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Abstract: We have mapped the region of Oran, Algeria, using multispectral remote sensing with different resolutions. For the identification of objects on the ground using their spectral signatures, two methods were applied to images from SPOT, LANDSAT, IRS-1C and ASTER. The first one is called Base Rule method (BR method) and is based on a set of rules that must be met at each pixel in the different bands reflectance calibrated and henceforth it is assigned to a given class. The construction of these rules is based on the spectral profiles of popular classes in the scene studied. The second one is called Spectral Angle Mapper method (SAM method) and is based on the direct calculation of the spectral angle between the target vector representing the spectral profile of the desired class and the pixel vector whose components are numbered accounts in the different bands of the calibrated image reflectance. This new method was performed using PCSATWIN software developed by our own laboratory LAAR. After collecting a library of spectral signatures with multiple libraries, a detailed study of the principles and physical processes that can influence the spectral signature has been conducted. The final goal is to establish the range of variation of a spectral profile of a well-defined class and therefore to get precise bases for spectral rules. From the results we have obtained, we find that the supervised classification of these pixels by BR method derived from spectral signatures reduces the uncertainty associated with identifying objects by enhancing significantly the percentage of correct classification with very distinct classes. [Copyright &y& Elsevier]

Abstract: Nowadays, hyperspectral remote sensing is a powerful tool for discrimination and accurate and rapid identification of mineral surfaces, due to the new technique of ground spectrometry. The objective of this article is the spectral identification of carbonate facies that exist in the Moroccan Atlantic High Atlas mountains, to establish a regional spectral library in order to prepare the implementation of regional maps with high spatial resolution. The spectra acquired in the visible-infrared (0.4 to 2.5μm) were used for characterizing and monitoring the evolution of diagenetic dolomite from the Lower Lias of the Arigh Ouzla formation that exists in the anticline Jbel Amsitten. The separation of facies, and the taking into account of the diversity in alteration phenomena, have imposed the normalization of the withdrawal of surface effects of dissolution and the restriction of the spectral window to avoid overlap of information. The characteristic absorption bands vary between 2.319 and 2.323μm and do not change between patina surface and fresh fractures. These values reflect the character totally dolomitic of the facies and can be used to estimate the degree of diagenesis, which gives more details with respect to previous sedimentological and petrographic descriptions. Analysis of the spectra has shown a relationship between the degree of crystallinity and depth of the absorption band could be established. [Copyright &y& Elsevier]

Abstract: The plains of Macta, where the Macta marshes are located, form a wetland with particular ecological characteristics in the Maghreb and are subject to distinct land use dynamics. The plant formations are exposed to multiple forms of degradation, primarily due to climate (period of dryness) and to increasing anthropogenic activities in the area. The new methods of breeding and cultivation contribute to ongoing degradation in this natural ecosystem, with a deterioration of the wetland''s biological potentialities. With the aim of safeguarding Macta''s marshes, a better knowledge of vegetation distribution patterns and dynamics, together with the interpretation of the remote sensing data and GIS, makes it possible to consider programmes of natural environment restoration and sustainable management. The results of land-use dynamics analysis show a decline in agricultural land use from 33,000 ha in 1958 to 21,000 ha in 2005. Halophytic vegetation currently occupies 47,000 ha, while in 1958 it occupied only 27,000 ha. Tamarix, Inula, Joncus and Scirpus species are experiencing a decrease in surface cover, while Salicornia, Suaeda, and Atriplex are extending their area. To cite this article: T. Sitayeb, K. Benabdeli, C. R. Biologies 331 (2008). [Copyright &y& Elsevier]

Abstract: This paper reports on small mountain glacier variations in the northern Belledonne region (French Alps). Between 1926 and 2006, the evolution is surveyed using remote-sensing techniques. Then, it is correlated with climate data for the same period. In the late 1920s and in 1980, there was a maximum extent of the glaciers. The 1980 surge is due to high precipitations during the late 1970s, a similar trend being punctually observed in 1993. Between 1980 and 2003, the Rocher Blanc glaciers have strongly receded, their total surface being divided by ten. From 1997 onward, the large retreat can be explained by the increase of the mean daily temperature, especially the minimum daily temperature. Moreover, unusually high temperatures have been registered during the summer 2003 heat wave. Small mountain glaciers appear to be more sensitive to climate change than larger ones. Their surfaces change within 6 to 12 months. [Copyright &y& Elsevier]

Abstract: Flash-flood events resulting from paroxystic meteorological events concentrated in time and space are insufficiently documented as they produce destructive effects. They are hardly measurable and present single features that are not transposable to another event. In the South of France, the flash flood of November 1999 gives a perfect illustration of these characteristics. The physical complexity of the process and consequently the volume and the variety of the data to take into account are incompatible with the real time constraint allocated to the forecasters confronted to the occurrence of such phenomena. So, we have to make choices to afford acceptable simplifications to the complete mechanical model. MARINE (‘Modélisation de l''Anticipation du Ruissellement et des Inondations pour des évéNements Extrêmes’) is the operational and robust tool we developed for flash-flood forecasting. This model complies with the criterions of real-time simulation. It is a physically based distributed model composed of two parts: first the flood runoff process simulation in the upstream part of the basin modelled from a rainfall–runoff approach, then the flood propagation in the main rivers described by the Saint-Venant equations. It integrates remote sensed data – Digital Elevation Model, land-use map, hydrographic network for the observations from satellites and the rainfall evolution from meteorological radar. The main goal of MARINE is to supply real time pertinent information to the forecasters. Results obtained on the Orbieu River (Aude, France) show that this model is able to supply pertinent flood hydrograph with a sufficient precision for the forecasting service to take the appropriate safety decisions. Furthermore, MARINE has already been tested in the French National Flood Forecasting Service of Haute-Garonne in real conditions. To cite this article: V. Estupina Borrell et al., C. R. Geoscience 337 (2005). [Copyright &y& Elsevier]

The aim of this work is to assess the use of (SPOT) multispectral visible infrared remote sensing to study microphytobentos assemblages in a shellfish ecosystem (Bay of Bourgneuf, France). SPOT satellite images (acquired at low tide in spring or autumn between 1986 and 1998) were calibrated using in situ radiometric data, and the normalised vegetation index (NDVI) obtained from these images showed microphytobenthos on bay mudflats. Proliferation was mainly along a north-south strip, essentially localised around the +2 m isobath and covering a surface area of 19 to 25% of the total mudflat area studied (420 to 550 ha). Three factors seem to be responsible for the spatial structure of the assemblages: bathymetry, nutrient input from the Falleron River and its channel, and the location of oyster-farming areas. Although spatial and spectral resolutions of multispectral remote sensing data have certain limitations, this approach opens up a new field of application for hyperspectral remote sensing, particularly for synoptic mapping of biomass distribution. To cite this article: V. Me´le´der et al., C. R. Biologies 326 (2003). [Copyright &y& Elsevier]