Etude des modifications environnementales à partir des données pluviométriques et NDVI de NOAA-AVHRR en Afrique de l’Ouest
2003
Hountondji, Yvon-Carmen | Ozer, Pierre | Tychon, Bernard
English. peer reviewed
Show more [+] Less [-]English. Since the late 1960s, The Sahel of West Africa is affected by a long-term drought and increasing human pressure on the environment leading to desertification processes. The Normalised Difference Vegetation Index (NDVI), calculated from satellite imagery, is a reliable index of the vegetation status as the vegetation response to rainfall is very strong in semiarid environments. This article presents the NDVI and rainfall evolution from 1981 to 1999 in nine locations along a north-south transect from north-western Niger to north-eastern Benin. These two parameters are then statistically analysed to identify breaks in the trends within the datasets. Over the 19 years analysed, it appears that five out of the nine locations have recorded a significant increase of rainfall, while only two presented a significant increase in NDVI. This dichotomy in observed trends may highlight the on-going slow processes of environmental degradation.
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