THE country’s irrigation system comprising three reservoirs, 19 barrages, 12 inter-link canals, 59,200 kilometres of irrigation canals and over 1,600,000 kilometres of water courses is one of the largest gravity flow irrigation system in the world.In addition, this system is supported by 44MAF of groundwater pumped through tube-wells. Of the total cultivated area of around 23 million hectares, 80 per cent is irrigated.
Revamping irrigation system
By
Bilal Hassan, Dr Rashid Ahmad & Khawar Jabran
THE country’s irrigation system comprising three reservoirs, 19 barrages, 12 inter-link canals, 59,200 kilometres of irrigation canals and over 1,600,000 kilometres of water courses is one of the largest gravity flow irrigation system in the world.In addition, this system is supported by 44MAF of groundwater pumped through tube-wells. Of the total cultivated area of around 23 million hectares, 80 per cent is irrigated.
However, rapidly increasing population and declining water availability due to gross mismanagement in the past have already created drought like conditions having serious implications for irrigated farming. The problem of water shortage has deepened due to river system losses in the form of about 38MAF annual discharge to the Arabian Sea without being utilised, limited storage capacity due to non-raising of heights of the existing water reservoirs and non-construction of new large and small dams, 25 per cent conveyance losses from the main canals and their branches, 20 per cent from main watercourses, 15 per cent from farmers watercourses and eight per cent from irrigation fields in the from of evaporation, seepage, percolation and overflow due to unlined canals, poor designed and maintained watercourses, defective irrigation practices, inequity in water distribution and lack of precision land leveling. As a result, crops are yielding 50-80 per cent below their demonstrated achievable potential and thus contributing to plausible gap between actual and potential yields of arable crops.
The situation calls for adoption of appropriate measures on the part of policy-makers and planners for revamping irrigation system for the sake of increasing irrigation efficiency. To improve the storage capacity of water and to ensure its proper utilisation, a major project of construction, repair and rehabilitation of barrages, headwork and re-modeling of canals, regular desilting of canals, distributaries and minors, redesigning and improvement of watercourses, post-improvement care by community participation approach and precision land leveling through laser technology is to be implemented which is essential to reclaim the barren land.
Hundreds of thousands of acre land could be made cultivable in the four provinces by providing additional water. For instance, considerable land area has become cultivable due to availability of additional water in Multan, Bahawalpur, Rahim Yarkhan, Rajanpur and other backward areas of Punjab due to rehabilitation of Taunsa Barrage and is playing an important role in the promotion of agriculture as well as socio-economic uplift of the farmers. Likewise, abundant water has become available for crop cultivation in Bhakar, Layya, Khushab, Muzaffargarh and other areas owing to remodeling of Thal Canal.
Construction of small dams to enhance storage capacity of water for agriculture is crucial in the backdrop of missing national consensus on construction of large dams. For example, small dams constructed in Rawalpindi, Jhelum, Chakwal and other arid areas are greatly helping in storage of water for agriculture practices.In the backdrop of growing shortage of water for irrigation, drip irrigation is an effective technique to improve irrigation efficiency, saving water and protecting land form water logging and salinity. Moreover, this system is of great importance in arid and semi-arid regions of the country such as Balochistan. Already the government has launched Rs75 billion subsidised drip irrigation programme for the next five years in a bid to improve irrigation efficiency. To add to this, working of drip irrigation at Nuclear Institute for Agriculture and Biology (NIAB) is quite impressive and provides a demonstration site for the education of extension workers, farmers and policy makers.Besides, sprinkler irrigation is another technique to utilise water equivalent to the water requirement of a crop and application of excess of water which may cause deep percolation and water logging could be avoided. Thus this system considerably increases irrigation efficiency.
Lack of precision land leveling has been contributing to application losses up to 50 per cent, uneven distribution of irrigation water, leaching of nutrients, water logging and salinity, loss of cultivated land due to excessive bunds, trouble in cultural practices and lower yield of crops. Realising the importance of land leveling, the Punjab government has launched a programme of providing the farming community laser sets in irrigated areas for the development of irrigated agriculture which is the hub of farming activities. It is estimated that this programme would help in curtailing 50 per cent application water losses and increase in cultivated area.
At the farm level, conservation practices such as zero-tillage sowing of wheat in rice-wheat cropping system could increase water use efficiency by 20 per cent, decreased cultivation cost of wheat by about 82 per cent, reduced energy consumption by 81 per cent and increased yield by 15 per cent.Likewise, suitable sowing method also helps improving irrigation efficiency. For instance, bed-furrow sowing of wheat and cotton increased irrigation efficiency up to 30per cent.Moreover, appropriate cropping pattern could have considerable effect on water saving. For instance, spring planted sugarcane crop requires 64-80 acre-inch of water per acre, while autumn cane crop requires 80-100 acre-inch of water per acre. Thus a crop water requirement is an important yardstick that could be used while selecting a crop in a particular region.
Importantly, the farming community needs to optimise plant population, use recommended irrigation methods, ensure timely sowing of crop, manage weeds free fields, adopt effective plant protection measures, optimal tillage during fallowing, use organic manures and where possible use mulches.
Problems like water theft, conflicts on the issues of water distribution, cutting of trees from canal banks and many other pilfering activities are prevailing unabated. Therefore, irrigation strategy encompassing appropriate measures for checking water theft from water courses and canals would directly benefit the farmers located at the tail ends. Socio-economic uplift of the farming community in irrigated tract is greatly associated with steady supply of irrigation water essential for increasing farm productivity.
