Reducing climate change induced risks and vulnerabilities from - PowerPoint PPT Presentation

Reducing climate change induced risks and vulnerabilities from Glacial Lake Outburst Flood (GLOF) in South Lhonak Lake in Sikkim Dhirendra G Shrestha, Additional Director, Department of Science and Technology Government of Sikkim, India

REDUCING CLIMATE CHANGE INDUCED RISKS AND VULNERABILITIES OF GLACIAL LAKE OUTBURST FLOOD(GLOF) FROM SOUTH LHONAK LAKE IN NORTH WEST SIKKIM

SOUTH LHONAK LAKE Index Parameters Location North-West, Sikkim Latitude 27 deg54’56.7” N Longitude 88 deg12’35 E Altitude 5245 Mtrs ASL Dimension Length: 2.32 KM Width: 120 to 707 Mtrs Total Area 130 Ha or 1.30 Sq KM (2016)

SOUTH LHONAK LAKE • State Action Plan For Climate Change for Sikkim (SAPCC) in it’s assessment explicitly mentions of the probability of GLOF due to climate change in 14 identified lakes of which South Lhonak Lake is the most vulnerable • The South Lhonak lake has grown in area by two times between 1965 and 1989. Significantly, there has been a sharp increase between 1989 to 2016. The size of the lake has increased by more than three times. From 1965 to 2016 the increase is about 7 times the original size.

GROWTH PROGRESSION – LISS III IMAGES South Lhonak Lake, 1965 South Lhonak Lake, 1997 South Lhonak Lake, 2017

RATIONALE Working Group 1.The Department of Science & Technology, Government of India constituted a Working Group in Ashwagosh Ganju August 2014 to: Snow & Avalanche Study Establishment, India a) conduct a scientific study & assessment of Dr Anil V Kulkarni vulnerability of South Lhonak Glacial Lake Divecha Center for Climate Change,IISc, India b) recommend suitable measures to reduce the level of water from the lake. Dr DP Dhobhal Wadia Institute of Himalayan Geology, India The WG Report recommended “Siphoning” as one of Dr Binay Kumar the mitigation methods best suited for South Lhonak Center for Development of Advanced Computing, with other engineering interventions. India Dr Satya Prakash Shukla 2. A Working Group meeting co-chaired by Director SDC Geological Survey of India, India with the presence of Advisor UNDP (3SCA Project) & Sikkim Government Officers decided to take up the Pilot Dhirendra G Shrestha Sikkim State Council of Science &Technology, Project to Reduce Risks & Vulnerabilities due to India potential GLOF threat at South Lhonak Lake in April 2017.

ELECTRICAL RESISTIVITY SURVEY Average depth of the massive dead ice layer in WS1_2, WS1_3 and WS1_4 is in the range of 7m to 15m. WS7_5and WS7_6 profiles have indicated depth of GROUND TRUTHING PARAMETERS: the ice at deeper 5 longitudinal profiles of the moraines was level along with surveyed:- seepage and or a)3 profiles : SW to NE directions with melting of buried electrode spacing of 10 meters each ice. covering the distance of 240 meters b)2 profiles : SE to NW directions with electrode spacing of 7 meters covering the distance of 168 meters. The profile distance was between 50 to 60 feet.

GEO PHYSICAL SURVEY FINDINGS • End moraine has massive dead ice in the core region whereas near the exit, it is relatively at deeper levels. • Massive dead ice layer is invariably overlain by ice-debris mixture. • Melting of this layer may lead to subsidence of the moraine ridge in future. • Relatively lower resistivity values along WS1_2 and WS7_5 profiles (closer to the lake) is attributed to the melting of the buried ice due to relatively warmer water

THE BATHYMETRIC SURVEY

BATHYMETRIC SURVEY - FINDINGS • The bathymetric study carried out in September 2014 in South Lhonak Glacier showed that the lake area is 126 hectare. • The underwater slope geometry of lake towards eastern side is not very steep, which indicates stable character of moraine dam having less vulnerable geometric structure. However, the mass melting of glacier and increasing volume of lake may affect the dam condition. • The longitudinal distance between 400 to 1400 m along the length of South Lhonak glacial lake has recorded maximum depth of 260 feet due to the threshold limit of ultrasonic depth finder. Therefore, for that particular profile, depth of 260 feet was used to for bathymetric analysis of lake . • The storage volume of the lake is 5, 36,38,863.54 m3 (say 53 million m3 = 536 billion liters of stored water) corresponding to the maximum depth of 260 feet.

MITIGATING RISK OF GLACIAL LAKE OUTBURST FLOOD(GLOF)

Interventions Undertaken 1. Designed and implemented an engineering model for siphoning of Reducing the risk of South water to reduce water level . Lhonak Glacial Lake Outburst 2. Developing a GLOF hazard specific Flood. evacuation and response plan for all the towns/settlements lying on the downstream of the lake. Mitigating the risk of disaster 3. Building awareness and developing and to build resilience of the capacity of the communities on the vulnerable communities. downstream of the lake to mitigate the risk of GLOF . 4. Establish an early warning systems (EWS) linked with the weather monitoring on climatic variables. 5. Helvetas group & other partners our assisting in designing a suitable and robust Early Warning System

SIPHONING OF LAKE WATER USING HDPE PIPE AND INSTALLATION OF EARLY WARNING SYSTEM

REDUCING THE RISK OF SOUTH LHONAK GLACIAL LAKE OUTBURST FLOOD Recce Mission, August 2018 • To reassess the vulnerability of the Activities South Lhonak Glacial Lake • 12 Member team led by Special Secretary. • To recommend best suited method to • Repairing of the pipes used for reduce the water level thereof Siphoning, readying the new pipes • Assessment of the vulnerability Recommendations • Manual clearing of debris to prepare the site for laying pipes • Installation of additional pipes for siphoning South Lhonak Glacial Lake with Lhonak Glacier in the background.

PROFILE OF SOUTH LHONAK GLACIAL LAKE

THE RECCE MISSION A team member crossing the Zemu Medical examination of a team member A team member manually carrying a River along the trekking route load of HDPE pipes (Approx: 8Kgs) Measurements being taken Inspection of existing pipes Process of making pipes leak proof

Follow up, September 2018 Activities • To manually clear the debris to increase • 20 Member team led by Disaster the outlet and make space for laying Management Officer, LR&DMD, GoS additional pipes The team consisted of community • To lay additional pipes for siphoning labourers & partners from SECMOL, Ladakh • Manual clearing of debris at the outlet of the lake • Laying of additional pipelines which brings the total pipelines to six of 100 meters in length. Siphoned water being released into the river

THE FINAL MISSION View of the terminal moraine and the Yaks being deployed to carry pipes Pipes being installed for siphoning outlet Additional water being siphoned off the Manual clearing of debris from the oulet Outlet cleared of debris and additional glacial pipeline installed

BUILDING RESILIENCE OF THE VULNERABLE COMMUNITIES Building adaptive capacity of the Interventions vulnerable communities • Awareness and Sensitisation Programmes held at different locations • Basic Search-Rescue and First Aid training being imparted to Disaster Management Teams • WhatsApp Group for daily monitoring of river water level formed amongst administrators, community members, hydel dam monitors, responders • Evacuation plan for vulnerable locations being mapped • EWS (Automatic + Community) being developed Evacuation map of Adarsh Goan

BUILDING RESILIENCE OF THE VULNERABLE COMMUNITIES Video Screening of GLOF hazard Skit show on Safe Evacuation at Meeting community members at at Rangpo Dikchu Singtam Technical presentation with Hydel Screenshot of WhatsApp Basic S&R and FA training imparted to DMTs Power Developers in Chungthang communication by NDRF

DRAFT GLOF MANAGEMENT PLAN – HELVETAS INTERCOOPERATION

LEARNINGS FROM THE PILOT EXERCISE

LEARNINGS • In most of the glacial lakes the period for working at the site is only two-three months • The unpredictable weather conditions, inhospitable and tough terrain makes it difficult to work. • Siphoning works successfully for draining water from glacial lakes as a medium term mitigation. • The interventions can be replicated Some members of the expedition with Army & Indo in other glacial lakes. Tibetan Border Police

MONITORING AND EVALUATION – UPSCALING WITH CONVERGENCE Priorities and actions of the State Government 1. Monitor the progress of Siphoning 2. Conduct scientific study of similar vulnerable glacial lakes 3. Replicate project learnings to build adaptive and mitigation measures to combat GLOF threat 4. Pursue regional cooperation through shared learnings and experiences 5. Incorporate EWS to enhance resilience of the vulnerable communities

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