Etude Des Anomalies De Résistivités Pour L’optimisation Des Implantations De Forages D’hydraulique Villageoise En Milieu De Socle: Cas De La Région Du Haut-Sassandra (Centre-Ouest De La Côte d’Ivoire)

Effective groundwater collecting in the basement requires characterization and identification of the productive aquifer systems that are developed there. Therefore, our study relates to the identification, analysis and description of success indicators of geophysical implantations. It about the type and form of anomaly and the type of survey curve. These indicators are obtained following interpretation of trainings and electrical soundings data. A statistical analysis of these indicators is done using the crosstab method. This reveals that drilling productivity is influenced by indicators mentioned above. Indeed, the combination of type A or H soundings obtained straight up CCL type and W or U form anomalies has the best results of up to 100% success rate. The flow rates obtained are generally large (Q> 4 m3 /h). On the other hand, drilling implanted from a type A sounding on a U or V form anomaly and CCE type has high failure rates (33% to 60%)

Evaluation des risques hydro-climatiques et environnementaux liés à l'occurrence de l’ulcère de Buruli dans la région de la Marahoué (Côte d’Ivoire)

Ce travail aborde un problème de santé dû à l’ulcère de Buruli en zone pré-forestière (zone de contact forêt- savane) dans la région de la Marahoué en Côte d’Ivoire. Cette maladie est due à une mycobactérie : la Mycobacterium ulcerans. L’objectif de cette étude est de déterminer des zones à risque à la Mycobacterium ulcerans afin de pouvoir protéger les populations vulnérables. Pour y parvenir, une approche combinée de systèmes d’information géographique et l’analyse multicritère a été adoptée. La cartographie des zones potentielles à risque à l’ulcère de Buruli révèle que le sud de la région présente un risque élevé de la transmission l’ulcère de Buruli. Ce risque élevé est lié à trois types d’indicateurs regroupant les facteurs. L’indicateur lié aux facteurs climatiques (précipitation, température et humidité relative) couvre 41,54% de superficie. L’indicateur lié aux facteurs environnementaux tels que l’indice de végétation (NDVI), l’indice d’humidité du sol (NDWI), l’altitude, l’hydrographie, et à la population, couvre 55,24% et l’indicateur lié à l’occupation du sol couvre 3,22% de la superficie. Par ailleurs, les résultats montrent que 57,17% de la superficie totale de la région est favorable à la transmission de l’ulcère de Buruli. Dans l’ensemble, les indicateurs climatiques, environnementaux, la population et l’occupation du sol constituent des facteurs de risques associés à l’émergence de l’ulcère de Buruli.© 2016 International Formulae Group. All rights reserved.Mots clés: Cartographie, risque, ulcère de Buruli, analyse multicritère, Côte d’IvoireEnglish Title: Assessment of hydro-climate and environmental risks associated with the Buruli ulcer occurrence in Marahoué region (Côte d’Ivoire)English AbstractThis study discusses a health care issue caused by Burili ulcers in pre-forested areas (contact area, forest-savanna) in Marahoué region of Côte d’Ivoire. That disease is caused by a mycobacterium: the Mycobacterium ulcerans. The aim of this work was to determine risk areas to Mycobacterium ulcerans in order to protect vulnerable populations. To achieve this objective, a combined approach of GIS and multi-criteria analysis has been proposed. The mapping of potential risk areas shows that the southern region has a high risk of transmission of Buruli ulcer. This risk is linked to three types of indicators grouping the factors. The indicator related to climatic factors (precipitation, temperature and relative humidity) covers 41.54% of the area. The indicator linked to environmental factors (vegetation index, humidity index of soil, altitude and hydrography) and population covers 55.24% and the indicator for the land use covers 3.22% of the area. Furthermore, the results show that 57.17% of the total area of the region are favorable for the transmission of Buruli ulcer. Overall, climate and environmental indicators, population and land use are risk factors for the emergence of Buruli ulcer.© 2016 International Formulae Group. All rights reserved.Keywords: Mapping, risk, Buruli ulcer, multi-criteria analysis, Côte d’Ivoir

Evaluation of the Gamma Law for Settling Velocity and Trapping Capacity Analysis of Suspended Particles in a Dam Reservoir (Lobo River in Côte d’Ivoire)

International audienceHuman activities and climate change are currently dominant processes that affect hydrological processes, resulting in alterations in water and sediment flows. Evaluation of the settling velocity of suspended solids is a critical parameter in modelling sediment transport. In this study, we investigated seasonal changes in suspended solids’ settling velocity and trapping capacity in the presence and absence of water turbulence on a dam reservoir. Using key parameters such as flow rate, mean settling velocity (V¯), critical velocity (vc), suspended solids concentration, ratio V¯/vc, and shape parameter ‘r’, the trapping capacity on the dam reservoir on the Lobo River in a tropical region was estimated. The results show that, considering the settling velocity of suspended solids, following the Gamma distribution law remains an innovative solution proposed to evaluate the trapping capacity in water reservoirs. The results show that the mean suspended solids settling velocity V¯ is well above the median rate V50%. For a parameter V¯/vc ≥ 4, there is an increase in the trapping capacity of the water retention. As established, a large proportion of the sediment is trapped. Furthermore, for a parameter V¯/vc ≤ 4, a decrease in the trapping capacity of the Lobo River water reservoir is observed

Impact of Meteorological Drought on Streamflows in the Lobo River Catchment at Nibéhibé, Côte d’Ivoire

International audienceThe management of water resources in watersheds has become increasingly difficult in recent years due to the frequency and intensity of drought sequences. The Lobo River catchment, like most tropical regions, has experienced alternating wet and dry periods. These drought periods have a significant impact on the availability of water resources in the basin. The objective of this study is to analyse the impact of meteorological drought on flows in the Lobo River catchment. Therefore, using the Normalized Precipitation and Evapotranspiration Index (SPEI) and the Drought Flow Index (SDI), the characteristics of droughts were studied. The results of this study show that meteorological droughts were more frequent than hydrological droughts in the Lobo River watershed. However, the hydrological drought was longer and more intense than the meteorological drought. The greater relationship between meteorological and hydrological drought was observed at the Daloa and Vavoua station (0.43 < r < 0.50) compared to the Zuenoula station (r < 0.5). In addition, there was a resumption of precipitation and runoff between 2007 and 2013 in the basin. The study of these climatic trends would be very useful in the choice of management and adaptation policies for water resources management