Techniques isotopiques (15N 18O) appliquees a l etude des nappes des alterites et du socle fracture de l ouest africain

Girard, Pierre

doi:10.1522/1486981

Cited by 8 publications

(6 citation statements)

References 31 publications

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“…Rainfall data were obtained from the International Atomic Energy Agency (IAEA) network (GNIP, 2011), from Niamey/ORSTOM stations (1992 to 1999) and IRI/Abdou Moumouni University of Niamey in Niger, located at an almost identical (190 m vs 225 m asl) altitude (Ousmane, 1988;Girard, 1993, Taupin et al, 2002, Guéro, 2003, Tremoy et al, 2012.…”

Section: Chemical and Isotope Analysesmentioning

confidence: 99%

Characterization of recharge mechanisms in a Precambrian basement aquifer in semi-arid south-west Niger

et al. 2018

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In the central part of the semi-arid Dargol Basin of southwestern Niger, most of the groundwater resource is contained in the fractured aquifers of the Precambrian basement. The groundwater resource is poorly characterized and this study is the first attempt to better describe the recharge mechanisms and hydrogeochemical behaviour of the aquifers. Hydrogeochemical and piezometric methods were combined to determine changes in recharge rate and origin of groundwaters for the shallow weathered aquifer and the deep fissured/fractured aquifer. At the basin scale, the groundwater fluxes towards the Niger River are influenced mainly by topography, with no visual long-term trend in groundwater levels (1980-2009). The hydrogeochemical signature is dominated by the calcic-bicarbonate to magnesian (70%) type. It shows evolution from an open environment with CO2 and low mineralized water (granitoids, alterites) towards a more confined environment with more mineralized waters (schists). Stable water isotopes (δ 18 O, δ 2 H) analysis suggests two main groundwater recharge mechanisms: (i) direct recharge with nearly no post-rainfall fractionation signature and (ii) indirect recharge from evaporated surface waters and/or stream-channel beds. Groundwater tritium content indicates that recharge is mostly recent, with an age less than 50 years (3 H > 3 TU), with only 10% indicating low or even no recharge for the past decades. A median value of the groundwater renewal rate estimated from individual values of tritium is equivalent to 1.3% y-1 , close to the one determined for groundwater samples dating to the early 1980s, thus indicating no measurable long-term change.

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Section: Chemical and Isotope Analysesmentioning

confidence: 99%

Characterization of recharge mechanisms in a Precambrian basement aquifer in semi-arid south-west Niger

et al. 2018

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“…During the dry season, particularly from March to May, the Harmattan brings temperatures of up to 50°C. Hydric deficits are thus major and surface water resources are almost non-existent, leaving only alluvial underground water for use by inhabitants (Girard, 1993). This has a negative impact on agriculture, which is an important economic activity but only weakly represented in terms of land use distribution.…”

Section: General Contextmentioning

confidence: 99%

“…The groundwater depth of the Niger Liptako aquifer is between 0 (Niger River) and 75 m and feeds mainly Niamey City. Other studies (Girard, 1993) have shown that some boreholes provide water unfit for human consumption (nitrogen pollution), while others are quickly drained. Hydro-geological characteristics such as aquifer recharge and sustainability are thus very difficult to understand in fractured basement.…”

Section: -Faults Of the North Continental Terminal Basin (N-s And N-smentioning

confidence: 99%

“…The Niamey area of Niger frequently faces water supply challenges, mainly groundwater pollution by nitrogen and water scarcity, particularly at the end of the dry season in April-May (Favreau et al, 2009;Girard, 1993) and has been chosen for this study as representative of the complexity of water resource management. Previous studies show that groundwater aquifers located around Niamey could increase water resources on a local scale (Leduc et al, 1996;Monfort, 1996).…”

Section: Introductionmentioning

confidence: 99%

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An integrated approach to hydro-geological lineament mapping of a semi-arid region of West Africa using Radarsat-1 and GIS

Corgne

Magagi

Yergeau

et al. 2010

Remote Sensing of Environment

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“…Au Niger, le rôle de la fracturation dans l'hydrodynamique souterraine est démontré par les travaux antérieurs (Ousmane, 1988 ;Girard, 1993 ; Corgne et al, 2010; Abdou Babaye, 2012).…”

Section: Introductionunclassified

Apport Des Images ETM+ Et Du Modèle Numérique De Terrain (MNT) A La Cartographie Des Fractures En Région Montagneuse : Secteur De Timia (Massif De l’Aïr, Nord Du Niger)

Alhassane¹,

Sani²,

Sandao³

et al. 2018

ESJ

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Timia is located at the Aïr massifs region. This locality, which is the substratum that constituted the basement formations, has some difficulty of water supply. This present study focuses on fractures mapping to acquire the best knowledge of the fractured aquifer in Timia zone. The methodological approach is based on landsat7 image processing and DEM, especially directional filtering and shaded digital terrain models. These diverse processing has shown complementarity between the satellites images and DEM in linear mapping on the one hand and in establishing a lineaments map on the other hand. The lineament map showed that the fractures network is distributed in the following directions: N0°-N10°, N140°-N170°, N 70°- N100°, and N30°-N50°. These fractures map, which was allowed to increase the density of faults from the previous studies, were used to actualize hydrogeological knowledge and in determining the favorable sites for drilling boreholes in Timia locality.

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Techniques isotopiques (15N 18O) appliquees a l etude des nappes des alterites et du socle fracture de l ouest africain

Cited by 8 publications

References 31 publications

Characterization of recharge mechanisms in a Precambrian basement aquifer in semi-arid south-west Niger

Characterization of recharge mechanisms in a Precambrian basement aquifer in semi-arid south-west Niger

An integrated approach to hydro-geological lineament mapping of a semi-arid region of West Africa using Radarsat-1 and GIS

Apport Des Images ETM+ Et Du Modèle Numérique De Terrain (MNT) A La Cartographie Des Fractures En Région Montagneuse : Secteur De Timia (Massif De l’Aïr, Nord Du Niger)

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