A spectral index for land degradation mapping using ASTER data: Application to a semi-arid Mediterranean catchment

Flagrant soil erosion in Morocco is an alarming sign of soil degradation. Due to the considerable costs of detailed ground surveys of this phenomenon, remote sensing is an appropriate alternative for analyzing and evaluating the risks of the expansion of soil degradation. In this paper, we character...

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Bibliographic Details
Published in:International journal of applied earth observation and geoinformation 2005-08, Vol.7 (2), p.140-153
Main Authors: Chikhaoui, Mohamed, Bonn, Ferdinand, Bokoye, Amadou Idrissa, Merzouk, Abdelaziz
Format: Article
Language:English
Subjects:
Applied geophysics
ASD and spectroradiometry
ASTER
Earth sciences
Earth, ocean, space
Erosion
Exact sciences and technology
Internal geophysics
Land degradation
Land degradation index (LDI)
Morocco
Spectral angle mapping (SAM)
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Summary:Flagrant soil erosion in Morocco is an alarming sign of soil degradation. Due to the considerable costs of detailed ground surveys of this phenomenon, remote sensing is an appropriate alternative for analyzing and evaluating the risks of the expansion of soil degradation. In this paper, we characterize the state of land degradation in a small Mediterranean watershed using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and ground-based spectroradiometric measurements. The two visible, the near-infrared and six shortwave infrared bands of the above sensor were calibrated using ground measurements of the spectral reflectance. Field measurements were carried out in the Saboun experimental basin located in the marl soil region of the Moroccan western Rif. The study leads to the development and evaluation of a new spectral approach to express land degradation. This index called Land degradation index (LDI) is based on the concept of the soil line derived from spectroradiometric ground measurements. In this study, we compare LDI and the spectral angle mapping (SAM) approaches to assess and map land degradation. Results show that LDI provides more accurate results for mapping land degradation (Kappa=0.79) when compared to the SAM method (Kappa=0.61). Validation and evaluation of the results are based on the thematic maps derived from the ground data (organic matter, clay, silt and sand) by kriging, DEM, slope gradient and photointerpretation.
ISSN:1569-8432
1872-826X
DOI:10.1016/j.jag.2005.01.002