Glacial Lake Outburst Flood GLOF Hazard

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Glacial Lake Outburst Flood (GLOF) Hazard
Zonation Mapping along Puna Tsang Chu,
between Khuruthang and Kalikhola.
Why? How?
Deo Raj Gurung, Geomorphologist, Department of
Geology Mines, Ministry of Trade
Industry November 30, 2006
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(No Transcript)
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Inventory of glaciers and glacial lakes in Bhutan
Himalaya.
420 Glaciers
1067 Glacial Lakes
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Basin wise distribution (in ) of glacial lakes
in Bhutan Himalaya.
Lakes in Puna-Tsang Chu basin constitute 38 of
total numbers of glacial lakes in Bhutan.
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Glacier in Puna-Tsang Chu basin constitute 42
of total glaciers in Bhutan.
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Basin wise (area in km2) representation of
glacial lakes in Bhutan Himalaya.
Total area of glacial lake in Puna-Tsang Chu
basin constitute 34 of the total lake area in
Bhutan.
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Basin wise (area in km2) representation of
glaciers in Bhutan Himalaya.
Paro Chu
Amo Chu
Thim Chu
Ha Chu
3
lt 1
1
lt 1
Northern Basin
Mo Chu
35
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Nyeri Ama
Pho Chu
lt 1
21
Dang Chu
Mangde Chu
3
lt 1
Chamkhar Chu
Kuri Chu
10
Dangme Chu
8
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Total area of glaciers in Puna-Tsang Chu
constitute 35 of the total glacier area of
Bhutan.
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Potentially dangerous glacial lakes of Bhutan
Pho Chu Sub Basin 9 Mo Chu Sub Basin
5 Chamkhar Chu Sub Basin 3 Kuri Chu Sub Basin
1 Mangde Chu Sub Basin 7
Out of 2794 glacial lakes, 25 has been identified
as potentially dangerous lakes.
Source DGM ICIMOD publication
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Basin wise distribution of potentially dangerous
lakes in .
56 of the potentially dangerous lakes in
Puna-Tsang Chu basin.
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Source Survey of Bhutan
Over 70 of the settlements are located along the
drainage basins.
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Some stretches of the road network follow major
river valleys
Source Survey of Bhutan
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Landuse map of Bhutan
Source MOA
Significant of cultivated land lie on the
valley bottom.
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Projects along Puna-Tsang Chu
With uncertainty looming at the source and so
much at stake along the downstream, it is only
wise to secure the downstream now.
Basochu Hydropower
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Map showing project area (between Punakha and
Kalikhola).
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Intended buffer of 5km (2.5km on each side)
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Conceptual model
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Different thematic data to be used
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Flood assessment
Maximum flood height in an event of flooding
(GLOF) is vital information in such assessment.
3 different scenarios
Source Google Earth
1 Luggye Tsho Raphstreng Tsho Thorthormi
(53million m3)
2 Luggye Tsho Raphstreng Tsho
3 Raphstreng Tsho Thorthormi
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Estimation of maximum flood height
1. Objective modeling
2. Subjective analysis
HEC-RAS (software with
hydrodynamic modeling capability)
Such modeling will be done for 3 different
scenarios including the worst case scenario each
using both the methods, giving 6 different hazard
maps.
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Volume of water at reservoir 18 million m3.
Figures from 1994 GLOF
Peak flow 2550 m3/Sec
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Final hazard zonation map
After validation final GLOF hazard map will be
produced for all 3 scenarios showing different
degree of hazard denoted by conventional color
coding.
Conventional color code will be adopted for
hazard representation
People installation are in danger. Prohibited
domain.
Risk to people installation is moderate.
Regulation domain.
Risk to people Installation is low or not at
all. Development domain.
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Evacuation sites
Using thematic maps and using multi-criteria
analysis in GIS, suitability analysis will be
done to identify safe sites to be used as
evacuation sites in case of GLOF.
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Hazard zonation map (Austro-Bhutan Project)
Tashi Delek and Thank you!
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QuickBird showing part of Thimphu city
Ground resolution 0.6 cm
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