Caractérisation Des Structures Géologiques Par Analyse Morphostructurale d’Image d’Ombrage (ASAR ENVISAT Et MNT SRTM) Et Géostatistique Du Sud De La Côte d’Ivoire

This paper focuses on characterizing the structural lineaments of the South of Côte d’Ivoire by using the morphostructural analysis of shading images technique (ENVISAT/ASAR and SRTM/DTM) and the geostatistical method for a better understanding of the fractured environment. This study is carried out on the basis of techniques of backscattered radar signal and the geomorphological analysis. This technical implementation significantly improves the mapping of the fractures of the study area. The number of fractures is estimated at 778. Direction N100-110° fractures are the longest and most representative. The fracture spacing fits better into the power law. The geostatistical analysis shows that the global fracturing variogram is spatially well structured. The fracture density in cumulative lengths is therefore identified with a regionalized variable. The fracturing map that is obtained represents a basic document in the fields of hydrogeology. This paper can be used for prospecting and production drilling campaigns and can be used also in geotechnics and mining prospecting

INHIBITION DE SCLEROTIUM ROLFSII SACC. (CORTICIACEAE), AGENT CAUSAL DE LA POURRITURE DU COLLET DE LA TIGE DE LA TOMATE (SOLANACEAE), PAR XYLOPIA AETHIOPICA (DUNAL) A. RICH (ANNONACEAE) ET TRICHODERMA SP.

Tomato (Solanum esculentum Mill) is one of the most consumed in the world with a production of 124 million tons of vegetables. However, the growth of this culture runs into constraints to plant health. To find alternatives to synthetic fungicides which represent the means of control used by most gardeners, a study was conducted on the extracts (essential oils and powders of fruits and leaves) of Xylopia aethiopica (Dunal) A . Rich. (Annonaceae) and two synthetic fungicides (Banko-plus and mancozebe) to test their antifungal potency of Sclerotium rolfsii. Fifteen isolates of Trichoderma sp. are also used for quality antibiotic and fertilizer for crops. At the end of the in vitro tests, it was revealed that the essential oil of fruits was higher than the other extracts on mycelial growth of Sclerotium rolfsii inhibition rate. Four isolates with the best attitudes to mycelial growth were used for in vivo testing. After in vivo assays, the essential oil of fruits and the 9th isolate of Trichoderma harzianum showed a good return on the growth parameters of tomato. The powdered fruit of Xylopia aethiopica also showed a good response to the incidence of the disease. The impact of the higher disease was 10.66 for the fruit powder and 5.96 for the essential oil of the fruit. This study offers the possibility of using essential oils and powdered fruit of Xylopia aethiopica in strategies to control Sclerotium rolfsii

Cartographie De La Sensibilite Aux Maladies Environnementales Respiratoires Dans Le District Sanitaire De Koumassi-Port-Bouët-Vridi (Sud De La Côte d’Ivoire)

In Côte d’Ivoire morbidity causes are related to diseases such as malaria, diarrhea, and acute respiratory infections (ARI), which are constantly evolving. Koumasi and Port-Bouet are the most affected municipalities in the country. This study aims to find environmental determinants of spatial distribution of the ARIs and identify the most sensitive areas to take action for prevention and effective control and targeted in order to reduce the prevalence of ARI. To achieve this goal, we have identified environmental factors associated with the occurrence of ARI. Different environmental and cartographic data were integrated into a GIS. A multi-criteria analysis was performed to determine the environmental parameters that expose more people to the occurrence of the IRA and the weights of these parameters. The combination of exposure maps was used to map the sensitivity to IRA. Multi-criteria analysis revealed that refuse dumps have the highest influence in the occurrence of the disease, followed by industrial facilities and permanent wastewater. The ARI sensitivity map obtained shows that neighborhoods Nord-est 2 and Zone industrielle in Koumassi municipality are most susceptible to ARI. In the municipality of Port-Bouet sensitivity is more pronounced at Vridi canal and Vridi 3. Special attention should therefore be granted these neighborhoods

Variabilité des descripteurs pluviométriques intrasaisonniers à impact agricole dans le bassin cotonnier de Côte d’Ivoire : cas des zones de Boundiali, Korhogo et Ouangolodougou

Objectif: Cette étude vise à caractériser l’évolution des descripteurs pluviométriques intrasaisonniers à impact agricole durant la saison culturale dans le bassin cotonnier ivoirien. A cet effet,Méthodologie et résultats: dix descripteurs pluviométriques intrasaisonniers susceptibles d’influencer l’agriculture ont été analysés à partir des données pluviométriques couvrant les périodes 1951-2000 et 2011-2016 et provenant des bases de données de la Société de Développement et d’Exploitation Aéroportuaire, Aéronautique et Météorologique et du Centre National de Recherche Agronomique. Les tests de tendance (Mann-Kendall) et de stationnarité (Pettitt) et une comparaison des périodes ont été appliqués aux variables déterminées. L’analyse des cumuls pluviométriques saisonniers, du nombre de jours de pluie et des précipitations moyennes journalières a mis en évidence une tendance significative à la baisse de ces paramètres sur la période 1951-2000. Les fins et les longueurs de la saison des pluies ont présenté respectivement une tendance significative à la précocité et au raccourcissement. Les autres descripteurs intrasaisonniers ont peu varié. En revanche, des ruptures statistiquement significatives ont été observées entre 1968 et 1979. La comparaison des périodes indique une dégradation des conditions climatiques pendant la période sèche (1971-2000). Ces dégradations se sont accentuées dans la période actuelle (2011-2016).Conclusion et application: Les nouvelles conditions climatiques observées dans le bassin cotonnier traduites par une variabilité des descripteurs intrasaisonniers rendent de plus en plus difficile la planification agricole. Dès lors, l’actualisation des calendriers culturaux dans le bassin cotonnier devient nécessaire.Mots-clés: Descripteurs intrasaisonniers, pluviométrie, agriculture, bassin cotonnier, Côte d’IvoireEnglish AbstractObjective: This study aims to characterize the evolution of agricultural impact intra-seasonal descriptors during the growing season in cotton production area of Côte d’Ivoire. For this purpose...Methodology and results: ten intraseasonal descriptors likely to influence agriculture were determined from rainfall data covering the periods 1951-2000 and 2011-2016 from the Airport, Aeronautical and Meteorological Development and Operations Company and the National Agronomic Research Center. Trend (Mann-Kendall) and stationarity (Pettitt) tests and an inter-period comparison were applied to the identified variables. Analysis of seasonal rainfall accumulations, number of rainy days and average daily rainfall amounts showed a significant downward trend over the period 1951-2000. The cessation and length of the rainy season showed a significant trend towards early onset and shortening respectively. Other intraseasonal descriptors do not varied significantly. In contrast, statistically significant breaks were observed between 1968 and 1979. The period comparison indicated a deterioration in conditions during the dry period (1971-2000). The comparison of the periods indicates a deterioration of the climatic conditions during the dry period (1971-2000). These degradations have increased in the current period (2011-2016).Conclusion and application: New climatic conditions observed in the cotton production area translated by a variability of intraseasonal descriptors are making agricultural planning increasingly difficult. It is therefore necessary to update the crop calendars in the cotton production area.Keywords: Intraseasonal descriptors, rainfall, agriculture, cotton production area, Côte d'Ivoir

INHIBITION DE SCLEROTIUM ROLFSII SACC. (CORTICIACEAE), AGENT CAUSAL DE LA POURRITURE DU COLLET DE LA TIGE DE LA TOMATE (SOLANACEAE), PAR XYLOPIA AETHIOPICA (DUNAL) A. RICH (ANNONACEAE) ET TRICHODERMA SP.

Tomato (Solanum esculentum Mill) is one of the most consumed in the world with a production of 124 million tons of vegetables. However, the growth of this culture runs into constraints to plant health. To find alternatives to synthetic fungicides which represent the means of control used by most gardeners, a study was conducted on the extracts (essential oils and powders of fruits and leaves) of Xylopia aethiopica (Dunal) A . Rich. (Annonaceae) and two synthetic fungicides (Banko-plus and mancozebe) to test their antifungal potency of Sclerotium rolfsii. Fifteen isolates of Trichoderma sp. are also used for quality antibiotic and fertilizer for crops. At the end of the in vitro tests, it was revealed that the essential oil of fruits was higher than the other extracts on mycelial growth of Sclerotium rolfsii inhibition rate. Four isolates with the best attitudes to mycelial growth were used for in vivo testing. After in vivo assays, the essential oil of fruits and the 9th isolate of Trichoderma harzianum showed a good return on the growth parameters of tomato. The powdered fruit of Xylopia aethiopica also showed a good response to the incidence of the disease. The impact of the higher disease was 10.66 for the fruit powder and 5.96 for the essential oil of the fruit. This study offers the possibility of using essential oils and powdered fruit of Xylopia aethiopica in strategies to control Sclerotium rolfsii

Modélisation statistique des pluies maximales annuelles dans le district d’Abidjan (sud de la Côte d’Ivoire)

Les valeurs extrêmes des variables hydroclimatiques présentent un intérêt tout particulier lorsqu’on parle en termes de risque. L'estimation de la récurrence de pluies extrêmes fournit des éléments indispensables pour la construction d'infrastructures telles que les digues, les ouvrages d'assainissement, etc., afin de protéger efficacement la population et leurs biens. Cet article a pour objectif de trouver une loi théorique qui peut montrer une bonne représentation de la fonction de distribution des pluies journalières maximales annuelles pour la prévention des risques liés aux inondations dans le district d’Abidjan au sud de la Côte d’Ivoire. Les données utilisées couvrent la période allant de 1961 à 2014. Des lois de distribution employées dans la conception des ouvrages hydrauliques ont ainsi été retenues dans cette analyse : la loi de Weibull, la loi de Gumbel et la loi log-normale. Elles ont été ajustées aux pluies journalières maximales annuelles et les paramètres ont été estimés de manière spécifique. Les fréquences empiriques ont été calculées à partir de la relation de Hazen. Les paramètres des différentes lois ont été déterminés par la méthode des moments pondérés. L’ajustement a été apprécié à partir de représentation graphique et du test du χ2. Deux critères (critère d’Akaike et critère bayésien) ont été retenus pour trancher sur le choix des meilleurs modèles. Les différentes lois ont montré en général une bonne adéquation à la série des pluies journalières maximales annuelles de la station de Port-Bouët (Abidjan). Cependant, la loi qui ajuste le mieux les pluies journalières maximales annuelles de la station de Port-Bouët (Abidjan) est la loi de Gumbel. Il est donc recommandé de travailler avec la distribution de Gumbel dans toute étude de dimensionnement d’ouvrages hydrauliques en général et dans le domaine des ouvrages d’évacuation des eaux pluviales en particulier dans le district d’Abidjan.The extreme values of hydroclimatic variables are of particular interest when speaking in terms of risk. The estimation of the recurrence of extreme rainfall provides essential elements for the construction of infrastructures such as dykes, sewage works, etc., in order to effectively protect the population and their property. The aim of this article is to find a theoretical law that can show a good representation of the distribution function of the annual maximum daily rainfall for the prevention of flood risks in the Abidjan district in the south of Ivory Coast. The data used cover the period from 1961 to 2014. Distribution laws used in the design of hydraulic structures have been retained in this analysis: the law of Weibull, the law of Gumbel and the lognormal law. They were adjusted to the maximum annual rainfall and the parameters were estimated in a specific way. The empirical frequencies were calculated from the Hazen relation. The parameters of the different laws were determined by the weighted moment method. Adjustment was assessed using graphic representation and χ2 test. Two criteria (Akaike criterion and Bayesian criterion) were used to select the best model. The different laws generally showed a good fit with the series of annual maximum daily rains of the Port-Bouët station (Abidjan). However, the law that best adjusted the annual maximum daily rainfall of the Port-Bouët station (Abidjan) was the law of Gumbel. It is therefore recommended to work with the distribution of Gumbel in any design study of hydraulic structures in general and in the field of storm drainage works especially in the district of Abidjan

Analyse des impacts des changements climatiques sur les normes hydrologiques en Afrique de l’Ouest : cas du district d’Abidjan (sud de la Côte d’Ivoire)

La connaissance des quantiles de précipitations extrêmes comme normes hydrologiques est nécessaire dans le cadre de projets d’aménagement pour la conception d’ouvrages hydrauliques et dans de nombreuses applications d’ingénierie. Dans un contexte de changements climatiques constatés en Afrique de l’Ouest, l’estimation des précipitations associées aux événements extrêmes est un sujet qui suscite des réflexions. Cette problématique soulève la question principale suivante : « Sur quelle base pourrait-on/devrait-on élaborer de nouveaux quantiles pour la gestion de projets de construction d’ouvrages hydrauliques? » Ainsi, l’objectif de cette étude est l’analyse des impacts des changements climatiques sur les normes hydrologiques relatives aux quantiles des pluies journalières maximales annuelles dans le district d’Abidjan (sud de la Côte d’Ivoire). L’approche méthodologique utilisée a consisté à la collecte de données de pluviométrie journalière pour la période 1961-2014. Les tests statistiques de base ont été effectués. Le choix du modèle statistique s’est porté sur la loi de Gumbel. Les paramètres du modèle ont été estimés et ont permis de calculer les quantiles sur plusieurs périodes de référence (1961-1990, 1971-2000, 1981-2010, 1961-2014) et plusieurs durées de retour (2, 5, 10, 20, 50 et 100 ans). Une comparaison des quantiles déterminés a été réalisée à partir des matrices d’écarts relatifs absolus. Les principaux résultats ont montré que les différentes séries définies sont constituées de valeurs indépendantes, stationnaires et homogènes. Les quantiles calculés varient pour une durée de retour donnée en fonction des périodes de référence choisies pour leur détermination. Cela traduit une non-stationnarité des quantiles due à l’instabilité du climat. Pour une meilleure sécurité des ouvrages hydrauliques, les recommandations de ce travail proposent d’utiliser les quantiles de la période historique (1961-1990) pour les périodes de retour inférieures à 50 ans. En ce qui concerne les durées de retour supérieures à 50 ans, il est possible d’utiliser les quantiles de deux périodes de référence (1961-1990, 1981-2010). Pour la valeur du gradex des méthodes empiriques de l’Office de la recherche scientifique et technique outre-mer (ORSTOM) et du Comité interafricain d’études hydrauliques (CIEH), il est recommandé de considérer 0,44 comme valeur pour le dimensionnement des ouvrages hydrauliques dans le district d’Abidjan.Knowledge of quantiles of extreme precipitation as hydrological standards is required for the design of hydraulic projects and many other engineering applications. In the context of climate change in West Africa, the estimation of precipitation associated with extreme events is an issue to be adressed. This raises one main question: "On what basis can new quantiles be developed for the management of hydraulic work construction projects?" The objective of this study is the analysis of the impacts of climate change on the hydrological standards relating to the quantiles of maximum daily rainfall in the Abidjan District (southern Ivory Coast). The methodological approach used was to collect daily precipitation data covering the period 1961-2014. Basic statistical tests were performed. The choice of the statistical model was based on Gumbel's law. The parameters of the model were estimated and the quantiles calculated for several reference periods (1961-1990, 1971-2000, 1981-2010, 1961-2014) and return periods (2, 5, 10, 20, 50 and 100 years). A comparison of the quantiles determined was performed from the absolute relative deviation matrices. The main results showed that the different series defined are made up of independent, stationary, and homogeneous values. The quantiles calculated vary for a given return period as a function of the reference periods chosen for their determination. This reflects a non-stationarity of the quantiles due to climate instability. For improved safety of hydraulic works, the recommendation of this work is to use quantiles of the historical period (1961-1990) for return periods of less than 50 years. For return periods over 50 years, it is possible to use quantiles of two reference periods (1961-1990, 1981-2010). For the gradex value of the empirical methods of ORSTOM (Office de la recherche scientifique et technique outre-mer) and Inter-African Committee for Hydraulic Studies (CIEH), it is recommended to consider 0.44 for sizing hydraulic works in the Abidjan District

Evaluation of Yahe® and Panda® 2.0 long-lasting insecticidal nets against wild pyrethroid-resistant Anopheles gambiae s.l. from Côte d’Ivoire: an experimental hut trial

International audienceAbstract Background Long-lasting insecticidal nets (LLINs) have played an important role in reducing the global malaria burden since 2000. They are a core prevention tool used widely by people at risk of malaria. The Vector Control Prequalification mechanism of the Word Health Organization (WHO-Vector Control PQ) established the testing and evaluation guidelines for LLINs before registration for public use. In the present study, two new brands of deltamethrin-impregnated nets (Yahe ® LN and Panda ® Net 2.0) were evaluated in an experimental hut against wild pyrethroid-resistant Anopheles gambiae s.l. in M’Bé nearby Bouaké, central Côte d’Ivoire. Methods The performance of Yahe ® LN and Panda ® Net 2.0 was compared with that of PermaNet 2.0, conventionally treated nets (CTN), and untreated net to assess the blood-feeding inhibition, deterrence, induced exophily, and mortality. Results Cone bioassay results showed that Panda ® Net 2.0, PermaNet 2.0 and Yahe ® LN (both unwashed and washed 20 times) induced > 95% knockdown or > 80% mortality of the susceptible Anopheles gambiae Kisumu strain. With the pyrethroid-resistant M’Bé strain, mortality rate for all treated nets did not exceed 70%. There was a significant reduction in entry and blood feeding ( p < 0.05) and an increase in exophily and mortality rates ( p < 0.05) with all treatments compared to untreated nets, except the CTNs. However, the personal protection induced by these treated nets decreased significantly after 20 washes. The performance of Panda ® Net 2.0 was equal to PermaNet ® 2.0 in terms of inhibiting blood feeding, but better than PermaNet ® 2.0 in terms of mortality. Conclusion This study showed that Yahe ® LN and Panda ® Net 2.0 met the WHO Pesticide Evaluation Scheme (WHOPES) criteria to undergo phase III trial at the community level. Due to an increasing spread and development of pyrethroid resistance in malaria vectors, control of malaria transmission must evolve into an integrated vector management relying on a large variety of efficient control tools. Graphical Abstrac

Analysis of trends in the rainfall-runoff relation in the context of climate change: case of the N'zo-Sassandra watershed (Western Côte d'Ivoire)

International audienceThe study area is the N'zo-Sassandra watershed (Ivory Coast) located between longitudes 7°15' and 8°05' West and latitude 6°50' and 7°50' North. Its surface is estimated at 4310 km2. The climate regime prevailing at the N'zo-Sassandra watershed at Kahin is a mountain climate (subequatorial regime) with annual rainfall amounts sometimes exceeding 2000 mm. N'zo-Sassandra has a single hydrological regime. The N'zo-Sassandra watershed is a part of the West forest zone characterized by a degraded dense forest. This study aims to identify trends in the rainfall-runoff relationship from an overall conceptual modeling monthly runoff. The data (rainfall, ETP, flow) used in this study cover the period of 1980-2000. The methodological approach is based on the one hand, on the evaluation criteria of the model used (GR2M) and secondly, on the crossed simulations method (1980-2000). The results showed that the GR2M model was efficient and robust on the N'zo-Sassandra watershed. Indeed, the values of the Nash-Sutcliffe obtained are greater than 60% in the calibration phase (81.95%) as validation phase (72.40%). Degradation recorded at the Nash-Sutcliffe criterion passing the validation phase in the calibration phase is less in absolute value than 10%. In addition, it is shown that there is a vast majority of the positive signs in relation to the negative signs. These results highlight the existence of non-stationarity of the rainfall-runoff relation at the N'zo-Sassandra watershed during the period 1980-2000, suggesting a rising trend of monthly runoff

Flood risk assessment and mapping in Abidjan district using multi-criteria analysis (AHP) model and geoinformation techniques, (cote d’ivoire)

Flood is one of the most destructive natural disasters of climate change effects in West Africa. Flood risk occurrence is a combination of natural and anthropogenic factors, which calls for a better understanding of its spatial extent. The aim of this paper is to identify, and map areas of flood risk in Abidjan district. This work is based on the integration of multi-criteria data including slope, drainage density, type of soil, Isohyet, population density, land use and sewer system density within ArcGIS interface. The resulting AHP flood risk map shows that areas under high and very high flood risk covers 34 % of the study area. The Analytic Hierarchy Process (AHP) method used as a multi-criteria analysis allowed the integration of several elements under two criteria, hazards and vulnerability, for flood risk assessment and mapping. Results revealed that, Abidjan district is heavily exposed to the risk of flooding. Eight out of thirteen (8/13) municipalities within the district are at a high risk of flooding which calls for decision makers to effectively develop strategies for future flood occurrences within the Abidjan district (South of Côte d’Ivoire)