Arunachal GLOF Risks That Loom over Assam

 The Union Home Secretary, Govind Mohan, urged the Himalayan and North East Region states to put up their projects on Glacier Lake Outburst Flood (GLOF) in consultation with respective stakeholders as per the National Programme on GLOF. This has put spotlight on high-risk lakes in Arunachal Pradesh. The National Disaster Management Authority (NDMA) has identified 27 high-risk lakes in high altitudes of five districts in Arunachal Pradesh. The Teesta-III Hydroelectric dam collapse at Chungthang in October last year in the catastrophe caused by GLOF of South Lhonak Lake in North Sikkim put NDMA on notice regarding vulnerability of existing and dams under construction in the Himalayan and Northeast region to GLOF occurrence and preparedness to deal with potential disaster. The NDMA has made GLOF studies mandatory in all new dams planned that have glacial lakes in their catchments. The Central Government has recently approved 13 major hydroelectric dams in Arunachal Pradesh, triggering concerns about dam safety and downstream concerns in Assam. Following the Chungthang catastrophe, the Central Water Commission decided to review the design of all the existing and under construction dams that are vulnerable to GLOF so that they have adequate spillway capacity for the combination of probable maximum flood, standard probable flood, and GLOF. A High-Level Committee chaired by the Union Home Minister has approved a GLOF risk mitigation project for Rs 150 crore for the States of Himachal Pradesh, Uttarakhand, Sikkim, and Arunachal Pradesh to support the efforts of state governments to take up various mitigation measures related to GLOF, the government told the parliament. A five-member committee of the Tawang District Disaster Management Authority (DDMA), which studied high-risk Jerjang Lake in the district, observed that in the event of a GLOF from the lake, several areas and camps of security forces could be severely impacted due to the high velocity of the water flow. The time it would take for floodwaters and debris to reach these areas is estimated to be very short due to the high velocity of the flow of the discharge water, according to an official release. Though the lake does not pose an immediate GLOF risk, regular monitoring is crucial for disaster preparedness. Another DDMA Tawang team that studied the high-risk Sangnga Nehgu Lake located at 16,000 feet altitude in August found that on August 14, a GLOF occurrence, the lake washed away more than five log bridges and damaged the tracks of yak herders at several locations. The team also observed, according to the official release, that there are still chances of GLOF occurrence from the same lake since the glacier on the back side of the lake is melting at a rapid rate, increasing the volume of water in the lake, which is alarming and calls for an urgent review of disaster preparedness. Of the 27 high-risk lakes in the state, the highest number of 16 are in Dibang valley districts, six are in Tawang district, three are in Anjaw district, and one each in Kurung Kumey and Shi Yomi districts. The GLOF catastrophe in Sikkim pressed the alarm bell on consequences of proposed construction of multiple mega dams in the Dibang valley and potential GLOF mitigation without comprehensive study on cumulative impact in downstream areas of the river catchment in Arunachal Pradesh and Assam. The GLOF risk mitigation in Dibang valley under the National GLOF Risk Management Programme, therefore, needs to consider the potential flood risk in Assam to reduce downstream risk. The national programme is aimed at reducing GLOF risk by focusing on three key areas of hazard assessment, monitoring through automated weather and water level monitoring stations, and reducing the volume of lake water. NDMA and Arunachal Pradesh sharing comprehensive data on GLOF studies in Arunachal in general and in respect of proposed mega dams in the Dibang valley with the Assam Government is critical to reviewing and making necessary changes in disaster management plans for extreme flood mitigation. GLOF, triggered by the bursting of South Lhonak Lake, was described as one of the worst climate-related disasters in 2023 by the World Meteorological Conference. Apart from melting of glaciers due to rises in temperature on account of climate change impact, the region being in a high earthquake-prone zone, the risk of GLOF occurrence is very high, which needs to be kept in mind while updating disaster management plans and developing GLOF and flood early warning systems. The cumulative risk from GLOFs in Brahmaputra tributaries in Arunachal Pradesh calls for comprehensive risk assessment in Assam. Such assessment cannot be in isolation of the downstream impact of dams in Arunachal Pradesh. The elaborate constitution of the proposed North East Water Management Authority will provide Assam with the much-needed platform to voice its concerns over GLOF risks compounding the dam-induced disasters. Expanding the scope of GLOF studies in Arunachal Pradesh to address downstream concerns in Assam is an urgent need of the hour.