Improved Water Conservation Techniques in Pakistan

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Fresh water resources of Pakistan are being used to fulfill the food requirements and to improve


the living standards of the population of Pakistan. But due to increasing onslaught of human


population, these resources continue to dwindle and are becoming scare. The country once


considered as a water surplus has emerged into a water deficit one. Despite having the worlds


largest contiguous irrigation system, it is facing the dilemma of water shortage and situation will


even exacerbate in the near future. The seepage losses in the irrigation network, mismanagement


in distribution system and over application at farm level have created the problems of water


logging and salinity.


Thousands of hectares of farmland are lost annually due to rising water tables. It is an established


fact that almost 20% of water is lost due to traditional surface irrigation methods at farmers


field. If this water is saved and consumptively used, additional arable and fertile lands essential


for modern agriculture could be brought under cultivation which otherwise are lying barren due


to water shortage. In order to achieve the comparable crop yields to that of other countries, to


save land from water logging and salinity, to feed ever increasing population of the country, and


to bring agriculturally potential land under cultivation, the potential of limited water resources


must be utilized to its full extent.


Since, new sources of water supply are becoming scare and are unlikely to be constructed in the


near future due to geo-political reasons, the emphasis must be given on the methods that can


salvage the supplies already being lost within the present irrigation system. Though the existing


water resources of the country are not sufficient to meet the crops water requirement, yet they


are not properly managed and efficiently used. The gap between the potential yields and actual


yields could be narrowed down by the efficient use of available resources.


Distribution system at outlet


The coordination between water users and the irrigation department has remained a major


problem since the existence of irrigation network that has resulted mismanagement, poor


maintenance, inequitable and unreliable distribution. Under prevailing rotational (warabandi)


irrigation system, the distribution of water to the outlets is inequitable. The outlets located at the


head and middle reaches of distributaries draw 3 to 6 times more than the actual allocated share,


whereas outlets at the tail reaches draw less than the actual allocated share, hence, the poor tail-


enders are always faced with shortage of water. Those who draw greater shares apply more water


than the crops water requirement resulting in excessive wet stresses to crops and excessive


leaching of nutrients, whereas, the tail ender apply less water than the crops water requirement


resulting in dry stresses to crops.


Under both stresses, not only crop yields exaggerate but the water use efficiency significantly


reduces. Some tail-enders compensate the inadequate supply with poor quality groundwater and


their fertile lands become prone to secondary salinization due lack of proper knowledge on


conjunctive use of such water. All this suggests proper management and adoption of scientific


approaches to utilize the water available at the outlet. This could be done at the farm level either


by improving the present application methods or by introducing highly efficient irrigation


methods.


Improvement in traditional methods


In fact, the farmers use traditional flood irrigation methods without consideration of land slope


and soil texture. Thus, more than 20% water is lost at the field level through deep percolation.


Similarly, furrows are prepared without proper knowledge on slope consideration. The farmers


need proper training on the application of furrow, border and basin irrigation methods. These


methods would still give high production if they are properly designed and applied according to


soil and water conditions. One of the factors identified for inefficient use of irrigation water


through these methods is poor leveling. The unleveled lands are characterized with nonuniform


distribution of irrigation water and deep percolation which requires excessive application that in


turn affects application efficiency. A properly leveled field with an appropriate layout and size


reduces application losses, ensures uniform distribution, and increases crop yields.


Potential of modern irrigation methods


Efficient irrigation methods like trickle, sprinkler, pitcher, and sub-irrigation are required to be


introduced at the tail reaches with water shortage problem. These methods are proven to be


efficient in terms of water saving but are considered expensive thus farmers are reluctant to use


them. However, the acceptance of these methods depends upon their success in terms of


maximum yield returns associated with minimum water required. Since these techniques have


potential to save lot of water, hence, more land could be brought under cultivation with small


amounts of water available, particularly, at the tail reaches of the conveyance systems. The


irrigation methods so introduced must be acceptable as well as economically affordable by the


farmers; hence government should take initiative and install demonstration plots at farmers


fields to introduce them. Once, the farmers will realize the benefits of water saved and returns


achieved, they will install such systems from their own resources.


Among the new methods mentioned, trickle irrigation has been reported one of the efficient


methods of water application than any of the conventional surface irrigation methods. It provides


prescribed amount of water, achieves high field application efficiency, offers better uniformity,


saves water, and ensures better yields. Also, the water is applied to plants in a precise quantity


thus their immediate water requirements are met.


Water storage ponds


The concept of water storage ponds at the farm level is quite new and needs research on how to


make it economically and physically viable. Their use is a premeditated management tool to


harvest water when it is in excess and utilize when needed. The storage capacity depends on the


size of the pond and availability of water to be harnessed. For example, a 40 m long, 20 m wide,


and 2 m deep pond will store 1600 m3. If an irrigator applies 5 cm irrigation depth then the


stored volume can irrigate at least 3.2 hectares. It is farmers choice to properly manage and


efficiently use the stored water as needed.


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Published in: Volume 07 Issue 25

Short Link: http://www.technologytimes.pk/?p=15855