The impact of past and present land use on a major coastal barrier system

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This paper considers the relative impacts of past and present land use on the stability of the major coastal barrier complex of the Younghusband Peninsula and Coorong lake chain of South Australia. Data have been obtained from field survey and mapping, field studies of soil shear strength, interviews, aerial photographs, archaeological survey, documentary and cartographic historical sources. The investigation shows that large-scale changes in dune stability have occurred in the prehistoric past, probably as a result of as yet unspecified climatological/ oceanographic fluctuations. The legacy of both pre-European aboriginal land-firing and of European pastoralism appears to have had a minor impact on the dunes compared to the more recent use of off-road recreational vehicles. Even in the most intensively used areas, however, local stability of the sand dunes occurs, apparently due to the exposure of prehistoric shell-middens interbedded with palaeosols, which together offer greater resistance to off-road vehicles than many other soils in the barrier system. There are important differences in the scale and type of geomorphic impact of the many kinds of vehicles now taken off-road, and in the attitudes of different users of the same type of vehicle. These attitudes and impacts interact with each other, and with various aspects of the physical geography of the region, to cause the pattern and rate of environmental degradation to spread in a characteristic manner. In particular, the character and distribution of scrub, mallee and lacustrine habitats, as well as of settlements, are shown to markedly affect the manner in which the entire network of tracks and used ground develops. The pattern of past and present access and communications routes seems to have been particularly important. For management purposes it is important to view these interactions not only at the level of the individual track or path, but also at the level of the entire National Park based on the coastal barrier system, and then to expand the management framework again to regional level at which the off-road vehicle problem must ultimately be resolved. These observations are incorporated into suggestions for improving the control of off-road recreational vehicle use in the barrier system, and in the region at large.