Effet de la Variabilité Pluviométrique sur les Écoulements de Surface dans le Bassin Versant de l’Agnéby au Sud-Est de la Côte d’Ivoire

The rainfall variability observed since the 1970s has resulted in a succession of years of drought. Generally, this has raged for thirty years in West Africa, in the Sahelian countries, and the countries along the Gulf of Guinea. It has resulted in severe decreases in rainfall and stream flows. This paper focuses on taking into account the rainfall variability on surface flows of the Agnéby watershed to better understand the evolution of the hydrological regime. To achieve this, the study was based on daily rainfall and flow data from 1955 to 2015. An analysis of the hydropluviometric indices has been performed. These indices associate several complementary methods such as the detection tests of the break in the average, the procedure for the segmentation of hydrological time series, the runoff coefficient, and the hydroclimatic average coefficient. The analysis reveal ruptures around 1960s and 1980s. These result in hydrological responses with deficits of -54% and - 36%. A significant resumption of the average flows is observed from 1996, with a rainfall surplus of + 7%, which has resulted in a hydrological response of 149%. This latter finding points out the entry into a new, more humid climatic period than that of the 1960s and 1980s at the scale of the Agnéby basin. This is confirmed by the increase of the hydroclimatic average coefficient up to 130% since the end of the 2010 decade. The annual rainfall obtained are also well comparable with those of the wet period (1997-2015) with a cumulative rainfall varying between 1280 mm and 1760 mm.La variabilité pluviométrique observée depuis les années 1970 s'est traduite par une succession d'années de sécheresse. Cela fait rage depuis trente ans en Afrique de l’Ouest en général, dans les pays sahéliens et dans les pays du golfe de Guinée. Elle en est résulté une diminution importante des précipitations et des débits des cours d’eau. Ainsi, cet article propose de prendre en compte la variabilité des précipitations sur les écoulements de surface du bassin versant d’Agnéby afin de mieux comprendre l’évolution du régime hydrologique. Pour atteindre cet objectif, les travaux ont été basés sur les données journalières des précipitations et des débits de 1955 à 2015. Une analyse des indices hydropluviométriques a été réalisée. Ces indices associent plusieurs méthodes complémentaires telles que les tests de détection de la rupture de la moyenne, la procédure de segmentation des séries temporelles hydrologiques, le coefficient de ruissellement et le coefficient de la moyenne hydroclimatique. Nos analyses révèlent des ruptures autour des années 1960 et 1980. Celles-ci entraînent des réponses hydrologiques avec des déficits de -54% et -36%. Cependant, on observe une reprise significative des débits moyens à partir de 1996, avec un excédent pluviométrique de + 7% qui a entraîné une réponse hydrologique de 149%. Cette dernière constatation marque l'entrée dans une nouvelle période climatique plus humide que celle des années 1960 et 1980 à l'échelle du bassin d'Agnéby. Ceci est confirmé par l'augmentation du coefficient moyen hydroclimatique jusqu'à 130% depuis la fin de la décennie 2010. Ainsi, les précipitations annuelles obtenues sont bien comparables à celles de la période humide (1997-2015) avec des précipitations cumulatives variant entre 1280 mm et 1760 mm

Effets De La Dynamique Du Couvert Végétal Sur Les Écoulements Dans Le Bassin Versant De La Lagune Aghien En Côte d‘Ivoire

The aim of this paper is to highlight the impact of anthropization on the runoff Djibi and Bete rivers, tributaries of the Ivorian Aghien watershed. The classification method with the maximum likelihood used to the diachronic study of satellite imagery Landsat Thematic Mapper (1987), Enhance Thematic Mapper Plus (2000) and Operational Land Imager (2015) and Geographic Information System remote sensing has been applied. It has permitted to note the total disappearance of the forest at risk of subsistence crops, fallows, habitats and bare soils. The forest area that was 4 ha in 1987 for the Bete Watershed has been destroyed entirely. This change in the land cover between 1987 and 2015 had considerable consequencies on the contributions of water to the level of the Djibi and Bete rivers. So bad slight values of the retention capacity indices underneath 100 reflect the anthropization of these watersheds. The use of rainfall series for the evaluation on the runoff from the Vuilllaume Dubreuil method (1975), reveals an increase in runoff coefficients from 20% to 21% in Djibi watershed and from 13% to 17% in Bete watershed between 1987 and 2015. Increasing these flow coefficients related to water in a watershed more and more urbanized inflow is a threat to the water quality and the security of area urbanized

Persistent Submicroscopic Plasmodium falciparum Parasitemia 72 Hours after Treatment with Artemether-Lumefantrine Predicts 42-Day Treatment Failure in Mali and Burkina Faso.

A recent randomized controlled trial, the WANECAM (West African Network for Clinical Trials of Antimalarial Drugs) trial, conducted at seven centers in West Africa, found that artemether-lumefantrine, artesunate-amodiaquine, pyronaridine-artesunate, and dihydroartemisinin-piperaquine all displayed good efficacy. However, artemether-lumefantrine was associated with a shorter interval between clinical episodes than the other regimens. In a further comparison of these therapies, we identified cases of persisting submicroscopic parasitemia by quantitative PCR (qPCR) at 72 h posttreatment among WANECAM participants from 5 sites in Mali and Burkina Faso, and we compared treatment outcomes for this group to those with complete parasite clearance by 72 h. Among 552 evaluable patients, 17.7% had qPCR-detectable parasitemia at 72 h during their first treatment episode. This proportion varied among sites, reflecting differences in malaria transmission intensity, but did not differ among pooled drug treatment groups. However, patients who received artemether-lumefantrine and were qPCR positive at 72 h were significantly more likely to have microscopically detectable recurrent Plasmodium falciparum parasitemia by day 42 than those receiving other regimens and experienced, on average, a shorter interval before the next clinical episode. Haplotypes of pfcrt and pfmdr1 were also evaluated in persisting parasites. These data identify a possible threat to the parasitological efficacy of artemether-lumefantrine in West Africa, over a decade since it was first introduced on a large scale

Estimation des pluies journalières extrêmes supérieures à un seuil en climat tropical : cas de la Côte d'Ivoire

The extreme rainfalls are the weather hazards that cause much damage and many casualties. The estimation of extreme rainfall is therefore of great interest to anticipate disasters such as floods and allow thoughtful planning of the territory. This study proposes through the approach values above a threshold of analyzing the probability distribution of extreme rainfall in Côte d'Ivoire. The series excesses over a threshold of 44 rainfall stations were analyzed over the period 1942-2002. The statistical analysis highlights optimal thresholds estimation of extreme daily rainfall between 32 mm and 55 mm. The majority (34) series of daily rainfall exceeding a threshold are adjusted by the generalized PARETO distribution with a shape parameter (k) significantly negative. The uncertainty in a parameter (k) is very important and increases the estimation threshold. Moreover, the spatial analysis of decadal and centennial daily rainfall shows that the highest values are mainly on the coast between latitudes 4˚30' and 5˚30' North, in the extreme West in mountainous areas and central West

Tissue reaction to polypyrrole-coated polyester fabrics: Anin vivostudy in rats

Electrically conductive polypyrrole is very attractive for tissue engineering because of its potential to modulate cellular activities through electrical stimulation. However, its in vivo behaviors have not been fully studied. This paper investigates the in vivo biocompatibility and biostability of PPy-coated polyester fabrics. Three PPy-coated fabrics were prepared using phosphonylation (PPy-Phos), plasma activation (PPy-Plas), and plasma activation plus heparin treatment (PPy-Plas-HE). Virgin and fluoropassivated fabrics (F-PET) were controls. The specimens were implanted subcutaneously in the back of rats for 3-90 days, then harvested and processed for enzymatic, histological, and morphological analyses. A noninvasive MRI method was used to continuously monitor the inflammation. The level of acid and alkaline phosphatase showed a similar or a less intensive cellular reaction by the PPy-coated fabrics, when compared to the controls. Histology supported the enzymatic results and showed a fast collagen infiltration at 28 days for the PPy-Phos fabric. MRI reported an overall decrease of inflammation over time, with the PPy-coated fabrics showing a similar or mild inflammation in contrast to the non-coated fabrics. PPy clusters and excessive PPy laminary coating on the PPy-Plas and PPy-Plas-HE were lost with the implantation. This experiment suggests a similar in vivo biocompatibility of the PPy-coated and noncoated polyester fabrics and the importance of achieving a thin, uniform PPy coating

Rainfall Variability across the Agneby Watershed at the Agboville Outlet in Côte d’Ivoire, West Africa

This study analyzes, at local and regional scales, the rainfall variability across the Agneby watershed at the Agboville outlet over the period 1950–2013. Daily rainfall data from 14 rain gauges are used. The methods used are based, firstly, on the rainfall index which aims to characterize the inter-annual and decadal variability of rainfall and, secondly, on the moving average to determine the dynamics of the mean seasonal cycle of the precipitations. Furthermore, the Pettitt test and the Hubert segmentation are applied to detect change-point in the rainfall series. At the basin scale, analysis of rainfall signals composites has shown that the rainfall deficit was more pronounced after the leap of monsoon. Dry years were characterized by an early monsoon demise which is remarkable after 1968. Moreover, the years after 1969 presented a shift of the peaks in precipitation for about 12 days. These peaks were reached early. The rainfall signal showed that the rainfall deficit for the period after 1968, relatively to the period before, was 10% in June against 36% in October for the average rainfall in the Agneby basin. At the local scale, the deficit of the peaks depends on the location. These rainfall deficits were 23% against 36.3% in June for the Agboville and Bongouanou rain gauges, respectively

IAHS2022 -Variability and change across space, time, extremes, and interfaces Rainfall risk over the city of Abidjan (Côte d'Ivoire): first contribution of the joint analysis of daily rainfall from a historical record and a recent network of rain gauges

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Application of the water evaluation and planning model (WEAP) to the management of surface water resources in the Ivory Coast basin of the Aghien lagoon

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