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This study aims to assess the performance of the Sentinel-2 and Landsat 8 sensors to map forest fires. We choose two fire events, the Haddad fire and the Sidi Ferdjani fire, in northwestern Tunisia in 2017. Several spectral indices were derived from each sensor and the performance of each spectral index was assessed. A validation exercise was undertaken for each fire to compare the spatial matching between the burned area retrieved from each spectral index and its homologue obtained from the Emergency Management Service (EMS). Our results indicate that ΔNBR and its relativized version RBR derived from both sensors exhibit the highest discrimination power (M-statistic values >2.5). The Sentinel sensor is slightly more efficient than the Landsat 8 in mapping burned scars, but both sensors produce acceptable results. We conclude that both sensors could be a good alternative to EFFIS data, particularly when there is a need to detect details inside the burned areas. [ABSTRACT FROM AUTHOR]

We used GIS and maximum entropy to predict the potential distribution of six snake species belong to three families in Kroumiria (Northwestern Tunisia): Natricidae ( Natrix maura and Natrix astreptophora), Colubridae ( Hemorrhois hippocrepis, Coronella girondica and Macroprotodon mauritanicus), and Lamprophiidae ( Malpolon insignitus). The suitable habitat for each species was modelled using the maximum entropy algorithm, combining presence field data (collected during 16 years: 2000-2015) with a set of seven environmental variables (mean annual precipitation, elevation, slope gradient, aspect, distance to watercourses, land surface temperature and normalized Differential Vegetation Index. The relative importance of these environmental variables was evaluated by jackknife tests and the predictive power of our models was assessed using the area under the receiver operating characteristic. The main explicative variables of the species distribution were distance from streams and elevation, with contributions ranging from 60 to 77 and from 10 to 25%, respectively. Our study provided the first habitat suitability models for snakes in Kroumiria and this information can be used by conservation biologists and land managers concerned with preserving snakes in Kroumiria. [ABSTRACT FROM AUTHOR]

The present work tests the use of hypsometric integral (HI) in identifying neotectonic and lithology signals in the Utica-Mateur basin (north-eastern Tunisia), a region recognised by low deformation rates. We computed HI values using three digital elevation models (DEMs) of 10, 30 and 90 m pixel resolution. We extracted maximum, minimum and mean elevations from each DEM. The obtained results reveal that the HI spatial distributions did not demonstrate clear spatial patterns and did not correlate with geological substrates. We also find that the distribution of HI is independent of the DEM resolution, but are influenced by the size of the moving window. By applying the hot spot analysis (Gi*-statistics) on extracted HI data, we find two main clusters with high (hot spots) and low (cold spots) HI values. These hot spots correspond mainly to active faults and coincide with shallow earthquake clusters in the study area. [ABSTRACT FROM AUTHOR]

The purpose of this study is to develop an overall methodology for assessing soil erosion hazard. Two models are implemented in Haffouz watershed (central Tunisia), which is generally prone to erosion processes. The first is a multi-parametric approach based on expert's knowledge and Analytic Hierarchy Process (AHP), while the second is a statistical technique based on logistic regression (LR). Six parameters (slope gradient, annual precipitation, lithofacies, vegetation index, drainage density, and land use) are used for both methodologies. A thematic layer map is generated for each parameter using geographic information system (GIS) and remote sensing, while the weighting coefficients of each methodology are used for the compilation of AHP and LR final maps. Both models give similar results depicting that, in general, a moderate hazard condition of soil erosion was found in the study area. The proposed approaches also resulted in the identification of the highly eroded areas, requiring immediate action. [ABSTRACT FROM AUTHOR]