Soil erosion by wind over tilled surfaces in South Tunisia

Abstract Wind erosion flux measurements and associated micrometeorological parameters were obtained in South Tunisia over agricultural plots that have been tilled with different ploughing tools (mouldboard, tiller, disc). Complementary measurements were also performed to characterize the surface properties, especially the geometric characteristics of the ridges and the soil grain size distribution. The results clearly show that the wind erosion fluxes are significantly higher over agricultural surfaces tilled by disc plough compared to those measured on the plot tilled with mouldboard or tiller ploughs. The difference in the erosion fluxes is about a factor 4 between disc and tiller and an order of magnitude between disc and mouldboard. These results strongly suggest that the new techniques of tillage, like disc, could increase drastically the soil erosion by wind, at least on agricultural plots constituted of loose soils. These results were also used to test the parameterization proposed by Kardous et al. (2005a,b) to simulate the horizontal fluxes of sediment produced by wind over ridged surfaces. The comparisons between the simulations performed by using this parameterization and the measured erosion fluxes show that this parameterization, despite its simplicity, reproduces quite satisfyingly the measurements whatever the type of surfaces and for both low and intense erosion events. However, sensitivity tests have pointed out that this parameterization is especially sensitive to the precision at which the geometric characteristics of the ridges are determined.