Flash flood changes Bhagirathi course, river returns to old path | India News

DEHRADUN: The flash flood in Dharali earlier this week reshaped the course of the Bhagirathi river, widening stream channels and altering river morphology, satellite tv for pc photographs from the Indian Space Research Organisation (Isro) confirmed. The high-magnitude flood eroded a particles fan on Kheer Gad – a tributary of the Bhagirathi positioned simply upstream of Dharali village – forcing it again to its earlier path and pushing the Bhagirathi in direction of the appropriate financial institution.Satellite imagery from Isro’s Cartosat-2S, evaluating knowledge from June 2024 and Aug 7 this 12 months, revealed an unlimited fan-shaped particles deposit roughly 20 hectares in measurement – measuring about 750m by 450m – on the confluence of Kheer Gad and the Bhagirathi, simply above Dharali. These photographs confirmed extensively altered river channels, submerged or buried buildings, and main topographical shifts.Piyoosh Rautela, senior geologist and former government director of Uttarakhand State Disaster Management Authority, mentioned pre-disaster photographs revealed a triangular particles fan on Kheer Gad’s left financial institution, simply 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. Traditionally, such deposits were only used for agriculture, with homes built on higher, stable ground to avoid landslide and flood risk,” he mentioned.He added that speedy tourism progress and the pilgrim inflow during the last decade, together with industrial exercise close to the highway, 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 mentioned.Hydrologists warned such sudden geomorphic changes might have cascading results far downstream. Altered river channels can enhance circulation velocity, change sediment transport, and destabilise banks kilometres away from the flood website. Over time, this may create new erosion hotspots, threaten bridges, and alter floodplains, forcing riverside communities to adapt to a brand new hydrological sample.Dean on the School of Environment and Sustainability in Bangalore-based Indian Institute for Human Settlement, Dr Jagdish Krishnaswamy, who’s an ecohydrologist and panorama ecologist, mentioned the Himalayas’ geology and local weather make them inclined 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 mentioned.He cautioned that embankments and retaining partitions typically give a “false sense of security” when infrastructure and houses are constructed on unstable floor. “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 mentioned.