Irrigation of Small-Level Basins in Egypt

A major effort is under way to rehabilitate Egypt's vast irrigation system and to improve its management. To be effective, planning decisions must be in concert with irrigation needs at the farm level. Data on conventional farm irrigation practices provide an objective rationale for irrigation planning. Intensive field studies of irrigation practices on fields containing small-level basins produce data descriptive of the magnitude and variability of application rate, application time (duration), applied depth, and application efficiency. Average application rates are between about 0.10 and 0.20(m3/s)/ha. Average application times are high, ranging between about 10 and 25 hr ha. Applied depths average between 7 and 13 cm. In the alluvial clay soils, average application efficiencies are about 0.70-0.75. In sandy soils, the average measured application efficiency is about 0.45. The variability in the observed values of each of these irrigation parameters is high: Coefficients of variation typically range from about 0.50 to 1.00. The data reveal no clear dependence of application efficiency on application rate. Though the variance in the data is considerable, a power-function dependence of application time on application rate is established. Thus, the delivery of larger flow rates to farm turnouts should produce savings in irrigation time and labor. However, larger flow rates cannot be expected to result in higher irrigation efficiencies unless farmers are assisted to understand better how to evaluate and manage irrigations under varied field conditions.