Measurements of hydraulic conductivity, K, on four forest catchments that show substantial differences in hydrological behaviour are reported. Field descriptions of principal profile forms and extended profile forms were used as criteria for determining catchment uniformity. Simple and rapid measurement methods for K were necessary. These are described, and one, the well permeameter method, has been further evaluated. Results of many measurements indicated that K distribution was very nearly log-normal for all catchment components and depth intervals studied. Strong variability with respect to K was apparent within each 'uniform' component; however, most of this variability was already present within very small areas. Subdivision of catchments using principal profile forms explained differences in mean K of an order of magnitude, extended principal profile form descriptions were useful to distinguish smaller, but significant, differences in mean K. The usefulness of these catchment conductivity data, for inter-catchment comparison, and for explaining storm-hydrograph shapes of individual catchments, is indicated.

Various concise equations have been proposed, and used, to describe the dynamics of one-dimensional, vertical, infiltration into uniform soils. Such equations, even when initial and boundary conditions are satisfied, do not describe infiltration with equal accuracy for all materials, especially when applied over a large time interval. Recently proposed equations appear more reliable and require only two, easily measurable, soil properties, viz., sorptivity and hydraulic conductivity, for application in most practical situations. Numerical, laboratory, and field data are presented. These adequately support the reliability of the solutions. The applicability of the solutions to field soils with systematically varying conductivity is more restricted than the two- or three-dimensional solutions.

Experimental shrinkage lines, obtained by simple measurements of vertical shrinkage and moisture loss, are shown for a swelling clay paste. Sample loading substantially lowered the void ratio at any given moisture content, although all shrinkage lines remained approximately parallel to each other. Ranges of 'zero', 'residual', and 'normal' shrinkage were readily identified for the loaded samples, but were less distinct for the unloaded samples.

Measurements of sorptivity are reported for a number of field soils. The main method, used in situ, is simple and consists of timing initial vertical flow of water into an undisturbed soil profile. This method relies on the assumption that, during the measurement time of 1-2 min, the first term of the infiltration equation i = St1/2 + At + Bt3/2 . . . dominates flow. In other methods horizontal inflow was timed into undisturbed soil blocks, and capillary rise was observed in undisturbed field cores. Sorptivity was quite variable on each site, with standard deviations of the same order as those found for hydraulic conductivity. For most soils the three methods estimated sorptivity differently, the field method giving the largest values. These differences were largely due to the effect of water depth over the soil on sorptivity. Head dependence of sorptivity, verified experimentally and with delta function theory, was particularly strong in soils of composite structure, where infiltration is dominated by structural cracks and root channels. These soils also have relatively large values of the ratio of hydraulic conductivity to sorptivity. Large ratios of hydraulic conductivity to sorptivity and strong head dependence of sorptivity may cause significant errors in calculating sorptivity in the field method. However, these errors are compensating, and analysis of the data indicates that over-estimation of sorptivity in such soils is at the most 5%. For subsoils and soils of single grain structure these errors were negligible. Average sorptivity values of some of these soils have given good quantitative agreement between theory and field data on two-dimensional flow.

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