Mapping the interactions between rivers and sand dunes: Implications for fluvial and aeolian geomorphology

• The first global inventory of river - dune interactions using satellite imagery.
• Systematic analysis of the interactions between fluvial and aeolian geomorphology.
• Characterising the impact of combined fluvial – aeolian systems on geomorphology.
• Determining the dominance of fluvial and aeolian systems in different settings.

The interaction between fluvial and aeolian processes can significantly change Earth surface morphology. When rivers and sand dunes meet, the interaction of sediment transport between the two systems can lead to change in either or both systems. However, these two systems are usually studied independently, which leaves many questions unresolved in terms of how they interact. This paper carries out a global inventory, using satellite imagery, to identify 230 sites where there are significant fluvial–aeolian interactions. At each location key attributes such as wind/river direction, net sand transport direction, fluvial–aeolian meeting angle, dune type and river channel pattern were identified and relationships between each factor were analysed. From these data, six different types of interaction were classified that reflect a shift in dominance between the fluvial and aeolian systems. Results from this classification confirm that only certain types of interaction were significant: the meeting angle and dune type, the meeting angle and interaction type and finally the channel pattern and interaction type. However, the findings also indicate the difficulties of classifying dynamic geomorphic systems from snapshot satellite images.