Predicting and controlling water logging and groundwater flow in sloping duplex soils in western Australia

Water logging and groundwater recharge were studied at a site in southwestern Australia characterised by sloping duplex soils in a Mediterranean environment. The specific objectives of the study were: (a) to determine the effectiveness of land management systems involving trees, shallow interceptor drains, and perennial pasture in reducing water logging and recharge risk; and (b) to predict water logging risk at the plot and catchment scale. We found that properties inherent in the site (soil hydraulics, topography, surface dams) had a larger control over seasonal water logging than differences in vegetation cover, with large variations in water logging and recharge over a relatively small area. Such variability would be difficult to capture in any detail using a process model of water logging. The tree/drain systems had local effects on water logging control, but this was mostly due to the direct effects of the trees, which provided localised discharge from deeper groundwater systems.