Summary
Rift Valley fever (RVF) is an acute arboviral
disease of domestic ungulates and humans in Africa and the Middle
East. Since the first epidemic in 1987, Senegal has been confronted
with recurrent episodes of the disease. This study aimed to model
spatial distribution of ruminants in the agropastoral area of Barkedji
(Senegal) where the disease is enzootic. In this Sahelian ecosystem,
livestock distribution mainly depends on the availability of resources.
Accordingly, remote sensing and geographic information systems (GIS)
were used to seek environmental indicators of livestock density. A
high-resolution Landsat image was associated with landscape field
data to describe the land-cover. A series of normalized difference
vegetation index values gave an estimation of the phytomass. In addition
the compounds of herders in the study zone were located and sampled.
Three surveys were conducted during the rainy season to record the
number of herds in each compound of the sample. All these data were
overlaid in the GIS. A discriminant analysis was performed to associate
the observed herd density with environmental data and to develop a
predictive model for the entire study zone. The final result was a
1-km resolution raster map of herd density during a normal rainy season.
Keywords
Geographic
information system, Livestock, Modelling, Pastoral system, Remote-sensing,
Rift Valley fever, Senegal.
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