The Rewetting of Partially Dried Grass Swaths by Rain: Part 3, Laboratory Investigation into the Rewetting Process

Abstract

A laboratory rig is described which was developed to investigate the behaviour of partially dried swaths when rewetted by simulated rainfall. Results are given from a series of experiments made using the rig. A previously reported distributed model, representing the rewetting of swaths in the field or laboratory, is developed further, particularly with regard to the processes which take place after rainfall has ceased. A least squares optimization procedure was used to fit moisture contents simulated by the model to experimental data, by estimating parameters of the model. Typical time constants for the processes were estimated as 15 h for absorption of surface moisture into grass tissue, and 0·8 h for runoff of surface moisture, with no noticeable differences between conditioned and unconditioned grass material. However, estimates of some other model parameters were considered to be less reliable than those previously reported from field experiments.