Revamping of watercourses

The launching of the multi-faceted $1.1 billion programme to revamp watercourses in the country for improved irrigation water utilisation, though rather late in the day, augurs well for Pakistan's agriculture sector which accounts for over 24 percent of its GDP.
Under the mega project, 86,000 big and small watercourses across the country will be renovated to improve their water holding and conveying capacity, as seepage causes a huge water loss every year. The second prong of this vital mega project is the planned introduction of drip/sprinkle system of irrigation that represents one of the best water conservation techniques developed by modern science.
An Islamabad-datelined agency report quoting Federal Minister of State for Food, Agriculture and Livestock, Muhammad Ali Malkani says that improved application efficiency can result in considerable saving of this precious, though fast depleting, resource. Increasing fresh water scarcity, deteriorating water quality, inadequate funding for irrigation development and maintenance projects, trans-boundary water-sharing, water-logging and salinity, ground water depletion, high sedimentation load and poor drainage, are some of the common problems faced by this sector.
It cannot be denied that scientific water management underpins agricultural profitability and food security, and the demand for water in developing countries is rapidly rising due to an increase in population, changing lifestyles and industrial expansion. This has necessitated the use of modern irrigation techniques to enhance agricultural productivity.
There is consensus among agricultural experts that Pakistan's vast irrigation system comprising three major reservoirs, 19 dams, 43 main canals and an aggregate conveyance length of 57,000 kilometers, has become quite inefficient due to aging, one result of which is the huge annual water seepage that amounts to as much as 35 maf of water, or equivalent to six Tarbela reservoirs! Obviously, Pakistan cannot afford such colossal waste of the precious resource through a preventable cause if it is to attain its food security targets. The loss must be stemmed to conserve water for targeted use to obtain increased agricultural productivity.
According to estimates, unlined canals can lose 30 to 50 percent of their transported water due to seepage. One US estimate says that the cost of lost water ranges from $20/acre ft to $300/acre ft, depending on the time of the year, weather conditions and its intended use. In the 1980s the World Bank's evaluation department had found that renovating watercourses in Pakistan could increase irrigation water supply at one-fifth of the cost of building a new large dam.
The total cost of lining distributaries and minors in Sindh alone has been calculated at Rs 64.5 billion, which will save 5.9 maf of water in the province or equivalent to the storage capacity of the proposed Kalabagh dam. Thus in Sindh alone the first part of the water conservation programme would amount to building one Kalabagh dam at a cost of $1.07 billion which is only 13.4 percent of the actual cost likely to be incurred at 2001 rates.
The revamping of watercourses through the use of modern engineering techniques can yield good results insofar as targeted utilisation of water is concerned, but it cannot serve as a substitute for building additional dams and reservoirs in the country. The huge quantity of water that flows down into the sea unutilised each year should also be dammed, and properly utilised.