The Global Digital Dune Map
1, Nick Lancaster2, Matt Telfer3
1Macquarie University, Sydney, NSW, Australia, 2Desert Research Institute, Reno, Nevada, USA, 3Plymouth University, Plymouth, UK
A new digital (GIS) map of global inland dunefields offers new insights into the distribution, character and environmental controls of sand dunes. This map combines existing GIS coverages, digitisation of previously published maps, where available, and substantial new mapping directly from base layer satellite imagery within ArcMap.
We have mapped all visible constructional aeolian landforms, (usually) with repeated, self-organised patterns. All inland dunes, regardless of the inferred level of activity, preservation, vegetation cover, or size have been mapped. Limitations of the mapping occur when satellite imagery is of poor resolution or quality, in areas of cultivation/cropping and where dunes are small. We have attempted to exclude sand sheets and streaks but there are still many ambiguous areas, for example fields of partly erosional, partly depositional small dunes associated with nebkha.
The new mapping has dramatically altered the picture of dunefield distribution in parts of Eurasia and South America in particular. New sand seas have been identified in high latitudes of western Siberia, for example, while proposed sand seas in South America (in the Pantanal) have been discredited. In other continents (North Africa, China, Australia, Central Asia) the mapping clarifies the boundaries and connections between dunefields but will also force revision of previous nomenclature.
The global perspective on dunefield distribution emphasises the role of sand supply on dunefield formation. This is not simply related to denudation/erosion rates but also to the non-aeolian sorting processes which concentrate sand and make it available aeolian reworking.
To date the mapping includes only polygons of dunefields without information on dune type or orientation. Additionally, we have mapped dune activity according to morphological classes to study climatic relationships (Lancaster and Hesse, this conference).
When complete, the map will be made freely available with the hope that it becomes an aid for researchers of aeolian geomorphology and continually updated as improved data and mapping become available.