Aeolian dust erosion on different types of hills in a rocky desert: Wind tunnel simulations and field measurements

Aeolian erosion of natural dust on two types of hills located in a rocky desert was investigated by means of wind runnel simulations and field measurements. The first hill showed an elongated, nearly symmetric shape and was oriented perpendicular to the wind, whereas the second hill was almost perfectly conical. Erosion was measured along three transects: one across the elongated hill (transect parallel to the wind) and two across the conical hill (transects perpendicular to each other and crossing at the summit). In the field, erosion was measured on erosion plots during two wind storms. In the wind tunnel, erosion was measured on topographic scale models. The wind tunnel experiments and field experiments showed good agreement: the greatest dust erosion was observed on the windward hillslopes, and more particularly on their upper part, close to the top. The highest erosion occured at or immediately before the top. Downwind of the top, on the leeslope, erosion drops considerably. It remains important on the whole leeslope, however, and remains visible in the valley floors, although erosion is low there. The areas that are most sensitive to wind erosion are accurately predicted in the wind tunnel simulations. In rocky deserts, wind storms have a large impact on the dust balance. Nearly all dust erosion takes place during storms that occur only once or a few times per year.