Infiltration‐Advance Equation for Finite Linear Source

Abstract

Several infiltration‐advance equations are developed for a finite linear source spreading water onto a smooth horizontal surface. These include ones for a noninfiltrating soil, one with a constant infiltration, and three functional forms of time‐variable infiltration. Along with the equations is a discussion of the spatial and temporal characteristics of the applied water slug from such a source. A transformation technique is also presented showing how to transform existing solutions of infitration advance in Cartesian space to the elliptical space of the finite‐line source. A general wetted‐surface‐area advance equation is also developed. The area advance equation is applicable to most physical irrigation situations on roughly horizontal ground using a source of any shape. The Horton cumulative infiltration equation associated with the fit of the wetted‐area advance equation to measured‐area advance values is compared to the infiltration values calculated using a volume‐balance technique for an actual irrigated basin.