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Hindustan Times
2 days ago
- Science
- Hindustan Times
Studies show frequency of cloudbursts increasing
The flash flooding and landslide triggered by torrential rain in Jammu and Kashmir has brought the spotlight on extreme weather events battering India's Himalayas this monsoon season, a trend that tracks with rising extreme weather events as global temperatures have risen. The incident in Jammu and Kashmir comes on the back of another deadly flood on August 5, when suspected glacier collapse triggered flash floods in Dharali region of Uttarakhand(PTI) The incident in Jammu and Kashmir comes on the back of another deadly flood on August 5, when suspected glacier collapse triggered flash floods in Dharali region of Uttarakhand. Extreme monsoon rainfall and flash floods also struck Kullu, Shimla, Lahaul and Spiti this week, continuing a pattern of escalating disasters across Uttarakhand, Himachal Pradesh and Jammu and Kashmir. Multiple peer-reviewed studies published since 2017 have documented the increasing frequency of cloudbursts and flash floods across the Western Himalayas. Experts attribute this to rising temperatures that increase the atmosphere's water-holding capacity, leading to more intense rainfall events, compounded by unplanned construction in vulnerable areas. The physics behind the increasing intensity are straightforward, according to Anil Kulkarni, distinguished visiting scientist at the Divecha Centre for Climate Change at the Indian Institute of Science. 'Higher temperature increases water holding capacity of the air,' Kulkarni explained. 'Mountainous regions due to higher slope are associated with upward movement of air mass. As atmospheric moisture is moved upward it increases size of water droplets, in the meantime, additional moisture is added at lower altitude. This significantly increases moisture in the air column. This leads to cloudburst.' Research data supports this mechanism. A study published in July in the Journal of Geological Society of India titled 'Uttarakhand: A Hotspot for Extreme Events?' documented a marked increase in extreme events over Uttarakhand after 2010, particularly during monsoon season. The research, led by Yashpal Sundriyal of Hemvati Nandan Bahuguna Garhwal University, analysed four decades of observational data from 1982 to 2020, including rainfall, surface radiative temperature, surface runoff and teleconnection indices. The study examined relationships between climate variability and global teleconnections including the North Atlantic Oscillation and El Niño-Southern Oscillation. Notably, the period 1998-2009 showed increased annual temperatures and decreased precipitation and surface runoff. A 2025 study published in Springer Nature titled 'A review of cloudbursts events in the Himalaya region, and 2D hydrodynamic simulation using MIKE models' found cloudbursts increasing in frequency across Uttarakhand, Himachal Pradesh, Jammu and Kashmir and Ladakh based on analysis from 1970 to 2024. Uttarakhand emerged as the most affected area, with Himachal Pradesh experiencing frequent events and Jammu and Kashmir showing rising trends. 'The region is characterised by frequent extreme rainfall events during the Indian Summer Monsoon and winter western disturbances,' the July study concluded. The escalating pattern builds on documented disasters, like the August 18, 2019 cloudburst in Uttarkashi's Arakot region that killed 19 people while affecting 38 villages across 70 square kilometres and stranding more than 400 people. Heavy rain caused a massive flash flood in Arakot Nala and induced a major landslide downstream, devastating the villages of Tikochi and Makudi. Climate change compounds the risk by exposing retreating glaciers to collapse. The Indian Institute of Science suspects a 'hanging glacier' feeding the Kheer Ganga channel contributed to the August 5 Dharali floods, while the National Disaster Management Authority's preliminary analysis indicated glacier collapse may have triggered the disaster, HT reported last week. The Divecha Centre has identified 219 hanging glaciers in the Alaknanda and Bhagirathi basins as part of ongoing geo-spatial mapping in Uttarakhand. Most glaciers are receding due to global warming, leaving them exposed to various disasters and collapse. Poor land use planning amplifies the destruction when extreme weather strikes, experts warn. 'These kinds of rainfall events are rare and take place once in 20 or 50 years. However nowadays such events are becoming frequent due to climate change,' said Manish Shrestha, hydrologist at the International Centre for Integrated Mountain Development. 'Such mudslides normally happen when there is very heavy rain upstream.' Referring to the Dharali disaster, Shrestha noted dense settlements near riverbanks that fall 'in the right of way of the river.' 'We should have a safe zone for buildings, hotels, and habitations. Zonation is important in such regions,' he said. The Western Himalayas' unique topography creates conditions ripe for extreme weather events. A 2024 paper published in the National Library of Medicine, led by the Centre for Remote Sensing and Geoinformatics at Sathyabama Institute of Science and Technology along with the India Meteorological Department, investigated the Nainital region of Uttarakhand and found correlations between pre-flood parameters including total aerosol optical depth, cloud cover thickness and water vapour. 'The Himalayan region, characterised by its substantial topographical scale and elevation, exhibits vulnerability to flash floods and landslides induced by natural and anthropogenic influences,' the study noted. Scientists have repeatedly called for comprehensive disaster preparedness measures to address the growing threat. The 2022 Geological Society of India study, titled: 'An Investigation of Cloudburst-triggered Landslides and Flash Floods in Arakot Region of Uttarkashi District, Uttarakhand' recommended 'pragmatic check dam policy and logical shifting of people' to safe areas before monsoon season in hazard-prone regions. Researchers from the Wadia Institute of Himalayan Geology noted such measures including early warning systems, Doppler radar installation and lightning sensors 'would be helpful for policymakers, planners, practitioners, and technologists' to aid sustainable development within the region. The pattern contrasts with neighbouring Nepal, where a 2024 study of 1971-2015 data found extreme daily rainfall declined overall, with western mountains getting wetter and eastern regions becoming drier after 2003.
Hindustan Times
4 days ago
- Science
- Hindustan Times
Hanging ‘vulnerable' glacier may have led to havoc in Uttarkashi
A team from the Indian Institute of Science (IISc) suspects that a 'hanging glacier' feeding the Kheer Ganga channel may have contributed to the series of flash floods in Dharali on August 5. Mud and debris after the August 5 flash floods in Uttarkashi. (PTI) HT reported on August 7 that a preliminary analysis by the National Disaster Management Authority indicated that a glacier collapse may have led to the flash floods. There are 219 hanging glaciers in the Alaknanda and Bhagirathi basins according to the Divecha Centre for Climate Change at IISc, which, as part of an ongoing study has just completed a geo-spatial mapping of hanging glaciers in Uttarakhand. A hanging glacier is one that originates high on the wall of a glacier valley and descends only part of the way to the surface of the main glacier. Also Read | Landslide blocks key route in Uttarakhand's Chamoli days after Uttarkashi flash floods 'Through geospatial analysis, we have mapped all 219 hanging glaciers in the Alaknanda and Bhagirathi basins. We also found that this particular glacier on the Kheer Ganga channel was in a very vulnerable position. In fact there are two hanging glaciers in the vicinity with a combined volume of approximately 1 cubic km. We have historical satellite images of the glaciers. The run-off time during the flash floods was very short. Normally, if flash flood is from rainfall then we can observe a gradual increase and then a decrease. But the sudden run-off points to two probabilities. One that the hanging glacier has fallen, or a lake has formed due to the obstruction of river flow. Then sudden outburst was caused due to overflown,' said Anil Kulkarni, distinguished visiting scientist, Divecha Center for Climate Change, Indian Institute of Science who has been studying the disaster since August 5. 'At IISc we have been doing a lot of modelling exercises to understand which portion of these hanging glaciers is vulnerable to detachment. Hanging glaciers are very sensitive to warming. For these the surface melt starts very early compared to other glaciers and these have been mapped,' added Kulkarni. The Himalayi Nagarik Drishti Manch has written to the Bhagirathi Eco-Sensitive Zone Monitoring Committee; secretary, ministry of environment, forests and climate change; and the Jal Shakti ministry on Monday seeking accountability for the Dharali disaster. They have referred to a letter by the same civil society organisations sent to the BESZ monitoring committee on April 30, 2024 warning about impending disasters stating that indiscriminate construction on river and hill zones should stop immediately. The Indian Army has airlifted ground penetrating radar devices from Siachen glacier, even as rescuers in Uttarakhand's Uttarkashi district are racing against time and digging holes in the muck debris to find missing people. People aware of the matter said the GPRs airlifted from Sichen are in addition to the existing ones that are being used by army personnel and other agencies. The ones brought from Siachen are usually used in cases of avalanches by the defence forces. Also Read | Uttarkashi: NGRI experts launch search operation to trace 66 missing in disaster-hit Dharal Separately, nearly 200 NDRF personnel too are using their own radars and life detection devices to find the people reported missing. Sites where the missing people could be trapped along the 4 km stretch between Dharali and Harshil have been divided by the state disaster management authority(SDMA) and allocated to different teams/agencies. Over the weekend, NDRF Delhi headquarters also sent two more ground penetrating radar devices to the team on the ground. 'There are mountains of muck debris at the site. Some buildings as tall as 2-3 storeys are totally buried in the mud debris. The rescue and search work there involves manually digging at places identified as locals and eyewitnesses. We hope to make progress,' a senior NDRF officer said.
Hindustan Times
07-08-2025
- Science
- Hindustan Times
Uttarakhand floods: Satellite images show disappearance of buildings, roads
The National Remote Sensing Centre's post-flash flood satellite images of the upper reaches of Uttarakhand indicate the accumulation of debris in and around Dharali, the disappearance of buildings, roads, and plantations, and sediments and debris covering a stretch of Bhagirathi and Kheer Ganga rivers. A bridge and what appear to be orchards are also inundated. Rescuers at the scene of the mudslide and flash floods. (AFP) Experts from the National Disaster Management Authority (NDMA) have said they were examining the possibility that a glacier collapse upstream of the channel feeding the Kheer Ganga triggered the floods. Anil Kulkarni, a distinguished visiting scientist at the Indian Institute of Science's Divecha Center for Climate Change, said past satellite images have helped understand the glacier dynamics. 'Kheer Ganga river originates from glaciated terrain. Satellite imagery from September 2022 was analysed. It is useful imagery as during this time snow had mostly melted and glacier ice and landforms can be seen clearly.' He said the satellite imagery indicates that glacier ice is mostly melted. He added that glacier ice can be seen in a very small area. '... well-developed deglaciated valley can be seen,' Kulkarni said in a note on Thursday. He added that the outlet of the deglaciated valley is bounded by an end moraine, and a small river passes between the end moraine and the side wall. 'Upstream of the end moraine, a meandering stream pattern was observed. It indicates flat terrain and also the formation of a lake in the past.' Kulkarni said. 'The flash flood mud flow may have been caused by to outburst of the lake.' NDMA officials were awaiting cloud-free satellite imagery to get further details on the glacier feeding Kheer Ganga. 'There are indications that a glacial snout at 6700 m detached some days ago...,' said NDMA advisor (mitigation) Safi Ahsan Rizvi on Wednesday. '...large glacio-fluvial debris deposits collected. Incessant rain over the past few days is believed to have led to the loosening of the debris. Once critical mass was crossed, the massive collection of debris cascaded downstream with water in the Kheer Ganga, accelerating due to the steep gradient up to Dharali.' Rizvi said that it is clear that none of the 195 at-risk glacial lakes are in the Dharali catchment. 'As per the National Remote Sensing Centre (NRSC) Atlas of 2023, there are 7500 glacial lakes greater than 0.25 ha in the Himalayas. Of these, NDMA categorised 195 as at-risk.'
Hindustan Times
11-05-2025
- Politics
- Hindustan Times
Looking to the future, a river runs through it
Perspective is a useful thing. Open Google Earth and zoom out a few thousand kilometres. Around the 30°N latitude, you will see a band of sand stretching across the Earth. The Thar Desert lies here, as do large parts of Pakistan — only, there is a thick green ribbon swirling through that country, thanks to the largesse of the Himalayan glaciers. The contrast between sand and green shows, more than any number ever could, how much Pakistan needs the Indus waters. They will not survive without it. The Indus system, more than the Ganga and the Brahmaputra systems, depends on glacier- and snow-melt for its waters, which, in turn, increases its climate vulnerability. What happens when these glaciers melt? Studies suggest that the water flow could rise over the next couple of decades and then fall. Already, in this time of relative plenty (considering what is to come), everybody wants more, especially in the dry season. Pakistan's Punjab wants more — sparking off protests in downstream Sindh. Pakistan, wary of any potential lessening, complains about Indian dams built on the western rivers — a neutral expert has deemed that the dams' designs abided by the now-in-abeyance Indus Waters Treaty (IWT). The current infrastructure cannot hold back water for too many days in May. But they can add to the confusion, especially when no intimation needs be provided to the downstream party. But, when the water pie shrinks, which it will, it won't shrink uniformly. As leading glaciologist, Dr Anil Kulkarni, recently said, the glaciers feeding the three eastern rivers — the Ravi, Sutlej, and Beas — are not only much smaller than those feeding the western rivers, they are also melting faster. The water pie to be shared between India and Pakistan — already more lopsided than the superficially-fair 'you take three, we take three' terms of the IWT suggest — will become far more unequal in the future. India, with its dry northwest, is unlikely to accept this division, especially in the current circumstances. The division of such water amongst the India's northwest states is another matter, as is the division between Punjab and Sindh in Pakistan. Those fights are like rearranging the deck chairs on the Titanic and will have to wait another day for their resolution. It's worthwhile asking how the Indus waters are used. Much of this flows into Pakistan, where much of it flows into fields. As per a 2019 World Bank Report, 'Pakistan is in the lowest 5% of countries in terms of water productivity', and 'is in the highest decile of countries in terms of water stress'. Water productivity is the economic output per unit of water withdrawn from the environment. Not a comforting thought. That India is also water-scarce adds an edge to this water-sharing. Given current economic incentives and voter preferences, this inefficiency is unlikely to change, and given the climate crisis and demographic realities, the scarcity will get worse. Something's got to give. Pakistan could up its water efficiency game (the World Bank has a slew of suggestions); it could also give more water to Sindh. It could appeal to the World Bank and others to exert pressure on India, as they once did. But the World Bank president, in response to a question on whether they would intervene in the treaty's abeyance, recently responded, 'No, we're not…there's a lot of speculation in the media on whether we'll fix it or not… it's all bunk!'. India could build additional infrastructure to divert the water to its own dry northwest, where this largesse would be welcomed with open arms. Pakistan, with its life on the line, is unlikely to sit quietly by. It could turn to its iron-friend for help, the one that is 'upstream-est' of them all. Or indeed, begin to look to an erstwhile part of itself in the east, putting new pieces in play in the subcontinental water theatre. All the while, the world warms. In this scenario, improving its own water productivity, as unsexy as that sounds, is India's best defence. Mridula Ramesh is a climate-tech investor and author of The Climate Solution and Watershed.
Hindustan Times
03-05-2025
- Science
- Hindustan Times
Climate crisis exposes flaws in Indus pact as some rivers may dry up quicker
The Indus river basin, among the most vulnerable regions globally to climate change, is experiencing dramatically different impacts across its eastern and western tributaries, recent scientific research has shown, potentially making previous agreements on sharing of waters between India and Pakistan irrelevant. Approximately 50-60% of the Indus basin's annual water discharge comes from snow and glacial melt, with recent research revealing stark differences in how climate change affects various parts of the basin. Recent papers have now found that western tributaries like the Indus, Kabul, Jhelum and Chenab are fed by glaciers with more stored water, while eastern tributaries including the Beas, Ravi, and Sutlej draw from significantly lower glacier stored water reserves. Crucially, the pace of glacial melt is higher in the Western Himalayas that feed eastern rivers compared to the Upper Indus basin. This east-west disparity challenges the fundamental assumptions of the 1960 Indus Waters Treaty, which allocated rivers based on historically stable flow patterns. 'From an entirely scientific perspective, the water sharing practices need to be revisited in view of climate change that can alter flow and increase disasters downstream,' said Anil Kulkarni, distinguished visiting scientist and glaciologist from Indian Institute of Science (IISc). The issue has gained renewed significance after India put the Indus Waters Treaty in abeyance following a terrorist attack in Kashmir on April 22. Under the treaty, India exclusively uses water from the eastern rivers (Ravi, Beas and Sutlej), while Pakistan has rights to the western rivers (Indus, Jhelum and Chenab), which hold 80% of the basin's water. A 2023 study titled 'Differential loss of glacier stored water in the Indus River basin', published in Current Science by researchers from the Birla Institute of Technology and Science, Indian Institute of Science, and Indian Space Research Organisation, used a combination of models to assess glacier stored water and mass loss. Their research found significant spatial variability in stored water and mass loss across the basin. 'Except for the upper Indus basin, all other sub-basins show a substantial rate of glacier mass loss, which can affect future water availability,' the paper concluded, suggesting the need to reconsider water-sharing practices. The upper Indus basin, allocated to Pakistan under the treaty, lies mainly in the Karakoram region, which exhibits the 'Karakoram anomaly' -- a surprising stability of glaciers despite the global trend of retreat. 'Latest projections indicate that glacial melt may begin in the upper Indus basin only in the 2050s. But other rivers and catchments will see far greater and faster glacial loss before then,' explained Kulkarni. 'The understanding is that water flow and hence availability will increase for the rest of the rivers (except Indus) now and then fall drastically around mid-century following extensive loss of glaciers.' A 2019 science policy brief by IISc's Divecha Centre for Climate Change predicted that due to high negative glacier mass balance and area loss, discharge for the eastern rivers (India's allocation) is expected to peak early in 2030, compared to 2070 for the western basin. According to research by the Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD), glacial mass balance rates vary significantly: Western Himalayan glaciers at -0.36 meter water equivalent per year since 2010, Karakoram at -0.09, and Eastern Himalayas at -0.51. These changes carry serious implications for the basin's more than 300 million residents, who already face increased uncertainty due to rising temperatures, extended dry periods, floods, unseasonal rain, and glacial lake outburst floods (GLOFs). Water demand is also expected to rise as climate impacts become more pronounced, further straining resources. 'So far, there have been about 150 GLOF events recorded in Pakistan and 60 in India - mostly after the 1950s,' said Sher Muhammad, remote sensing Specialist at ICIMOD. 'The recorded fatalities in India due to these GLOFs are over6,000, compared to 11in Pakistan.' Pakistan experienced devastating floods in 2022 following extreme summer heat, resulting in 1,100 deaths and affecting 33 million people. The Indus basin spans 1.1 million square kilometres across four countries: 52% in Pakistan, 33% in India, 8% in China, and 6% in Afghanistan. From 1991 to 2015, the mean temperature across the Western Himalaya and Karakoram regions rose by 0.65°C, according to monitoring by the Indian Institute of Science. Future projections suggest that even if global warming is limited to 1.5°C, warming in the Hindu Kush Himalaya will be higher, with a 4–25% increase in monsoon rainfall expected long-term. Himanshu Thakkar of South Asia Network on Dams, Rivers and People emphasised that 'contribution from glaciers and snow to western rivers is higher compared to eastern rivers. Monsoonal flow also contributes to eastern rivers. Apart from conflict and geopolitics, these rivers are a source of life to people.'
