25 years of off road vehicles on the beach ....
The increased use of off-road vehicles in coastal environments is a growing concern for environmental managers. Intensive field studies have conclusively shown that sand dune biodiversity, structure and stability can be affected by even minimal off-road vehicle traffic. Anecdotal evidence of their effects has been observed on the Nullarbor coast south of Yalata in South Australia where extensive sand dune transgression is evident. The Nullarbor coast is approximately 100 kilometres long, extending up to four kilometres inland. Little data is available to evaluate claims of dune transgression caused by off-road vehicles, however archival aerial photography offers the opportunity to increase our understanding.
This study aims to objectively determine any correlation of track proliferation to the dune dynamics of the study site. Exposed dune boundaries and visible off-road tracks were digitised from visual interpretation of the orthorectified 1:40,000 scale aerial photographs. A GIS was used to calculate dune boundary differences and their proximity to tracks and track density across the time series. Subsequently, the effects of off-road vehicle use on dune movement were analysed using correlation analyses of the density and proximity to areas of apparent sand dune migration.
Although results indicated increased off-road vehicle use as well as a net inland sand dune migration, no direct correlation between the two could be confirmed. The lack of correlation is due to vegetated dune colonisation in areas of high track proliferation as well as dune transgression in relatively pristine areas. The results of this study do not refute the possible impacts of vehicular traffic on sand dune movement, however natural processes appear to overshadowed them.