Assessing the Environmental Characteristics of the Margaret River Wine Region, Australia: Potential New Geographical Indication Sub-Units

Six sub-regions of the Margaret River Geographical Indication were proposed in 1999 in an attempt to characterize local variations in grape-growing conditions. Detailed environmental data has since been produced and this article aims at reassessing the proposed sub-regions by means of a GIS-based spatial analysis of the new datasets. Topography, climate, and a variety of soil parameters were reviewed, and a relevant set submitted to an unsupervised isocluster classification to determine the natural clustering of environmental parameters. The analysis shows that the initial sub-regions do not consistently respect climate patterns and soil type distribution. It is proposed to distinguish twelve natural units by considering temperature and rainfall gradients as well as the presence of the Dunsborough Fault system which appears to have a significant control on soil distribution. This study also shows that average growing season temperatures have gained +0.2°C across the peninsula from 1961–2000 to 2001–2015.