The Boulon Djounga eastern perimeter is part of the Tiawa operating permit of the Société des Mines du Liptako (SML), located in the central southwestern part of Liptako (Niger). In this study, we used field...The Boulon Djounga eastern perimeter is part of the Tiawa operating permit of the Société des Mines du Liptako (SML), located in the central southwestern part of Liptako (Niger). In this study, we used field data, Reverse Circulation (RC) surveys and chemical analyzes of gold to determine the characteristics of gold and its mineralization style. The eastern perimeter of Boulon Djounga is represented by a succession of metabasalts and metasediments both intersected by intrusions of quartz and dolerite dykes, and covered by sandstone and clayey rocks. Gold is present in low contents (0.00 - 0.30 ppm) in the sedimentary cover and in medium (0.30 - 1.00 ppm) or high contents (1.00 - 4.534 ppm) in the metasediments, and in the gray quartz veins and locally in the volcanics. It exists in a disseminated state or in a concentrated state in the surrounding areas in the form of discrete grains associated with sulphurous minerals (pyrite: FeS<sub>2</sub>, chalcopyrite: CuFeS<sub>2</sub> or arsenopyrite: FeAsS). The presence of gold in the quartz veins, and the NE-SW and NW-SE orientations of the ore bodies suggest that the eastern Boulon Djounga gold mineralization would be established during a late magmatic extensive phase.展开更多
This study aims to characterize the different lithofacies of the Ct<sup>3</sup> formation in the Niamey region, and to determine the distribution of major and trace elements, in order to highlight the cond...This study aims to characterize the different lithofacies of the Ct<sup>3</sup> formation in the Niamey region, and to determine the distribution of major and trace elements, in order to highlight the conditions for the establishment of iron mineralization. A lithological column, synthesizing sections of selected outcrops in the vicinity of Niamey, was produced. The chemical compositions of the selected samples were determined by X-ray fluorescence (XRF) spectrometry. Microscopic analysis of the thin sections determined the gœthitic nature of the oolitic iron ore. The oolites show a quartz, limonitic or gœthitic nucleus. Sometimes the nucleus is absent. From a morphoscopic point of view, two types of oolites have been distinguished: spherical-shaped and ellipsoidal-shaped oolites. The oolites are either contiguous or disseminated, as the case may be, in a limonitic to goethitic cement or in a fine sandstone matrix. The larger oolites (pisolites) are relatively friable. They reflect the influence of a relatively turbulent to submerged environment. The hardground of the iron mineralized horizons are covered by quartz grains. They are indicative of a submerged or emergent environment. X-ray fluorescence analysis shows high Fe<sub>2</sub>O<sub>3</sub> contents<sub> </sub>(50% to 80%) and variable contents of major elements SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub>, MnO, MgO, CaO, K<sub>2</sub>O and P<sub>2</sub>O<sub>5</sub> associated with certain trace elements such as Th, U, V, Y, Zn, Zr and As. The results of the study are an important tool for decision-makers to adopt effective prevention/remediation measures for groundwater contamination in the Continental terminal aquifer systems.展开更多
The Urban Commune of Maradi in Niger experienced increasingly frequent flooding following rainy episodes generating volumes and water flows that are difficult to control in recent years. This study aims to determine t...The Urban Commune of Maradi in Niger experienced increasingly frequent flooding following rainy episodes generating volumes and water flows that are difficult to control in recent years. This study aims to determine the impacts of runoff water in Commune II of Maradi City and to assess the role of urban planning in runoff management, as well as the strengths and weaknesses of urban sanitation in Maradi. The methodological approach used consisted of: 1) an interpretation of documentary data, 2) gathering information on runoff at several sites in the study area, and 3) interviews and questionnaires with local communities. This approach made it possible to understand the degree of vulnerability of the populations to flooding and then to propose sustainable solutions to reduce the vulnerability of the affected populations, through the implementation of effective urban rainwater management practices (USWMP). The results show that the impacts of runoff are mainly related to the lack of adequate storm water drainage networks in the area, but also to the nature of the habitats. Geomorphological factors such as the nature of the soil, the slope of the terrain and the altitude increase the degree of risk. In addition, the inadequacy and dilapidation of the drainage systems of the canals and above all the anarchic occupation of the land linked to accelerated urbanization are the cause of flooding by stagnation of rainwater. A phenomenon now linked to numerous deteriorations of urban equipment, the runoff of rainwater in the city of Maradi carries so many pollutants that municipalities, businesses and individuals should put in place pollution prevention measures.展开更多
In the basement of southwestern Niger, weathering and fractured zones concentrate most of the groundwater. This study focuses on fractured media and aims to identify areas of productivity in this aquifer to improve th...In the basement of southwestern Niger, weathering and fractured zones concentrate most of the groundwater. This study focuses on fractured media and aims to identify areas of productivity in this aquifer to improve the region’s water coverage. The cartographic approach developed made it possible to establish synthetic maps based on multi-criteria analysis. The hydrogeological parameters selected include fracturing data, drainage system, slope and piezometric level as well as shallow and deep lithology. The choice of these criteria is based on their physical meaning but also on the availability of data. The integration of all the criteria in a GIS allowed to generate maps of recharge and potential productivity of fractured aquifers in the area. The validation of these thematic maps with independent data confirms their utility as reference standards for accessibility for future resource exploitation. Like any spatialization tool, potential recharge maps will provide valuable information about areas where infiltration is more important, and help control and manage risk zoning. The upward evacuation effect is even more prominent along the lineaments, faults or fractures: thus, to avoid possible pollution and to locate the future hydraulic structures, the analysis of the potential recharge zones remains necessary. The potential productivity index map, in addition to the very punctual sites identified by the fracturing study, made it possible to define areas of high potential productivity.展开更多
The trivialization of empty spaces has long been practiced in the city of Maradi (Niger), particularly in the Zaria 2 (Commune II) and Ali Dan Sofo (Commune III) districts. With stalls in the streets and illegal dumpi...The trivialization of empty spaces has long been practiced in the city of Maradi (Niger), particularly in the Zaria 2 (Commune II) and Ali Dan Sofo (Commune III) districts. With stalls in the streets and illegal dumping grounds, empty plots and the surrounding areas are fairly privileged sources of various wastes. This study aims at analyzing the impact of these empty plots on the local population, through several aspects, especially in terms of the modes of occupation, internal and surrounding practices, physical environment and biodiversity, sanitation and elimination of waste. To do so, two methodological approaches were used: a survey on local population and in situ observation of these spaces. The results not only reveal a difficult proximity situation to the unbuilt but also showed that empty plots constitute not only a form of vegetation conservation for the future as well as clean surfaces which would be called upon to characterize the potential recharge of groundwater. The most potentially useful organic waste would be that of Kadro, especially feathers from poultry that could be used as compost in the fields. In addition to the degradation of urban environments (63% of respondents), the unbuilt area also contributes to poverty reduction and increases food security (69% of respondents). To reduce the negative impacts, the rewarding strategies would be awareness-raising and monitoring measures coupled with a policy of protection and environmental remedies.展开更多
The present study concerns the lowlands of the Birnin Lokoyo watershed located in the Matankari Rural Commune (Southwestern borders of the large Iullemmeden basin in the Niger). Dominated by the Birnin Lokoyo pond, th...The present study concerns the lowlands of the Birnin Lokoyo watershed located in the Matankari Rural Commune (Southwestern borders of the large Iullemmeden basin in the Niger). Dominated by the Birnin Lokoyo pond, this watershed faced with the continuous silting up of the minor bed, dissipates further upstream in the east, so that it moves downstream to the west for the benefit of the populations of Matankari city. The main objective of this work is to analyze the representative elements of the new climatic and environmental situation as well as the various factors determining the surface conditions in the watershed. The methodological approach is based on documentary research, field observations, individual surveys and interviews with targeted groups. The results show that the silting up of the lowlands is the result of the concomitant degradation of the plant cover and the soils, which, as a result, triggered the development of crusting surfaces and area erosion on the slopes. The study underlined the importance of endogenous knowledge in the choice of remedies against the silting up of lowlands. In addition, rational land management practices on plateaus and structures (within the watershed) do not seem to be in phase with topographical factors and the tectonic framework. This work is part of the vision of better management of glacis on the banks, but also of sills subject to regressive erosion upstream and in order to guide the policies of resilience of the populations.展开更多
Due to increasingly extreme climatic conditions in the Sahel, irrigated crops are emerging as imperative innovations for agricultural transformation and resilience. This study is designed to assess the impact of marke...Due to increasingly extreme climatic conditions in the Sahel, irrigated crops are emerging as imperative innovations for agricultural transformation and resilience. This study is designed to assess the impact of market gardening on soil, water and plant cover in the western Niger Republic. Semi-structured survey data were collected from 78 site operators in the Imanan rural municipality (Filingué, Tillabéry). In addition to the survey, a photographic collection illustrated certain observable facts in the field. The survey shows that the wooden enclosures (70.65% of respondents) around the fields are renewed every year. The impacts are then substantial: deforestation of plateaus, clearing of valleys for new extensions, loss of wildlife habitat, changes in the water flow regime resulting from a geomorphological change in the commune. Itou, the preparation of the planks consumes a lot of water. Thus, the new sinking of water points and the load pressure increase the drawdowns of wells and boreholes in the sites (75.46% of respondents). The frequent spills of waste oil on the sites, as well as the numerous potato storage pits, are among the factors and vectors most likely to contaminate the soils and aquifers of the study area. Market gardening destabilizes the soils and induces regressive erosion as well as area runoff of rainwater on all sites and on the slopes. On the other hand, slash-and-burn practices, drying of branches intended for fences, as well as rain-fed cowpea crops, promote improved physical properties and soil fertilization. To reduce the risks of disintegration and especially of silting up of sites, the study suggests a policy of live hedges and wire fences so that common spaces can be imposed on operators.展开更多
文摘The Boulon Djounga eastern perimeter is part of the Tiawa operating permit of the Société des Mines du Liptako (SML), located in the central southwestern part of Liptako (Niger). In this study, we used field data, Reverse Circulation (RC) surveys and chemical analyzes of gold to determine the characteristics of gold and its mineralization style. The eastern perimeter of Boulon Djounga is represented by a succession of metabasalts and metasediments both intersected by intrusions of quartz and dolerite dykes, and covered by sandstone and clayey rocks. Gold is present in low contents (0.00 - 0.30 ppm) in the sedimentary cover and in medium (0.30 - 1.00 ppm) or high contents (1.00 - 4.534 ppm) in the metasediments, and in the gray quartz veins and locally in the volcanics. It exists in a disseminated state or in a concentrated state in the surrounding areas in the form of discrete grains associated with sulphurous minerals (pyrite: FeS<sub>2</sub>, chalcopyrite: CuFeS<sub>2</sub> or arsenopyrite: FeAsS). The presence of gold in the quartz veins, and the NE-SW and NW-SE orientations of the ore bodies suggest that the eastern Boulon Djounga gold mineralization would be established during a late magmatic extensive phase.
文摘This study aims to characterize the different lithofacies of the Ct<sup>3</sup> formation in the Niamey region, and to determine the distribution of major and trace elements, in order to highlight the conditions for the establishment of iron mineralization. A lithological column, synthesizing sections of selected outcrops in the vicinity of Niamey, was produced. The chemical compositions of the selected samples were determined by X-ray fluorescence (XRF) spectrometry. Microscopic analysis of the thin sections determined the gœthitic nature of the oolitic iron ore. The oolites show a quartz, limonitic or gœthitic nucleus. Sometimes the nucleus is absent. From a morphoscopic point of view, two types of oolites have been distinguished: spherical-shaped and ellipsoidal-shaped oolites. The oolites are either contiguous or disseminated, as the case may be, in a limonitic to goethitic cement or in a fine sandstone matrix. The larger oolites (pisolites) are relatively friable. They reflect the influence of a relatively turbulent to submerged environment. The hardground of the iron mineralized horizons are covered by quartz grains. They are indicative of a submerged or emergent environment. X-ray fluorescence analysis shows high Fe<sub>2</sub>O<sub>3</sub> contents<sub> </sub>(50% to 80%) and variable contents of major elements SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub>, MnO, MgO, CaO, K<sub>2</sub>O and P<sub>2</sub>O<sub>5</sub> associated with certain trace elements such as Th, U, V, Y, Zn, Zr and As. The results of the study are an important tool for decision-makers to adopt effective prevention/remediation measures for groundwater contamination in the Continental terminal aquifer systems.
文摘The Urban Commune of Maradi in Niger experienced increasingly frequent flooding following rainy episodes generating volumes and water flows that are difficult to control in recent years. This study aims to determine the impacts of runoff water in Commune II of Maradi City and to assess the role of urban planning in runoff management, as well as the strengths and weaknesses of urban sanitation in Maradi. The methodological approach used consisted of: 1) an interpretation of documentary data, 2) gathering information on runoff at several sites in the study area, and 3) interviews and questionnaires with local communities. This approach made it possible to understand the degree of vulnerability of the populations to flooding and then to propose sustainable solutions to reduce the vulnerability of the affected populations, through the implementation of effective urban rainwater management practices (USWMP). The results show that the impacts of runoff are mainly related to the lack of adequate storm water drainage networks in the area, but also to the nature of the habitats. Geomorphological factors such as the nature of the soil, the slope of the terrain and the altitude increase the degree of risk. In addition, the inadequacy and dilapidation of the drainage systems of the canals and above all the anarchic occupation of the land linked to accelerated urbanization are the cause of flooding by stagnation of rainwater. A phenomenon now linked to numerous deteriorations of urban equipment, the runoff of rainwater in the city of Maradi carries so many pollutants that municipalities, businesses and individuals should put in place pollution prevention measures.
文摘In the basement of southwestern Niger, weathering and fractured zones concentrate most of the groundwater. This study focuses on fractured media and aims to identify areas of productivity in this aquifer to improve the region’s water coverage. The cartographic approach developed made it possible to establish synthetic maps based on multi-criteria analysis. The hydrogeological parameters selected include fracturing data, drainage system, slope and piezometric level as well as shallow and deep lithology. The choice of these criteria is based on their physical meaning but also on the availability of data. The integration of all the criteria in a GIS allowed to generate maps of recharge and potential productivity of fractured aquifers in the area. The validation of these thematic maps with independent data confirms their utility as reference standards for accessibility for future resource exploitation. Like any spatialization tool, potential recharge maps will provide valuable information about areas where infiltration is more important, and help control and manage risk zoning. The upward evacuation effect is even more prominent along the lineaments, faults or fractures: thus, to avoid possible pollution and to locate the future hydraulic structures, the analysis of the potential recharge zones remains necessary. The potential productivity index map, in addition to the very punctual sites identified by the fracturing study, made it possible to define areas of high potential productivity.
文摘The trivialization of empty spaces has long been practiced in the city of Maradi (Niger), particularly in the Zaria 2 (Commune II) and Ali Dan Sofo (Commune III) districts. With stalls in the streets and illegal dumping grounds, empty plots and the surrounding areas are fairly privileged sources of various wastes. This study aims at analyzing the impact of these empty plots on the local population, through several aspects, especially in terms of the modes of occupation, internal and surrounding practices, physical environment and biodiversity, sanitation and elimination of waste. To do so, two methodological approaches were used: a survey on local population and in situ observation of these spaces. The results not only reveal a difficult proximity situation to the unbuilt but also showed that empty plots constitute not only a form of vegetation conservation for the future as well as clean surfaces which would be called upon to characterize the potential recharge of groundwater. The most potentially useful organic waste would be that of Kadro, especially feathers from poultry that could be used as compost in the fields. In addition to the degradation of urban environments (63% of respondents), the unbuilt area also contributes to poverty reduction and increases food security (69% of respondents). To reduce the negative impacts, the rewarding strategies would be awareness-raising and monitoring measures coupled with a policy of protection and environmental remedies.
文摘The present study concerns the lowlands of the Birnin Lokoyo watershed located in the Matankari Rural Commune (Southwestern borders of the large Iullemmeden basin in the Niger). Dominated by the Birnin Lokoyo pond, this watershed faced with the continuous silting up of the minor bed, dissipates further upstream in the east, so that it moves downstream to the west for the benefit of the populations of Matankari city. The main objective of this work is to analyze the representative elements of the new climatic and environmental situation as well as the various factors determining the surface conditions in the watershed. The methodological approach is based on documentary research, field observations, individual surveys and interviews with targeted groups. The results show that the silting up of the lowlands is the result of the concomitant degradation of the plant cover and the soils, which, as a result, triggered the development of crusting surfaces and area erosion on the slopes. The study underlined the importance of endogenous knowledge in the choice of remedies against the silting up of lowlands. In addition, rational land management practices on plateaus and structures (within the watershed) do not seem to be in phase with topographical factors and the tectonic framework. This work is part of the vision of better management of glacis on the banks, but also of sills subject to regressive erosion upstream and in order to guide the policies of resilience of the populations.
文摘Due to increasingly extreme climatic conditions in the Sahel, irrigated crops are emerging as imperative innovations for agricultural transformation and resilience. This study is designed to assess the impact of market gardening on soil, water and plant cover in the western Niger Republic. Semi-structured survey data were collected from 78 site operators in the Imanan rural municipality (Filingué, Tillabéry). In addition to the survey, a photographic collection illustrated certain observable facts in the field. The survey shows that the wooden enclosures (70.65% of respondents) around the fields are renewed every year. The impacts are then substantial: deforestation of plateaus, clearing of valleys for new extensions, loss of wildlife habitat, changes in the water flow regime resulting from a geomorphological change in the commune. Itou, the preparation of the planks consumes a lot of water. Thus, the new sinking of water points and the load pressure increase the drawdowns of wells and boreholes in the sites (75.46% of respondents). The frequent spills of waste oil on the sites, as well as the numerous potato storage pits, are among the factors and vectors most likely to contaminate the soils and aquifers of the study area. Market gardening destabilizes the soils and induces regressive erosion as well as area runoff of rainwater on all sites and on the slopes. On the other hand, slash-and-burn practices, drying of branches intended for fences, as well as rain-fed cowpea crops, promote improved physical properties and soil fertilization. To reduce the risks of disintegration and especially of silting up of sites, the study suggests a policy of live hedges and wire fences so that common spaces can be imposed on operators.
