DUNE CHANGE IN TIME AND SPACE – GLOBAL AND REGIONAL PATTERNS

Understanding of the pattern of low- and mid-latitude desert dune field development and change in response to climatic and other variations in boundary conditions is now being facilitated by the development of a global database of geographically located chronologic information compiled from published sources as one of the main products of INQUA Project 0704 - Sand seas and dune fields of the world: a digital Quaternary atlas.

The database contains information on luminescence and radiocarbon dates from dunes on all continents, together with pertinent stratigraphic and geomorphic information. Access to a consistent data set from multiple sources permits statistical analysis of chronometric data to visualize and quantify rates of dune sand accumulation as well to determine spatial and temporal variations in periods of dune sand accumulation. Regional and global comparisons are facilitated by the compilation of data from many different studies.

Examples of analyses of data assembled so far reveal significant variability in the styles and rates of dune accumulation in different arid environments, as well as between dunes of different morphological types. In many areas, dune accumulation appears to be characterized by relatively short episodes of rapid geomorphic change and dune sand accumulation separated by long periods of quiescence or stability characterized by low rates of dune change and sand accumulation.

Analyses of the data also suggest that dune accumulation appears to respond to changes in boundary conditions in a complex manner determined by dune morphological type, antecedent conditions, and relationships between sediment supply, availability, and mobility. Rates of accumulation may vary widely on the same dune, as well as from dune to dune in the same area, raising important questions regarding field sampling strategies and the significance of results obtained from sparsely-sampled dune systems.