This document discusses glacial lake outburst floods (GLOFs) and risk reduction strategies. It provides examples of past GLOF events in Nepal that damaged downstream areas. Methods to reduce GLOF risk include glacial lake inventories, monitoring potentially dangerous lakes, assessing hazards and vulnerabilities, establishing early warning systems, implementing mitigation measures like controlled lake drainage, building community preparedness, and transboundary cooperation. The document outlines community involvement in early warning systems and preparedness training. It highlights case studies of GLOF risk reduction at Tsho Rolpa Lake in Nepal through the construction of an outlet canal and community participation efforts.

1. Strengthening Water Resources Management in
Afghanistan (SWaRMA)
Training Workshop on Multi-scale Integrated River Basin Management from a HKH perspective
GLOF Risk Reduction
Finu Shrestha, Sharad Joshi, Anna Sinisalo

2. Glacial lake
Lake
Glacial lake is formed as the result of glacier melt/shrink,
which often left behind large debris deposits
Lakes may be formed either within part of the eroded
landform (e.g. bed rock dammed) or build behind a dam
formed by moraines, ice and/or landslide debris
Glacial lakes are not only the important refresh water resources, but also
act as a trigger of many glacial hazards such as glacial lake outburst flood
(GLOF) and debris flow

3. Glacial lake outburst flood (GLOF)
When the natural dam fails
Failure can happen due to erosion, seepage, a buildup of water
pressure, rock fall, ice or large snow avalanche and an earthquake

4. Past GLOF events in Nepal
Dig Tsho GLOF event of 1985 Chhukung village downstream of Imja TshoDudh Koshi below Imja lake showing remains of
damage from the 1977 Nare GLOF
Photo: Sharad P. Joshi

5. • Glacial lake inventory
• Monitoring of potentially dangerous glacial lakes
• GLOF risk knowledge (Triggering factors to GLOF)
• Risk assessment (GLOF hazard and vulnerability mapping)
• Early warning system (EWS)
• Mitigation measures
• Capacity building and training
• Public awareness and education
• Emergency preparedness and response
• Transboundary GLOF issues
• Regulation and enforcement
How risk is reduced?
Community involvement

6. Early warning systems (EWS))
The transmitter station of
Sangma Kharka outside Tsho
Rolpa Lake receives signals
from sensors and transmits to
other remote warning stations
GLOF Sensor and early warning
system in the Bhote Koshi,
(a) Sensor at River Level,
(b) Sensor at Friendship Bridge,
(c) Early warning system siren
Case studies (Tsho Rolpa & Bhote Koshi in Nepal)

7. Siphon across the end moraine
Mitigation measures of Tsho Rolpa glacial lake to reduce
its water level
Moraine-dammed lake with
a natural spillway (left) and
an artificial outlet (right)
Mitigation measures being
implemented at the end
moraine
Construction of the outlet
canal and gates
Mitigation measures
Tsho Rolpa Lake in Nepal

8. Outlet canal with gated structure to drain water at Tsho Rolpa Glacial Lake
Mitigation measures

9. • Awareness raising programmes
• Participate in the exercises and rehearsal of emergency plan &
programmes.
• Community leaders should be trained
• Put communities in charge of early warning
Community participation in risk reduction

10. Example: Tsho Rolpa Glacial Lake
Tsho Rolpa glacial lake Nov 1994 (SPJ) Tsho Rolpa glacial lake Nov 2018 (G.Earth)

12. GLOF in Panjshir Province, Afghanistan
12 July, 2018

13. Field photographs showing the crack in the
moraine dam at lake snout and remnant of the
lake after breach. Source: MEW
Pleiades image (0.5m ) from 19 July, 2018. Black boundary shows the crack in the moraine dam at
lake snout and blue boundary shows the lake area before the breach

14. Group Work!
Group Work!

15. Imja Lake Mitigation, 2016

16. Bhutan: Lake Mitigation

17. Atro Sar Lake

21. Group work
Is a lake dangerous?
If No, Why?
If Yes, what are the triggering factors for
GLOF?
What can be done to GLOF Risk
reduction?

23. RIVER BASINS & CRYOSPHERE 23
Thank you