PROBLEMS ENCOUNTERED IN ESTIMATING EFFECTIVE PRECIPITATION

摘要

In irrigation practice, effective rainfall is defined as the amount of total precipitation retained by the soil and available for use for crop production. This is in sharp contrast to the hydrologic definition of effective precipitation as rainfall that produces surface runoff.nAssessment of the adequacy of rainfall amount and distribution to fully supply the crop water requirements is a basic step in determining if irrigation is needed. A deficiency in meeting this need provides an estimate of the net irrigation requirement.