Dune mobility

Data from 3 Geomet stations (Jornada, Gold Spring, and Yuma) have been used to test the climatic index of dune mobility developed by Lancaster (1988), as part of a program to understand the response of aeolian processes to climatic change and variability. The test of the index involved comparison of values of the index calculated using climatic data derived from the Geomet stations with measurements of sand transport rates at the same locations.

Results

• Changes in measured rates of sand transport closely parallel temporal changes in the dune mobility index (Fig. 1).

  
  
  

• The mobility index is, however, a relatively poor predictor of the magnitude of actual sand transport on a year to year basis (Fig. 2). This is because sand transport rates at these sites are strongly influenced by vegetation cover, the state of which may lag changes in annual precipitation.

  
  

• There is, however, a good relation between the mean annual mobility index and mean annual rates of sand transport (Fig 3).

  
  

• The dune mobility index is a valid predictor of the long term state of the aeolian system and can be used confidently for the purposes for which it was originally intended.