The Beas River Floods 2023: A Watershed Moment for Paradigm Shift Towards Urbanization And Development in the Higher Himalayan Valleys

The present study is done in the Beas river (Manali to Mandi town) after the July 2023 flood to assess the geomorphic and geological vulnerability of the terrain and understand the role of human intervention in the disaster. The study is based on preliminary field obser­vations and morphometric analysis that indicates that the surfaces proximal to the trunk riverbed and the ephemeral tributary channels suffered maximum damage. Along the upper Beas river, the lateral erosion caused by hyperconcentrated flows saturated with paraglacial sediments partly obstructed the river and also increased the erosivity that also led to remobilization of midchannel bars along with the uprooted trees. In the downstream (southern mountain front), maximum damage was caused by activating seemingly dormant ephemeral tributary channels. The slope-channel coupling locally bulked the sediment supply of the trunk river. The disaster was force amplified when the river was temporarily obstructed by the manmade structures (e.g., suspension bridges), and most importantly, urban settlements (largely hotels) on the flood plain. Also, many public buildings suffered as these were constructed in/along the ephemeral tributary channels, which were temporarily blocked by these structures, as well as by logged tree trunks. The Beas flood is yet another brutal reminder to change our perception towards the developmental approach, given that extreme events are projected to increase in the Himalaya