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