Infiltration from a Trickle Source: II. Experimental Data and Theoretical Predictions

The theory of transient infiltration from a trickle source, as developed in Part I of this work, was compared with experimental results. Laboratory experiments using a loamy soil were conducted under conditions similar to those assumed in the two‐dimensional plane flow model. Field data were collected from a sandy soil that was wetted by commercial trickles. The field conditions were similar to those assumed in the cylindrical model. The effect of trickle discharge rates on the water content distribution and on the location of the wetting front was considered. The functional relationship between water diffusivity and water content was estimated by a computer technique that complements the conventional method for diffusivity determination. These data, together with the soil water retention curve were used to estimate the hydraulic conductivity as a function of water content. The agreement between theory and experiment, as expressed by water content distribution and location of the wetting front, is generally good and suggests that the theory is applicable to many field situations. Significant discrepancies between observed and theoretical results were obtained only in one case, where the rate of trickle infiltration was large. The theory, as well as the experimental data, indicate that for the conditions studied, an increase in the trickle discharge rate results in an increase in the horizontal wetted area and a decrease in the soil wetted depth.