Snow/Ice melt and Glacial Lake Outburst Flood in Himalayan regionrivers.bee.oregonstate.edu/sites/default/files/WorkshopPPTs/... · Snow/Ice melt and Glacial Lake Outburst Flood in

Snow/Ice melt and Glacial Lake Outburst Flood in Himalayan region

Dr. SANJAY K JAIN

NATIONAL INSTITUTE OF HYDROLOGY

ROORKEE

“Modelling and management flood risk in mountain areas”

17-19 Feb., 2015 at Sacramento, California, USA

About 35% of the geographical area of India is covered by mountains and

58% of this is accounted for by the mighty Himalayas in which more than

5000 glaciers covering about 38000 km2 area.

There are 22 major river systems with about 1 million km2 catchment area

lying in the Himalayas, with snow and glacier melt runoff of more than 50%.

The seasonal snow and glacier melt coming from the Himalayan Rivers is a

dependable source of water for irrigation, hydroelectric power and drinking

water supply.

The hydropower generation contributes about 26% of total installed capacity

in India in which Himalayan river systems contribute 78% of the total Indian

hydropower potential.

Snow melt modelling is a crucial element to predict runoff from snow-

covered or glacierised areas, as well as for snow/ice melt flooding

The flood due to glacial lake outburst is one of the major issue because of

climate change.

Himalayan Water Resources

Terai <300m

Siwalik 900-1500m

Lesser

Himalaya 3600-4600m

Greater Himalaya > 4600m

Outer Himalaya 1500- 3500m

Tibetan Plateau

4000m

Western Disturbances

Nov. – March/April

SW Monsoon

June – Sep Glaciers – 10%

Winter snow cover 35-50 %

Maximum monsoon precipitation at

1500 – 3000 m asl

INDUS, GANGA, BRAHMAPUTRA BASINS

4

It is known that the effect of global climate change on

hydrologic systems, especially on mountain snow and

glacier melt, can modify the timing and amount of runoff in

mountainous watersheds.

Streamflow simulation and forecast is of great importance

to water resources management and planning, and can

provide a firm basis for forecasts of water resources

availability while minimizing the risk and loss from floods

caused by rapid snow and glacier melt.

When the ground is frozen, the water produced by the

melting snow is unable to penetrate and runs off over the

ground surface into streams and lakes.

The situation can become of even greater concern if the

rising snowmelt runoff is compounded by runoff from heavy

rainfall.

SNOW/ICE MELT FLOOD

Glacial Lake And Glacial Lake Outburst Flood (GLOF)

Glacial dammed lakes are formed by accumulation of water from the melting of Snow and Ice cover and by blockage of end moraines.

A glacial lake outburst flood (GLOF) can occur when a lake contained by a glacier or a terminal moraine dam fails.

The bursting of moraine-dammed lakes is often due to the breaching of the dam by the erosion of the dam material as a result of overtopping by surging water or piping of dam material

GLOF STUDIES HAVE

BEEN CARRIED OUT FOR

LAKES IN THE BASINS

OF GHARWAL

HIMALAYA, EASTERN

HIMALAYA AND BHUTAN

HIMALAYS

SNOW AND GLACIER MELT

Location of the study area and meteorological stations in the Satluj basin

STREAM FLOW MODELLING IN SATLUJ BASIN

NOAA-AVHRR Images (2004)

MODIS SNOW Data Product (2004)

MODIS LST Data Product (2004)

Snow Cover Depletion Curve

Lapse Rate estimation from MODIS LST maps

METHODOLOGY

STREAM FLOW MODELLING

Main steps in modelling are as follows:

Division of Basin Into Elevation Bands

Processing of Meteorological Data

• Temperature Distribution

• Precipitation Distribution

Form of Precipitation

Variability of Snow Covered Area

Melt due to rain

Degree Day Factor for Snow and Ice

Routing of Surface and Sub Surface Flow

Simulation of Runoff (2000-2001)

Simulation of Runoff (2001-2002)

To estimate the flood due to GLOF

Valley planning and flood management

To formulate emergency procedures such as warning system, evacuation plan etc.

To identify and solve unexpected flood problems due to accidents

To remove fear in public and make the public aware of the risk

To analyze past accidents for advancement of the state of art

ASSESSMENT AND SIMULATION OF GLACIER LAKE OUTBURST FLOODS IN HIMALAYAN REGION

For estimating the Glacial Lake Outburst flood, the following approach and methodology has been adopted:

Inventory of glacier and glacial lakes

Finding out the potentially dangerous glacial lakes

Estimation of Glacial lake volume and finalisation of Glacial lakes for GLOF simulation

Estimation of breach parameter for GLOF/dam breach simulation and the consequent dam breach flood using MIKE11 model Channel routing of dam breach flood through the entire reach of river from the GLOF site to the site to get the magnitude of flood peak at site.

METHODOLOGY

)2()NIRGREEN(

)NIRGREEN(NDWI

GREEN is a band that encompasses reflected green light

and NIR represents reflected near-infrared radiation

The selection of these wavelengths was done to :

(1) maximize the typical reflectance of water features by using

green light wavelengths

(2) minimize the low reflectance of NIR by water features; and

(3) take advantage of the high reflectance of NIR by terrestrial

vegetation and soil features.

Normalized Difference Water Index

IDENTIFICATION OF GLACIAL LAKES

NDWI<T1

Slope<10% R1>T2

Glacial Lake

Yes

No Lake

R2<T3

No Lake

Slope<10%

Glacial Lake

Ye

s

Ye

s

No

Ye

s

No

No

No Lake

No Lake

Ye

s

Algorithm to automatically classify glacial lakes on IRS Images, using a decision tree. Ti represents

a threshold, whose value is determined empirically on each scene by visual inspection.

R1= BGreen/BNIR

R2= BNIR/BSWIR

CRITERIA FOR IDENTIFICATION OF DANGEROUS LAKE

Rise in lake water level

In general the lakes which have a volume of more than 0.01 km3 are

found to have past events. A lake which has a larger volume than this

is deeper, with a deeper part near the dam (lower part of lake) rather

than near the glacier tongue, and has rapid increase in lake water

volume is an indication that a lake is potentially dangerous.

Activity of supraglacial lakes

Groups of closely spaced supraglacial lakes of smaller size at glacier

tongues merge as time passes and form bigger lakes. These activities

of supraglacial lakes are indications that the lakes are becoming

potentially dangerous.

POSITION OF LAKES

The potentially dangerous lakes are generally at the lower part of the

ablation area of the glacier near to the end moraine, and the mother

glacier should be sufficiently large to create a potentially dangerous

lake environment.

The valley lakes with an area bigger than 0.1 km2 and a distance less

than 0.5 km from the mother glacier of considerable size are

considered to be potentially dangerous.

DAM CONDITIONS

The natural conditions of the moraine damming the lake determine the

lake stability. Lake stability will be less if the moraine dam has a

combination of the following characteristics:

• narrower in the crest area

• no drainage outflow or outlet not well defined

• steeper slope of the moraine walls

• ice cored

• breached and closed in the past and refilled again with water

seepage flow at moraine walls

CONDITION OF ASSOCIATED MOTHER GLACIER

The following general characteristics of associated mother glaciers

can create danger to moraine-dammed lakes:

• hanging glacier in contact with the lake,

• bigger glacier area,

• fast retreating,

• debris cover at glacier tongue area,

• steep gradient at glacier tongue area,

PHYSICAL CONDITIONS OF SURROUNDINGS

• potential rockfall/slide (mass movements) site around the lake which

can fall into the lake suddenly

• snow avalanches of large size around the lake which can fall into the

lake suddenly

• neo-tectonic and earthquake activities around or near the lake area

• climatic conditions of successive years being a relatively wet and

cold year followed by a hot and wet or hot and arid year

Glacier and Glacier lake mapping

Drainage network and Length of stream d/s lake

DEM of the basin

Cross Section at regular interval downstream of lake

Area and Volume of the lake

Breach width and Depth

100 year return flood if available

GLOF SIMULATION: INPUT REQUIRED

MIKE11 DAM BREAK MODELLING

LAKE DEPTH

The empirical relations as available by Huggel et al. (2002) is:

The lake volume D = 0.104 A0.42

where D is the depth of lake in m and A is the lake area in m2.

LAKE VOLUME

The empirical relations as available by Huggel et al. (2002) is:

The lake volume V = 0.104 A1.42

where V is the lake volume in m3 and A is the lake area in m2.

Chorabari Lake

Chorabari Lake outburst - (June 17, 2013)

GLOF: CASE STUDIES

Satellite pictures shows that the glacial regions above Kedarnath had received

fresh and excess snowfall when heavy rainfall hit the region.

(Source NRSC,2013)

SNOW COVER DURING MAY-JUNE 2013

Chubda Lake

x-section of downstream lake

0

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Distance from right bank to left bank in meter

Elevatio

n in

m

eter

xsec_dam

xsec_5km from dam

xsec_10km from dam

xsec_15km from dam

xsec_20km from dam

xsec_25km from dam

xsec_30km from dam

"xsec_35km from dam

xsec_40km from dam

xsec_45km from dam

xsec_50km from dam

xsec_55km from dam

xsec_60km from dam

xsec_65km from dam

xsec_70km from dam

xsec_75km from dam

xsec_80km from dam

xsec_85km from dam

xsec_90km from dam

xsec_95km from dam

xsec_100km from dam

xsec_105km from dam

xsec_110km from dam

xsec_115km from dam

00:00:00

21-4-2006

04:00:00 08:00:00 12:00:00 16:00:00 20:00:00 00:00:00

22-4-2006

04:00:00 08:00:00 12:00:00 16:00:00 20:00:00 00:00:00

23-4-2006

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[m^3/s] Time Series Discharge

GLOF HYDROGRAPH AT CHAMKHARCHU H.E. PROJECT BHUTAN

10251.71 cumec

5068.59 cumec

2 hour 10 minutes

4920 m V=54.18 Mm3

D=40 m

900 m

118.84 km

KURI-GONGRI HE PROJECTS, BHUTAN

Kuri basin

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1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 103109115121127133139145151157163169175181187

Ele

vatio

n (m

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Distance (m)

Cross-section of Kuri Basinxsec at dam site

xsec at 1 km from dam site








































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00:00:00 02:09:36 04:19:12 06:28:48 08:38:24 10:48:00

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3 /s)

Time (hh:mm:ss)

GLOF

KURI

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00:00:00 02:09:36 04:19:12 06:28:48 08:38:24 10:48:00

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char

ge (m

3/s

)

Time (hh:mm:ss)

GLOF

KURI

8478.9 cumec

6821.0 cumec

4690 m V=11.62 Mcum

D=40 m

1 hour 50 minutes

194 km

KURI-GONGRI HE PROJECTS, BHUTAN

Gongri basin

0

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1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106 113 120 127 134 141 148 155 162 169 176 183

Ele

vati

on

(m

)

Distance (m)

Cross section Of Gongri Basinxsec at lakexsec at 1km from lakexsec at 2km from lakexsec at 3km from lakexsec at 4km from lakexsec at 5km from lakexsec at 6km from lakexsec at 7km from lakexsec at 8km from lakexsec at 9km from lakexsec at 10km from lakexsec at11 km from lakexsec at 12km from lakexsec at 13km from lakexsec at 14km from lakexsec at 15km from lakexsec at 16km from lakexsec at 17km from lakexsec at 18km from lakexsec at 20km from lakexsec at 21km from lakexsec at 22km from lakexsec at 23km from lakexsec at24 km from lakexsec at 25km from lakexsec at 26km from lakexsec at 27km from lakexsec at 28km from lakexsec at 29km from lakexsec at 30km from lakexsec at 31km from lakexsec at 32km from lakexsec at 33km from lakexsec at 34km from lakexsec at 35 km from lakexsec at 36km from lakexsec at37km from lakexsec at 38km from lakexsec at 39km from lakexsec at 40km from lakexsec at 41km from lakexsec at 42km from lakexsec at 43km from lakexsec at44km from lakexsec at 45km from lakexsec at 46km from lakexsec at 47km from lakexsec at 48km from lakexsec at 49km from lakexsec at 50km from lakexsec at 51km from lakexsec at 52km from lakexsec at 53km from lakexsec at 54km from lakexsec at 55km from lakexsec at 56km from lakexsec at 57km from lakexsec at 58km from lakexsec at 59km from lakexsec at 60km from lakexsec at 61km from lakexsec at 62km from lakexsec at 64 km from lakexsec at 66km from lakexsec at 68km from lakexsec at 69km from lakexsec at70 km from lakexsec at 71km from lakexsec at 72km from lakexsec at 74km from lakexsec at 75km from lakexsec at 76km from lakexsec at 77km from lakexsec at 78km from lakexsec at 79km from lakexsec at 80km from lakexsec at 81km from lakexsec at 82km from lakexsec at 83km from lakexsec at 84km from lake

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00:00:00 01:26:24 02:52:48 04:19:12 05:45:36 07:12:00 08:38:24 10:04:48 11:31:12

Dis

char

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3 /s)

Time (hh:mm:ss)

GLOF

GONGRI

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Dis

char

ge (m

3 /s)

Time (hh:mm:ss)

GLOF

GONGRI

4685.3 cumec

3850.5 cuemc

4564 m

45.56 Mm3

D=25 m

1 hour 20 minutes

114.3 km

LACHUNG HE PROJECT, SIKKIM, INDIA

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1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 106 111 116 121 126 131 136

distance(m)

ele

va

tio

n(m

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xsection at lake

xsection at 1km from lake

xsection at 2 km from lake
































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TIME (HH:MM)

Q (

m3/s

)

BhimkyongHEP

GLOF

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0:00 1:12 2:24 3:36 4:48 6:00 7:12 8:24 9:36

TIME (HH:MM)

Q (

m3/s

)

Bop HEP

GLOF

Site-I Site-II

919.04 cumec 919.04 cumec

751.10 cumec 749.29 cumec

50 minutes

V= 54.18 Mcum

D= 16 m

Site-I 32 km

Site-II

36 km

Site-III

38 km

4812 m

TAWANG H.E. PROJECT, ARUNCHAL PRADESH

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1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106 113 120 127 134 141 148 155 162 169 176 183

Elevatio

n(m

)

Distance (m)

Cross- section of Twang Basin xsec at lake

xsec at 1km from lake

xsec at 2 km from lake






















xsec at29 km from lake


























2959.00 cumec 3120.00 cumec

2791.56 cumec

2792.05 cumec

12 minutes 12 minutes

4348 m

1525 m

V= 11.62 Mcum

V= 10.85 Mcum

D-25 m 4564 m

36 km

40 km

1000

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Ele

va

tio

n (m

)

Distance from right bank to left bank (m)

at 5 Km from Lake

at 10 km from lake

at 15 Km from lake

at 20 Km from Lake

at 25 Km from Lake

at 30 Km from Lake

at 35 Km from Lake

at 40 Km from Lake

at 45 Km from Lake

at 50 Km from Lake

at 55 Km from Lake

at 60 Km from Lake

at 65 Km from Lake

at 70 Km from Lake

at 75 Km from Lake

at 80 Km from Lake

at 85 Km from Lake

at 90 Km from Lake

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00:57 02:09 03:21

Dis

cha

rge

m3/

s

Time (h)

Dam breach flood just down stream to lake

Bhutan

S.No

.

DATE RIVER BASIN LAKE CAUSE

OF GLOF

1 1957 Pho Chu Tarina Tso Not

known

2 1960 Pho Chu Unnamed Not

known

3 1960 Chamkhar Chu Bachamancha

Tso

Not

known

4 7 Oct 94 Pho Chu Luggye Tso Moraine

collapse

RECENT GLOF EVENTS - BHUTAN

Bhutan

S.No. DATE RIVER

BASIN

LAKE

CAUSE OF

GLOF

1 12 Jul 91 Tamakoshi Chubung Moraine collapse

2 3 Sep 98 Dudh Koshi Tam Pokhari Ice avalanche

3 15 Aug 03 Madi River Kabache Lake Moraine

collapse

4 8 Aug 04 Madi River Kabache Lake Moraine

collapse

RECENT GLOF EVENTS - NEPAL

METHODS FOR MITIGATING THE IMPACT OF GLOF

REDUCING THE VOLUME OF LAKE WATER

Possible peak surge discharge from a GLOF could be reduced

by reducing the volume of water in the lake. In general, any one

or combination of the following methods may be applied for

reducing the volume of water in the lake:

Controlled breaching

Controlled breaching can be carried out by blasting, excavation,

or even by dropping bombs from an aircraft.

Construction of an outlet control structure

For more permanent and precise control of lake outflows, rigid

structures made out of stone, concrete, or steel can be used.

Pumping or siphoning out the water from the lake, and

Making a tunnel through the moraine dam

Tunneling through moraines or debris barriers, although risky

and difficult because of the type of material blocking the lake,

has been carried out in several countries.

PREVENTATIVE MEASURES AROUND THE LAKE AREA

Any existing and potential source of a larger snow and

ice avalanche, slide, or rock fall around the lake area,

which has a direct impact on the lake and dam has to be

studied in detail. Preventative measures have to be

taken such as removing masses of loose rocks to

ensure there will be no avalanches into the lake.

Real-time monitoring, early warning systems and

preparedness education are the most beneficial ways to

minimize risk.

Preparedness –hazard mapping, improving

communication, education to create awareness

Glacier and snow-melt have major contribution to

the river flows in the region. It is necessary to

characterize the glaciers in different climatological

regions of the basin

The rate, volume and timing of snow melt are likely

to change, therefore, impact of climate change on the

snowmelt runoff and total streamflow of the large

Himalayan rivers should be investigated using GCMs

output as input to the calibrated hydrological

models.

Studies on the trend of changes in snow cover over

the Himalayas/basins along with retreat of glaciers

need immediate emphasis.

Concluding Remarks

Climate warming will increase the frequency and risk of

GLOFs

Regular mapping and monitoring of lakes are needed

Potentially dangerous glacial lakes must be provisionally

identified and prioritized for further investigation

Potentially dangerous lakes must be monitored on a

continuous basis

High resolution time series satellite image are useful for

this purpose

Appropriate measures to reduce the potential risks from

these lakes

Concluding Remarks

THANKS

Documents

Snow/Ice melt and Glacial Lake Outburst Flood in Himalayan regionrivers.bee.oregonstate.edu/sites/default/files/WorkshopPPTs/... · Snow/Ice melt and Glacial Lake Outburst Flood in