any pre-existing structures or villages, and even on the tunnel itself in some cases. It is clear from the accident that took place in May 2020 in the Ramban district on the National Highway region, when the front face of a tunnel that was under construction collapsed and several construction workers were trapped within. The incident occurred between Ramban and Ramsu which has been a hotspot for landslide activities for ages. The incident could have been avoided and 10 lives could be saved if a proper landslide inventory of the region was considered on serious notes.

In another incident of 8 July 2023, a significant portion of a road on the Jammu-Srinagar route collapsed which was captured on film and has since gone viral. The landslide caused the road that connected two tunnels on the national highway to be swept away halting the traffic movement. Once such mass movements have been started, it is challenging and costly to get things back to where they were stable. These devastating incidents of landslides along NH44 also take place because of improper channeling of streams coming from upslope. Despite being well acquainted with the perennial streams draining the slope area, no proper engineering measures for their channeling has been done till now. This situation escalates during the rainy season when these streams get filled with more water coming down the slope with all force, washing away all that comes in its path. 

Landslides along NH44 prove to be devastating not only to public property and human lives but the artificial slopes that created downslopes also threaten the aquatic flora and fauna of the mighty river Chenab that drains the foothills of the area. Because these artificial slopes are so unstable, slips are common after heavy rains due to erroneous dumping of material from the active slope or from the tunnels down the slope. While it is true that human beings have an innate need to progress with developmental activities and the building of new roads and trains, this should in no way be done at the expense of the environment, especially not now, when the entire globe is battling with the effects of climate change in the form incessant rains.

Recommendations

Mapping with the objective of developing early warning systems can help reduce the number of lives lost and, if the process is adhered to, can also be included in planning.

According to the IndiaSpend article, the Geological Survey of India (GSI) has completed a nationwide landslide susceptibility mapping project at a scale of 1:50,000 covering 85% of the total 420,000 square km of landslide-prone terrain in the entire nation. The region depicted on these maps is currently being expanded, and at the same time, efforts should be made to localize them to ensure they are as accurate as possible.

In order to establish the alignment of the tunnels, it is necessary to delve further into the geomorphological factors, such as whether or not there are ongoing or inactive landslides as they are particularly susceptible to alterations of the stress-strain in the rock mass generated by subterranean excavation, either using a conventional or mechanical approach. 

During the process of tunnel excavation, it is essential to make both short-term and long-term predictions on the progression of landslides. When used for this purpose, the data from satellite interferometry can be quite helpful in identifying sections of slopes that are characterized by active motions and assessing how they have evolved over the past few decades.

Conclusion 

The impact of landslides on NH-44 is severe, affecting the entire Kashmir valley, Leh, and Ladakh, resulting in loss of lives and significant economic damage. To mitigate risks, early warning systems based on comprehensive landslide susceptibility mapping are recommended, using advanced technologies such as satellite interferometry to monitor slope movements. Understanding the geological risks and implementing sustainable development practices is crucial for safeguarding lives, property, and the environment in this fragile region.

References

Malik, Y.A.; Singh, R.; Sharma, P.; Scholar, M.T. Road Accidents and Safety Challenges-Case study of Srinagar-Qazigund National Highway (NH-44) (ISSN NO: 0972-1347). Available online: http://www.ijics.com/gallery/61-june-1334.pdf

Bhasin, R.; Grimstad, E. Case Studies of Tunnels to Bypass Major Landslides in the Himalaya. J. Rock Mech. Tunn. Technol. 2018, 24, 69–80.

‘12% Indian Land Prone To Landslides; Accounted For 18% Deaths Worldwide During 2004-16’ (indiaspend.com)