Desert channel erosion, accretion characteristics and their implications for aeolian–fluvial interactions: a case study in a desert watershed in the Ordos Plateau, China

The significance of aeolian–fluvial interactions in controlling the geomorphology of the landscape in semi-arid desert dune fields has long been appreciated, but limited field data are available to examine how these modern aeolian–fluvial processes interact with the desert channel. In this study, based on desert channel changes and flash flood monitoring during a field survey, we characterize the responses of the desert channel to interactions between fluvial and aeolian processes in an ephemeral desert river in the ten kongduis region in the Hobq Desert in the Ordos Plateau (China). We find that the desert channel is the key place for interactions between aeolian and fluvial processes and has a significant impact on erosion and sediment yield. The pattern of aeolian–fluvial interactions in this area is that aeolian processes can move dunes and narrow the channels in the dry season, but storm floods can cause hyper-erosion of dune-covered banks and widen the channels, which are characterized by hyper-concentration flows during the flood season. Based on the cross-sections, the results show that the channel cross-section accretion area in the dry season was 0.4 times and 0.2 times the channel erosion area in the flood seasons of 2011 and 2012, respectively, of which the left bank accretion area in the dry season was 0.3 times and 0.1 times the left bank erosion in the flood seasons of 2011 and 2012, respectively. In the flood season, the dune-covered left bank erosion and sediment yield were 3.5 times those of the right bank on average. For channel lateral movement, the channel narrowing width caused by aeolian dune accretion in the dry season was 1/6 of the channel widening induced by storm-flood erosion in the flood season. Therefore, aeolian–fluvial interactions control the landform and landscape evolution in this desert area.