Soil Moisture and Runoff Processes at Tarrawarra

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Soil Moisture and Runoff Processes at Tarrawarra

246 A Western and R Grayson

spatial organisation feature that is not captured by standard geostatistical techniques

(variography). We were able to show that indicator geostatistics (indicator

variograms) are also unsuitable for characterising connectivity, despite suggestions

to the contrary in the literature (Western et al., 1998b). However, connectivity

statistics (Allard, 1994, 1993) provide an appropriate statistical tool for

characterising spatial connectivity (Western et al., 2000).

The use of patterns in model testing is valuable but has some limitations.

Many of the simulated patterns were quite similar and it was difficult to assess

visually which was the better simulation, especially when patterns for all

twelve occasions were considered. There is a need for quantitative pattern

comparison techniques that account for a range of different scales including

points, hillslopes and catchments. The statistics used for these comparisons

need to be chosen carefully so that hydrologically important aspects of the

patterns are compared. This might require the comparisons to focus on specific

components of the landscape, for example, drainage lines rather than

ridge tops, or on correctly simulating pattern features such as connectivity.

It is also important that any quantitative approach be able to deal with

several different types of data. Here the combined use of soil moisture pattern,

saturation deficit time series and runoff time series data was extremely

valuable.

ACKNOWLEDGEMENTS

The Tarrawarra catchment is owned by the Cistercian Monks (Tarrawarra) who have provided

free access to their land and willing cooperation throughout the project. Funding for the

above work was provided by the Australian Research Council (project A39531077 and

S3913076), the Cooperative Research Centre for Catchment Hydrology, the Oesterreichische

Nationalbank, Vienna (project 5309), and the Australian Department of Industry, Science and

Tourism (International Science and Technology Program).

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