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.

The performance and characteristics of small, porous cup, soil-water extractors, installed in a soil with known water-transmission properties, are described. Cup conductivities decreased sharply during an 8 week period and, in the absence of other flux limiting factors, would limit water entry in the permeable topsoil but not in the slowly permeable subsoil. Measured cup water uptake however was much less than that predicted from either cup conductivity or soil water transmission properties. This is attributed to flow impedance near the cup walls. Under these conditions flow distribution in a soil with extractor cups would be much closer to that of an unextracted soil than is predicted from soil water flow theory.

An initial appraisal of the mechanisms involved in reactive solute transport through a weathered soil profile was made by following the movement of potassium and chloride during prolonged leaching on a sprinkle-irrigated native forest plot. The soil was an acid, strongly base-unsaturated red duplex soil with a high surface and subsurface hydraulic conductivity. Water movement was followed by tensiometers located at regular depth intervals to 1.5 m, and soil water samplers with ceramic cups were used to collect soluble potassium and chloride. Some 650 mm of water moved beyond 1.5 m depth in the profile, but chloride did not move beyond 1 m. Nearly all of the potassium was retained in the soil above 0.6 m depth. Although both ions underwent ion exchange, adsorption of potassium was reasonably uniform through the profile, whereas chloride adsorption increased with depth. Immediate ground- and stream-water contamination did not occur under these conditions.