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Theoretical assessment of short wavelength infrared for monitoring natural vegetation in Burkina Faso

Bégué A., Mauriès F., Lainé G.. 1997. In : Cecchi G., Engman E.T., Zilioli E. Earth surface remote sensing. Bellingham : SPIE, p. 15-25. (SPIE Proceedings, 3222). Earth Surface Remote Sensing, 1997-09-21/1997-09-25, Londres (Royaume-Uni).

Western Burkina-Faso is a pole of intense population migration that conducts to problems of space saturation and land degradation. The present study deals with the natural vegetation characterization of this region using the High Resolution Hisible and InfraRed (HRVIR) sensor that will be launched on SPOT4. We adopted a theoretical approach which consists in evaluating the capacity of the future Short Wavelength InfraRed (SWIR) band to discriminate natural vegetation types using a 3D radiative transfer model (Myneni's model). Simulations were conducted with realistic input parameters (different vegetation structure, soil, satellite, atmospheric conditions) during dry and rainy seasons. The outputs of the simulations (bi-directional reflectances, Vegetation Indices) were used to study the sensitivity of the SWIR to vegetation type and to external conditions. The results show that the SWIR band is well correlated with the Red channel during the wet season, and with the Near InfraRed (NIR) and Red channels during the dry season. Its sensitivity to the atmosphere is low and the sensitivity to the soil type is medium. The sensitivity to the woody cover is high during the dry season (about 1.6 points of reflectance per 10% of woody cover) but is still equivalent to the NIR sensitivity. Spectral Vegetation Indices including SWIR do not provide additional information on the structure of the vegetation canopy.

Mots-clés : végétation; rayonnement infrarouge; utilisation des terres; déboisement; télédétection; cartographie; Évaluation; burkina faso

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