Capillary‐Tube Infiltration Model

Abstract

The concept of treating soil matrix as a bundle of capillary tubes was used extensively in the analytical description of hydraulic conductivity of unsaturated soils. Such a concept has seldom been used in the development of infiltration models. The advantage of considering soil matrix as a collection of capillary tubes is that the water flow in large tubes can be separated from the flow in small tubes. Such a separation is desirable in the study of soil macropore flow where the flow in large pores is primarily responsible for ground‐water contamination and recharge. The purpose of this paper is to derive an infiltration model based on the concept of a bundle of capillary tubes for the study of soil macropore flow. The model presented a spatially varied wetting front and was an improvement over the Green‐Ampt infiltration model, which predicted a constant depth front. The soil macropore flow was represented graphically as a finger on a depth‐water content plot.