Irrigation
Need And
Importance Of Irrigation
1. Most of the plain areas of
Pakistan have been built by alluvial soil brought by the River Indus and its
tributaries. But due to deficient rainfall, agricultural activities cannot be
performed without adopting some artificial means of irrigation. So the areas
lying between the rivers have provided irrigation facilities through canals and
various types of crops are grown in these areas.
2. The Rivers of our country used to
take millions of gallons of water into the Arabian Sea. That water is being
used for canal irrigation and a number of dry desert areas have become fertile
and productive regions of our country.
3. The supply of water in our rivers
remains irregular during the year. To regulate the water supply throughout the
year the year the water is stored by constructing barrages, dams and weirs etc.
4. The slope of our country lies from
north east towards south. This helps in the construction of canals and water
can easily be distributed through canals from higher regions to lower areas.
5. All the rivers of our country come
from snow-covered mountainous areas, having abundance of rainfall in summer, in
those rivers a huge amount of water comes due to heavy rainfall and the melting
of snow during summer. Thus we store this surplus water in huge dams which is
used for irrigation purposes in dry season.
6. The upper and lower areas of Indus
plain have soft soil, where digging of canals is easier, and cheap labour is
available in abundance. That reduces the cost of construction. That is why
canal irrigation is preferred in our country.
7. Canal water adds to the fertility
of the soil by bringing a number of organic and in-organic matters with it, while
the water of tube -wells lacks all these matters, so people prefer canal
irrigation.
8. Canal irrigation is the cheapest
and easiest means by which vast areas can be commanded and made productive.
Means Of
Irrigation In Pakistan
The following means of irrigation are
practiced in various areas of our country:
1.Wells or
Tube-wells
This is one of the oldest methods of
irrigation which is being used from ancient times in our country. Well
irrigation is quite common in piedmont areas of North Eastern Mountains and in
the vicinity of rivers where the water-table is high. They are found all over
the plain where canal water is not available and water table is high enough for
their construction. Many shallow wells are dug by hand the areas where the
water table is not far below the surface of the earth .The water is then lifted
by “Charas” or “Persian wheels” driven by oxen or camels.
In areas where the water table is low
and cheap electric power is available, tube wells are used; due to shortage of
canal irrigation water ,government is encouraging the farmers to dig more and
more tube wells.
2. Canals
Irrigation from rivers is an ancient
practice. It was being carried before the birth of Christ in various areas of
our country, but the modern system of large perennial canals was introduced by
the Britishers. The first modern canal in Punjab was opened in 1859;it was
taken out from river Ravi at madhopur (Gurdaspur district, India).After that a
number of canals have been taken out from various rivers and our country has got
one of the most excellent systems of irrigation in the world. The canals found
in our country may be divided into the following types:
(a)Perennial
Canals
Those canals which supply water to
their commanded areas throughout the year are known as perennial canals. To
regulate the supply dams and barrages have been built. Most of the canals of
our country are of this type.
(b)Non
Perennial Canals
Such canals runs only during the
summer and the rainy season .They are closed down during winter months when there
is not enough water in the rivers. Some of the canals from Sutlej, the Sidhnal
canals from Ravi and Haveli canals from Chenab are of this type. Only one crop
can be harvested in the commanded areas of such types of canals.
(c)
Inundation or Flood Canals
These canals work only during the
rainy season, when the rivers have a plenty of water .Because no dam or barrage
is built at their head, their construction cost being low, they also help in
reducing the flood water and save the area from many dangers. Many old canals
from the Indus and Chenab are of this type.
(d) Karez
In Baluchistan short underground
canals called Karez have been built to carry the water which soaks into the
ground at the foot of the mountains to the fields and villages .As the canals
are underground no water is wasted by evaporation. In Quetta and Pashin
districts this system is very popular and a large area of this region is
irrigated by the Karez system.
Canal Systems
The irrigated area is served by more
than 40 major canal commands. Main canals start from a barrage or dam or weir
on a river. A barrage feeds one or more main or link canals. A number of minor
tributaries feed out of the main canal and these in turn, serve a number of
outlets to the farmers water-courses each of which irrigates between 60 and 240
hectares.
There are three major groups of canal
system:
(i) Canals on upper Indus Tributaries
(ii) Systems on the Indus
(iii) Systems west of the Indus.
(i) Systems
On Upper-Indus Tributaries
The principal canal systems are: from
the Jhelum,(a) Upper Jhelum canal, which starts from Mangla, joins the Chenab
at Khanki to give its surplus water to the lower Chenab canal, and (b) the
Lower Jhelum canal which starts from Rasul:from the Chenab (a) the upper Chenab
canal starting from marala and joining the Ravi near Ballokin to supplement the
water supply of the Lower Bari Doab canal,(b) the lower Chenab canal from
Khanki, and (c) the Haveli system of canals from the Trimu weir below the
junction of the Chenab and the Jhelum; from the Ravi,(a) the upper Bari Doab
canal, which begins in Madhopur (India),irrigating mainly the Indian
Punjab,with only its Lahore branch reaching Pakistan,(b) the Lower Bari Doab
canal from Balakot and (c) the Sidhanaj Canals from the left bank of the Ravi
at Sidhnal ;from the Sutlej, the Sutlej valley project, in which canals depart
from the river Gandas in Ghwala, Sulaimanke, Islam and below the junction of
the Sutlej with the Chenab at Panjnad.
The upper Jhelum, the upper Chenab, and
the lower Bari Doab canals together form The Triple Project, which was designed
to carry surplus water from the Jhelum to the Chenab, and from the Chenab to
the Ravi.
(ii) Systems
On The Indus
The largest dam on the Indus has been
built at Tarbela. Other barrages, in descending order along the river, are
Jinnah barrage near Kalabagh, part of the Thal project; Taunsa Barrage 290 km. further
downstream, which has 100,000 kw power station in addition to diversion works; Guddu
Barrage,150 km. upstream from Sukkar; Sukkur or Liodyd Barrage, the oldest
barrage on the river, and Ghulam Mohammad Barrage, near Kotri.
(iii) Systems
West of The Indus
These include (a) the Swat Canals
departing from the river at Malakand (upper Swat canal) and Abazal (Lower Swat
Canal); (b) the warsak Multipurpose Project on the Kabul River 30 kms.north
west of Peshawar which includes a 160,000 KW power plant; and (c) the kurram
Garhi Project on the kurram and barren rivers in Bannu tehsil.
In addition to these major projects. Some
smaller dams have also been built by the Water and power Development Authority
(WAPDA).These include rail Dam, Gomal Dam Multi-Purpose Project Khanpur Dam, and
Hab Dam. The Agricultural Development Corporation has set up the small Dam
Organization to construct dams of localized utility storing the flood water of
hill stream. A number of such dams have been constructed in the dry
sub-mountain areas of the north west.
Mangla And
Tarbella Dam
The Mangla Dam
Under the Indus Basin Treaty, this is
the second largest multi-purpose project designed to control and conserve the
flood water of the Jhelum for use mainly as replacement irrigation supplies for
the area which was served by the three eastern rivers. On the Jhelum river near
the village of the Mangla, about two miles upstream from the regulator of the
upper Jhelum Canal and about 20 miles from Jhelum town, a dam of the embankment
type has been built. The dam has crest length of about 11,000 feet and its
height is 380 feet. The reservoir created by the dam is about 40 miles long, having
a storage capacity of 5.5 million acre feet. It is the second largest earth
filled dam of our country. The project is providing 400,000 kilowatts of
electricity and 88 lakh acre feet water for irrigation purposes. The design of
the dam has a provision for future extension. Its height can also be increased
about 99 feet and storage capacity can also be increased upto 9.6 million acre
feet and electricity generated can also be increased from the present 400,000
k.w. to one million k.w. The Mangla lake has been developed as a fishing centre
and a health and tourist resort. This project was completed in 1967.
The Tarbela Dam
This is one of the largest earth and
rock filled dam in the world. This dam has been built on the river Indus at
Tarbela,15 miles from Maripur and 30 miles from Attock. This is also a
multipurpose project .The dam has a gross storage capacity of 11.1 million acre
feet. It is 9,000 feet long and 485 feet high. A 50 mile long lake has been
built behind it. It will provide 21 lakh kilowatts of electricity and 93 lakh
acre feet of water for irrigation when completed .It construction started in
1968 under the Indus Basin Treaty, and the dam was completed in 1974.The
installation of 10 units of electricity has been completed in 1985.There is
proposal of or the Tarbela project that 2 large off-channel reservoirs will
have to be built to increase storage and lengthen the life of the generating
facilities, since silting is expected to reduce the life of main dam. Water
from Tarbela will be used in the Haro and Soan Basins and for replacement the
supplies will be diverted to the Chashma Jhelum link canal and thence to the
Trimmu-Sidhnaj-Mailsi-Bahawal link system. This project will help other
barrages to retain the supply of water.
Barrages
According to Indus Basin Treaty five
barrages have been built and various link canals have been taken out from these
barrages.
1.Chashma
Barrage
A barrage has been built on River
Indus at Chashma .A link Canal has been taken out from the right bank of
Chashma providing water to canals of jhelum and Chenab. The work of Chashma was
Bank is under progress. It is hoped that after completion, this canal will
irrigate large area of barren land in Dera ismail Khan and dera Ghazi Khan Districts.
The other Barrages from where the following link canals have been taken out are:
The other Barrages from where the following link canals have been taken out are:
1. Rasul at Jhelum
2. Near Qadirabad on Chenab
3. Near Sighnaj on Ravi
4. Near Mailsi below the existing
Islam headworks on the Sutlej.
All these Barrages have a total
length of nearly 3 1/2 miles. These barrages are providing about 100,000 cusecs
of water to their link canals.
Link Canals
1. The Rasul-Qadirabad
A 30 miles long canal has been built
linking Rasul with Qadirabad and 19,000 cusecs water has been brought from
Jhelum to Chenab.
2. Qadirabad-Balloki
Qadirabad-Baloki link canal is
supplying 18,600 cusec combine water of Jhelum and Chenab to Ravi at baloki. It
is about miles long.
3. The
Balloki Sulemanki Link
This link canal is providing 6,500
cusec water of Ravi to the Sutlej canals, e.g. Pakpattan and Depalpur canals.
4. The
Chashma-Jhelum Link Canal
This link canal is 63 miles long and
it is supplying 21,700 cusecs water of Indus from Chashma to Jhelum so that the
supply of water at Trimmu head works can be maintained.
5. Trmmu-Sidhnal
Link Canal
Trmmu-Sidhnal link canal is providing
11,000 cusec combined water of Indus ,Jhelum and chenab at Sidhnal on Ravi
6. The
Sidhnal-Mailsi-Bahawal Link
It is a sixty miles long canal, which
is carrying the Indus, Jhelum and Chenab waters to the Islam head works canals
from the Sutlej.
7. The
Taunsa-Punjnad Link Canal
This link canal is 38 miles long .It
is carrying the Indus water for use at the Panjnad head works. The link canals
have a total length of 388 miles with a total capacity of about 100,000 cusec, but
the present supply of water from the canal is insufficient for our requirements
and a large amount of water is obtained from tube wells and other means.
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