PRESENTATION on

FLOOD RISK MITIGATION MEASURES FOR THE RIVER INDUS & NALLAHS IN LEH TOWN

byZainab Jalis, Amir Ali Khan, Sirajuddin Ahmed

REQUIREMENT OF FLOOD MITIGATION MEASURES

The Flood Mitigation Measures is required to take care of the following:

• Lessen the adverse impact of floods on socioeconomic conditions

• Controlling/ Preventing further damage to the infrastructure and

property; 

• Restoring normal living conditions in the affected area.

• Saving human life

ABOUT LEH

LEH

• Leh, the capital of Ladakh is situated at an

altitude of 3,500m above MSL.

• The geographical coordinates of Leh are

34.17° North latitude and 77.58° East longitude

• Leh encompasses an area of 19.08 sq kms

within municipal limit

• As per census 2001, the population of Leh is

recorded as 28,639

• The temperature ranges from −40 °C in winter to +35°C in summer

• Rainfall is very low with annual precipitation of around 10cm mainly in the form

of snow.

• Air is very dry and relative humidity ranges from 6% to 24%.

HAZARD PROFILE OF LEH TOWN

Leh town is vulnerable to a large number of natural as well as man-made

disasters as follows:

• The Ladakh Region is situated in seismic zone IV close to Karakoram fault

zone, Eastern Karakoram, Ladakh which is highly prone to earthquakes.

• Most disastrous among natural furies are flash floods which creates havoc in

Leh due to following reasons:

Cloud burst

Excessive melting of snow in the upper reaches of glaciers

Sudden removal of cloud cover / long sunny days after a period of

sustained snow fall

• Snow avalanche in snow covered mountainous regions of Leh

Recently Flash Floods has occurred in Leh on August

5, 2010 , affected the whole Ladakh region.

Damage pattern

• About 193 peoples were died & 200 were missing.

• Approx 908 no. of houses have been destroyed in

Leh.

• 80% of Infrastructure was damaged i.e. roads &

bridges

• Heavy damage to irrigation systems head works of

canals, protection works of rivers & canals.

• Main hospital of Leh town (Sonam Norboo

Memorial Hospital) was totally damaged.

The impact of disaster in Leh was more because there

has not been any Flood Mitigation Measures in place.

LEH FLASHFLOODS, AUGUST 2010

MANITSELDING

NEED OF THE STUDY

• Leh is situated in mountainous regions, which are most disaster prone

because of the topography and inaccessibility of affected areas.

• Cloud burst occurred in mid last year is the recent example.

• In Leh there is no Flood Mitigation Measure Strategy in place.

• Keeping in view the peculiar geographic and topographical conditions

prevailing in Leh town.

• Need for formulating and implementation of Flood Mitigation Measure

Strategic Plan is must to reduce the damages and making Leh a safer

town.

DRAINAGE PATTERN

• River Indus flows south of the town

of Leh from east to west.

• In the north of Leh town towards

Gangles, rivulet namely Leh Nallah

(Gangles Tokpo) with its tributary

streams namely Gyulang Tokpo and

Togar Tokpo form the natural

drainage system with their own

valley formation.

• These two streams meet the

Gangles Topko at Horzey.

• The Leh town has been growing in

the Gangles valley.

Leh town boundary

Leh Nallah

RECOMMENDATIONS

Construction of Embankments near inhabited areas along River Indus & Leh Nallah

• Embankment Design:With the help of discharge data procured, Using Gumbels extreme distribution function design discharge can be calculated.

RECOMMENDATIONS

TYPICAL SKETCH OF PROPOSED EMBANKMENT ON RIVER INDUS AT LEH(FOR MAXIMUM FLOOD DISCHARGE FOR A RETURN PERIOD OF 100 YEARS)

RECOMMENDATIONS

Detention Basins3 nos of detention basins have been proposed• one Detention Basin in the upper

reaches of Gangless,• second at polo ground & • third one at ice hockey groundwhich will receive the diverted additional water of the Flash Flood through a tunnel and finally spreads in the detention basin.

At outlet point of detention basin a gabion structure with suitable diameter RCC pipes for controlled release of water shall be provided. Early warning system should be implemented so that alarm/signals can be raised in any eventuality of raising the water level in Nallahs.

Wire Crate / Gabion walls / Bunds in Giamtsa, Gyalong & Shenam Nallah

Check Dams across the rivers / Nallah

Channelization of River/ Nallah at Vulnerable locations

Removal of Impediment to flow

Relocation / Re - settlement Relocation & Rehabilitation of encroachments on a nallahs is required

RECOMMENDATIONS

Plan of Detention Basin at upper reaches of Gangles Nallah

THANK YOU