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Water Users Association and Irrigation Management - Institute for ...

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<strong>Water</strong> use efficiency<br />

Poor water use efficienc/ is a major cause of rising water tables. Rosergrant (1991), cited<br />

in Crosson & Anderson (1992), estimates the water use efficiency in many systems in Asia<br />

<strong>and</strong> shows that it varies between 25 <strong>and</strong> 40 percent. That is, 60 to 75 percent of the total<br />

volume of water channeled to farms is not available <strong>for</strong> crop use. The inefficient<br />

application of irrigation water by farmers as a major contributory factor to increasing water<br />

tables has been noted extensively (Aceves-Navarro 1985; Postel 1985; FAO 1988 <strong>and</strong><br />

1990; World Bank 1991).<br />

Aceves-Navarro (1985) reports that in Mexico, when irrigation was introduced in the arid<br />

areas, fanners believed that, as more water was applied, a higher yield was obtained. This<br />

belief led to serious seepage <strong>and</strong> salinity problems in the Mexican irrigation districts. In the<br />

Chashma project in Pakistan with a shift to more water-dem<strong>and</strong>ing crops such as rice <strong>and</strong><br />

sugarcane, there was excessive irrigation by farmers during the early stages of project<br />

development when water was abundant. As a result, water tables rose more quickly than<br />

expected leading to the need to invest in drainage works at an earlier date than anticipated<br />

(World Bank 1991).<br />

In India, the typical situation in most irrigated comm<strong>and</strong>s is violation of cropping pattern<br />

<strong>and</strong> over watering in the head reaches <strong>and</strong> lack of water at the tail. This has contributed<br />

significantly to localized waterlogging <strong>and</strong> salinization in the head reaches of the comm<strong>and</strong><br />

area of major protective irrigation projects. <strong>Water</strong>logging <strong>and</strong> salinization in the head<br />

reaches especially aggravated monsoon waterlogging in eastern India (World Bank 1991).<br />

The main cause of waterlogging appears to be excess water application due to excessive<br />

paddy cultivation (Abbasi 1991). The Tenth Five Year Plan mentions that unsustainable<br />

practices like excessive use of water together with imbalanced use of fertilizers especially<br />

after the green revolution has affected the soil health <strong>and</strong> environment adversely.<br />

Carruthes (1985) notes that the shift from seasonal to perennial irrigation in Egypt, India<br />

<strong>and</strong> Pakistan could not be efficiently h<strong>and</strong>led by farmers <strong>and</strong> seepage increased. In addition<br />

7 <strong>Water</strong> usc efficiency refers to the relationship between the amount of water required <strong>for</strong> a particular purpose<br />

<strong>and</strong> the quantity of water delivered. <strong>Irrigation</strong> water use et11ciency is measured at three different levels:<br />

conveyance, distribution, <strong>and</strong> at the field.<br />

16

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