JORDANIAN STUDENTS LEARNING ENGLISH: STRATEGY DEPLOYMENT

Gender and language proficiency are among the key factors that may impact learning strategy use. Thus, this study explored the impact of gender, perceived language proficiency, and academic level on learning strategy use by 111 English-major EFL students whose native language is Arabic. Using Oxford’s Strategy Inventory for Language Learning (SILL), the study revealed that females opt to use strategies more frequently than do males. The results also showed that the higher the proficiency level of the students was, the more frequent strategy use was. The most prevalent among the different strategy types was metacognitive ones when the least was memory. These findings are discussed and implications are set accordingly

Soil surface moisture estimation over a semi-arid region using ENVISAT ASAR radar data for soil evaporation evaluation

The present paper proposes a method for the evaluation of soil evaporation, using soil moisture estimations based on radar satellite measurements. We present firstly an approach for the estimation and monitoring of soil moisture in a semi-arid region in North Africa, using ENVISAT ASAR images, over two types of vegetation covers. The first mapping process is dedicated solely to the monitoring of moisture variability related to rainfall events, over areas in the "non-irrigated olive tree" class of land use. The developed approach is based on a simple linear relationship between soil moisture and the backscattered radar signal normalised at a reference incidence angle. The second process is proposed over wheat fields, using an analysis of moisture variability due to both rainfall and irrigation. A semi-empirical model, based on the water-cloud model for vegetation correction, is used to retrieve soil moisture from the radar signal. Moisture mapping is carried out over wheat fields, showing high variability between irrigated and non-irrigated wheat covers. This analysis is based on a large database, including both ENVISAT ASAR and simultaneously acquired ground-truth measurements (moisture, vegetation, roughness), during the 2008–2009 vegetation cycle. Finally, a semi-empirical approach is proposed in order to relate surface moisture to the difference between soil evaporation and the climate demand, as defined by the potential evaporation. Mapping of the soil evaporation is proposed

Soil moisture mapping in a semiarid region, based on ASAR/Wide Swath satellite data

In this paper, an operational algorithm is proposed for the mapping of surface moisture over the northern and central parts of Tunisia, in North Africa. A change detection approach is applied, using 160 multiincidence Envisat ASAR Wide Swath images acquired in the horizontal polarization over a 7 year period. Parameterization of this algorithm is considered for three classes of vegetation cover density (NDVI0.5), retrieved from SPOT-VGT decadal images. A relative soil moisture index, ranging between 0 (for the driest surfaces) and 1 (for saturated soils), is proposed for each date, with a resolution of 1 km. The retrieved soil moistures are validated by means of ground measurements based on continuous thetaprobe measurements, as well as low-resolution (25 km) ERS and ASCAT soil moisture products from the Vienna University of Technology (TU Wien). A qualitative relationship between spatiotemporal variations of moisture and precipitation is also discussed

Soil clay content mapping using a time series of Landsat TM data in semi-arid lands

Clay content (fraction < 2 mu m) is one of the most important soil properties. It controls soil hydraulic properties like wilting point, field capacity and saturated hydraulic conductivity, which in turn control the various fluxes of water in the unsaturated zone. In our study site, the Kairouan plain in central Tunisia, existing soil maps are neither exhaustive nor sufficiently precise for water balance modeling or thematic mapping. The aim of this work was to produce a clay-content map at fine spatial resolution over the Kairouan plain using a time series of Landsat Thematic Mapper images and to validate the produced map using independent soil samples, existing soil map and clay content produced by TerraSAR-X radar data. Our study was based on 100 soil samples and on a dataset of four Landsat TM data acquired during the summer season. Relationships between textural indices (MID-Infrared) and topsoil clay content were studied for each selected image and were used to produce clay content maps at a spatial resolution of 30 m. Cokriging was used to fill in the gaps created by green vegetation and crop residues masks and to predict clay content of each pixel of the image at 100 m grid spatial resolution. Results showed that mapping clay content using a time series of Landsat TM data is possible and that the produced clay content map presents a reasonable accuracy (R-2 = 0.65, RMSE = 100 g/kg). The produced clay content map is consistent with existing soil map of the studied region. Comparison with clay content map generated from TerraSAR-X radar data on a small area with no calibration point revealed similarities in topsoil clay content over the largest part of this extract, but significant differences for several areas. In-situ observations at those locations showed that the Landsat TM mapping was more consistent with observations than the TerraSAR-X mapping

Soil clay content mapping using a time series of Landsat TM data in semi-arid lands

Clay content (fraction < 2 mu m) is one of the most important soil properties. It controls soil hydraulic properties like wilting point, field capacity and saturated hydraulic conductivity, which in turn control the various fluxes of water in the unsaturated zone. In our study site, the Kairouan plain in central Tunisia, existing soil maps are neither exhaustive nor sufficiently precise for water balance modeling or thematic mapping. The aim of this work was to produce a clay-content map at fine spatial resolution over the Kairouan plain using a time series of Landsat Thematic Mapper images and to validate the produced map using independent soil samples, existing soil map and clay content produced by TerraSAR-X radar data. Our study was based on 100 soil samples and on a dataset of four Landsat TM data acquired during the summer season. Relationships between textural indices (MID-Infrared) and topsoil clay content were studied for each selected image and were used to produce clay content maps at a spatial resolution of 30 m. Cokriging was used to fill in the gaps created by green vegetation and crop residues masks and to predict clay content of each pixel of the image at 100 m grid spatial resolution. Results showed that mapping clay content using a time series of Landsat TM data is possible and that the produced clay content map presents a reasonable accuracy (R-2 = 0.65, RMSE = 100 g/kg). The produced clay content map is consistent with existing soil map of the studied region. Comparison with clay content map generated from TerraSAR-X radar data on a small area with no calibration point revealed similarities in topsoil clay content over the largest part of this extract, but significant differences for several areas. In-situ observations at those locations showed that the Landsat TM mapping was more consistent with observations than the TerraSAR-X mapping

Echelle spatiale et temporelle de l'exposition des mobilités quotidiennes et résidentielles face aux crues rapides : proposition d'une méthodologie fondée sur les échelles

International audienceThis contribution exposes a project called MobiClimEx funded by the French Research Agency (ANR). It focuses on the question of mobility facing the recurrence of extreme precipitations and floods, enhanced with climate change, particularly in Mediterranean area. Mobility is addressed both in its short terms aspects at the event scale (daily mobility) and in long terms at the biographic scale (residential mobility). The aim of this project is to develop an interdisciplinary approach addressing both physical and social dynamics involved at different levels (dimensions) and for different scales (spatial and temporal, but also jurisdictional or institutional). The main point is to define how a relevant combination of scales allows handling all the dimensions. The proposed methodology is tested on a field case (the Gard Department), located in the South-East of France, particularly prone to flash floods. This region was exposed to particularly strong events in 1958, 1988, 2002, 2005, 2008 and 2014. The first question that we ask is: can we observe/distinguish an impact of flash floods on short and long term mobility? It has been already showed that daily mobility, and especially drivers, are particularly exposed to flash floods (Ruin et al, 2008 ). Furthermore, we know through previous works on mobility that residential choices have a strong impact on the daily mobility in general. Can we conclude that certain residential choices increase daily mobility exposure to flash floods? Furthermore, can we observe an influence of floods on land-use policies and residential choices? How do the flooded areas evolve after an event? What does that mean to live in flood prone areas? Based on rebuilt past events observed on field, we assess the problems posed by maintaining the current social and climatic dynamics in the future. Beyond the presentation of the proposed exercise on mobility, this contribution aims also at exploring scales and concepts allowing analyzing cycles of adaptations in land use or in political regulations. Finally, the proposed methodology aims at understanding the socio-hydro-meteorological dynamics leading to high impact events in the past, in order to build, with stakeholders, scenarios able to imagine future dynamics