Irrigation plays a key role in Pakistan’s strategy for increasing agricultural productivity. No doubt that surface irrigation has allowed the extension of cultivation into areas and seasons that lack sufficient rainfall for agriculture, and has raised yields above what was possible under rain-fed agriculture.
But ground water is also very important, because the public canal irrigation system does not provide farmers with adequate water.
Attention to efficient water management is becoming increasingly important all around the world as water scarcity, degradation of its quality, and competition between agriculture and other sectors’ demands place pressure on this vital resource. Thus appropriate management of water resources is essential for agricultural production, food security and sustainable management of natural resources. This is particularly true in an arid ecology like ours where agriculture is heavily dependent on irrigation.
Irrigation provides crucial water for agricultural production on more than 80 per cents of the gross cropped area in Pakistan. Most of this irrigation comes through public canal systems, which deliver surface water to approximately 70 per cent of the irrigated area. The Indus basin system was designed more than a century ago, with the objective of spreading scarce water over as large an area as possible.
At that time planned cropping intensities were 50 to 75 per cent that is, only half the command area was to be irrigated in the Rabi season (mid-October to mid-April), and up to a quarter in Kharif (mid-April to mid-October).
The low water availability and rigid delivery pattern were not adapted to meet the demands of the more intensive agriculture that came in the wake of the green revolution and increasing population pressure in Pakistan. Moreover, allowance was not made for water losses in the channels. Further problems with operation and maintenance of the canal systems also resulted in non-availability of water at the tail-end distributors and watercourses.
Although the development of dams and barrages has made possible some expansion of canal irrigation but still available surface supplies are limited and cannot meet the demand for intensive irrigation of our predominantly arid environment.
Throughout the 1970s and 1980s groundwater irrigation has been the most rapidly growing source of irrigation. Even now it serves approximately 25 per cent of the irrigated area and provides over 36 percent of the irrigation water available at the farm gate. Groundwater has become a crucial input both as a sole source of irrigation and used in conjunction with surface irrigation in canal irrigation commands.
The government policy on groundwater development from the mid-1950s to 1980s focused on public tube wells, under the $10 billion Salinity Control and Reclamation Programme (SCARP). The public control of the extensive groundwater pumping programme was based on the rationale that such arrangement would enable the government to meet multiple ground-water objectives in an efficient and equitable manner. These objectives were
* providing vertical drainage for controlling water logging and salinity problems, especially in saline groundwater areas;
* increasing cropping intensities and agricultural production and
* reducing inequity in access to groundwater.
However, certain institutional problems as well as technical difficulties resulted in disappointing performance of public tube wells as the system was tied to the rigid warabandi (rotational discharges) as public canal system. Consequently it did not increase flexibility of irrigation.
Further increased operation and maintenance expenses for public tube wells, which consumed 60 per cent more then the entire national budget for canal operation and maintenance in 1983-84 together with the poor performance of public tube wells in timeliness and reliability of irrigation supplies, led the government to devolve responsibility for groundwater irrigation development from the public to the private sector.
The number of public and private tube wells in Pakistan has increased from 3000 in 1947 to around 600000 at present. At the same time, overall constraints to renewable groundwater supplies place limits on the number of tube wells that can be installed and operated in a sustainable manner. A growing number of areas are already experiencing net groundwater withdrawals and falling water tables. According to a study conducted in 1991 by NESPAK the pumping exceeds recharge by more than 25 per cent in Punjab. Therefore, strategies are required to improve the equity of access to groundwater resources.
Electricity pricing is an important policy instrument to influence the number of tube wells and reliability of groundwater withdrawals. Electric-powered pumps generally have lower operation and maintenance costs than diesel operated pump sets. A flat rate power tariff structure for tube wells in our country, under which the tube-well owner pays a monthly fee per horsepower of the motor regardless of the quantity of electricity consumed, stimulates over pumping of groundwater, particularly in the areas in which the water table is being depleted. Much of the policy toward groundwater, dating back to the early SCARP programmes, has been based on the need to lower water tables to control water logging and salinity. While water logging is still a serious problem in almost all countries an accelerated groundwater usage has led to falling water tables in many areas.
Over-exploitation not only reduces the availability of the resource and raises pumping costs for all, but also contributes to salinization of groundwater. This calls for a regulatory role for the government to develop ground water resources.
At present there is an urgent need for developing clear information on available recharge, water quality, current exploitation levels, and remaining potential. This data needs to be regularly updated and made available to farmers at the local/sub-district level. Such information will certainly help farmers and government officials in making appropriate decisions on sustainable groundwater use.
Ground water is not the only factor affecting the efficiency and equity of irrigation in our country. The Indus basin canal irrigation system remains the most important source of water in Pakistan. It contributes to agricultural production through direct surface irrigation and is the primary source of recharge of ground water.
Ground water irrigation development cannot be understood without considering the physical framework of canal irrigation. These canals offer farmers cheaper water of higher quality than groundwater, and they provide the source of most ground water recharge. At the same time, shortages and unreliability of canal water have also created much of the demand for ground water.
Therefore importance of ground water irrigation development needs to be recognized immediately. Despite its importance, there is still not enough concern at national level about protecting our ground water resources. It seems that being ‘out of sight’ has caused ground water to be ‘out of political mind’ of our policy makers. It is merely due to this reason that we do not understand serious economic implications of not resolving ground water demand and supply management. Before we reach the point of no return, we must act now.