. .

Irrigation scenario in Pakistan

  1. The NFC award
  2. The Sugar crisis
  3. Agri-tax: A challenging task
  4. Water crisis in Karachi
  5. Irrigation scenario in Pakistan

The greatest drawback of the irrigation system is drainage which had not been given due attention

By Dr. S.M. ALAM
NIA, Tandojam
Jun 12 - 18, 2000

The greatest assets the country possess is the mighty river Indus (originating from a lake near Tibet and finally entering into Arabian sea at Karachi, Sindh, Pakistan), with its tributaries and the vast network of canals, channels and water courses extending upto 40000 miles in length and commanding nearly 34.5 million acres representing a substantial parts of hectares of culturable area. Pakistan has been gifted with fertile cultivable land and a most suitable climate of diversified agricultural activities compiled with one of the best canal irrigation network of the world, Pakistan is number two, in terms of canal irrigation among the renowned agricultural countries of the world, the number one being Egypt Irrigated cultivation of Pakistan is as high 72 per cent compared to 15 per cent of the world as a whole, 24 per cent of India, 49 percent of Israel, 15 per cent of Thailand and just 12 percent of USA a country which is the biggest in surplus production of agricultural commodities. Irrigated land is twice as productive as rain-fed cropland the one sixth of the world's cropland that is irrigated producing about a third of the world food and currently 235 million ha are under irrigation. Productive agriculture has been made possible only through an extensive irrigation system that traverses the length and breadth of this tract. It is the productive agriculture in this irrigated tract, which sustains our national economy to the maximum. Irrigation water is thus our life blood.

The present day canal irrigation network in the country developed over a period of one and a half century is considered to be one of the largest contiguous irrigation system in the world. An efficient and smooth running of our gigantic irrigation system depends entirely on an equitable flow of water in the rivers. This in turn would depend wholly on a smooth and clean flow from the watersheds. The pattern of rainfall and the extent of productive cover on watersheds are not conducive to regular and smooth flow in Natural precipitation comes mostly in the form of heavy showers m the monsoons i.e. July to September and likely to cause disruption of soil particles from the steep and rugged slopes of our hilly watersheds in the absence of a protective cushion of vegetation. The result is large-scale erosion and enormous quantities of run off 'causing floods in the rainy season'. For the rest of the period, the rivers remain dry for want of rain and runoff. Agriculture as such cannot thrive in such a situation. Also the gigantic dams, which are the reservoirs of our irrigation system, are likely to be damaged and filled up quickly from the silty materials. The irrigation resources have to be harnessed to the maximum to achieve the long cherished goal of bringing the yields of crops to the levels obtained in elsewhere. A serious disadvantage in canal irrigation faced by the growers is that due to time rotation {warabandi} system water cannot be made available as and when needed. In the month of September -December the requirement of water for cotton and wheat is high, the availability is low and canal closures are common with the result that a farmer gets his water supply he uses it lavishly causing considerably wastage and rise in watertable and consequently of waterlogging and salinity which destroy the otherwise fertile land at the rate of one acre a minute.

Furthermore, the cutting of the banks of the water courses at several places to irrigate the land is not only labour expensive but weakens the banks and causes leakage. Moreover, the canals being unlined bring about considerable loss of water by seepage system through beds of the canals and sites which not only reduces the availability of water but adds further to the waterlogging and concentration of salts near the main canals and branches. Rainfall is an additional factor in the rise of water table. The bunds in the fields check the runoff and the standing water brings about waterlogging. Rainfall is a dominant factor in the rise of water table. The greatest drawback of the irrigation system was that drainage which had not been given due attention as a part of irrigation. Annual net addition of salts is of order of 1.3 tons per acre in the southern region of the country and 0.4 tons in the northern and average annual addition of salts to the Indus is as high as 16 million tons. The best way to keep the soils relatively free of salinity is to have it regularly cropped. It is now an urgent need for optimum utilization of the existing water resource in the country for maximizing food production to cater to the needs of fast growing population.

The total requirements of water was essential to be at 260 million acres feet for the existing available land, while the Indus system had only 140 MAF available annually, out of which currently 110 MAF was being diverted into the huge canal system. By construction of more dams it would be possible to store another 10 MAF of water thus bringing the total availability of water for irrigation of 120 MAF per annum. Even this quantity was considered to be far less than the total anticipated water requirement. The main objective is to improve and maintain the water course to perform other function related to obtaining of agricultural inputs. Improvement in the existing position can only be maintained through reclamation of waterlogged areas and providing of proper drainage, prevention of salinity, control of seepage losses from canals improved from water management and conjunctive use of surface and ground water.