Authors: Brier, D. And G. W. Robertson
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Published in: CBE Journal » CBE Journal Volume 9 (1967)

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Description: The planning and design of an irrigation scheme requires reliable estimates of the mean and extreme water demands and of the return periods for specified supplemental irrigation water rates. Actual long-term observations of these characteristics under the prevailing climate and a specific type of crop production are seldom available. Me teorological budgeting techniques have been successfully used for estimating the required information from standard climatological data which are available for a nearby weather station over a reasonably long period. Because monthly means and totals of climatic elements mask daily extremes during the course of a season, any analysis in connection with water requirements should be based on daily weather observations. Robertson and Holmes (12) demonstrated the use of standard daily climatic data in determining when and how much water to apply throughout the season. Rickard (11) examined estimated day-to-day changes in soil moisture over 44 seasons and calculated the irrigation requirements for two soil moisture deficit levels. A natural moisture budget, with irrigation superimposed when certain moisture conditions occurred, was applied to four storage models on a daily basis by Ayers (1) to calculate amounts of water and number of irrigations required at each of 11 stations in Southern Ontario. Instructions for calculating irrigation need by meteorological budgeting techniques are available (4, 10, 12, 14, 16). In studies of irrigation requirements it is usually assumed that the total daily water loss from soil and vegetation is at the potential rate. Evapotranspiration, however, is controlled by both soil moisture supply and energy received by crops. Because soil moisture in the top layers decreases rapidly after irrigation and because a young crop does not cover the ground completely, it is most likely that the daily evapotranspiration even though from an irrigated crop may be at times less than the potential rate. In fact, Cackett and Mettelerkamp (6), working with field beans under irrigation, found a close relationship between the ratio of actual evapotranspiration (Et) to Class A Pan evaporation (E

Keywords: estimating supplemental irrigation water requirements for climatological data
Citation: Brier, D. and G. W. Robertson 1967. ESTIMATING SUPPLEMENTAL IRRIGATION WATER REQUIREMENTS FOR CLIMATOLOGICAL DATA. Canadian Agricultural Engineering 9(1):46-50.
Volume: 9
Issue: 1
Pages 46 - 50
Date: 1967
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Coverage: Canada
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