INFILTRATION-ADVANCE EQUATION FOR FINITE LINEAR SOURCE

Several infiltration-advance equations arc developed for a finite line ar source spreading water onto a smooth horizontal surface. These incl ude 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 characterist ics of the applied water slug from such a source. A transformation tec hnique is also presented showing how to transform existing solutions o f infiltration advance in Cartesian space to the elliptical space of t he finite-line source. A general wetted-surface-area advance equation is also developed. The area advance equation is applicable to most phy sical irrigation situations on roughly horizontal ground using a sourc e of any shape. The Horton cumulative infiltration equation associated with the fit of the wetted-area advance equation to measured-area adv ance values is compared to the infiltration values calculated using a volume-balance technique for an actual irrigated basin.