28 research outputs found
Coupling modeling and remote sensing for the determination of high-flow drilling locations in the Lobo watershed at Nibehibé in CÎte d'Ivoire
Access to drinking water remains at the center of major development projects in CĂŽte d'Ivoire, particularly in the Lobo watershed, located in the Precambrian basement area which is made up of magmatic and metamorphic rocks. The exploitation of the basin's groundwater is marked by numerous failures in the boreholes drilled. Thus, this study aims to implement a land management tool to identify areas of high aquifer productivity in order to reduce the failure rate of drilling in the Lobo watershed. The methodology adopted was to map the recharges and fractures through the coupling of agro-hydrological modeling with SWAT, remote sensing and GIS. The results obtained show that the SWAT model was sensitive to 13 hydrological parameters and particularly to groundwater-related parameters. The statistical and graphical criteria of the SWAT model showed good performances (the Nash-Sutcliffe "NS" and determination "R2" coefficients > 0.6) for the calibration period (1982-1993) and (NS and R2 â„ 0.5) for the validation period (1979-1981). The monthly volumes of water recharging the groundwater tables range from 43 m3 to 5770 m3. The superposition of the recharge map on the fracturing map, based solely on geophysical surveys (presence of fractures), shows the potential sites for the installation of high flow boreholes. These sites could be located at the level of the mega fractures in the zones where the volumes of water reserves remain higher or equal to 3363 m3/month
CaractĂ©risation hydrogĂ©ochimique des eaux souterraines du dĂ©partement de Man (Ouest de la CĂŽte dâIvoire)
Cette Ă©tude avait pour but de comprendre le fonctionnement hydrogĂ©ochimique des eaux souterraines du dĂ©partement de Man situĂ© Ă lâOuest de la CĂŽte dâIvoire. Elle a fait appel aux mĂ©thodes de statistique descriptive, hydrochimique (diagramme de Piper) et Ă lâanalyse en Composantes Principales (ACP) pour connaĂźtre la qualitĂ©, les faciĂšs chimiques et les phĂ©nomĂšnes de la minĂ©ralisation des eaux souterraines. LâĂ©chantillonnage a concernĂ© 19 forages et les paramĂštres chimiques analysĂ©s sont Ca2+, Mg2+, Na+, K+, NH4+, SO42- , HCO3- , NO3-, Cl-, NO2- , Cu2+, Fe2+, PO43- et Al3. Les rĂ©sultats de la statistique descriptive ont montrĂ© que les eaux avaient une tempĂ©rature moyenne de 27,34°C en saison sĂšche et 28,005°C en saison pluvieuse. Les eaux Ă©taient acides pendant les deux saisons. Les valeurs de pH Ă©taient comprises entre 5,58 et 7,74 avec une moyenne de 6,673±0,541 en saison sĂšche et entre 5,25 et 7,11 avec une moyenne de 6,223±0,441 en saison pluvieuse. Elles Ă©taient peu minĂ©ralisĂ©es, avec des moyennes de conductivitĂ© Ă©lectrique de 219,51 ÎŒS/cm en saison sĂšche et 206,50 ÎŒS/cm en saison pluvieuse. Ces eaux prĂ©sentaient un faciĂšs bicarbonatĂ© calcique et magnĂ©sien majoritaire (Ca-Mg- HCO3), un faciĂšs chlorurĂ© calcique et magnĂ©sien (Ca-Mg-Cl) au cours des deux saisons et un faciĂšs bicarbonatĂ© sodique et potassique en saison pluvieuse (Na-K-HCO3). Les principaux phĂ©nomĂšnes Ă lâorigine de la minĂ©ralisation des eaux Ă©taient la minĂ©ralisation-temps de sĂ©jour, lâapport superficiel et la dĂ©gradation anthropique de la qualitĂ© des eaux et la pollution organique. Ces rĂ©sultats constituent une base de donnĂ©es dans la gestion des eaux souterraines de la rĂ©gion
Assessment of Wells Water Quality and their Suitability for Drinking in M'Bahiakro City (CĂŽte d'Ivoire)
The present study was carried out to assess the quality and the suitability of the well waters for drinking in Mâbahiakro city (centre-east of CĂŽte dâIvoire). The work was performed on 71 wells in February 2012 (dry season) and June 2012 (rainy season). Groundwater levels and physico-chemical parameters (pH, temperature, electrical conductivity, redox potential (Eh), Total Dissolved Solid (TDS) and Salinity) were measured to assess the water table fluctuation and the groundwater quality. Standardized Principal Component Analysis (SPCA) was calculated to group the well waters and to evaluate their suitability for drinking according to different classes. Water table varies between 125 and 135 m during the dry season and between 127 and 136 m during the rainy season with a West-Est flow direction. The recharge values ranged between 0.57 m and 5.57 m. Wells waters are generally acidic (pH<6.5), high mineralized with conductivities and Total Dissolved Solids (TDS) respectively above 600 ”S/cm and 300 mg/l. Well water salinity values ranged between 0.30 and 0.5%. The Standardized Principal Component Analysis (SPCA) allowed distinguishing three important groups of water within Mâbahiakro area: the first group of wells with high mineralized water, the second group of wells with high potential redox (Eh) and the third group of wells with pH closer to neutral. The first and second groups are not very suitable for drinking because they are suspected of being contaminated by anthropogenic sources such as septic tanks and wild dump. Waters of these wells need to be treated before any domestic use
Yam Cropping System in Cote dâIvoire: Current Practices and Constraints
Yam is the first food crop in CĂŽte d'Ivoire. It is being cultivated under a traditional technique system with low output. Detailed profiling of the current practices and opportunities for improvement is essential to increase the benefits of yam for food security and income in the country. This study diagnosed the current practices, constraints, and requirements in order to gain insight on the yam cropping system for research and development in CĂŽte d'Ivoire. The surveys were conducted in seven (7) regions in the main yam production area. Groups of 60 producers per region were investigated. Individual surveys were also conducted on-farm, particularly for diagnosing the physical environment and yam-based production systems. As results, yambased production systems are characterized by mixed cropping (cassava, corn and vegetable crops) and/or rotation with various other crops (rice, groundnut, vegetable crops, âŠ). Preferred plots for yam cultivation are forest, savannah or fallow areas. The major constraints in yam cultivation were the effects of environmental stresses, labor scarcity, pest damage, tuber and seed storage difficulties as well as the low market value of yam. The most cultivated yam varieties are BĂštĂš-BĂštĂš and Florido for Dioscorea alata and Lokpa for Dioscorea rotundata. The cropping system, the species and varieties vary according to the region, the topo sequence and the type of soil. Knowledgebuilding that take into account constraints related to yam cultivation, for each production area, can serve as guidance for variety breeding and cultivation environment redefinition
Development of a Model for Assessing Vulnerability to Pollution of Groundwater in Fissured Aquifers: The Case of the Ehania Watershed (South-Eastern Côte dâIvoire)
International audienceThe protection of aquifers is a major concern for the authorities, especially in areas where there are large agro-industrial exploitations. The objective of this study is to define a new method of aquifer protection based on the characteristics of the structures of aquifers. The intrinsic vulnerability mapping method, PaPRI was used. It is a variant of the PaPRIKa method applied in karstic environment which has been adapted for its application in basement environment. This method uses three factors, including aquifer protection (P), using the soil cover, the unsaturated zone and the thickness of the alteration layer, (R) for the rock type and (I) for infiltration which including slope and drainage density. PAPRI is a method based on the weighting of different factors. The results obtained show 4 classes that evolve from low vulnerability classes (5% of the study area) to high and very high vulnerability classes (58%) and average vulnerability classes (37%). The classes of high and very high vulnerability, which indicate the zones that are very exposed to pollution, are more present in the central-northern part of the study area, with a few appearances towards the south. These zones could be related to topography due to the often very high slopes observed in the area. One of the advantages of this new method lies in the characterization of the alterations that strongly influence the migration of pollutants towards the water tables according to their nature and their thickness
Dynamique forestiĂšre et pression urbaine dans le Parc national du Banco (Abidjan, CĂŽte dâIvoire)
Since 1960s, the Ivorian government care about his forest conservation. Thus, the Ivory Coast has set up a network of protected areas to conserve its forests and biodiversity. Located in Abidjan, the Banco National Park (PNB) and its periphery face a deeply environment changes in recent decades. This research aims to describe and analyze the various threats to urban pressure, including the risks of deforestation and pollution around and inside the PNB. To achieve these objectives, the analysis of the land cover and vegetation change help to understand the environmental dynamics of the Banco forest. The inventory and mapping of the types of risk and their impact on PNB enable to show the most vulnerable areas due to anthropogenic pressures and urbanization. The study of the types of human pressures in PNB is conducted through observations to detect spatial changes in recent years. The study also relies on an aerial photograph of 1955 and Spot satellite image taken in 1998. Aerial photography was acquired at the Centre of Cartography and Remote Sensing and the National Geographic Institute (IGN-Paris). The satellite image was obtained with the ISIS program of Spot Image. These data were used to map land cover in 1955 and 1998 and compare the evolution of the vegetation through a diachronic analysis.Indeed, in the year 1955, the land in the park and its periphery showed that the landscape was dominated by the forest despite the presence of a few urban space. The forest covered an area of 5462 ha while secondary forest covered an area of 9220 ha. These two types of forest represented nearly 90 % of the landscape of the study area. In 1998, 3450 ha of forest and 434 ha of forest plantations represente the vegetation of the PNB. Bordered by four towns, the Banco National Park suffers from the consequences of rapid urbanization. This rapid growth in the district of Abidjan has created many environmental problems, including the proliferation of shantytowns, inadequate facilities and transport infrastructure, sanitation and housing. The park is bordered to the north, east and south many poor neighborhoods without sanitation equipment. The PNB is to be the outlet for solid and liquid waste from households. Municipal storm water is discharged into the park. Multiple industrial units, informal activities and new residential areas bordering the park which is already facing since a decades to the creation of many facilities (creation of motorways, express roads, infrastructure and equipment necessary to meet demand of urban water, electricity etc..). In addition, many areas of PNB are subject to land claims, including the north-east and south of the park. These disputed areas are correlated with particular types of communities along the villages of Anonkoua Kouté Sagbé and north-Agban Attié and Agban-village southeast, and southwest Andokoi. In order to improve the protection of PNB and to enable his participation in economic development of people, its directors have established a policy of participatory management. This strategy involves local people in conservation. The association of local people in the community management of forest resources can empower them by involving them in monitoring missions, recovery and development. The development of the park through ecotourism, the development of alternative activities toward poachers and illegal loggers are among the many strategies implemented to save this threatened ecosystem. Ecotourism has become the most important policy of participatory management of public administrators of PNB
Dynamique forestiĂšre et pression urbaine dans le Parc national du Banco (Abidjan, CĂŽte dâIvoire)
La problĂ©matique de la conservation de la forĂȘt ivoirienne et de ses ressources est au centre des prĂ©occupations des pouvoirs publics depuis les annĂ©es 1960. Ainsi, la CĂŽte dâIvoire a-t-elle mis en place un rĂ©seau dâaires protĂ©gĂ©es, notamment plusieurs parcs nationaux, pour conserver ses massifs forestiers et leurs biodiversitĂ©s. SituĂ© Ă Abidjan, le Parc National du Banco (PNB) et sa pĂ©riphĂ©rie connaissent de profondes mutations environnementales depuis quelques dĂ©cennies. Ces mutations liĂ©es principalement aux activitĂ©s humaines et Ă lâurbanisation rapide du district dâAbidjan provoquent une dĂ©gradation du massif forestier du PNB. Cette recherche vise Ă dĂ©crire et Ă analyser les diffĂ©rentes menaces liĂ©es Ă la pression urbaine, notamment les risques de dĂ©forestation et de pollution qui exposent certaines zones du PNB. Pour atteindre ces objectifs, lâanalyse de lâĂ©volution de la vĂ©gĂ©tation, des types dâoccupation du sol, des recompositions territoriales et des jeux des diffĂ©rents acteurs est mise Ă profit pour comprendre les dynamiques environnementales de la forĂȘt du Banco et sa pĂ©riphĂ©rie. Lâinventaire et la cartographie des types de risque ainsi que leurs impacts sur le PNB permettent dâidentifier les zones les plus vulnĂ©rables aux pressions anthropiques et Ă lâurbanisation. LâĂ©tude des types de pressions humaines sur la forĂȘt du PNB est menĂ©e Ă travers des observations de terrain pour dĂ©tecter les changements spatiaux des derniĂšres annĂ©es. LâĂ©tude sâappuie Ă©galement sur une photographie aĂ©rienne de 1955 et une image satellite Spot prise en 1998. La photographie aĂ©rienne a Ă©tĂ© acquise auprĂšs du Centre de Cartographie et TĂ©lĂ©dĂ©tection (CCT-Abidjan) et de lâInstitut GĂ©ographique National (IGN-Paris). Lâimage satellite a Ă©tĂ© obtenue grĂące au programme ISIS de Spot Image. Ces donnĂ©es ont permis de cartographier lâoccupation du sol en 1955 et 1998 et de comparer lâĂ©volution de la vĂ©gĂ©tation Ă travers une analyse diachronique.Les rĂ©sultats de lâĂ©tude montrent que dans les annĂ©es 1955, le paysage du PNB et sa pĂ©riphĂ©rie Ă©tait dominĂ© par la forĂȘt malgrĂ© la prĂ©sence de quelques tĂąches urbaines. La forĂȘt couvrait une superficie de 5462 ha tandis que la forĂȘt secondaire occupait une surface de 9220 ha. Ces deux formations forestiĂšres reprĂ©sentaient prĂšs de 90 % du paysage de la zone dâĂ©tude. En 1998, 3450 ha de forĂȘt et 434 ha de plantations forestiĂšres constituent la vĂ©gĂ©tation du PNB. BordĂ© de quatre communes, le Parc National du Banco subit les consĂ©quences de lâurbanisation galopante. Cette croissance rapide du district dâAbidjan a engendrĂ© de nombreux problĂšmes environnementaux, notamment la multiplication des quartiers prĂ©caires qui bordent le parc au nord, Ă lâest et au sud, lâinsuffisance des Ă©quipements et infrastructures de transport, dâassainissement et de logement. Ainsi, le PNB est-il devenu lâexutoire des dĂ©chets solides et liquides des mĂ©nages abidjanais. Les eaux pluviales communales, notamment Ă Abobo au nord, AdjamĂ© Ă lâest et Yopougon au sud sont Ă©galement Ă©vacuĂ©es dans le parc. De multiples unitĂ©s industrielles, des activitĂ©s informelles et de nouveaux quartiers rĂ©sidentiels bordent le PNB qui fait dĂ©jĂ face depuis des dĂ©cennies aux amĂ©nagements divers (crĂ©ation dâautoroutes, de voies express, dâinfrastructures et dâĂ©quipements nĂ©cessaires Ă la satisfaction de la demande urbaine en eau, Ă©lectricitĂ©, etc.). En outre, de nombreuses zones du PNB font lâobjet de revendications fonciĂšres, notamment le nord-est et le sud du parc. Ces zones contestĂ©es se situent dans les villages dâAnonkoua KoutĂ© et de SagbĂ© au nord, Agban-attiĂ© et Agban-village au sud-est, et Andokoi au sud-ouest. Pour rĂ©pondre aux problĂšmes liĂ©s Ă lâaction des populations dans le PNB et sa pĂ©riphĂ©rie, les gestionnaires ont mis en place une sĂ©rie de mesures alternatives pour amĂ©liorer sa conservation. En effet, dans le but de le protĂ©ger davantage et de le faire participer au dĂ©veloppement Ă©conomique des populations, ses administrateurs ont mis en place une politique de gestion participative. Cette stratĂ©gie permet dâassocier les populations locales Ă sa conservation. Lâassociation de celles-ci Ă cette gestion communautaire des ressources forestiĂšres permet de les responsabiliser en les impliquant dans les missions de surveillance, de valorisation et dâamĂ©nagement. La mise en valeur du parc notamment Ă travers lâĂ©cotourisme, le dĂ©veloppement dâactivitĂ©s alternatives Ă lâattention des braconniers et des exploitants illĂ©gaux font Ă©galement partie des nombreuses stratĂ©gies mises en place pour sauver cet Ă©cosystĂšme menacĂ©. LâĂ©cotourisme est ainsi devenu le fer de lance de la politique de gestion participative des administrateurs publics du PNB.Since 1960s, the Ivorian government care about his forest conservation. Thus, the Ivory Coast has set up a network of protected areas to conserve its forests and biodiversity. Located in Abidjan, the Banco National Park (PNB) and its periphery face a deeply environment changes in recent decades. This research aims to describe and analyze the various threats to urban pressure, including the risks of deforestation and pollution around and inside the PNB. To achieve these objectives, the analysis of the land cover and vegetation change help to understand the environmental dynamics of the Banco forest. The inventory and mapping of the types of risk and their impact on PNB enable to show the most vulnerable areas due to anthropogenic pressures and urbanization. The study of the types of human pressures in PNB is conducted through observations to detect spatial changes in recent years. The study also relies on an aerial photograph of 1955 and Spot satellite image taken in 1998. Aerial photography was acquired at the Centre of Cartography and Remote Sensing and the National Geographic Institute (IGN-Paris). The satellite image was obtained with the ISIS program of Spot Image. These data were used to map land cover in 1955 and 1998 and compare the evolution of the vegetation through a diachronic analysis.Indeed, in the year 1955, the land in the park and its periphery showed that the landscape was dominated by the forest despite the presence of a few urban space. The forest covered an area of 5462 ha while secondary forest covered an area of 9220 ha. These two types of forest represented nearly 90 % of the landscape of the study area. In 1998, 3450 ha of forest and 434 ha of forest plantations represente the vegetation of the PNB. Bordered by four towns, the Banco National Park suffers from the consequences of rapid urbanization. This rapid growth in the district of Abidjan has created many environmental problems, including the proliferation of shantytowns, inadequate facilities and transport infrastructure, sanitation and housing. The park is bordered to the north, east and south many poor neighborhoods without sanitation equipment. The PNB is to be the outlet for solid and liquid waste from households. Municipal storm water is discharged into the park. Multiple industrial units, informal activities and new residential areas bordering the park which is already facing since a decades to the creation of many facilities (creation of motorways, express roads, infrastructure and equipment necessary to meet demand of urban water, electricity etc..). In addition, many areas of PNB are subject to land claims, including the north-east and south of the park. These disputed areas are correlated with particular types of communities along the villages of Anonkoua KoutĂ© SagbĂ© and north-Agban AttiĂ© and Agban-village southeast, and southwest Andokoi. In order to improve the protection of PNB and to enable his participation in economic development of people, its directors have established a policy of participatory management. This strategy involves local people in conservation. The association of local people in the community management of forest resources can empower them by involving them in monitoring missions, recovery and development. The development of the park through ecotourism, the development of alternative activities toward poachers and illegal loggers are among the many strategies implemented to save this threatened ecosystem. Ecotourism has become the most important policy of participatory management of public administrators of PNB
Dynamique forestiĂšre et pression urbaine dans le Parc national du Banco (Abidjan, CĂŽte dâIvoire)
Since 1960s, the Ivorian government care about his forest conservation. Thus, the Ivory Coast has set up a network of protected areas to conserve its forests and biodiversity. Located in Abidjan, the Banco National Park (PNB) and its periphery face a deeply environment changes in recent decades. This research aims to describe and analyze the various threats to urban pressure, including the risks of deforestation and pollution around and inside the PNB. To achieve these objectives, the analysis of the land cover and vegetation change help to understand the environmental dynamics of the Banco forest. The inventory and mapping of the types of risk and their impact on PNB enable to show the most vulnerable areas due to anthropogenic pressures and urbanization. The study of the types of human pressures in PNB is conducted through observations to detect spatial changes in recent years. The study also relies on an aerial photograph of 1955 and Spot satellite image taken in 1998. Aerial photography was acquired at the Centre of Cartography and Remote Sensing and the National Geographic Institute (IGN-Paris). The satellite image was obtained with the ISIS program of Spot Image. These data were used to map land cover in 1955 and 1998 and compare the evolution of the vegetation through a diachronic analysis.Indeed, in the year 1955, the land in the park and its periphery showed that the landscape was dominated by the forest despite the presence of a few urban space. The forest covered an area of 5462 ha while secondary forest covered an area of 9220 ha. These two types of forest represented nearly 90 % of the landscape of the study area. In 1998, 3450 ha of forest and 434 ha of forest plantations represente the vegetation of the PNB. Bordered by four towns, the Banco National Park suffers from the consequences of rapid urbanization. This rapid growth in the district of Abidjan has created many environmental problems, including the proliferation of shantytowns, inadequate facilities and transport infrastructure, sanitation and housing. The park is bordered to the north, east and south many poor neighborhoods without sanitation equipment. The PNB is to be the outlet for solid and liquid waste from households. Municipal storm water is discharged into the park. Multiple industrial units, informal activities and new residential areas bordering the park which is already facing since a decades to the creation of many facilities (creation of motorways, express roads, infrastructure and equipment necessary to meet demand of urban water, electricity etc..). In addition, many areas of PNB are subject to land claims, including the north-east and south of the park. These disputed areas are correlated with particular types of communities along the villages of Anonkoua Kouté Sagbé and north-Agban Attié and Agban-village southeast, and southwest Andokoi. In order to improve the protection of PNB and to enable his participation in economic development of people, its directors have established a policy of participatory management. This strategy involves local people in conservation. The association of local people in the community management of forest resources can empower them by involving them in monitoring missions, recovery and development. The development of the park through ecotourism, the development of alternative activities toward poachers and illegal loggers are among the many strategies implemented to save this threatened ecosystem. Ecotourism has become the most important policy of participatory management of public administrators of PNB
Study of Groundwater-river Interactions Using Hydrochemical Tracers in Fissured Rock: Case of the Lobo Watershed at NibĂ©hibĂ© (Central-West, CĂŽte dâIvoire)
Water is a vital resource for all populations. However, there are warning signs that the water from the Lobo River used by SODECI to supply drinking water to the population is declining in quantity during the dry season and its quality is becoming poor due to climate variability and anthropogenic activities. However, the river is able to maintain a certain flow, probably with the contribution of groundwater. It is therefore a question of whether there is really a connection between surface water and groundwater. The aim of this study is to characterize the groundwater-river interactions based on the physico-chemical parameters of the Lobo watershed in NibĂ©hibĂ©. The approach adopted is a coupled statistical-geochemical approach applied on data from two sampling campaigns (dry and rainy season). This coupled approach consisted, on the one hand, in understanding the chemical specificities within the water classes using the piper diagram and, on the other hand, in classifying the waters according to their physico-chemical similarity and highlighting the phenomena at the origin of the water mineralization using the Kohonen self-organized map (SOM). The results obtained from the piper diagram show that in both the wet and dry seasons, the chemical signature of the waters remains controlled by two main hydrochemical facies: the chlorinated calcium-magnesium nitrate hydrofacies and the bicarbonate calcium-magnesium hydrofacies. Kohonen's self-organized map has established that the mineralization of groundwater, under natural conditions, comes from the nature of the rocks crossed during infiltration and from the contact time between water and minerals. This work provides managers with decision-support tools for planning and searching for groundwater in support of surface water to reinforce the drinking water supply of the populations in this watershed. 
Spatio-temporal characterization of the physico-chemical quality of groundwater: Case of the Lobo watershed (Centre-west of CĂŽte d'Ivoire)
International audienc