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Communication incl. Poster: BibTeX citation key:  Ndionea
Ndione, J.-A., Lacaux, J.-P., Tourre, Y. M., Vignolles, C., Fontanaz, D. & Lafaye, M. 2009. Building an earlywarning system (EWS) for Rift Valley Fever in Ferlo (Senegal): what can be expected from remote sensing? Work presented at Third International AMMA Conference, July 20—24, at Ouagadougou, Burkina Faso.
Added by: Devic 2009-09-04 11:17:40    Last Edited by: roussot 2010-01-22 13:13:00
Categories: Environment and Climate Monitoring, Society-Environment-Climate interactions
Keywords: Early warning system, Health, Satellites
Creators: Fontanaz, Lacaux, Lafaye, Ndione, Tourre, Vignolles
Publisher: African Monsoon Multidisciplinary Analyses (Ouagadougou, Burkina Faso)
Collection: Third International AMMA Conference

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Popularity index:  60.75%
Maturity index:  published

The small size and complex distribution of ponds require the use of high-spatial resolution satellite images for adequate detection. Here the use of SPOT-5 images (10m-resolution) allows for detailed assessment of spatio-temporal evolution of ponds, through two new indices: the Normalized Difference Pond Index (NDPI) and the Normalized Difference Turbidity Index (NDTI). Moreover, another product is proposed: the Zone Potentially Occupied by Mosquitoes (ZPOM). During the apex of the summer monsoon, it is found that RVF mosquitoes occupy 25% of the Barkedji area, while only 0.9% of the same area is covered by ponds. Overlapping areas occupied by grazing cattle and mosquitoes, enhance RVF virus transmission. Temporary ponds could be considered as a good epidemiologic indicator for different vectors of infectious diseases. The goal is to first use operational and high-spatial resolution remote sensing images to detect all ponds for potential mosquitoes’ presence and breeding sites. The resulting ZPOM is obtained from entomological field-studies and mapped using flying ranges and spatial distribution of vectors. The second step is to establish dynamic maps of mosquitoes’ density, starting from regular data of the rainfall events. This work is carried out by integrating results of studies on mechanisms of emergence, proliferation and diffusion of the vectors (the distribution of rainfall events (frequency and intensity), the flying range of mosquitoes and their aggressiveness). Then, after developing hazard maps, vulnerability (host’ evaluation) and risk maps (host exposure to vectors), all fundamental components of our HEWS are already defined.
Thanks to remotely sensed operational indices and products presented here are meant to better understand the mechanisms at stake and to contribute to the development of early warning systems in a changing climate and environment. Combining a multi-disciplinary and integrated approach involving rainfall data (seasonal forecasts and near real-time observations), ponds and differences in ZPOMs as a function of ecozones, biological data such as vector aggressiveness, virus transmission and pastoralism, should make it possible to evaluate dynamical RVF risks.
Added by: roussot    Last Edited by: roussot