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Hazard Zonation for Glacial Lake Outburst Flood (GLOF) in Bhutan
Himalaya
A mode of Adaptation to the impacts of climate change
DGM-NCAP Project
KarmaDepartment of Geology & Mines
Ministry of Economic AffairsRoyal Government of Bhutan
Location
NEPAL BHUTAN
CHINA
INDIA
Population : 6,34,982Religion : Mahayana BuddhismArea : 47000 Km2
Glaciers & Glacial lakes in Bhutan
Glaciers = 677Glacial Lakes = 2674Potentially dangerous lakes = 25
Types of glaciers and glacier lakes
Glaciers : 1. Debris covered glacier (D-type)2. Debris free glacier (C-type)
Glacial lakes: Moraine dam
Relation Between Temperature rise and Glacier Mass Balance
-1.5
-1.0
-0.5
0.0
0.5
1.0
1850 1870 1890 1910 1930 1950 1970 1990 2010Years
-15000
-10000
-5000
0
Glacier shrinkage
Global
Impacts of global warming in Asia IPCC 2001
Types of GlacierClean (C-type)
Debris covered (D-type)
Oct. 1999
Oct. 1984Change in GlacierChange in GlacierChange in GlacierChange in Glacier
Oct. 1999
Oct. 1984
Change in GlacierChange in GlacierChange in GlacierChange in Glacier
Jichu Dramo Glaciers
12 m Retreat rate with 2-3 m surface lowering (Naito et al 2000)
Source : Karma et al 2003
Debris covered glacier
Formation of Glacier Lake
• Melting process– as vertical thinning of glacier
• Glacier retreat– as horizontal expansion of lake
melt stress
glacier retreat
Mechanism of Expansion
• Small ponds on the debris-covered area• Aggregated medium pond, expansion
begin• Large lake, rapid expansion continue• Final stage, no more expansion
GLOF depends on the moraine strength
Lugge II
Lugge
Thorthormi
Raphsthreng
Expansion of Rapstreng Tso
1993, SPOT
Expansion of Thorthormi
1993, SPOT
Expansion of Lugge Tso
1993, SPOT
Impact of Glacier retreatFrom WFP Program Report in Nepal 2005
For 3 Countries (Nepal, India, China)
1.Fresh Water Regime
- Glacier retreat increase river levels---Flooding (IPCC 2001)
- Ice volume reduces with time- -- Reduction in run offsExample
- Reduction on Ganges river by two-third-37 % India’s irrigated land- 500 million people
Impact of Glacier Retreat
2. Glacial Lake Outburst Flood
-Dig Tso in 1985 (Nepal)
- Zhangzangbo in 1964 &1981(China)
- Lugge Tso in 1994 (Bhutan)
Impact of Glacier Retreat
3. National Economic Loss
- Hydro Power
- Major Industries relying on water
- Water sensitive agriculture sector
Possible triggers and causes for GLOF in the Himalayan mountains
Risk in Bhutan
Puna Tsang Chu
What Can We do?
• Mitigate critical glacial lakes at the source
• Installation of Technical Early Warning System
• Hazard zonation for GLOF
To Save Lives and minimize damages to the property of the people
Recent Projects
DGM – NCAP Project- Hazard zonnation for GLOF along Puna
Tsang Chu from Khuruthang to Lhamoizinkha
DGM-UNDPGEF Project- Assessment for early warning system for
GLOFDGM-UNDPGEF Project-Lowering of thorthormi lake
Project Area : DGM-NCAP project
• Hazard maps exist till Khuruthang
• Major developmental activities
• Settlements
Hazard maps existDGM-NCAP Project Area
Project Aims & Objective
• Base map for policy & decision makers and planners.
• To save lives & properties
• To render higher degree of safety to the local communities in the future.
Hazard zonation map for GLOF of the area
Methodology
• Subjective Analysis• Multi-criteria Evaluation
1993, SPOT
BASIS :
Worst Case Scenario
(Rapstreng + Thorthormi)
Rapstreng Tso Thorthormi
Spot 1993
What we did?
Delineated areas with different colour code representing different hazard level
Low hazard zoneBLUE
Medium hazard zoneYELLOW
High hazard zoneRED
Hazard & Vulnerability map
Vulnerability Assessment
00
00
01
No. of
Bridges
02
03
04
Historical
Monuments
17
14
06
No. of
Livestock
0.13
0.93
0.70
Area
(Km²)
3.439644BlueLow
2.5112230YellowMedium
1.9413646RedHigh
Road Length
(Km)
No. of People
No. of Buildings
Map
Color
Hazard Level
0.28
0.03
0.06
Built Up Area
(Km²)
0.420.390.59BlueLow
0.010.070.02YellowMedium
0.010.120.02RedHigh
Forest Cover
(Km²)
Arid Land
(Barren, Open, Scrubs) (Km²)
Cultivated Land
(Km²)
Map
Color
Hazard Level
Vulnerability Assessment
00
06
01
No. of
Bridges
04
06
16
Historical
Monuments
1072
220
28
No. of
Livestock
39.921781669BlueLow
8.64836173YellowMedium
5.22362117RedHigh
Road Length
(Km)
No. of People
No. of Buildings
Map
Color
Hazard Level
ProjectProject Frame WorkFrame Work
Subjective Analysis Multi-Criteria Evaluation
Verification
Data Collections
GLOF Hazard Analysis
Data Processing
Overlay
High hazard
Quick Bird ImageExisting Data
Field Data
Hazard
Hazard Map
Final Hazard map Vulnerability Assessment
GIS - Database
THANK YOU & TASHI DELEK
Consequence of global warming