Abstract
Large infiltration ponds (10–15 m2) were used, in conjunction with a ring infiltrometer and a well permeameter, to determine the infiltration characteristics of a complex lateritic soil profile in the jarrah (Eucalyptus marginata) forest of Western Australia. Simultaneous measurements of soil water content and soil water potential allowed a description of the infiltration and redistribution in the soil profile. The infiltration ponds effectively measured the conductivity of a subsurface lateritic duricrust which was found to have a relatively high saturated hydraulic conductivity (Ks) of 2.7 m d−1, despite its apparently massive and extensive nature. Removal of the topsoil identified large (≈1 m2) infilled holes penetrating the duricrust over about 6% by area. Measurements indicated that these large ‘holes’ had a high Ks value (≈ 10 m d−1), whereas the remaining duricrust had a lower Ks value (≈ 2m d−1). These results have implications for probable maximum flood design calculations and assessing the hydrological impact of extensive open-cut bauxite mining.