MEASUREMENTS OF CUMULATIVE INFILTRATION AND WETTING FRONT LOCATION BY TIME DOMAIN REFLECTOMETRY

Abstract

Knowledge of wetting front location and cumulative infiltration during irrigation and rainfall events are important to many areas of soil science. We tested a new procedure using time domain reflectometry (TDR) to estimate wetting front location and cumulative infiltration. The method is based on an assumption of a uniform soil water content behind the wetting front. Measurements of wetting front location and cumulative infiltration were made with 0.144-m-long TDR probes vertically inserted into homogeneous loamy sand columns. Unlike previous procedures using TDR, the new procedure could be applied to short TDR probes (≤ 0.3 m) because the procedure did not require determination of a reflection of electromagnetic waves from the wetting front in TDR traces. The method gave satisfactory estimates of both wetting front location and cumulative infiltration.