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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 1.The Department

• f

Science & Technology, Government of India constituted a Working Group in August 2014 to: a) conduct a scientific study & assessment of vulnerability of South Lhonak Glacial Lake b) recommend suitable measures to reduce the level of water from the lake. The WG Report recommended “Siphoning” as one of the mitigation methods best suited for South Lhonak with other engineering interventions.

• 2. A Working Group meeting co-chaired by Director SDC

with the presence of Advisor UNDP (3SCA Project) & Sikkim Government Officers decided to take up the Pilot Project to Reduce Risks & Vulnerabilities due to potential GLOF threat at South Lhonak Lake in April 2017.

Ashwagosh Ganju Snow & Avalanche Study Establishment, India Dr Anil V Kulkarni Divecha Center for Climate Change,IISc, India Dr DP Dhobhal Wadia Institute of Himalayan Geology, India Dr Binay Kumar Center for Development of Advanced Computing, India Dr Satya Prakash Shukla Geological Survey of India, India Dhirendra G Shrestha Sikkim State Council of Science &Technology, India

Working Group

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 the ice at deeper level along with seepage and

• r

melting

• f

buried ice.

GROUND TRUTHING PARAMETERS: 5 longitudinal profiles of the moraines was surveyed:- a)3 profiles : SW to NE directions with electrode spacing

• f

10 meters each 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
• verlain 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

• f 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 water to reduce water level . 2. Developing a GLOF hazard specific evacuation and response plan for all the towns/settlements lying on the downstream of the lake. 3. Building awareness and developing capacity of the communities on the 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

Reducing the risk of South Lhonak Glacial Lake Outburst Flood. Mitigating the risk of disaster and to build resilience of the vulnerable communities.

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

South Lhonak Glacial Lake

• To recommend best suited method to

reduce the water level thereof Activities

• 12

Member team led by Special Secretary.

• Repairing
• f

the pipes used for 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

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

Activities

• 20 Member team led by Disaster

Management Officer, LR&DMD, GoS The team consisted of community 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

Follow up, September 2018

• To manually clear the debris to increase

the outlet and make space for laying additional pipes

• To lay additional pipes for siphoning

THE FINAL MISSION

Yaks being deployed to carry pipes View of the terminal moraine and the

• utlet

Pipes being installed for siphoning Manual clearing of debris from the oulet Additional water being siphoned off the glacial Outlet cleared of debris and additional pipeline installed

BUILDING RESILIENCE OF THE VULNERABLE COMMUNITIES

Building adaptive capacity of the vulnerable communities

Interventions

• 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

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

DRAFT GLOF MANAGEMENT PLAN – HELVETAS INTERCOOPERATION

LEARNINGS FROM THE PILOT EXERCISE

• 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

in other glacial lakes.

Some members of the expedition with Army & Indo Tibetan Border Police

LEARNINGS

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

Sikkim the only Organic State in the World!

Thank you