Andrew W Western 1
Rodger B Grayson 1
Guenter Bloeschl 2
Garry R Willgoose 3
Thomas A McMahon 1
Workshop on Scale problems in hydrology, 17-20 June, 1996, Hotel Schlo§ Krumbach, near Vienna, Austria, Institut fŸr Hydraulik GewŠsserkunde und Wasserwirtschaft, Technische UniverstŠt Wien / Centre for Water Research, The University of Western Australia, p. 31.
Soil moisture plays an important role in rainfall-runoff behaviour, land-atmosphere interactions and pedogenesis over a wide range of scales. Runoff processes are associated with both organised and random spatial variations in soil moisture at the hillslope and small catchment scales. These spatial variations are being studied in detailed field experiments at Tarrawarra, Victoria, Australia. This catchment is located in undulating terrain and has hillslopes with podzolic soils and typical slopes of 15% and valley floors with clay soils. The climate is temperate and the average rainfall is 1000Êmm.
Soil moisture at Tarrawarra is being mapped on a 10x20Êm grid over the entire catchment (over 500 sites) and on a 2x2Êm grid over smaller areas within the catchment. Soil moisture measurement is performed in the top 30Êcm of the soil profile using hydraulically inserted Time Domain Reflectometry probes mounted on an all terrain vehicle fitted with a position fixing system. A range of other data including soil moisture profile, meteorological, surface runoff, soils, topography, surface roughness, vegetation and remote sensing data are also being collected.
Results to date show that the spatial distribution of soil moisture exhibits both organisation and randomness. During late winter (wet) conditions the soil moisture is strongly organised by the topography while it is much more random during summer (dry) conditions. The range in observed soil moisture is smaller during dry conditions which reflects both the feedback between soil moisture and evapotranspiration and the lack of lateral water movement during drier periods. Correlation analyses have been conducted between soil moisture and a range of terrain parameters including slope, aspect, tangent curvature, profile curvature, specific upslope area and ln(a/tanb) to determine which topographic parameters may be used to predict the spatial pattern of soil moisture.
Back to Andrew Western's Home Page
Back to the Department of Civil and Environmental Engineering
Created: January 1996
Last Modified: 31 August 1998
Access: Unrestricted
This page, its contents and style, are the
responsibility of the author and do not necessarily represent the views,
policies or opinions of The University of Melbourne