The effect of surface variability factors on wind‐erosion susceptibility: A field study in SW Niger

Abstract

AbstractThe effects of several surface treatments and factors that influence wind‐erosion susceptibility were measured with the means of a mobile wind tunnel. The test surfaces are situated in the SW part of the Republic of Niger in W Africa. The measurement program included the determination of total and dust‐mass fluxes and surface‐specific wind‐erosion parameters like aerodynamic roughness and friction velocities. Different treatments and variations were investigated on one typical and common sand surface type: different densities of stone cover, different kinds of millet‐residue alignments, and different topsoil humidities as well as the effect of different densities of fallow vegetation. The on‐site experiments in a controlled wind‐tunnel environment allowed the observation of effects that were only scarcely described in wind‐erosion literature. Increased stone cover resulted in increased emission due to increased turbulence and channelling effect, in spite of increased surface roughness. Millet‐residue alignment in transversal orientation to the wind direction resulted in far higher emission reduction as documented in the literature. Topsoil humidity, though far above the known threshold for erosion, could not completely inhibit particle entrainment because of the quick development of a thin superficial layer of dry particles.