Hydraulic conductivity measurement of forest catchments

Abstract

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.