Dharali cloudburst: Why Uttarakhand faces nature's fury so frequently

India Today

20 hours ago

Every monsoon, Uttarakhand braces itself for the worst from nature, and almost every year, the hill state nestled in the Himalayas falters under the weight of yet another natural disaster. The August 5 cloudburst and resulting flash floods and landslides that wrecked Dharali village near Gangotri is a fresh wake-up call for a state serially bearing the brunt of calamities—cloudbursts, flash floods, landslides, avalanches and land subsidence—for over two decades now.Take some of these grim tragedies. The 2013 Kedarnath floods, caused by a Himalayan glacial lake bursting above the revered Hindu shrine, killed over 6,000 people. More recently, in 2021, an avalanche in Chamoli damaged a key hydropower project while flash floods in Uttarkashi swept away several villages. The monsoon season in 2023 caused nearly 100 landslide-related deaths. Earlier that year, Joshimath reported major land subsidence. And last year, the state recorded over 1,800 landslides during monsoon.advertisementThe August 5 cloudburst in Uttarkashi triggered flash floods and massive landslides, sending within minutes scores of homes, shops, hotels and properties into the Dhauli Ganga river. At least five people are dead and 100 missing. Dharali, the epicentre of the damage, lies in the Bhagirathi Eco-Sensitive Zone. Experts say constructions on river floodplains and other unchecked activities may have worsened the impact of the calamity.These are not one-off events but pointers to a deeper and long-ignored crisis. Uttarakhand's geography and how that is being managed make the state particularly vulnerable. The question no longer is whether disasters will happen but why they are striking so often, and with such force.
According to the 2023 Landslide Atlas of India, prepared by the Indian Space Research Organisation (ISRO), India is the fourth most vulnerable in the world to landslide risk, with more than one death per 100 sq km reported each year.Most landslides in India happen during the monsoon months, from June to September. The country alone accounts for 16 per cent of all rainfall-related landslides globally. These are caused by natural triggers, such as heavy rain, weakening of rocks and earthquakes, yet increasingly as much by anthropogenic activities such as construction and mining.Landslides happen in various forms, such as debris flow, rock-falls and slides, and can be caused by rain, erosion from floods, earthquakes, snowmelt or human activity such as overgrazing, cutting of trees and unplanned development. In Uttarakhand, the conditions seem fertile for such disasters.The 2023 Landslide Atlas includes a landslide exposure analysis for 147 districts across 17 states and two Union territories in India's mountainous regions, based on key socioeconomic parameters. Rudraprayag district in Uttarakhand, which has the highest landslide density in the country, also ranks the highest in terms of exposure to population and number of houses. Tehri Garhwal is ranked second. Other Uttarakhand districts in the top 25 include Chamoli (19th), Uttarkashi (21st) and Pauri Garhwal (23rd).Charu C. Pant, retired professor of geology and former dean in the faculty of science at Kumaun University, Nainital, explains that the Great Himalayan Granite stone plays a key role in the geological instability of the region, particularly in the Main Central Thrust zone, which is one of the most active and critical fault lines in the Himalayas.advertisementUttarakhand includes both the Lesser and Greater Himalayas, and the zone where the two meet is known as the Main Central Thrust. 'This zone, spread across northern India till Arunachal Pradesh, is very fragile,' informs Pant.This granite body, emplaced deep in the earth's crust around 20-25 million years ago, is part of the Greater Himalayan Sequence, considered a key tectonic unit of the Himalayas and sitting right above the Main Central Thrust. As the Indian plate continues to push into the Eurasian plate at the rate of 55 mm per year, the granite mass acts like a hard, brittle block lodged between two tectonic forces.According to experts, pressure and heat generated along this fault line cause intense deformation in the surrounding rocks. But granite itself is relatively rigid and does not absorb stress easily. Instead, the energy is transferred to the adjacent rocks, which are already fractured from earlier tectonic activity. These rocks gradually become crushed, sheared and pulverised.As a result, the presence of this hard granite in a tectonically active zone acts like a wedge that grinds and weakens the rocks around it. Over time, this has created a deeply fractured and unstable zone along the Main Central Thrust, making it prone to landslides, rock-falls and rapid erosion, especially during heavy rainfall or seismic activity, say experts.advertisement'Another reason behind these natural disasters is that the valleys from which our rivers flow are very narrow. The water-bearing clouds formed over these valleys are trapped between tall and steep mountains and start to precipitate, often resulting in cloudbursts. That causes landslides and heavy water, along with mud, stones and more, reaching the lower areas as furiously flowing debris. These debris flows have a higher erosive power because of the solid elements they carry,' says Pant.Pant says the western disturbances—weather systems originating over the Mediterranean Sea and travelling eastward across Iran, Afghanistan and Pakistan before reaching northern India—can make things worse. 'The disturbances bring moisture that often causes winter rain and snow in the Himalayan region. When combined with the monsoon, the intensity of the rainfall increases,' he explains.Pant adds that while these phenomena are not new, what complicates the scene is the unprecedented construction in the Himalayan region, including on riverbeds, and rising population and human activity. For instance, at least 12 big or small hydel projects for Uttarakhand are currently in different phases of planning or approval. Similarly, the Rs 12,000 crore Char Dham Highway project, essentially about 900 km of road-widening, has been mired in controversy since being sanctioned in 2016 owing to mishaps.advertisementWith this growing pressure, natural calamities are taking a far heavier toll than before. As Dharali in Uttarkashi counts its dead and prays for those missing, Pant underlines that governmental intervention must go beyond relief and rehabilitation for singular tragedies. The need, he says, is to create a stringent policy of keeping the riverbeds free of construction and implementing the recommendations of environmental assessments for development projects sans any pressure. In short, redoing the rulebook and sticking to it.Subscribe to India Today Magazine- EndsMust Watch