Green‐Ampt Analysis of Wetting Patterns for Surface Emitters

Abstract

A three‐dimensional Green‐Ampt analysis is developed, and the infiltration capacity curve for a three‐dimensional infiltration model is presented. The infiltration‐capacity curve represents the time distribution of wetting‐pattern volume of a water source with unlimited inflow supply. A significant feature of the infiltration‐capacity curve is that the infiltration‐capacity rate increases with time during extended infiltration periods. This feature is different from the one‐dimensional infiltration model where the infiltration‐capacity rate decreases with time. The infiltration‐capacity curve is applied to describe the wetting pattern of a surface emitter with a constant discharge by matching the emitter discharge with the average infiltration‐capacity rate. Algebraic solutions of the wetted radius and the maximum wetting‐pattern depth are derived. Graphical solutions of the infiltration‐capacity curve are presented. A numerical example is prepared to illustrate the procedure for estimating time of application, wetting pattern volume, emitter discharge, and irrigation period of a surface emitter in a drip‐irrigation system.