Normal distribution water application for drip irrigation schedules

Because emitter flow and emitter discharge along a lateral line can be considered to have normal distributions, the probability density function and the cumulative probability density of the normal distribution can be applied to derive equations for irrigation application efficiency, storage efficiency, deep seepage, and deficit. All of these equations were derived and expressed as a function of an a-value, which indicates the location of a required irrigation depth in the normal distribution and the coefficient of variation of emitter flow of a drip irrigation system. A simple drip irrigation schedule was developed by setting the a-value at zero so that the irrigation application efficiency, storage efficiency, deep seepage, and deficit can be expressed only as a function of the coefficient of variation of emitter flow. It was found that the design range for the coefficient of variation of emitter flow is less than 20%; both the irrigation application efficiency and the storage efficiency are greater than 92%.