Latest news with #Cartosat-2S
NDTV
7 hours ago
- Climate
- NDTV
ISRO Pics Show Impact Of Floods On Uttarakhand's Dharali, Bhagirathi River
New Delhi: The Indian Space Research Organisation has released satellite images from before and after flashfloods and landslides in Uttarakhand's Uttarkashi district in the first week of August show dramatic changes to the epicentre - Dharali village, which was almost completely destroyed. An ISRO picture from June last year shows the Bhagirathi River flowing past a small patch of land on which several houses, small orchards, and other small buildings can be seen. Then, in a second picture from August 7 that patch of land is completely flooded - as if it were never there - and the houses on it washed away. The interior parts of Dharali village, where the Kheer Gad River, a small tributary, flows into the Bhagirathi, have also been washed away. Roads and a small bridge crossing the Kheer Gad have been wiped off, and the curve of the Bhagirathi now resembles a large crater after sediment and debris was dumped at this point. The deposit measures a staggering 20 hectares. Satellite Insights Aiding Rescue & Relief Ops ISRO/NRSC used Cartosat-2S data to assess the devastating Aug 5 flash flood in Dharali & Harsil, Uttarakhand. High-res imagery reveals submerged buildings, debris spread (~20ha), & altered river paths, vital for rescue teams on… — ISRO (@isro) August 7, 2025 On Monday morning district officials told news agency ANI nearly 1,300 people were rescued and/or evacuated after the tragedy struck. Garwhal Commissioner Vinay Pandey said rescue ops have now been closed, and road connectivity, for the most part, had been restored. "The Valley Bridge has been restored... road connectivity should be fully restored by evening. Essential supplies like food, warm clothing, and daily items are being distributed. District officials are monitoring the situation and will disburse aid announced by the state..." he said. Mr Pandey confirmed that 43 people, including nine Army personnel, are still missing. "And the number of missing Nepali workers has dropped from 29 to 24. Additional information is being sought to further reduce the list. Updates will be provided..." he told ANI. At least five deaths have been confirmed so far. These and other ISRO satellite images have revealed the scale of destruction, and have also identified flooded areas and guided search-and-rescue teams to these priority locations. Meanwhile, rain early this morning threatened to hamper any still-ongoing operation in or around the village of Dharali. The weather department issued a 'yellow' alert for all districts. Also, a 'red' alert for heavy to very heavy rain over the next few hours in Almora, Dehradun, Haridwar, Nainital, Pauri and Udham Singh Nagar districts. Heavy rain was also reported from capital Dehradun and the already-affected Uttarkashi district.
Time of India
20 hours ago
- Science
- Time of India
Flash flood changes Bhagirathi course, river returns to old path
1 2 DEHRADUN: The flash flood in Dharali earlier this week reshaped the course of the Bhagirathi river, widening stream channels and altering river morphology, satellite images from the Indian Space Research Organisation (Isro) showed. The high-magnitude flood eroded a debris fan on Kheer Gad - a tributary of the Bhagirathi located just upstream of Dharali village - forcing it back to its earlier path and pushing the Bhagirathi towards the right bank. Satellite imagery from Isro's Cartosat-2S, comparing data from June 2024 and Aug 7 this year, revealed a vast fan-shaped debris deposit roughly 20 hectares in size - measuring about 750m by 450m - at the confluence of Kheer Gad and the Bhagirathi, just above Dharali. These images showed extensively altered river channels, submerged or buried buildings, and major topographical shifts. Piyoosh Rautela, senior geologist and former executive director of Uttarakhand State Disaster Management Authority, said pre-disaster images revealed a triangular debris fan on Kheer Gad's left bank, just upstream of its confluence with the Bhagirathi. "This deposit was formed during a previous catastrophic downslope movement that diverted Kheer Gad's course at the time. by Taboola by Taboola Sponsored Links Sponsored Links Promoted Links Promoted Links You May Like Brigade Avalon: 4 Acres of Prime Whitefield Luxury Homes Brigade Avalon Contact Us Undo Traditionally, such deposits were only used for agriculture, with homes built on higher, stable ground to avoid landslide and flood risk," he said. He added that rapid tourism growth and the pilgrim influx over the last decade, along with commercial activity near the road, had prompted settlement on the alluvial fan. "The flash flood eroded the entire fan deposit and Kheer Gad reclaimed its previous course. Currently, the debris has pushed the Bhagirathi's flow towards the right bank, but it will eventually erode this deposit in time," he said. Hydrologists warned such sudden geomorphic changes could have cascading effects far downstream. Altered river channels can increase flow velocity, change sediment transport, and destabilise banks kilometres away from the flood site. Over time, this can create new erosion hotspots, threaten bridges, and change floodplains, forcing riverside communities to adapt to a new hydrological pattern. Dean at the School of Environment and Sustainability in Bangalore-based Indian Institute for Human Settlement, Dr Jagdish Krishnaswamy, who is an ecohydrologist and landscape ecologist, said the Himalayas' geology and climate make them prone to such shifts. "These are the world's youngest mountains - tectonically active, geomorphologically dynamic, and generating some of the highest sediment loads globally. Glacier retreat, both natural and intensified by warming, releases vast amounts of debris, which intense rainfall can mobilise into avalanches and mudslides. This sediment can drastically alter river courses, especially where loose deposits exist on lower slopes or in narrow valleys," he said. He cautioned that embankments and retaining walls often give a "false sense of security" when infrastructure and homes are built on unstable ground. "Given the Himalayas' dynamic geomorphology and the increasing intensity of rainfall, extreme caution is needed in designing and locating any infrastructure. Otherwise, we are exposing people and assets to unacceptably high risk," he said.
Time of India
a day ago
- Science
- Time of India
Dharali flash flood changes Bhagirathi course, river returns to old path
1 2 Dehradun: The flash flood in Dharali earlier this week reshaped the course of the Bhagirathi river, widening stream channels and altering river morphology, satellite images from the Indian Space Research Organisation (Isro) showed. The high-magnitude flood eroded a debris fan on Kheer Gad — a tributary of the Bhagirathi located just upstream of Dharali village — forcing it back to its earlier path and pushing the Bhagirathi towards the right bank. Satellite imagery from Isro's Cartosat-2S, comparing data from June 2024 and Aug 7 this year, revealed a vast fan-shaped debris deposit roughly 20 hectares in size — measuring about 750m by 450m — at the confluence of Kheer Gad and the Bhagirathi, just above Dharali. These images showed extensively altered river channels, submerged or buried buildings, and major topographical shifts. Piyoosh Rautela, senior geologist and former executive director of Uttarakhand State Disaster Management Authority, said pre-disaster images revealed a triangular debris fan on Kheer Gad's left bank, just downstream of its confluence with the Bhagirathi. "This deposit was formed during a previous catastrophic downslope movement that diverted Kheer Gad's course at the time. by Taboola by Taboola Sponsored Links Sponsored Links Promoted Links Promoted Links You May Like If You Have Arthritis Avoid This Food Active Life Journal Learn More Undo Traditionally, such deposits were only used for agriculture, with homes built on higher, stable ground to avoid landslide and flood risk," he said. He added that rapid tourism growth and the pilgrim influx over the last decade, along with commercial activity near the road, had prompted settlement on the alluvial fan. "The flash flood eroded the entire fan deposit and Kheer Gad reclaimed its previous course. Currently, the debris has pushed the Bhagirathi's flow towards the right bank, but it will eventually erode this deposit in time," he said. Hydrologists warned that such sudden geomorphic changes could have cascading effects far downstream. Altered river channels can increase flow velocity, change sediment transport, and destabilise banks kilometres away from the flood site. Over time, this can create new erosion hotspots, threaten bridges, and change floodplains, forcing riverside communities to adapt to a new hydrological pattern. Dean at the School of Environment and Sustainability in Bangalore-based Indian Institute for Human Settlement, Dr Jagdish Krishnaswamy, who is an ecohydrologist and landscape ecologist, said the Himalayas' geology and climate make them prone to such shifts. "These are the world's youngest mountains — tectonically active, geomorphologically dynamic, and generating some of the highest sediment loads globally. Glacier retreat, both natural and intensified by warming, releases vast amounts of debris, which intense rainfall can mobilise into avalanches and mudslides. This sediment can drastically alter river courses, especially where loose deposits exist on lower slopes or in narrow valleys," he said. He cautioned that embankments and retaining walls often give a "false sense of security" when infrastructure and homes are built on unstable ground. "Given the Himalayas' dynamic geomorphology and the increasing intensity of rainfall, extreme caution is needed in designing and locating any infrastructure. Otherwise, we are exposing people and assets to unacceptably high risk," he said. Stay updated with the latest local news from your city on Times of India (TOI). Check upcoming bank holidays , public holidays , and current gold rates and silver prices in your area.
News18
3 days ago
- Climate
- News18
Uttarakhand: Roads near Bhanrepani blocked, machines used to clear debris
Chamoli (Uttarakhand) [India], August 8 (ANI): Work is going on war footing with the help of machines to clear debris on roads near Bhanrepani on the Badrinath National Highway that were blocked in the aftermath of landslides that hit the area a day ago, the Chamoli Police said on Friday. Posting a status on social media X updated today on 2:30 pm, the Chamoli Police wrote, 'The road is blocked since yesterday due to landslide near Bhanrepani on Badrinath National Highway. The work of opening the road by machines is going on a war footing." Meanwhile, the Uttarakhand government confirmed the evacuation of 566 people till noon today from Dharali and Harsil in the Uttarakashi district, where Tuesday's massive flash floods disrupted normal authorities said that the evacuation of nearly 300 more stranded individuals is currently Indian Army is using dog squads, drones, and ground-penetrating radar for search and rescue operations in the General of Police (DGP) Deepam Seth is overseeing the ongoing rescue and relief measures in reviewed the rescue operations by holding a meeting with the police officers in Matli and gave necessary instructions to everyone to speed up the relief and rescue on Thursday, the Indian Space Research Organisation (ISRO) confirmed the usage of Cartosat- 2S data to assess the flash floods in Dharali and Harsil. High resolution images have revealed submerged buidlings, spread debris, and altered river paths whic are also an important information for the rescue teams on ground.
News18
3 days ago
- Science
- News18
Dharali Cloudburst: Did River Kheer Ganga Follow Its Old Route? ISRO Satellite Images Stir Debate
Last Updated: The destruction in Uttarkashi's Dharali raised questions whether Kheer Ganga river, which caused the devastation, simply returned to an ancient path long buried under settlements The destruction in Uttarkashi's Dharali town has raised troubling new questions, not just about what happened on August 5, but about whether the Kheer Ganga river, which caused the devastation, simply returned to an ancient path long buried under settlements. New satellite images released by the Indian Space Research Organisation (ISRO) and the National Remote Sensing Centre (NRSC) show that the river, instead of curving as it usually does before meeting the Bhagirathi, surged straight through buildings and roads, as if reclaiming an older route. Captured by the Cartosat-2S satellite, the high-resolution images offer a before-and-after view of the disaster zone. The first image, from June 13, shows Dharali in a calm state. The second, taken on August 7, just two days after the flood, reveals an area covered in mud, debris, and rock over an estimated 20 hectares, right up to the banks of the Bhagirathi river. At first, a cloudburst was suspected. But that theory was quickly ruled out. The Meteorological Centre confirmed that only 24 mm of rainfall was recorded across Uttarkashi district on August 5, far below the 100 mm-per-hour threshold needed to declare a cloudburst. In fact, Uttarkashi has seen among the lowest rainfall figures in the state this monsoon. If not rain, then what? One compelling theory comes from D D Chauhan, visiting professor at the Nityanand Research Institute, Doon University. He believes the river may have reverted to an older course under extraordinary pressure. 'The Kheer Ganga usually takes a bend before meeting the Bhagirathi," said Chauhan, adding, 'But on August 5, the river came down carrying heavy debris and boulders, and instead of turning, it moved straight, right through an area where homes, hotels, and lodges had been built." Chauhan suggested that this abrupt shift may have been triggered by a glacial lake burst. Several small glacial lakes feed the Kheer Ganga at high altitudes. With continuous rains, even if not extreme, the water levels in one of these lakes may have breached a threshold, releasing a sudden and massive outflow. The lake water, mixed with glacial debris, would have surged into the river, amplifying the volume and destructive power of the Kheer Ganga without needing a cloudburst. The satellite images appear to support this theory. They show how Dharasu, the larger region around Dharali, is surrounded on three sides by the Bhagirathi. The Kheer Ganga cuts through from the mountains and typically turns before merging with the Bhagirathi. On August 5, it didn't turn. The river's straight run through residential and commercial areas, where it wasn't expected to flow, suggests either a diversion caused by forceful debris movement or a return to a previous natural path that had been altered or encroached upon over time. ISRO has confirmed that the debris field covers 20 hectares and reaches the Bhagirathi's banks. Further scientific analysis is underway to establish whether a glacial lake outburst flood (GLOF) was the primary trigger, and whether future risks are likely in similar Himalayan towns built close to dynamic river systems. The Dharali tragedy draws eerie parallels with past disasters in Uttarakhand. In February 2021, a glacier collapse in Chamoli led to a catastrophic flood in the Rishi Ganga and Dhauliganga rivers, killing more than 200 people. In 2013, the infamous Kedarnath calamity was also caused by the breaching of a glacial lake, leading to a death toll of nearly 5,000. view comments First Published: News india Dharali Cloudburst: Did River Kheer Ganga Follow Its Old Route? ISRO Satellite Images Stir Debate Disclaimer: Comments reflect users' views, not News18's. Please keep discussions respectful and constructive. Abusive, defamatory, or illegal comments will be removed. News18 may disable any comment at its discretion. By posting, you agree to our Terms of Use and Privacy Policy.
