Characterization of the rainy season in Burkina Faso and it's representation by regional climate models

International audienceWest African monsoon is one of the most challenging climate components to model. Five regional climate models (RCMs) were run over the West African region with two lateral boundary conditions, ERA-Interim re-analysis and simulations from two general circulation models (GCMs). Two sets of daily rainfall data were generated from these boundary conditions. These simulated rainfall data are analyzed here in comparison to daily rainfall data collected over a network of ten synoptic stations in Burkina Faso from 1990 to 2004. The analyses are based on a description of the rainy season throughout a number of it's characteristics. It was found that the two sets of rainfall data produced with the two driving data present significant biases. The RCMs generally produce too frequent low rainfall values (between 0. 1 and 5 mm/day) and too high extreme rainfalls (more than twice the observed values). The high frequency of low rainfall events in the RCMs induces shorter dry spells at the rainfall thresholds of 0. 1-1 mm/day. Altogether, there are large disagreements between the models on the simulate season duration and the annual rainfall amounts but most striking are their differences in representing the distribution of rainfall intensity. It is remarkable that these conclusions are valid whether the RCMs are driven by re-analysis or GCMs. In none of the analyzed rainy season characteristics, a significant improvement of their representation can be found when the RCM is forced by the re-analysis, indicating that these deficiencies are intrinsic to the models. © 2011 The Author(s)

Hydrological balance of the Boura dam (Burkina Faso)

In developing countries, where many basins are ungauged or poorly gauged, small reservoirs could be used as hydrometric stations for estimating runoff of small watersheds upstream of the dams. Thus, hydrological monitoring of dam is essential in water resources management by predicting where there may be shortages or surplus water

Fonctionnement hydrique de différents types de formations éoliennes en milieu sahélien Burkinabè

 Le Sahel burkinabé, comme l’ensemble des régions sahéliennes, est confronté depuis quelques décennies à divers phénomènes de dégradation naturelle et anthropique des écosystèmes. C’est particulièrement le cas des formations éoliennes, les seules unités écologiques susceptibles d’être utilisables dans cette région car présentant une capacité d’infiltration notable et supportant l’essentiel de la végétation. Compte tenu du rôle assigné à ces formations éoliennes dans cette zone, des mesures de terrain ont été effectuées pour évaluer l’impact de la dégradation du milieu sur leur fonctionnement hydrique (pluie, ruissellement, conductivité hydraulique à saturation, masse volumique apparente sèche, fonction K(O) par infiltromètrie à 50 cm de profondeur, charge de pression, teneur en eau par la méthode neutronique). C’est dans ce contexte qu’un dispositif expérimental de neuf sites de mesure a été installé dans trois zones bien distinctes. Les résultats obtenus durant cette année de mesure mettent en évidence une nette différenciation du fonctionnement hydrique des sols selon l’état de surface.  Les sites situés sur croûte d’érosion et sur croûte de dessiccation en transition vers une croûte d’érosion, présentent en saison des pluies des conductivités hydrauliques à saturation variant entre 2.7 à 25 mm/h. Ces sites, favorables au ruissellement superficiel, ont des coefficients de ruissellement qui varient entre 60 et 85 %. Leur stock hydrique est de l’ordre de 30 mm pour la période du 13 juillet 2003 au 28 août 2003 après un cumul pluviométrique de 276 mm. Quant aux sites placés sur croûte de dessiccation (S5, S8 et S9), leurs conductivités hydrauliques à saturation sont plus élevées (de l’ordre de 34 à 41% en saison des pluies) que celles des autres sites, leur coefficient de ruissellement moyen est de l’ordre de 28%. Ce sont des milieux favorables à l’infiltration avec un stock hydrique d’environ 80 mm pour la période du 13 juillet 2003 au 28 août 2003 et pour le même cumul pluviométrique que précédemment

A Theoretical Analysis of the Geography of Schistosomiasis in Burkina Faso Highlights the Roles of Human Mobility and Water Resources Development in Disease Transmission

We study the geography of schistosomiasis across Burkina Faso by means of a spatially explicit model of water-based disease dynamics. The model quantitatively addresses the geographic stratification of disease burden in a novel framework by explicitly accounting for drivers and controls of the disease, including spatial information on the distributions of population and infrastructure, jointly with a general description of human mobility and climatic/ecological drivers. Spatial patterns of disease are analysed by the extraction and the mapping of suitable eigenvectors of the Jacobian matrix subsuming the stability of the disease-free equilibrium. The relevance of the work lies in the novel mapping of disease burden, a byproduct of the parametrization induced by regional upscaling, by model-guided field validations and in the predictive scenarios allowed by exploiting the range of possible parameters and processes. Human mobility is found to be a primary control at regional scales both for pathogen invasion success and the overall distribution of disease burden. The effects of water resources development highlighted by systematic reviews are accounted for by the average distances of human settlements from water bodies that are habitats for the parasite's intermediate host. Our results confirm the empirical findings about the role of water resources development on disease spread into regions previously nearly disease-free also by inspection of empirical prevalence patterns. We conclude that while the model still needs refinements based on field and epidemiological evidence, the proposed framework provides a powerful tool for large-scale public health planning and schistosomiasis management

Apport des multifractals à l'études des longues series pluviométriques

No abstract availabl

Tests de robustesse des modèles hydrologiques dans un contexte de changement climatique en Afrique de l’Ouest et Centrale

International audienc