An immense flood that suddenly descended from the high and inaccessible Tibetan plateau of the Himalayas created such a horrifying scene in the border and low-lying areas that the soul can shudder. The water, mud and debris of huge boulders that came with tremendous velocity from the mountains blew away everything in its path like straw. In this unexpected deluge, 384 people were swept away, strong five-storey concrete buildings got submerged in water like cards and heavy steel and RCC bridges collapsed in the blink of an eye. According to eyewitnesses and geologists, this was not an ordinary seasonal flood, but an uncontrolled disaster caused by the breach of a giant natural water barrier built over the mountains. How water created a 'time bomb' in the mountains of Tibet: The truth about landslides and natural dams This heart-wrenching tragedy began in the extremely narrow and high mountain corridors of Tibet. Analysis of geological reports and satellite imagery revealed that due to excessive rainfall and geological movement, a large part of a huge mountain broke and fell into the narrow valley of the main river. This giant landslide completely blocked the natural path of the flowing river. Due to the blockage of the river, millions of gallons of water started accumulating behind it and within a short time a huge artificial lake was formed. Locally it is called 'Landslide Dam'. Due to the continuous water coming from above and melting snow, the pressure on this raw dam made of mud and stones kept increasing. Eventually, the weak natural wall could not support the enormous weight of the water and broke with a loud bang. Deadly impact of Glacier Lake Outburst (GLOF) According to scientists, not only the landslide dam, but also the bursting of glacial lakes present in the higher areas of Tibet (GLOF – Glacial Lake Outburst Flood) was one of the main links of this disaster. Due to the melting of Himalayan glaciers due to global warming, huge water reserves are stored behind moraines (pebbles) at their mouths. When the amount of water in these lakes exceeds the limit or a heavy iceberg breaks and falls into them, this natural barrier collapses. When millions of cubic meters of water falls down a steep slope from a height of several thousand feet, its speed and power become like that of a powerful missile. This water flows down, uprooting all the soil, trees and huge rocks along the way, due to which its destructive potential increases many times as compared to normal water. 5 storey buildings were razed to the ground, strong bridges were wiped out. When this floodwater passed through the valleys and reached the towns and settlements below, people did not even get a moment to run towards safe places. The height and velocity of the water was so great that the concrete 5-storey buildings built on the banks of the river were uprooted from their foundations and submerged in deep water within seconds. The heavy boulders that came flowing with the water hit the strong pillars of the bridges like a hammer, due to which the heavy bridges that had been standing for years broke from the middle and were swept away. Roads were completely cut off, electricity and communication networks were disrupted and the entire area was reduced to a huge pile of debris. In this sudden debris flow, 384 people lost their lives or went missing in the deep flow. It also became extremely challenging for rescue teams to reach the affected areas as the main connectivity roads and bridges were completely destroyed. Transboundary disaster: Why is this tragedy a big lesson for the lower Himalayan countries? The Tibetan Plateau is considered the 'Water Tower' of Asia, from where major rivers like Brahmaputra (Yarlung Tsangpo), Indus, Sutlej, Koshi and Mekong originate and flow into India, Nepal and other neighboring countries. Any geological or meteorological disturbances in the upper catchment areas of Tibet directly threaten the lower coastal and border areas. This deluge is a clear indication of how important it is to have real-time monitoring of the upper reaches of transboundary rivers. When an artificial lake is formed in the upper region or the water level of a glacier lake increases, it is essential for timely satellite data and early warning alerts to reach the downstream countries, so that loss of life and property can be prevented by evacuating the lower areas in time. Challenge Ahead: Satellite Monitoring and Strong Early Warning System The incidence of such flash floods is continuously increasing due to climate change and seismic activities in the Himalayan region. This tragedy has made it clear that merely building conventional river embankments is not sufficient for safety. For this, space-based radar imaging, automatic water level sensors on rivers and high-tech early warning systems will have to be installed in remote hilly areas. Unless there is an accurate forecast of natural hazards and arrangements for advance evacuation are made, the deluge that suddenly descends from the mountains will continue to cause such devastation.
