Assessing river morphological changes induced by large ice-rock avalanches: The 2021 Chamoli disaster region using UAV-LIDAR data.

The Chamoli disaster of 2021 in the Rishiganga valley, triggered by a massive ice-rock avalanche, displayed a characteristic example of the complex dynamic in the glacier and fluvial systems under a warming climate. Here, we present cutting-edge UAV-LiDAR technology to examine the post-disaster morphological changes in the headwater river systems of Rishiganga, specifically focusing on river incision and channel morphological changes. Employing multi-period digital elevation models, we present the region's substantial increases in river incision and channel widening. A considerable increase in river width was also recorded following the event. Our research concludes that landslides act as a significant control of channel morphology in the Himalayan terrain. By unravelling the complex dynamics of river morphology caused by extreme events, this study contributes significantly to the literature in the context of bedrock river incision and landscape evolution.