Infiltration from a strip source

Abstract

This study addresses infiltration from strip sources of water on the soil surface. The problem arises as the limiting case of furrow irrigation as well as for closely spaced surface drip emitters. Previously, the most common approach used for describing flow from strip sources was numerical modeling based on Richards' equation. This work investigates a third approach borrowed from previous applications for infiltration from disc sources. The assumption is that when the cumulative infiltration is expressed per unit area of the wetted strip, the difference of that value and one‐dimensional infiltration is linear with time. We test the assumption directly by doing numerical experiments with six representative soils and using various strip widths, boundary, and initial water contents. The general conclusions are that the differences between the cumulative infiltration per unit source area for a strip and a planar source are linearly related to time but that a single value of the proportionality factor γ is generally inadequate. Values of γ are found between 0.64 and 1.16. An effort was made to relate γ to soil hydraulic parameters and strip width as well as to the boundary and initial conditions. Once γ is defined, the strip infiltration follows immediately if the corresponding one‐dimensional solution is known without the necessity of performing a two‐dimensional simulation.