Natural hazards, infra development magnified Chamoli disaster: ICIMOD
Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD) has underlined the link between the February 7 glacier breach disaster in Uttarakhand’s Rishi Ganga river with infrastructure development, particularly the construction of hydropower projects in the higher reaches of the Himalayas.
In its analysis of the disaster published on March 3 titled “Understanding the Chamoli flood: Cause, process, impacts, and context of rapid infrastructure development” by cryosphere experts, hydrologists, climate scientists have concluded that the Hindu Kush Himalayas are a multi-hazard environment and that hydropower projects, apart from amplifying disaster risk, impact environmental flows, water quality, and the health of aquatic and terrestrial ecosystems. On the other hand, these projects are also facing risks from climate change-related flow variations, extreme events, erosion and sedimentation, and glacial laker outburst floods (GLOFs)/ Landslides Dammed Outburst Flood (LDOFs).
The analysis is significant because the Defence Geo-informatics Research Establishment, under Defence Research and Development Organisation, had recently said the tragedy was not “immediately” a human-induced disaster. “There is a need to look upon the demographic pressures in a systematic way but as far as this particular tragedy is concerned in our preliminary investigations the role of human activity is not the immediate cause... It [glacial breach] was far away from the area where several constructions [NTPC hydel power project in Tapovan and Rishi Ganga hydel plant] are taking place,” said Lokesh Sinha, director of DGRE.
“HKH is a multi-hazard environment. Often these hazards are of a cascading nature with multiple hazards interconnected with a primary hazard trigger and a chain of secondary and tertiary hazards. Human interference in the mountain environment is rapidly increasing. Mountain settlements are increasing in size and land use patterns are changing. Infrastructure such as roads and hydropower projects are rapidly penetrating mountain landscapes. The interplay between natural hazards with human settlements and infrastructure is an important aspect, which can significantly escalate the impacts of event like the Chamoli flood,” ICIMOD said in its analysis.
A cascading disaster is a common phenomenon observed in the Hindu Kush Himalayas region and one of the prominent recent examples is the Uttarakhand flood of 2013, which started with heavy rainfall and caused a chain of events, including landslides, flash floods, and the Chorabari lake outburst and debris flow, which killed more than 6,000 people and damaged roads, bridges, and buildings, the analysis said, adding that “Similar hazard events or in combination with other geophysical processes can damage several hydropower stations, which can be further exacerbated with future floods in the context of global climate change also suggest that snow avalanches involving wet snow even in winter will occur more frequently in the mountainous regions.”
There are 105 existing hydropower projects (HP) (≥ 40 MW) with an installed capacity of 37 GW, 61 projects (≥40 MW) currently under construction (39 GW) and 890 projects (≥10 MW) in various stages of planning (242 GW) in the Karakoram-Himalaya region. Most of the existing hydropower projects were built in the past two or three decades. Now projects are gradually moving upstream where the exposure to mountain hazards is high, the chances of multiple hazards happening in combination and occurring more frequently, and cascading effects can create compounding impacts on the system.
Overall, ICIMOD has concluded that the Chamoli flood was not caused by a GLOF as there were no significant glacial lakes in the area. The flood was triggered by a massive rockslide just below Ronti peak, of ~22 million m3 of rock mixed with ice and snow. The energy of the fall melted the ice creating the source of flood. This also remobilised the debris and ice on the valley floor and created an excessive flood wave. A couple of days prior to the flash floods, a strong western disturbance had resulted in heavy precipitation, which may have increased the flood magnitude downstream.
The disaster and related debris flow are likely to have caused damage to four hydropower projects along the Rishi Ganga, Dhauliganga and Alaknanda river path. The Rishi Ganga Hydropower Project (13.2 MW) near Raini village, located 14km downstream from the impact site was the first to be hit by the debris after the rockslide. The unfinished Tapovan Vishnugad Hydropower Project (520 MW) , 8km downstream from Rishi Ganga Hydropower Project, was the second hydropower plant hit by the flood. The Vishnuprayag Hydro Electric Project 35km downstream and Vishnugad Pipalkoti Hydro Electric Project 55km downstream may have also been impacted.