Soil Erosion by Wind in Southern Tunisia Cultivated Lands and Rangelands: Experiments and Modeling

Southern Tunisia, below the 200 mm an(-1) isohyet, is naturally susceptible to wind erosion resulting from harsh climatic conditions and inappropriate use of natural resources. Moreover, the use of new agricultural techniques instead of the traditional ones and plowing to cultivate crops (cereals and olive trees particularly) has amplified soil erosion by wind during the last decades. This work aims to focus on quantifying wind erosion in Southern Tunisia to determine the most susceptible areas. Particular attention has been carried to the description and assessment of land use (rangelands, the extension of cultivated lands, change of agricultural practices, etc.). Then, an approach combining experiences on parcels and modeling is implemented. The modeling approach is based on estimated wind erosion flux with a grid mesh size of 10 km x 10 km for the main landscape units (land use) and depending on agricultural practices with the wind erosion model "Dust Production Model.' We first identified the most frequent and intense simulated zones sources of sand and dust emission. We also evaluated the relative contribution of both range-lands and cultivated lands to the wind erosion horizontal fluxes. The results suggest that most simulated wind erosion flux stays predominant in rangelands, representing the dominant encountered land use unit. When examining the sediment flux in the cultivated lands, we observe that these surfaces contributed little, and the easiest and most eroded by wind are cereal fields then olive orchards.