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Proceedings Paper

Monitoring the evolution of desertification processes from 1973 to 1987 in Damagaram (Niger) with Landsat multispectral scanner and thematic mapper
Author(s): Philippe Trefois
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Paper Abstract

Desertification of the Damagaram region (Sahelian zone of Niger) is represented by several processes: decrease or modification of the vegetation, deflation of sandy soils by the wind and exhumation of lateritic crusts, modification of the pattern of dunes, increase of erosion by water. A field survey was performed by a pluridisciplinary team in order to observe and define the expressions of desertification. The spectral signatures of various soils, rocks and vegetation were measured using a high resolution field spectroradiometer. The measured spectral properties of well defined objects were used to validate the calibration of the satellite data and to define the endmembers in models of spectral unmixing. Landsat multi spectral scanner (MSS) scenes of March 11, 1973 and January 10, 1976, and a thematic mapper (TM) scene of January 4, 1987, were made compatible, and several techniques of image processing were tested and compared: ratios (leaf area index, normalized difference vegetation index, redness, clay index), principal components analysis and spectral unmixing. The interpretation of the resulting images allowed a semi-quantitative monitoring of the evolution of the significant components of the landscape. Local variations of soils and vegetation are particularly well enhanced, whereas the global situation did not change drastically from 1973 to 1987.

Paper Details

Date Published: 31 January 1995
PDF: 14 pages
Proc. SPIE 2314, Multispectral and Microwave Sensing of Forestry, Hydrology, and Natural Resources, (31 January 1995); doi: 10.1117/12.200778
Show Author Affiliations
Philippe Trefois, Musee Royal de l'Afrique Centrale (Belgium)

Published in SPIE Proceedings Vol. 2314:
Multispectral and Microwave Sensing of Forestry, Hydrology, and Natural Resources
Eric Mougin; K. Jon Ranson; James Alan Smith, Editor(s)

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