INTERNATIONAL COMMISSION
ON LARGE DAMS
----TWENTY THIRD CONGRESS
ON LARGE DAMS
BRAZIL, JUNE 2009
----
INDUS BASIN – ROLE OF DAMS IN AGRO-BASED ECONOMY OF PAKISTAN*
Sardar MUHAMMAD TARIQ
Chairman, Pakistan Water Partnership
Pakistan
1.
SYNOPSIS:
Pakistan since its independence in August 1947 has heavily dependent on
agro-based economy. Though contribution of agricultural sector to Pakistan’s
GDP has been gradually declining with the development of other economic
sectors such as industries, etc. public sector largely depends on agriculture for its
growth, employment and foreign exchange earnings. The Indus Basin irrigated
area is the main contributor to Pakistan’s agro-based economy. This paper
develves in detail about the history of basin itself and the development of water
infrastructure particularly major multipurpose storage dams and their role in
providing sustainable agro-based economy. The paper also deals with the major
hydrological problems the Indus Basin has to face as a result of partition of the
sub-continent into two independent states of India and Pakistan followed by
Indus Waters Treaty of 1960. With establishment of world’s largest infrastructure
in a single hydrological basin, Pakistan has to confront serious problems of water
logging and salinity. This paper further describes the methods and technologies
adopted in dealing with twin menace of water logging and salinity, and mega
sedimentation problems created as a result of changing the course of rivers in
the basin.
2.
INDUS BASIN
-----------------------*BASSIN D'INDUS - RÔLE DES BARRAGES DANS L'ÉCONOMIE D'AGRO-BASED DU PAKISTAN
The vast Indus Plains covers an area of 207,200 square km and extends
1900 km from lower Himalayan foothills to the Arabian Sea, are underlain by
sandy alluvium to depths over 305 meters in the upper reaches and upto 61
meters in the lower reaches close to the Arabian Sea. The Indus Plains
constitutes a large and highly transmassive aquifer system with usable storage
volume much greater than all the existing and potential storage reservoirs on the
River Indus and its tributaries. Annual recharge to this ground water reservoir is
estimated at 56 million cubic meter of which some 44 billion cubic meter is
usable.
2.1
Upper Indus Basin Catchment
The upper catchment of Indus Basin is dominated with the great Himalayan
ranges which influence its weather, trap the monsoons to shed their moisture as
snow and rain, and regulate the water cycle. The 400,131 square km Himalayan
watershed of Indus and its tributaries includes world’s largest glaciers outside the
polar region. They are the great natural storage reservoirs that feed and regulate
the Indus and its tributaries. It is estimated that these glacier hold upto one trillion
cubic meter of water. Storage dams built since 1960 on Indus are miniatures as
compared to these natural reservoirs. In the upper reaches Indus flows, fed and
regulated by snow capped mountains, numerous glaciers and extensive ice
fields, first westward and then southwards cutting its way through the deepest
gorges in the world – some more than 4570 meter deep.
2.2
Lower Mountain Catchment
In the lower mountain catchment of the Indus and its tributaries where the
lower Himalayan and Siwalik ranges extend over 65,000 square km of
sedimentary rock and gravel formations, part of monsoon rainfall percolates and
is stored temporarily in the porous formation and is released later through springs
or natural reservoir that feeds the rivers in the dry season. The aggregate
capacity of this reservoir once amounted to more than 12 billion cubic meter but
extensive deforestation over the years led to serious soil erosion, reduced the
storage capacity and increased the hazards of floods and sedimentation inflows
in the rivers and reservoirs.
2.3
Lower Indus Plains
The Lower Indus Plains having alluvial river channels with aggregate length
of 3540 km and width ranging from 2 km to 4 km also serve as natural reservoirs
regulating the river flows. During high river storages, the channels are filled, the
flood peaks are moderated and water seeps into the wide alluvial banks. When
the river stage drops, the channels storage is released and the bank storage
seeps out slowly as return flows. The releases from channel storage during the
late summer season vary from 4 BCM to 6 BCM while those from bank storage
amounting to some 4 BCM take place throughout winter season. The timing and
quality of the storage releases are determined by the operations of the rivers and
storage reservoirs. Effective management of the rivers to prevent deterioration is
essential to maintain the gains from these natural storages on sustainable basis.
3.
DEVELOPMENT OF INDUS BASIN – HISTORIC PERSPECTIVE
The Indus River which irrigates the Indus Basin has seven major
tributaries, five on the east and two on the west in addition to numerous small
rivers which also join the main Indus on the west. The integrated water resources
management is not a new concept as far as Indus Basin is concerned. The upper
Punjab was the first to conceive and practice it. The triple canal project was
designed to integrate the three eastern rivers by constructing control works and
link canals in 1905-7 and operating the link canals as an integrated system. It
was a marvel of innovative engineering which heralded a new era of efficient and
equitable use of water resources and made Punjab the granary of the sub
continent. However the partition of the sub continent in August 1947 cut across
this irrigation network whereby control structures on eastern canals fell within the
territory of India and canals remained within Pakistan. Soon after the partition,
India conveyed its intention of diverting the waters of eastern rivers. This would
have meant strangulating the agro-based economy of a newly created Pakistan
whose 75% of GDP was solely dependent on agriculture as other sectors of the
economy were non-existent.
4.
INDUS BASIN WATERS TREATY OF 1960
With stoppage of water from the three eastern rivers by India, Pakistan’s 3
million hectare of fertile land of West Punjab, the food basket of Pakistan would
have gone barren. This created a serious water dispute between India and
Pakistan. However, over a period of 8 years of exhaustive negotiations under the
auspices of the World Bank from 1952 to 1960 the famous Indus Waters Treaty
between India and Pakistan was signed in September 1960. The World Bank
was also a signatory to this transboundary water allocation. Under the Treaty,
India was given exclusive rights to the uses of water of three (3) eastern rivers
with limited uses of waters of western rivers and Pakistan got exclusive rights on
the waters of three (3) western rivers. Pakistan was given a grace period of 10
years to complete its Indus Basin Replacement Works. This Treaty though
extensively lauded internationally as an example of resolving transboundary
water issues between two sovereign states, created some serious hydrological
shocks and challenges for Pakistan. The first challenge as stated earlier arose
because the lines of partition of the Indo-Pak subcontinent separated the irrigated
heart land of Punjab from the life-giving waters of the three eastern rivers.
The second challenge was that there was a serious mismatch between the
location of Pakistan’s water (in the western rivers) and the major irrigated areas
in the east.
5.
INDUS BASIN REPLACEMENT WORKS
To overcome major water challenges, Pakistan had to undertake major
engineering works within a fixed time period of 10 years. The initial works
included construction of mega rock and earth fill dam on one of the western rivers
i.e. Jhelum River at Mangla, construction of inter-river link canals to transfer the
waters of western rivers to eastern rivers with a number of Headworks and
Barrages and later the world largest volume rock and earth fill dam i.e. Tarbela
Dam was also built on River Indus, the largest river of the Indus Basin Rivers
System. With additional storage water available at Tarbela, additional canals and
control structures were constructed in all the four Provinces of Pakistan. With the
construction of Tarbela, Mangla and Chashma Multi-purposes storage dams,
storing close to 20 billion cubic meters of water and water distribution network
consisting of 19 barrages, 60,000 km of main canals and 1.60 million km of
secondary and distributary canals, the Indus Irrigation System became the
largest contiguous irrigation system in the world (Fig. 1).
Fig. 1
Schematic Diagram of Indus Basin Irrigation System
To further resolve internal contentious issues of water rights and water
distribution within the country, Inter-Provincial Water Apportionment Accord was
signed in 1991 among all the four Provinces which determined the 10-daily
historic shares of each of 43 canal commands. To ensure equitable distribution of
waters among the Provinces, Indus River System Authority known as IRSA was
created under the Act of Parliament to act as a watchdog in ensuring accord
implementation.
With transboundary water sharing Treaty of 1960 and Inter-Provincial
Water Apportionment Accord of 1991 and 10-daily historic water share of each
canal command and rotational water sharing within each canal command area,
Pakistan has now well-developed water distribution system with proper check
and balance mechanism in place.
6.
ROLE OF MULTIPURPOSE DAMS IN THE MODERN ECONOMY OF
PAKISTAN

With the construction of multipurpose storage dams and extensive water
conveyance and distribution network, the desert literally bloomed with
irrigated agriculture providing the platform for the development of the
modern economy of Pakistan.

The three multipurpose reservoir store some 20 billion cubic meter of
water and numerous control and diversion structures regulate close to
130 billion cubic meter of irrigation water annually to some 18 million
hectares of agricultural land increasing the cropping intensity from 80% to
150%. The Storage dams help to great extent in reducing the gap
between water availability and crop water requirement thus enhancing
crop productivity manifolds.

The engineering structures and reservoirs cumulatively provide 800 km of
navigation routes to over 200,000 people living along and in close vicinity
of the reservoirs and canals.

The water economy provided valuable base for development of other
economic sectors with the availability of cheap and renewable
hydropower, more than 3,000 ago-based industries have been
established all over the country and there has been a gradual shift over
the last 30 years contribution of irrigated agriculture from 75% to the GDP
has reduced to present 24% with the growth of industries and other
modern economies. Inspite of all this irrigated agriculture still plays a vital
role in the overall economy and employs 46% of labour force, provides
90% of food grains and earns 60% of the foreign exchange for the
country.

The water structures and storage dams provide largest inland water
bodies for fish culture and meet the dietary requirement of millions of
people living in the central and northern parts of Pakistan in addition to
providing livelihood to thousands of fishermen families. Some 50 priced
varieties of fish are cultured in the reservoirs in addition to hundreds of
fresh water species.

Pakistan is one of the most arid countries of the world with average
rainfall of 240 mm per year. 75% of this rainfall is available in 90 days of
the summer. The storage reservoirs helped Pakistan to integrate wet
season with the dry season and over 10 billion cubic meter of water is
now transferred through storage reservoirs from wet season to dry season
which boosted the agricultural production in addition to meeting the water
requirement of other sectors such as industries, environment, water
supplies and sanitation etc. With storage reservoir, the canal diversion
increased from 80 BCM to 130 BCM annually.

Inland reservoirs and water bodies provide safe heaven to millions of
migratory birds. The regulations of water round the year through storage
reservoirs minimizes the salt-water intrusion in the coastal areas in
addition to recharging the ground water which now contributes 40% of
water requirements of all sub sectors. The ground water reservoir spreads
over some 194,000 square km mostly recharged by storage reservoirs
and canals network.

During construction of massive water structures and mega multipurpose
storage dams, a unique opportunity was provided to the indigenous
labour force and close to some 50,000 unskilled labourer were trained in
various trades by American and European Contractors and an unmatched
force of skilled labourers consisting of construction supervisors,
surveyors, dozer/dumper/crane/grader operators, welders, etc was
produced. This trained labour force produced in sixties and seventies
coincided with the development of petro-based economy of Middle East
and Gulf States and immediately got opportunity for lucrative employment
in these countries. This labour force was then remitting foreign exchange
to the tune of US$ 4 billion per annum, the largest foreign exchange
earnings for the country. The cumulative remittances by this trained
Pakistani labour force over a period of 10 years surpasses the amount
spent on the construction of Indus Basin Replacement Works including
mega storage dams required under the Indus Waters Treaty of 1960.

The Indus Basin Rivers deposit close to 300 million tons of sediments
annually in the storage reservoirs. During annual draw-down, the
deposited silt is excavated by the locals and sold to farmers as a
replacement soil on their agricultural land, a commercial activity which has
become very payable during the recent years and provides handsome
earnings to the local population.
7.
MANAGEMENT CHALLENGES OF DEVELOPMENT WORKS
The heroic era of water engineering in Pakistan resulted in mega
management challenges. The natural flow regime was drastically altered; rivers
which has previously meandered over wide plains were now confined within
narrow channels; sediments (amounting to some 300 million tons) which
previously nourished the delta were trapped; and vast quantities of water were
disgorged into desert, substantial parts of which were of oceanic origin and highly
saline. The extensive irrigation network and large amount of seepages resulted in
billions of cubic meters of water getting stored in the naturally deep aquifers. In
many areas, water tables reached the level of the land, giving rise to the twin
menace of water logging and salinity. However, with good thinking and
application of water science and economics, the solution apart from lining of
canals and putting less water on the land, the enhanced use of ground water
offered the best solutions. This resulted in increasing evapotranspiration, drawing
down the ground water table and leaching much of the salts down and out of root
zones. The good thinking and good planning were classic “public good”. The
good luck driver of this revolution was the modest but transforming tubewell and
diesel engine for the simple reason that this decentralized “on demand” source of
water closely matching crop water requirement enabled them to greatly increase
their yields and farm incomes. In the public sector the introduction of tile and
surface drains measuring 16,000 km have also played major role in lowering the
water table and taking away drainable surpluses.
Similarly the sediment flow into the reservoir is another serious problem
gradually reducing the storage lives of dams. With young geological formations,
steep slopes and large flows, the Indus and its tributaries bring in some 300
million tons of sediments annually, Indus being the fifth largest sediment carrying
river in the world. Whereas catchment management for the Jhelum river has
positively reduced the sediments in Mangla Reservoir, Similar efforts have not
been very successful for the catchment of Tarbela Dam on Indus River. To
address Tarbela sedimentation issue comprehensive model studies have been
carried out with little success. It is now decided to construct additional storages
on Indus to prolong the life of Tarbela reservoir.
The climate change is further going to add new dimension to these
challenges. It is a far drawn conclusion that to successfully combat the impacts of
climate change storage reservoirs with proper management are going to play
extremely important role in mitigating the negative impact on water resources of
the country in meeting its multi-sectoral demands in addition to effectively
controlling the floods and droughts.
References:
[1]
TARIQ S.M. Water Management in Pakistan.
[2]
TARIQ S.M. Environmental Impacts of Tarbela Dam.
[3]
KIRMANI S.S. Water Sector Investment Plan – Policy and Management
Issues.
[4]
BRISCO JOHN, QAMAR USMAN. Pakistan’s Water Economy Running
Dry, The World Bank.
[5]
DUDER J.N., MUFTI J.I., TARIQ S.M. Mangla and Tarbela Dams and
Reservoirs – An Environmental Overview.