Dam Break Study-Hunza River by NESPAK

ATABAD LANDSLIDE

In the name of Allah the Most Gracious the Most Merciful

ATABAD LANDSLIDE

DAM BREAK STUDY OF

ATABAD LANDSLIDE

MARCH 2010

National Engineering Services Pakistan (Pvt.) Ltd.

ATABAD LANDSLIDE

THE DAM BREAK ANALYSIS HAS BEEN

CARRIED OUT BY NESPAK TO ANSWER THE

FOLLOWING QUESTIONS;

1.WHAT IS THE LOCATION & COMPOSITION OF LANDSLIDE?

2.WHAT IS THE CAPACITY OF LAKE THAT HAS BEEN FORMED?

3.WHEN THE LAKE WOULD OVERTOP THE LANDSLIDE MASS?

4.WHAT WOULD BE THE PEAK FLOOD DISCHARGE AT

VARIOUS LOCATIONS ALONG HUNZA RIVER DOWNSTREAM

OF LANDSLIDE?

5.WHAT WOULD BE THE DEPTH AND VELOCITY OF WATER AT

VARIOUS LOCATIONS?

ATABAD LANDSLIDE

THE DAM BREAK ANALYSIS HAS BEEN CARRIED

OUT BY NESPAK TO ANSWER THE FOLLOWING

QUESTIONS (CONTD….);

6. HOW MUCH IS THE WARNING TIME FOR VARIOUS

VILLAGES/GILGIT CITY ?

7. WHAT ARE THE AREAS THAT WOULD BE AFFECTED IN CASE

OF DAM FAILURE ?

8. UPTO WHICH LOCATION ON THE RIVER THE DAMBREAK

FLOOD WAVE WOULD BE HIGHLY DESTRUCTIVE?

9. WHAT ARE THE MAJOR AND IMMEDIATE STEPS/ DECISIONS

REQUIRED AT THIS STAGE?

ATABAD LANDSLIDE

THE KEY PROFESSIONALS INVOLVED IN THIS

ANALYSIS ARE;

Dr. TAHIR HAYAT VICE PRESIDENT (GT&GE)

MIRZA ASIF BAIG GENERAL MANAGER (WRD)

Dr. MANSOOR HASHMI GENERAL MANAGER (WRD)

Engr. SHAHRUKH LATIF CHIEF ENGINEER (WRD)

Engr. YASIR ABBAS SENIOR ENGINEER (WRD)

Mr. ADIL LATIF GIS/RS-ANALYST

Mr. MUHAMMAD AKRAM SURVEYOR

Mr. RAZZAQ AHMAD DRAFTSMAN

AND SUPPORTING STAFF

ATABAD LANDSLIDE

LOCATION MAP

Gilgit

ATABAD LANDSLIDE

SATELLITE MAP OF LANDSLIDE AREA

ATABAD LANDSLIDE

GEOLOGICAL MAP OF LANDSLIDE AREA

ATABAD LANDSLIDE

ATABAD LANDSLIDE

FIVE SOIL AND ONE ROCK (GRAVEL) SAMPLE WAS

COLLECTED FROM THE LANDSLIDE DAM SITE.

THREE SAMPLES OF THE DUST WERE COLLECTED AS

SAMPLE 1, 2 AND 3, WHILE TWO SAMPLES OF THE BLACK

CLAY WERE COLLECTED AND LABELED AS SAMPLE 4 AND 5.

THESE SAMPLES WERE SUBJECTED TO LABORATORY

TESTS.

THE RESULTS OF LABORATORY TESTS SHOW THAT THE

DUST SAMPLES ARE VERY FINE ROCK FLOUR AS THEY

SHOW 30% TO 80% MATERIAL PASSING NO. 200 SIEVE YET

THESE HAVE NO PLASTICITY.

SOIL AND ROCK SAMPLES

ATABAD LANDSLIDE

THUS THE VISUAL OBSERVATIONS AT THE SITE ARE

CONFIRMED THAT THE BLACK SOIL HAS ORGANIC CONTENT

AND IT IS VERY FINE AND PLASTIC. ON THE OTHER HAND THE

DUST AT SITE IS ALSO VERY FINE BUT NON-PLASTIC.


THE BLACK SOIL SAMPLES (SAMPLE 4 AND 5) INDICATE A

VERY FINE SOIL WITH ALMOST 100% PASSING NO. 200

SIEVE IN BOTH CASES AND HAVING LL OF 28% AND PL

RANGING FROM 21% TO 22%.

THE ORGANIC MATTER CONTENT IS 0.95% AND 1.10% FOR

THE TWO BLACK CLAY SAMPLES, PEGMATITE AND

APALITE.

ATABAD LANDSLIDE


THE GRAVEL SAMPLES COLLECTED FORM THE SITE

INDICATE THAT THESE ARE GANODIORATIC ROCKS WITH

INTRUSION OF GRANITE, PEGMATITE AND APALITE.

ATABAD LANDSLIDE

A VIEW OF SLUSH MATERIAL PRESENT IN THE UPSTREAM AREA.

ATABAD LANDSLIDE

A VIEW OF NARROW UPSTREAM VALLEY.

ATABAD LANDSLIDE

A DISTANT VIEW OF WIDE VALLEY NEAR GULMIT.

ATABAD LANDSLIDE

A VIEW OF SHISHKAT BRIDGE. NOTE THE EXPANDING LAKE WATER LEVEL TOUCHING THE FOUNDATIONS.

ATABAD LANDSLIDESOURCE INFORMATION

CONTOUR SURVEY OF LANDSLIDE MASS SPOT-5 SATELLITE IMAGERY DATA (LANDSLIDE AREA ONLY) ASTER DATA (30 M RESOLUTION) SURVEY OF PAKISTAN (SOP), G.T SHEETS

DAILY FLOW AND INSTANTANEOUS PEAK FLOW DATA AT HUNZA RIVER AT DANIYOR BRIDGE (1962-ONWARDS) GILGIT RIVER AT GILGIT (1962-ONWARDS) INDUS RIVER AT PARTAB BRIDGE (1960-ONWARDS) INDUS RIVER AT SHATIAL BRIDGE (1984-ONWARDS) INDUS RIVER AT BESHAM (1960-ONWARDS)

ATABAD LANDSLIDESOURCE INFORMATION

CROSS SECTIONAL SURVEY TOTAL = 140 CROSS SECTIONS HUNZA RIVER = 128 CROSS-SECTIONS GILGIT RIVER = 12 CROSS-SECTIONS

CROSS SECTIONS EXTRACTED FROM ASTER DATA FROM GILGIT TO BESHAM TOTAL = 90 CROSS SECTIONS AT EVERY 3 KM

ATABAD LANDSLIDE

TOPOGRAPHIC SURVEY OF LANDSLIDE

FLOW PATH

Section Across Dam

LegendL-Section

X-Section

ElevationHigh : 2500

Low : 2312

ATABAD LANDSLIDE

LONGITUDINAL SECTION OF LANDSLIDE ALONG POSSIBLE FLOW PATH

Flow Direction

ATABAD LANDSLIDE ANALYSIS OF G.T SHEET, ASTER DEM & RIVER SURVEY

ATABAD LANDSLIDE

ELEVATION CAPACITY CURVE OF LAKE

ATABAD LANDSLIDE


ATABAD LANDSLIDE


ATABAD LANDSLIDE

DAM-BREAK STUDIESSCENARIO ANALYSED

DAM BREAK STUDY HAS BEEN CARRIED OUT FOR TWO CONDITIONS

1. FOR 18m CUT ( ALREADY ACHIEVED)

2. FOR 30m CUT (MAY BE ACHIEVED BEFORE OVERTOPPING)

ATABAD LANDSLIDE

ESTIMATED MONTHLY AVERAGE FLOWS AT LANDSLIDE LOCATION

254

232

218

502 15

09

5061

9841

4267

1326

658

486

1009

1

0

2000

4000

6000

8000

10000

12000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Flow

(ft3 /s

)

0

50

100

150

200

250

300

Flow

(m3 /s

)

ATABAD LANDSLIDE

OBSERVED MONTHLY AVERAGE FLOWS ATDANIYOR, GILGIT AND PARTAB BRIDGE

0

1000

2000

3000

4000

5000

6000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Flow

(m3 /s

)

0

50

100

150

200

Flow

x 1

000

(ft3 /s

)

Hunza River at Daniyor Gilgit river at Alam Bridge Indus River at Partab/Bunji

ATABAD LANDSLIDE

ESTIMATED TIME TO OVERTOP

ATABAD LANDSLIDE


ATABAD LANDSLIDE


ATABAD LANDSLIDE

DAM-BREAK STUDIES HYDROLOGIC ENGINEERING CENTRE’S RIVER ANALYSIS SYSTEM (HEC-

RAS) VER-4.0 HAS BEEN USED IN THIS DAM BREAK STUDIES

HEC-RAS IS A ONE-DIMENSIONAL HYDRODYNAMIC MODEL DEVELOPED BY U.S ARMY CORPS OF ENGINEERS

HEC-RAS CAN MODEL BOTH OVERTOPPING AND PIPING FAILURE OF EARTHEN DAMS

THE RESULTING FLOOD WAVE IS ROUTED DOWNSTREAM USING UNSTEADY FLOW EQUATIONS

ATABAD LANDSLIDEDAM-BREAK STUDIES

ESTIMATION OF BREACH PARAMETERS

THE BREACH PARAMETERS INCLUDE TIME TO BREACH BOTTOM WIDTH OF BREACHED SECTION BOTTOM ELEVATION OF BREACHED SECTION SIDE SLOPES AT BREACHED SECTION BREACH WEIR COEFFICIENT

0 200 400 600 8002250

2300

2350

2400

2450

2500

2550

Latest Cross sections70_1_n = 0.1 Plan: 70 3/16/2010 RS = 100100 IS

Station (m)

Ele

vatio

n (m

)

Legend

WS Max WS

EG Max WS

Ground

Bank Sta

.1



BOTTOM WIDTH OF BREACHED SECTION HAS BEEN ESTIMATED AS 190 M BOTTOM ELEVATION OF BREACHED SECTION HAS BEEN ESTIMATED AS

2300 M LEFT AND RIGHT SIDE SLOPES HAS BEEN ESTIMATED AS 1 VER. : 1 HOR. BREACH WEIR COEFFICIENT HAS BEEN ESTIMATED AS 2.6 VARIOUS TIME TO BREACH HAS BEEN ANALYZED RANGING FROM 1 HOUR

TO 24 HOUR




OUTFLOW FLOOD HYDROGRAPH

THE FLOOD HYDROGRAPH AS A RESULT OF RELEASE OF ALL LAKE CONTENTS

2300 2400 0100 0200 0300 040030Dec2009 31Dec2009

0

20000

40000

60000

80000

Plan: 70 River: Hunza Reach: 1 RS: 101935.7

Time

Flow

(m3/

s)

Legend

Flow3,319,578 ft3/s

ATABAD LANDSLIDE

DAM-BREAK STUDIESSUMMARY OF SCENARIO ANALYSED

SCENARIO ID TIME TO BREACH DESCRIPTION

18-1 1 hour

Cut Depth = 18 mOvertopping Level =2398 m

Dam Height = 108 mLake Volume = 195 MCM

18-3 3 hour

18-6 6 hour

18-24 24 hour

30-1 1 hour

Cut Depth = 30 mOvertopping Level =2386 m

Dam Height = 96 mLake Volume = 133 MCM

30-3 3 hour

30-6 6 hour

30-24 24 hour

ATABAD LANDSLIDE

Lake

DAM-BREAK STUDIESRIVER SCHEMATISATION

LAKE

LANDSLIDE

HUNZA RIVER

River Reach Length = 100 kmfrom landslide location to

confluence with Gilgit River

Confluence with Gilgit River

ATABAD LANDSLIDE

0 20000 40000 60000 80000 100000 1200001200

1400

1600

1800

2000

2200

2400

Latest Cross sections70_1_n = 0.1 Plan: 70 3/16/2010

Main Channel Dis tance (m)

Ele

vatio

n (m

)

Legend

EG 29DEC2009 2400

WS 29DEC2009 2400

Crit 29DEC2009 2400

Ground

DAM-BREAK STUDIESRIVER BED PROFILE

LAKE

LANDSLIDE

HUNZA RIVER

Reach Length = 100 kmSlope of River = 0.009

(900 meters drop in 100 km)


ATABAD LANDSLIDE

DAM-BREAK STUDIESFLOOD WAVE PROPOGATION

LAKE

LANDSLIDE


ATABAD LANDSLIDE

0 20000 40000 60000 80000 100000 1200001200

1400

1600

1800

2000

2200

2400

Latest Cross sections70_1_n = 0.1 Plan: 70 3/17/2010

Main Channel Dis tance (m)

Ele

vatio

n (m

)

Legend

EG Max WS

WS Max WS

Crit Max WS

Ground

DAM-BREAK STUDIESMAXIMUM WATER SURFACE ALONG THE RIVER

LAKE

LANDSLIDE


ATABAD LANDSLIDE

MAX WATER COMPUTATIONS COMPUTATIONSSCHEMATISATION

SUMAIR

KARIMABAD

ATABAD LANDSLIDE

0 100 200 300 400 5002060

2080

2100

2120

2140

2160

2180

1 hour breach@2398 Plan: 70 3/23/2010 RS = 84943.89

Station (m)

Elev

atio

n (m

)

Legend

EG 30DEC2009 0006

WS 30DEC2009 0006

Ground

Bank Sta

MAX WATER COMPUTATIONS

ATABAD LANDSLIDE

0 100 200 300 400 5002060

2080

2100

2120

2140

2160

2180


Station (m)

Elev

atio

n (m

)

Legend

EG Max WS

WS Max WS

Ground

Bank Sta

Max Depth =35m

Depth above Left

Bank =22m

Depth above RightBank =28m


ATABAD LANDSLIDE


ATABAD LANDSLIDE

0 200 400 600 800 1000 1200 1400 16001540

1560

1580

1600

1620

1640

1660


Station (m)

Elev

atio

n (m

)

Legend

EG 30DEC2009 0006

WS 30DEC2009 0006

Ground

Bank Sta


ATABAD LANDSLIDE

0 200 400 600 800 1000 1200 1400 16001540

1560

1580

1600

1620

1640

1660


Station (m)

Elev

atio

n (m

)

Legend

EG Max WS

WS Max WS

Ground

Bank Sta


Microsoft Office PowerPoint 97-2003 Pres

ATABAD LANDSLIDE

Overtoping at El. 2398m, Dam height 108m1 hour Breach

0

20000

40000

60000

80000

100000

21:3

6

22:4

8

00:0

0

01:1

2

02:2

4

03:3

6

04:4

8

06:0

0

07:1

2

08:2

4

09:3

6

10:4

8

12:0

0

Flow

(m3 /s

)

Just Downstream Landslide At Confluence with Gilgit


SCENARIO-18-1

Time From Start of Breach to Arrival of Peak at Gilgit Confluence

= 4.5 hrs3,248,950 ft3/s

706,000ft3/s

ATABAD LANDSLIDE


05000

1000015000200002500030000350004000045000

21:3

6

22:4

8

00:0

0

01:1

2

02:2

4

03:3

6

04:4

8

06:0

0

07:1

2

08:2

4

09:3

6

10:4

8

12:0

0

Flow

(m3 /s

)



SCENARIO-18-3


=5.25hrs

1,447,900 ft3/s

671,000 ft3/s

ATABAD LANDSLIDE


0

5000

10000

15000

20000

25000

21:3

6

22:4

8

00:0

0

01:1

2

02:2

4

03:3

6

04:4

8

06:0

0

07:1

2

08:2

4

09:3

6

10:4

8

12:0

0

Flow

(m3 /s

)



SCENARIO-18-6


= 6.5 hrs 812,000 ft3/s

600,000 ft3/s

ATABAD LANDSLIDE


01000200030004000500060007000

21:3

6

22:4

8

00:0

0

01:1

2

02:2

4

03:3

6

04:4

8

06:0

0

07:1

2

08:2

4

09:3

6

10:4

8

12:0

0

13:1

2

14:2

4

15:3

6

16:4

8

18:0

0

19:1

2

20:2

4

21:3

6

Flow

(m3 /s

)



SCENARIO-18-24


= 11 hrs 247,000 ft3/s 212,000 ft3/s

ATABAD LANDSLIDE

DAM-BREAK STUDIESFLOOD WAVE JUST DOWNSTREAM OF LANDSLIDE

SUMMARY OF SCENARIO 18-1, 18-3, 18-6 & 18-24

Overtoping at El. 2398m, Dam height 108m

0100002000030000400005000060000700008000090000

100000

21:3

6

22:4

8

00:0

0

01:1

2

02:2

4

03:3

6

04:4

8

06:0

0

07:1

2

08:2

4

09:3

6

10:4

8

12:0

0

Flow

(m3 /s

)

1 hour Breach 3 hour Breach 6 hour Breach 24 hour Breach

3,248,950 ft3/s

1,447,900 ft3/s

812,000 ft3/s

247,000 ft3/s

ATABAD LANDSLIDE


01000020000300004000050000600007000080000

21:3

6

22:4

8

00:0

0

01:1

2

02:2

4

03:3

6

04:4

8

06:0

0

07:1

2

08:2

4

09:3

6

10:4

8

12:0

0

Flow

(m3 /s

)



SCENARIO-30-1


= 5.25 hrs 2,684,000 ft3/s

635,600 ft3/s

ATABAD LANDSLIDE


05000

100001500020000250003000035000

21:3

6

22:4

8

00:0

0

01:1

2

02:2

4

03:3

6

04:4

8

06:0

0

07:1

2

08:2

4

09:3

6

10:4

8

12:0

0

Flow

(m3 /s

)



SCENARIO-30-3


= 6 hrs 1,025,000 ft3/s

530,000 ft3/s

ATABAD LANDSLIDE


0

5000

10000

15000

20000

21:3

6

22:4

8

00:0

0

01:1

2

02:2

4

03:3

6

04:4

8

06:0

0

07:1

2

08:2

4

09:3

6

10:4

8

12:0

0

Flow

(m3 /s

)



SCENARIO-30-6


= 7.5 hrs 565,000 ft3/s

388,000 ft3/s

ATABAD LANDSLIDE


0

1000

2000

3000

4000

5000

21:3

6

22:4

8

00:0

0

01:1

2

02:2

4

03:3

6

04:4

8

06:0

0

07:1

2

08:2

4

09:3

6

10:4

8

12:0

0

13:1

2

14:2

4

15:3

6

16:4

8

18:0

0

19:1

2

20:2

4

21:3

6

Flow

(m3 /s

)



SCENARIO-30-24


= 12.5 hrs 177,000 ft3/s

172,000 ft3/s

ATABAD LANDSLIDE

DAM-BREAK STUDIESFLOOD WAVE JUST DOWNSTREAM OF LANDSLIDE

SUMMARY OF SCENARIO 30-1, 30-3, 30-6 & 30-24Overtoping at El. 2386m, Dam height 96m

0100002000030000400005000060000700008000090000

100000

21:3

6

22:4

8

00:0

0

01:1

2

02:2

4

03:3

6

04:4

8

06:0

0

07:1

2

08:2

4

09:3

6

10:4

8

12:0

0

Flow

(m3 /s

)

1 hour Breach 3 hour Breach 6 hour Breach 24 hour Breach

2,684,000 ft3/s

1,025,000t3/s

565,000 t3/s

177,000 t3/s

ATABAD LANDSLIDE

DAM-BREAK STUDIESFLOOD PEAK ARRIVAL TIMEFOR VARIOUS SCENARIOS

Scenario

Time from Start of Breach to

Peak Reaching Gilgit Confluence

(hours)18-1 4.5018-3 5.2518-6 6.50

18-24 11.030-1 5.2530-3 6.0030-6 7.50

30-24 12.50


FLOOD PEAK COMAPARISON FOR VARIOUS SCENARIOS

Scenario

Peak Flow at Landslide

Peak flow reaching Gilgit

Confluence

Max. Water Depth at

Landslide

Max. water depth reaching

Gilgit Confluence

(m3/s) (m3/s) (m) (m)

18-1 92,000 20,000 52 15

18-3 41,000 19,000 24 15

18-6 23,000 17,000 19 14

18-24 7,000 6,000 11 9

30-1 76,000 18,000 33 14

30-3 29,000 15,000 21 13

30-6 16,000 11,000 16 12

30-24 5,000 5,000 9 8

ATABAD LANDSLIDE

DAM-BREAK STUDIESMAX DEPTH, VELOCITY AND TIME TO MAX DISCHARGE

ALONG HUNZA RIVER (18-1 SCENARIO)

VillageMax Depth

above river Bed (m)

Max velocity (m/s)

Time of maximum Discharge

Ahmedabad 47.2 10.6 30 min

Faisabad 49.4 11.2 40 min

Atit 52.0 12.7 55 min

Karimabad 40.4 8.6 1 hour

Aliabad, Sumair 46.4 7.5 1 hour 15 min

Murtazabad 50.6 10.3 1 hour 30 min

Toshot 46.0 9.4 1 hour 40 min

ATABAD LANDSLIDE


ALONG HUNZA RIVER (18-1 SCENARIO) (Cont..)

VillageMax Depth

above river Bed (m)

Max velocity (m/s)


Miacher 40.0 13.5 1 hour 50 minMinapin Nagar ,

Pisan 37.3 11.0 1 hour 55 min

Kahnabad, Thole nagar 48.8 5.8 2 hours 5 min

Nilt Nagar 48.8 5.8 2 hours 5 min

Jafarabad 48.8 5.8 2 hours 5 min

Sikandarabad 48.8 5.8 2 hours 5 min

Chalt 30.5 6.3 2 hours 25 min

ATABAD LANDSLIDE


ALONG HUNZA RIVER (18-1 SCENARIO) (Cont..)

VillageMax Depth

above river Bed (m)

Max velocity (m/s)


Jaglot 22.6 8.4 3 hours 30 min

Nomal 15.8 5.1 3 hours 50 min

Danyor 15.0 11.1 4 hours 15 min

ATABAD LANDSLIDE

DAM-BREAK STUDIESHISTORIC OBSERVED INSTANTANEOUS FLOOD PEAKS

HUNZA RIVER AT DANIYOR

0

5000

10000

15000

20000

25000

1966

1968

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

Flow

(m3 /s

)

Flood Peak in 18-1 Scenario


ATABAD LANDSLIDE

DAM-BREAK STUDIESHISTORIC OBSERVED INSTANTANEOUS FLOOD PEAKS

HUNZA RIVER AT DANIYORScenario

Peak flow reaching Gilgit Confluence

(m3/s)

Compared with Historic Peak at Daniyor Bridge

Danger level

18-1 20,000 3.8 times Exceptionally High



18-24 6,000 1.2 times High




30-24 5,000 Same High


IMPACT ON TARBELA RESERVOIR

IN ORDER TO CHECK THE IMPACT OF THIS FLOOD WAVE ON INDUS RIVER UP TO TARBELA RESERVOIR, THE MODEL HAS BEEN EXTENDED UPTO THAKOT ON INDUS RIVER.

A RIVER REACH OF 350 KM FROM GILGIT CONFLUENCE TO BESHAM HAS BEEN ANALYZED USING HECRAS.

TARBELA RESERVOIR IS ABOUT 100 KM DOWNSTREAM OF BESHAM.

CROSS-SECTIONS HAVE BEEN EXTRACTED FROM ASTER DATA.

ATABAD LANDSLIDE

WAVE PROPOGATION

FROM GILGIT TO BESHAM,

ATABAD LANDSLIDE


FROM GILGIT TO BESHAM, SCENARIO-18-1

Safe Safe

danger

ATABAD LANDSLIDE



SafeSafe

danger

ATABAD LANDSLIDE



Safe Safe

ATABAD LANDSLIDE

PartabHistoric Instantaneous Peaks

02000400060008000

1000012000140001600018000

1960

1962

1964

1966

1968

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

Flow

(m3 /s

)DAM-BREAK STUDIES

FLOOD WAVE PROPOGATION Historic Peaks at Partab/Bunji



ATABAD LANDSLIDE

ShatialHistoric Instantaneous Peaks

0

2000

4000

6000

8000

10000

12000

14000

1960

1962

1964

1966

1968

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

Flow

(m3 /s

)DAM-BREAK STUDIES

FLOOD WAVE PROPOGATION Historic Peaks at Shatial



ATABAD LANDSLIDE

BeshamHistoric Instantaneous Peaks

02000400060008000

10000120001400016000

1960

1962

1964

1966

1968

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

Flow

(m3 /s

)DAM-BREAK STUDIES

FLOOD WAVE PROPOGATION Historic Peaks at Besham

Flood Peak in 18-1 ScenarioFlood Peak in 30-1 Scenario

ATABAD LANDSLIDE

DAM-BREAK STUDIESFLOOD INNUNDATION

MAP

ATABAD LANDSLIDE

DAM-BREAK STUDIESFLOOD INNUNDATION

MAP

ATABAD LANDSLIDE

DAM-BREAK STUDIESFLOOD INNUNDATION MAP

ATABAD LANDSLIDE

THE LANDSLIDE AT ATABAD TOOK PLACE ON 4TH JANUARY 2010

THAT CREATED A LANDSLDIE DAM ACROSS THE HUNZA RIVER.

THE LOCATION IS ABOUT 30 KM UPSTREAM OF ALIABAD AND ABOUT

10 KM DOWNSTREAM OF GULMIT.

THE LANDSLIDE TOOK PLACE AT THE AREA LOCATED ON A FAULT

LINE, WHICH HAS CREATED A HIGHLY CRUSHED ROCK MASS.

THE LANDSLIDE MATERIAL CONSISTS OF A MIXTURE OF LARGE

BOULDERS, COBBLES, SILT AND PLASTIC CLAY. THE PERCENTAGE

OF EACH VARIES ON THE LANDSLIDE MASS.

CONCLUSIONS

ATABAD LANDSLIDE

THE LANDSLIDE DAM HEIGHT (lowest point) IS 126 (413 ft) METERS

ABOVE THE RIVER BED LEVEL, WIDTH 250 TO 350 METERS AND

LENGTH ALONG THE RIVER IS 2000 METERS.

THE LANDSLIDE DAM CREATED A POTENTIAL STORAGE OF 305 MCM

IF IT FILLED TO THE TOP.

WITH A SPILLWAY CUT DEPTH OF 18 METERS THE STORAGE

POTENTIAL REDUCES TO 195 MCM (36% reduction).

A SPILLWAY CUT DEPTH OF 30 METERS REDUCES THE STORAGE

POTENTIAL TO 133 MCM (56% reduction).

CONCLUSIONS (Cont)

ATABAD LANDSLIDE

USING RIVER FLOW DATA, WITH THE PRESENT 18 METER (about 60 ft)

DEEP SPILLWAY CUT, IT IS ESTIMATED THAT THE LANDSLIDE DAM

WOULD START OVERTOPPING BETWEEN 12TH MAY TO 21ST JUNE,

2010.

WITH A 30 METER (about 100 ft) DEEP SPILLWAY CUT IT IS

ESTIMATED THAT THE LANDSLIDE DAM WOULD START

OVERTOPPING BETWEEN 30TH APRIL TO 10TH JUNE, 2010.

CONCLUSIONS (Cont)

ATABAD LANDSLIDE

HYDROLOGIC ENGINEERING CENTRE’S RIVER ANALYSIS SYSTEM

(HEC-RAS) Ver-4.0 HAS BEEN USED BY NESPAK IN THE DAM BREAK

STUDIES.

TWO DIFFERENT SPILWAY CUT DEPTHS HAVE BEEN ASSUMED i.e. 18

METERS AND 30 METERS.

FOR EACH SPILLWAY CUT DEPTH, FOUR DIFFERENT TIMES TO

BREACH HAVE BEEN MODELLED i.e. 1 HR, 3 HR, 6 HR AND 24 HR.

THUS IN TOTAL EIGHT DIFFERENT DAM BREAK SCENARIOS

HAVE BEEN MODELLED.

THE MODEL HAS BEEN BASICALLY RUN TO SHOW THE EFFECT TILL

GILGIT BUT THE MODEL HAS BEEN EXTENDED TO SHOW RESULTS

UP TO BESHAM

CONCLUSIONS (Cont)

ATABAD LANDSLIDE

FOR A 18 METER DEEP SPILLWAY CUT, THE RESULTS OF DAM BREAK

STUDY ARE SUMMARISED AS:

CONCLUSIONS (Cont)

ScenarioPeak Flow at

Landslide(m3/s)


(m3/s)

Max Depth* at Gilgit

Confluence (m)

Time to maximum dischargeat Gilgit

Confluence(hours)

1-hour Breach 92,000 20,000 15 4.5

3-hour Breach 41,000 19,000 15 5.25

6-hour Breach 23,000 17,000 14 6.5

24-hour Breach 7,000 6,000 9 11

* From River Bed

ATABAD LANDSLIDE

FOR A 30 METER DEEP SPILLWAY CUT, THE RESULTS OF DAM BREAK

STUDY ARE SUMMARISED AS:

CONCLUSIONS (Cont)

ScenarioPeak Flow at

Landslide(m3/s)


(m3/s)

Max Depth* at Gilgit

Confluence (m)

Time to maximum dischargeat Gilgit

Confluence(hours)

1-hour Breach 76,000 18,000 14 5.25

3-hour Breach 29,000 15,000 13 6

6-hour Breach 16,000 11,000 12 7.5

24-hour Breach 5,000 5,000 8 12.5

* From River Bed

ATABAD LANDSLIDE

WHEN COMPARED TO HISTORICAL FLOOD DATA:CONCLUSIONS (Cont)

ScenarioPeak flow reaching Gilgit Confluence

(m3/s)

Compared with Historic Peak at Daniyor Bridge

Danger level




18-24 6,000 1.2 times High




30-24 5,000 Same High

ATABAD LANDSLIDE

THE MODEL HAS BEEN EXTENDED UP TO BESHAM.

CONCLUSIONS (Cont)

ScenarioPeak flow reaching

Partab Bridge(m3/s)

Compared with Historic Peak at Partab Bridge

Danger level


30-1 11,000 0.9 times High

ATABAD LANDSLIDE

THEREFORE, IT CAN BE SAID THAT EXCEPT FOR THE SCENARIOS

18-1 AND 18-3, THE FLOOD PEAK AT PARTAB BRIDGE WOULD BE

LESS THAN THE HISTORICAL PEAK OF 1963.

THE EFFECT DOWNSTREAM OF PARTAB BRIDGE WILL NOT BE

HIGHER THAN ANY HISTORICAL FLOOD OF RECENT PAST (1960

ONWARDS) FOR ALL SCENARIOS

THE EFFECT AT TARBELA WILL NOT BE SIGNIFICANT.

CONCLUSIONS (Cont)

ATABAD LANDSLIDE

AN EMERGENCY PREPAREDNESS AND ACTION PLAN (EPAP) SHOULD

BE PREPARED ON THE BASIS OF THE DAM BREAK STUDY RESULTS.

THE GUIDING PRINCIPLE SHOULD BE TO “PREPARE FOR THE WORST

WHILE HOPING FOR THE BEST”.

THE 18-1 SCENARIO (18 meters deep cut; 1 hr time to breach) IS THE

WORST CASE SCENARIO. THIS SHOULD BE USED TO PREPARE THE

EMERGENCY PLANS.

THE MAIN IMPACT OF THE DAM BREAK WILL BE FROM FLOOD

INUNDATION AND HIGH VELOCITY OF FLOOD WAVE

THE SECONDARY EFFECT WILL BE FROM LANDSLIDES IN THE LAKE

AREA DUE TO RAPID DRAWDOWN AND IN THE DOWNSTREAM AREA

DUE TO RIVER BANK EROSION.

RECOMMENDATIONS

ATABAD LANDSLIDE

THE RESULTS INDICATE DANGER TO:

PEOPLE LIVING ON LOWER ELEVATIONS CLOSE TO THE RIVER

BANKS

PEOPLE LIVING CLOSE TO TERRACE EDGES OR ON UNSTABLE

SLOPES

ROADS AND BRIDGES ON LOWER ELEVATIONS WHERE FLOOD

WATER IS EXPECTED TO RISE.

ALL THE PEOPLE AT RISK WILL HAVE TO BE EVACUATED AND MOVED

TO HIGHER ELEVATIONS / STABLE AREAS.

EMERGENCY PLANS SHOULD BE PREPARED KEEPING IN MIND THAT

THE ROADS AND BRIDGES COULD BE WIDELY DAMAGED UP TO

CONFLUENCE WITH INDUS / RAIKOT BRIDGE

RECOMMENDATIONS (Cont)

ATABAD LANDSLIDE

A 24 HR MONITORING OF THE LANDSLIDE DAM SHOULD BE STARTED.

LINES OF COMMUNICATION AND WARNINGS SHOULD BE ESTABLISHED

FOR UPSTREAM AND DOWNSTREAM COMMUNITIES.

ALL THE COMMUNITIES LIVING IN THE DANGER AREA SHOULD BE

ALERTED NOW AND GIVEN THE KNOWLEDGE ABOUT THE DAM BREAK

SCENARIOS AND WHAT TO DO IN CASE OF EMERGENCY (EVACUATION

PLAN).


ATABAD LANDSLIDE

THREE ALERT STATES SHOULD BE MADE:

LEVEL ONE: WATER LEVEL JUST TWO METERS BELOW CUT LEVEL

LEVEL TWO: WATER STARTS TO FLOW OVER THE CUT

LEVEL THREE: DAM EROSION IN PROGRESS; DAM BREACH IS

IMMINENT.

NESPAK SURVEYORS SHOULD MOVE WITH THE NDMA / ARMY TEAMS

TO MARK HIGHEST FLOOD LEVELS FOR THE 18-1 SCENARIO

IMMEDIATELY.

ALL STAKE HOLDERS (ARMY, FWO, NDMA, LOCAL ADMINISTRATION)

SHOULD BE TAKEN ON BOARD FOR THE EMERGENCY PREPAREDNESS

AND ACTION PLAN (EPAP).


ATABAD LANDSLIDE

THANK YOU

National Engineering Services Pakistan (Pvt.) Ltd.

ATABAD LANDSLIDEFLOOD MARK AT SARAT BRIDGE

35 m above Bridge Deck (18-1 Scenario)

Flow Direction

ATABAD LANDSLIDEFLOOD MARK AT GANESH BRIDGE


Flow Direction

Ganesh Bridge

ATABAD LANDSLIDEFLOOD MARK AT BAST FAIZA ABD BRIDGE


Flow Direction

Bridge

ATABAD LANDSLIDE

FLOOD MARK AT SIKANDRABAD BRIDGE15 m above Bridge Deck

(18-1 Scenario)

Bridge

Flow Direction

Documents

Dam Break Study-Hunza River by NESPAK