Apport des données Landsat Thematic Mapper pour la cartographie des sols dans la région de Menzel Habib

Un essai de cartographie des sols a été réalisé au niveau de la zone de Menzel Habib, située en Tunisie présaharienne dans la région naturelle des basses plaines méridionales. Cette zone fait partie d’un Réseau d'Observatoires de Surveillance Écologique à Long Terme (ROSELT) mise en place par l’Observatoire du Sahel et du Sahara(OSS), dans le cadre d’un programme de suivi environnemental de la désertification. Ainsi, conformément aux objectifs généraux de ce programme insistant sur l’intérêt de la valorisation et l’exploitation des données anciennes pertinentes en relation avec le thème recherché par la présente étude. On a adopté une approche méthodologique reposant principalement sur la classification multispectrale d’une image satellite en ayant recours aux cartes des ressources en sols et pédologiques existantes. Il en ressort une carte pédologique couvrant toute la zone de Menzel Habib répartis en huit classes.Mots-clés : sols, cartographie, classification multispectrale, image satellite

The Olive Mills Waste Water (OMW) as an Organic Amendment for Controlling Wind Erosion in Southern Tunisia by Improving the Soil Surface Structure

Abstract: Spraying OMW on poor sandy soils in the olive orchards induces increasing of the organic matter content, the formation of aggregates and improving the soil structure stability. Hence, OMW can be an alternative and effective way to control this polluting sewage. Since 1995 a field experiment is running in an olive plot in chammakh-Zarzis, south Tunisia, where rates of 50, 100 and 200 m 3 of OMW were sprayed yearly on 1 ha fields with 16 olives trees per ha. Data collected in 2006 showed an increase in organic matter content from originally 0.06 to 1.27 %, an increase in the amount of aggregates > 2 mm to 34%, and an increase in the threshold friction velocity for deflation to 12 m sec -1 for the 200 m 3 ha -1 application

Research of Lean Premixed Flame by Chemiluminescence Tomography

An experimental research of lean premixed flame in a swirl burner is performed using CH* chemiluminescence imaging. The images of flame are acquired and the flame structure is investigated. The position of flame front, represented by the area with highest rate of exothermic chemical reactions, is deduced from the acquired images. To identify the flame front using two dimensional images, a method of image tomography is applied. A tomography of the images is numerically performed using an in-house developed numerical Abel transform. It is found that flame tomography enables precise location of flame front in turbulent flows. The tomography research is compared and analyzed with the numerical results of the same burner

Assessing the effectiveness of sustainable land management policies for combating desertification: A data mining approach.

This study investigates the relationship between fine resolution, local-scale biophysical and socioeconomic contexts within which land degradation occurs, and the human responses to it. The research draws on experimental data collected under different territorial and socioeconomic conditions at 586 field sites in five Mediterranean countries (Spain, Greece, Turkey, Tunisia and Morocco). We assess the level of desertification risk under various land management practices (terracing, grazing control, prevention of wildland fires, soil erosion control measures, soil water conservation measures, sustainable farming practices, land protection measures and financial subsidies) taken as possible responses to land degradation. A data mining approach, incorporating principal component analysis, non-parametric correlations, multiple regression and canonical analysis, was developed to identify the spatial relationship between land management conditions, the socioeconomic and environmental context (described using 40 biophysical and socioeconomic indicators) and desertification risk. Our analysis identified a number of distinct relationships between the level of desertification experienced and the underlying socioeconomic context, suggesting that the effectiveness of responses to land degradation is strictly dependent on the local biophysical and socioeconomic context. Assessing the latent relationship between land management practices and the biophysical/socioeconomic attributes characterizing areas exposed to different levels of desertification risk proved to be an indirect measure of the effectiveness of field actions contrasting land degradation