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4559 ABSTRACTThe quantification of evapotranspiration from irrigated areas is important for agriculture water management, especially in arid and semiarid regions where water deficiency is becoming a major constraint in economic welfare and sustainable development. Conventional methods that use point measurements to estimate evapotranspiration are representative only of local areas and cannot be extended to large areas because of heterogeneity of landscape. Remote sensing based energy balance models are presently most suited for estimating evapotranspiration at both field and regional scales. In this study, SEBAL (Surface Energy Balance Algorithm for Land), a remote sensing based evapotranspiration model, has been applied with Landsat ETM+ sensor for the estimation of actual evapotranspiration in the Habra plain, a semiarid region in west Algeria with heterogeneous surface conditions. This model followed an energy balance approach, where evapotranspiration is estimated as the residual when the net radiation, sensible heat flux and soil heat flux are known. It involves in the input the remote sensing land surface parameters such as surface temperature, NDVI and albedo. Different moisture indicators derived from the evapotranspiration were then calculated: evaporative fraction, Priestley-Taylor parameter and surface resistance to evaporation. These calculated indicators facilitate the quantitative diagnosis of moisture stress status in pixel basis. The study area contains extremes in surface albedo, vegetation cover and surface temperature. The land uses in this study area consists of irrigated agriculture, rain-fed agriculture and livestock grazing. The obtained results concern the validation of the used model for spatial distribution analysis of evapotranspiration and moisture indicators. The evaluation of daily evapotranspiration and moisture indicators are accurate enough for the spatial variations of evapotranspiration rather satisfactory than sophisticated models without having to introduce an important number of parameters in input with difficult accessibility in routine. In conclusion, the results suggest that SEBAL can be considered as an operational method to predict actual evapotranspiration from irrigated areas having limited amount of ground information.

The purpose of this study was to provide an inventory and an analysis of plant species occupying Beni-Haoua, a mountainous coastal ecosystem, with a rarely studied well-developed forest. As a result, 87 species were recorded in 7 sites, the Jaccard classification resulted in 4 groups of sites with significantly different diversities. According to the ϕ-coefficient of association, which can be used as a measure of fidelity, among the 87 species, 34 diagnostic species were distributed over four plant communities, with a fidelity value ranging from 55 to 100%, 28 differential species, among which 16 species were common to 2 plant communities and 12 common to 3 plant communities. The redundancy analysis (RDA) showed that among the studied environmental variables, altitude and pH were the most important ones. Indeed, according to the detrended correspondence analysis (DCA), plant species occurrence and distribution in the study area were affected by a strong altitudinal gradient.

To develop agriculture in mountainous areas, environmental analysis is a necessary step. However, the classical methods of agro-ecological diagnosis, which are numerous and diversified, do not allow to study large spaces in a reasonable period of time and often do not meet the expectations of the practitioner of the field. The aim of this project is to implement an approach consisting of conducting an environmental analysis with a preference for the choice of a spatial dimension ( level of perception ) in line with the needs of the farmer ( agricultural spatial unit ). This analysis will be based on the most relevant physical, biotic and socio-economic indicators using two distinct but complementary approaches: - Firstly, by the synthetic view of the landscape offered by satellite imagery by limiting the number of ground surveys, a space remote sensing approach will be adopted; - Then, by the performance allowed by the Geographical Information System (GIS) tool, the spatially referenced data will be combined; - Finally, on the basis of the results of the agro-ecological diagnosis using the geomatics tool (cartography, remote sensing and GIS), development guidelines will be outlined to develop mountain lands (soil, water) and preserve the agro-ecosystems weakened by three (03) Test sites selected on a north-south transect in the Tlemcen wilaya.

The wilaya of Saida is experiencing an alarming degradation of ecosystems resulting in the degradation of plant cover, alteration of soil quality and erosion of plant biodiversity. This alarming situation has its origins in various problems such as: human actions, climate change and the lack of an environmental policy. Our study was conducted on the development of a methodology for multidisciplinary mapping combine's phytoecological between diagnosis and application of remote sensing and Geographic Information Systems G.I.S For an inventory and characterization of the actual state of the plant biodiversity of the region. The exploitation of satellite data from the Landsat satellites, combined with field studies through systematic sampling, allowed us to map vegetation and a map of plant communities.