Wind erosion flux measured over various land cover types in the arid region of southern Tunisia during 2012-2016

[Lien vers la fiche source] Data distributed here are part of the project “Quantification des émissions d'aérosols terrigènes en fonction de l'usage des sols : exemple du sud tunisien” funded by the CNRS/INSU LEFE program. The south of Tunisia is a region very prone to wind erosion because the soils have a fine sand texture, the vegetation is sparse, and precipitation scarce. It also presents a variety of landscapes and land uses on a relatively small area. This region thus represents a unique opportunity to study wind erosion intensity on different types of land surface, but also on different types of land use. This is why, from November 2012 to June 2016, six sites were instrumented to monitor wind erosion in the most extended land uses existing in southern Tunisia: rangeland on sand, rangeland on flat bed, chott, olive grove, oasis, cereal field. The distributed data document 1) the site characteristics, 2) the saltation flux, 3) the meteorological parameters (wind speed and direction, rainfall), 4) barley height collected from 07/11/2012 to 22/06/2016. Data include: (1) site characteristics: it includes (i) the location, geographical coordinates, land use of the experimental sites, and (ii) the texture and dry size distribution of the soil surface. (2) saltation flux: saltation flux was monitored using masts equipped with Big Spring Number Eight (BSNE) sand traps (Fryrear, 1986), and with a large wind vane so that the opening of all BSNE always faced the wind. The highest BSNEs on the mast had an opening of 10 cm² while the lowest one had a smaller opening (2 cm²). One mast of 7 BSNE sand traps was installed on each site except in Nadhour Rwag where 3 masts of 3 BSNE sand traps were installed to account for the variability in wind erosion that may be induced by the presence of the small bushes of Rhanterium suaveolens and Anabasis articulata. In Chammakh, the mast of 7 BSNE sand traps was installed at the center of a square delimited by olive trees. After accounting for the collection efficiency of the sand traps (assumed to be 100% as suggested by Goossens et al. (2000)), the saltation flux was computed by vertical integration of the cumulative masses collected at the different heights using the exponential formula proposed by Williams (1964). (3) meteorological parameters: in Menzel Habib and Sidi Toui, wind speed and direction were measured at 3 m agl using a 2 dimensional (2D) sonic anemometer (WindSonicTM Gill Instruments Ltd), and rainfall using an ARG100 Tipping Bucket rain gauge (Campbell® Scientific company). Data were acquired using a CR200X data logger (Campbell® Scientific company), with a nominal data acquisition time of 5-min for all parameters measured with a frequency of 0.1 Hz. Given the high variability of both wind speed and direction on a 5-min time step, the maximum and mean values of wind speed, and the mean and standard deviation of wind direction measured over this interval were recorded. 5-min rainfall corresponds to the accumulated bucket tippings over this interval with one tipping corresponding to 0.2 mm of rainfall. (4) in the oued Fessi, barley height was measured by using a meter tape and photographs were used to check the estimates.