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Saving irrigation water




  • ABOUT 22 per cent of the gross domestic product (GDP) comes from the agriculture sector. Crops are cultivated in irrigated as well as rain-fed areas. However, irrigated farming is most important. Growth of agriculture, however, depends upon environment.About 18.78 million hectares of total 22.94 million hectares cropped area is irrigated. The main sources of irrigation water are canals and underground water pumped through tube-wells. The country is endowed with huge water resources including precipitation (rainfall, dew, fog, hails etc.,), surface water and ground water.

    ABOUT 22 per cent of the gross domestic product (GDP) comes from the agriculture sector. Crops are cultivated in irrigated as well as rain-fed areas. However, irrigated farming is most important. Growth of agriculture, however, depends upon environment.About 18.78 million hectares of total 22.94 million hectares cropped area is irrigated. The main sources of irrigation water are canals and underground water pumped through tube-wells. The country is endowed with huge water resources including precipitation (rainfall, dew, fog, hails etc.,), surface water and ground water.

    The Indus Basin Irrigation system is the world’s largest integrated irrigation network that comprises of three large water reservoirs, 19 barrages, 12 inter-river link canals, 43 irrigation canals including perennial, annual, flood and over 107,000 watercourses.The total length of canals is around 61,000km whereas watercourses and farm channels measures 1.6 million kilometres. The system drains an average of 106 MAF of surface water each year for irrigation purpose. It is supplemented by 43 MAF ground water pumped by means of tube-wells per annum.Irrigation water is a key input for growth and development of crops that contribute to value-added in agriculture and the GDP, significantly. Regular supply of irrigation water is essential to sustain crop productivity. In case, one or two critical growth stages go without irrigation during the lifecycle of a crop, it would result in significant reduction in crop production. The adverse effects on per hectare yield of crops in 2000-01, 2001-02 and 2003-04 was due to unprecedented water shortage.

    Irrigation efficiency of canal system is poor due to considerable loss of water in the form of seepage, percolation, and evaporation. About 35 per cent water is lost through canals, 24 per cent though larger and smaller distributaries and 25 per cent during field application.As the agriculture is primarily dependent upon canal irrigation system, maintaining and improving this system is, therefore, crucial for sustainability of crop yield and thereby agriculture. Crop productivity could be improved either by enhancing per hectare yield or by increasing area under arable crops. Water is essential in either case.

    Water management and conservation practices should be given top propriety. Crop management practices that are helpful for saving water and improving water use efficiency at field level include selection of suitable cultivar, timely sowing, optimum plant population, recommended sowing method, standard irrigation methods, application of fertilizers in balanced amount, irrigation at right time, weed eradication and adequate plant protection measures.Fine seedbed preparation, levelling of field, deep ploughing, and incorporation of farm yard manures and commercial fertilizers and artificial or natural mulching are soil management techniques that are helpful in conserving water resources.

    Lining of canals and watercourses with protected material like cement is essential to plug seepage and percolation losses but this practice is time consuming and costly. However, a multiple approach viz., engineering cum vegetative would be greatly helpful in curtailing the problem of seepage, evaporation and percolation.Defective water rotation programme, inefficient cropping pattern, low cropping intensity, use of outdated irrigation technology, and lack of investment for renovation of the irrigation system are major impediments in conserving water resources.An acute shortage of irrigation water in certain parts of Sindh has restricted the cotton sowing. The Irrigation Department has resorted to the rotation programme due to low level of water canals. After germination of cotton seed, the first watering is required within seven days, but farmers failed to irrigate them on time due to the rotation programme and sprouted plants died. They cannot survive without water when the temperature is also high.

    The correct planting of crops and an efficient irrigation system can reduce water use by 50 to 70 per cent and overall water consumption by up to 25 per cent. Water specialists were becoming more and more convinced that the country is at present on the threshold of a serious water crisis. Water shortage is not only observed in irrigation but also in other uses and it was necessary to develop new water-saving technologies. Conservation and development of natural water asset is of utmost importance.To prevent future shortage of water, it is imperative to take all possible measures against degrading water resources.Again, there is a need to improve water rotation programme to insure that crops get irrigation at the right time. It happens that there is excessive availability of irrigation water when crop doesn’t need it and the result is loss of water. Growers are suggested to irrigate crops optimally because over and under-irrigation is detrimental for crop growth and development.

    To cope with water shortage, complete reorganization of water sector institutions through mergers, economic utilization of water resources of the country, procurement of additional storage for crops round the year, building storage to overcome droughts and to develop comprehensive water and hydro resource policy are necessary.

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