k barrage 2014 - pm world library...the existing barrage remained safe, but the overflow of banks...

PM World Journal Flood at Khanki Barrage 2014 Vol. III, Issue XII – December 2014 by Zafar Ahmed www.pmworldjournal.net Personal Story

© 2014 Zafar Ahmed www.pmworldlibrary.net of 7

FLOOD AT KHANKI BARRAGE 20141

By Zafar Ahmed

The River Chenab is one of the largest rivers of the Indus basin. The river Chenab basin measures

about 67,500 km² of area. The River originates at 77°-30°E and 32°-50°N in Lahul and Spite

district in Himachal Pradesh India. It flows through the Baralcha pass at an elevation of 5,000 M

and enters the State of Jammu and Kashmir (India). Many streams join on both sides of the river in

high mountainous region of about 500 kms long and flows out into the plains and enter Pakistan

near Marala Barrage, in district Sialkot. After flowing through 600 km it joins the river Indus and

then falls into the Indian Ocean near Karachi after a further 600 km.

The Khanki Headworks is the Oldest Barrage on River Chenab and was completed in 1892 with a

most economical design. It was shuttered type weir comprising 8 Spans of 500 ft and Rope Bridge

for controlling staff to move across the river. It is 56km downstream from Marala Barrage and is

one of the oldest weirs in the Indian sub-continent. The water is diverted to a canal at left bank,

irrigating 1.2 million hectors of land in 7 districts of central Punjab in Pakistan.

The existing Khanki Headworks has the capacity to pass the flood of 800,000 cusecs and in case of

higher floods, some discharge is passed through breaches of u/s guide banks towards an

unpopulated area to avoid any damage to the weir structure.

The average annual rainfall in the area is 950 mm and mean annual temperature is 30c°. The main

weather system which causes heavy rainfall is due to monsoon incursion from Arabian Sea and Bay

of Bengal during July to September. The floods in River Chenab result from heavy rainfall in upper 1 This story describes events that affected the project on which the author is current working.

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drainage basin which falls under the most active monsoon belt. The snow melt contributes on the

average 40% of the total flow in July, and peak values occurring in months of August and

September are due to monsoon rains. The history of past 92 years’ floods is shown in table.

`

Due to the ageing effects of old barrage, a new 4400 ft long barrage having 65 bays with

controlling gates and bridge is being constructed downstream of existing barrage at the cost of

about $ 200 million. The works at new barrage started in October 2013 and is planned to be

completed in 42 months. As per schedule, the Contractor M/S Descon Engineering Limited

completed 30% of sub-structures including protection works in the first working season (October

2013 – June 2014) before the start of first flood season (July-September 2014) and cleared the river

bed from temporary structures and coffer dam to pass the monsoon floods.

160

257

203 26

6.8

225 26

175

074

7.3

249

352.

425

627

8.1

208 27

3.8

189.

112

3.4

264.

518

4.8

145.

628

7.4

288.

422

0.6

173.

215

2.6 22

9.6

251.

243

8.5

225

1011

.721

7.9 31

5.3

315

806.

734

0.7

261.

510

86.4

401.

710

2170

9.5

354

345.

318

6.7

406.

220

0.7

631.

624

0.7

235.

436

227

5.1

311.

528

1.7

856.

319

7.9

666.

261

547

2.1

433.

124

6.9

194.

856

3.9

261.

930

3.9

167.

430

9.1

341

109.

486

4.2

512.

234

5.7

314.

691

0.5

439.

442

5.2

630.

585

1.3

847.

722

0.3

177.

830

9.3

162.

8 244.

437

1.8

151.

134

368.

078

422.

7430

2.19

721

5.41

210

5.35

833

4.43

716

6.38

3

947.

099

0

200

400

600

800

1000

1200

1922

1924

1926

1928

1930

1932

1934

1936

1938

1940

1942

1944

1946

1948

1950

1952

1954

1956

1958

1960

1962

1964

1966

1968

1970

1972

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

2010

2012

2014

Peak

Dis

char

ge (

thou

sand

s of

cus

ec)

Years

ANNUAL PEAK DISCHARGES AT KHANKI HEAD

WORKS (1922-2014) IN thousands of cusecs





Works in Progress to Complete before July 2014

The working Contractor encircled about 15 % of the river bed through coffer dams to continue the

works during flood season to complete the Head Regulator structure, Silt Excluder, Guide Bank,

Divide Wall and other protection works. They planned to pass about 600,000 cusecs in the

remaining river width.

The Contractor continued works in the enclosed 15% of river bed area without danger, as the

average flow in the River Chenab at Khanki remained less than 80,000 cusecs from July to August

2014.

With the beginning of September, heavy continuous rains started in the catchment area of river

Chenab due to a monsoon incursion from Bay of Bengal. The water in the river started to increase

on 3rd

September 2014. The discharge was 650, 000 cusecs on 5th

and 6th

September. It passed

safely in the available river bed width. It started to recede at 1200 hrs and all the stakeholders were

happy that the flood has passed and was now receding.

At 1600 hours on the 6

th September 2014, an alarming situation created a panic when it was

announced that one peak discharge of about 1 million cusecs was expected early next morning. It

was a very surprising / devastating situation for the safety of the old barrage structure and the under

construction works which were continued as per plan in the enclosed area of 15 % of the river bed.

The time was very short to take and implement important decisions in order to pass the peak flood

that was more than the capacity of existing barrage that was coming in few hours. The Punjab

Irrigation Department, The Project Director, CRE, the Consultants SMEC International and the





Contractor M/s Descon, local representatives joined hands and heads to protect the existing Barrage

structure, already completed works, and to safely pass the flood peak when it reached the Barrage.

It was decided to remove the coffer dam immediately which encircling the working area at left

bank. Secondly, to immediately strengthen the upstream banks to protect the populated and

industrial areas, and to prepare and blast the breaching section by Army corps of Engineers at the

u/s right bank which diverts the part of flood water towards unpopulated area to pass the part of

peak flood through the breaching section. The Contractor mobilized all available resources so that

the coffer dam obstructing the flow could be removed as early as possible. As huge flood was

coming so Contractor’s camps, offices, records, computers, costly items had to be protected and

Plant and moving equipment had to be removed as soon as possible as the flooding of the adjoining

area was inevitable.

The water level started to increase at 0200 hrs and it was at its peak at 0700 hrs in the morning of

7th

September 2014. The water was overtopping from the D/S Abutment stone walls. The peak

discharge recorded was 947,099 cusecs (27,000 cubic meters per second) at the Old Khanki

Barrage. As planned, the u/s right bank breaching section was detonated before the peak discharge,

easing the pressure at the Barrage structure.

The Peak Flood Passing at U/S of Barrage

The peak flood measured as 947,099 cusecs (27,000 Cubic meters per second). It overflowed from

the Abutment wall of both banks eroding nearby areas; this also eroded the banks of the existing

canal, also eroded trees along the banks, and a few were as old as 150 years. The Contractor’s camp

was flooded as 5-6 ft water flowed through the camps.





FLOOD DAMAGES:

The existing Barrage remained safe, but the overflow of banks eroded existing canal banks. The

Contractor M/s Descon working for the new Barrage also suffered losses due to flooding of their

offices, warehouses, slag - cement store yard, the temporary works and under construction road

along left bank. The works for new Barrage suffered about 60 days delays. The Contractor, M/s

Descon was determined to overcome the delay in the next working season from October – June

2015.





RESTORATION WORKS:

The Punjab Irrigation Department immediately decided to restore all the works so that the Canal

which was feeding a large area could be operated as early as possible. The working Contractor was

instructed to mobilize and restore the canal banks and eroded portions. The variation works started

immediately and the canal was ready to receive water after 12 days.

The Works in Progress now for Main Barrage





About the Author

Zafar Ahmed

Pakistan

Zafar Ahmed, by profession a Civil Engineer, has worked in Middle

East countries at planning and managing construction of heavy projects. He participated in planning

and construction of the first balanced cantilever bridge over river Indus at old and historical

crossings of invaders to India near Attock, about 35 years before. He also worked for large Hydro

power projects of 1600 MW, 1500 MW and 1000 MW in Pakistan. Zafar participated in the

rehabilitation of Adam – Salalah road, 200 km stretch and new dual carriageway from Sohar to

Buraimi in Oman. He has therefore been engaged in planning and construction of multibillion $

construction projects overseas and in Pakistan. Presently he is working as resident civil works

consultant with SMEC international at Khanki Barrage.

Zafar can be contacted at [email protected]



mailto:[email protected]

k barrage 2014 - pm world library...the existing barrage remained safe, but the overflow of banks...

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