Water Resources of Pakistan

1. CE-402 Irrigation Engineering
1
04. Water Resources of Pakistan
B.Sc. Civil Engineering 8th Semester
Muhammad Ajmal (PhD)
Lecturer
Agri. Engg. Deptt.

2. Water Resources of Pakistan
 Water stress occurs when the demand for water exceeds the available
amount during a certain period or when poor quality restricts its use.
 Water stress causes deterioration of fresh water resources in terms of
quantity (aquifer over-exploitation, dry rivers, etc.) and quality
(eutrophication, organic matter pollution, saline intrusion, etc.).

3. Water Resources of Pakistan
 Quick Facts
 Around 66% of the world’s population may be water stressed by 2025, and
around 1.8 Billion will be suffering from absolute water scarcity
 Approximately 50% of the global population will be living under high
water-stress by 2030
 The largest number of water-stressed countries is in Sub-Saharan Africa,
with the most water stressed region being the Middle East
 Close to 700 Million people in 43 countries suffer from water scarcity
 The Pakistan Council of Research in Water Resources (PCRWR) has warned that the country may
run dry by 2025 if the authorities didn't take an immediate action. According to a yet-to-be
released report, parts of which have been made available to the media, the Islamic country
touched the "water stress line" in 1990 and crossed the "water scarcity line" in 2005.
 If this situation persists, Pakistan is likely to face acute water shortage or drought-like situation in
the near future, predicts the PCRWR, which is affiliated with the South Asian country's Ministry
of Science and Technology.

4. Water Resources of Pakistan
 The water supply available to agriculture is derived from three main sources:
✓ Rainfall which occurs directly on the crop areas,
✓ Surface water from rivers or storage reservoirs, and
✓ Usable ground water from the aquifers.
 Rainfall is normally inadequate to sustain more than a very low level of agricultural
production, particularly in the semi-arid conditions of Pakistan.
 Pakistan has one of the largest irrigation systems in the world comprising:
o Three major reservoirs with a design capacity of about 20 Billion Cubic Meters
(BCM),
o 23 barrages, headworks and siphons,
o 45 main irrigation canals commanding an area of about 16.6 million hectares.

5. Water Resources of Pakistan
 Irrigated agriculture is the backbone for economy of the country where over
93 % of the available water resources are consumed.
 Irrigation is used on 80% of all arable land and meets almost 90% of all food and
fibers requirements.
 Agriculture is the single larges sector of economy accounting for about a
quarter of the country’s Gross Domestic Products (GDP).
 It employs 44% of the labor force, supports 75% of the population and accounts
for 60% of foreign exchange.

6. Water Resources of Pakistan
 The increased population, urbanization, industrialization and agricultural
activities however widened the gap between water demand and supply.
 The water shortfall that was 11% in 2004, is expected to increase to 31%
by 2025.
 The per capita water availability which was about 5600m3 in 1947 has
now reduced to about 1000 m3 converting the country to a water scare
condition.
 Due to poor maintenance and old irrigation system, the overall efficiency
is less than 40%.

7. Water Resources of Pakistan
 Out of 142 BCM of water available at the canal headworks, only 55
BCM is used by crops. The remaining 87 BCM (60%) is lost during
conveyance through canal distributaries, minors, watercourses and in
fields.
 In Pakistan the development of rainfed area is completely ignored. The
dry farming is practiced on about 12 Mha that is 40% of the Culturable
land. It just contribute less than 10% to the total production.
 The main reasons for the low productivity are:
o Low and erratic rainfall
o Soil erosion
o Poor use of land and water resources due to small and fragmented
land holdings, and
o Low agricultural inputs.

8. Water Resources of Pakistan
 In Pakistan there are two main seasons:
❖ Kharif Season (Summer ) from 1st April to the end of September.
❖ Main crops are Maize, Cotton, Tobacco etc.
❖ Rabi Season (Winter) from 1st October to the end of March.
❖ The main crops grown in such season are wheat, barley, potatoes etc.
 Intensity of irrigation is defined as the percentage of Culturable
commanded area proposed to be irrigated either in a crop season or during
a year.
 For example if CCA of an irrigation field is 120 hectares, out of which
90 hectares of the land is cultivated during Kharif season, and 60 hectares
in Rabi season. the intensity of irrigation during Kharif season will be
(90/120) * 100 = 75%. The intensity of irrigation during Rabi crop will be
(60/120) * 100 = 50%.
 Here, the yearly intensity of irrigation is equal to the sum of the two, i.e.
equal to 125 %. It means yearly intensity of irrigation is > 100%.

9. CE 402 Irrigation Engineering
Assignment #1
 Problem No. 1
❖ The gross command area of an irrigation project is 1.5 lakh hectares, where 7,500
hectares are unculturable. The area of kharif crop is 60,000 hectares and that of Rabi crop
is 40,000 hectares. The duty of Kharif is 3000 hectares/cumec and the duty of Rabi is
4000 hectares/cumec. Find (a) The design discharge of channel assuming 10%
transmission loss, (b) Intensity of irrigation for Kharif and Rabi.
 Problem No. 2
❖ A channel is to be designed for irrigating 5000 hectares in kharif crop and 4000 hectares
in Rabi crop. The water requirement for kharif and Rabi are 60 cm and 25cm respectively.
The Kor period for kharif is 3 weeks and for Rabi is 4 weeks. Determine the discharge of
the channel for which it is to be designed.

10. Questions?
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