Groundwater is naturally protected against pollution through its filter layer which is the soil. However, the development of human activities, including the use of chemicals, gradually reduces the purifying action of ...Groundwater is naturally protected against pollution through its filter layer which is the soil. However, the development of human activities, including the use of chemicals, gradually reduces the purifying action of this layer. It is therefore essential to develop strategies for a better management of this precious resource. The general objective of this work is to establish the piezometry of the aquifer of the Continental Terminal in the borehole fields of Godomey and Ouedo to improve the delineation of protection perimeters around the boreholes of Ouedo. The study was conducted using three methods that were the FCR method, the infiltration method and the method of Krijgsman and Lobo-Ferreira. The exploitation of the piezometric map enabled to obtain the hydraulic gradient of 0.165%. The radii of immediate protection’s perimeters (PPI) range from 55.653 m to 99.755 m. The retained close protection’ perimeters (PPR) and remote protection’s perimeters (PPE) have an ellipsoidal shape. Their upstream radii range from 220.72 m to 390 m for PPR and from 356.52 m to 659.52 m for PPE;the downstream radii range from 213.06 m to 387.25 m for PPR, and from 321.28 m to 603.97 m for PPE;the radii perpendicular to the flow direction to the right of each borehole vary from 212.58 m to 381.16 m for PPR, and from 336.11 m to 602.67 m for PPE. Probable risks identified for groundwater contamination in these protection areas are the discharge of domestic waste water, solid wastes and the use of chemical fertilizers and pesticides in farming practices.展开更多
Hydrogeological modeling is an interesting and widely-used approach to improving our understanding of groundwater,both to test existing hypotheses on the behavior of hydrosystems and to predict their responses to vari...Hydrogeological modeling is an interesting and widely-used approach to improving our understanding of groundwater,both to test existing hypotheses on the behavior of hydrosystems and to predict their responses to various natural or man-made problems.Today,software such as Leapfrog Geo offers the possibility of building a 3D geological model with a more accurate representation of the subsurface.Statistical tools such as ordinary kriging can be used to simulate the spatial distribution of groundwater.These modeling approaches were combined to improve knowledge of the groundwater flow context within three massifs on the island of Grande Comore.The delineation of the 3D geometry of litho-stratigraphic units has enabled a more detailed conceptualization of groundwater flows in a complex volcanic environment.Piezometric interpolations were used to validate aquifer geometry.It has been demonstrated that an implicit geological model coupled with piezometry can provide very interesting information on the hydrogeological configuration of a volcanic massif.In the Karthala and Badjini massifs,the respective confined and semi-confined configurations of the aquifers are observed,with thicknesses that progressively decrease with distance from the coast.In the Grille massif,on the other hand,the aquifer configuration is unconfined,with thickness increasing with distance from the coast.In all three massifs,the flow of water in the underground hydrosystems is from the central part towards the coast,naturally following the geological configuration of the ground.It should be noted that the absence of data in the central parts of the massifs still leaves uncertainties about the geometry in these parts of the aquifers.However,the models that have been established provide valid hypotheses for characterizing the hydrogeological configuration at the scale of each massif.展开更多
in arid and semi-arid areas, artificial recharge is a key technology in groundwater resources management, and a reliable estimate of artificial recharge is necessary to its sustainable development. Several methods are...in arid and semi-arid areas, artificial recharge is a key technology in groundwater resources management, and a reliable estimate of artificial recharge is necessary to its sustainable development. Several methods are available to estimate the artificial recharge; however, most of them require field data or model parameters, thus limiting their applications. To overcome this limitation, we presented an analytical method to estimate the artificial recharge through monitoring the water release by piezometer and analysing the controlling factors of the artificial recharge from a hill dam in Tunisia. A total of 97 measurements of water flow in the streambed recorded from 4 gauging stations were analysed. Results indicated that the average infiltration velocity ranged from 0.043 to 0.127 m/d and the infiltration index varied from 7.6 to 11.8 L/（s.km）. Pearson＇s correlation coefficient analysis shows that the infiltration index, the stream gradient, the thickness of unsaturated zone, the number of infiltration pond, the stream geometry, and the water flow rate were found to be the main factors in determining the infiltration. The high correlation coefficients （0.908 for the number of infiltration pond and 0.999 for the stream geometry） mean that the number of infiltration pond and the stream geometry are the most influential factors. Time variations of groundwater level were used to analyze the recharge effects on the piezometry of aquifer. The analysis showed that during the artificial recharge, the water table increased at a rate of 5 mm/d and that the increase was limited to the area surrounding the recharge site. Based on the results of the study, building infiltration ponds along streambed and improving the potential of rainwater harvesting over the study area are recommended.展开更多
In Mauritanian, 4/5 of the territory is subject to an arid climate, where groundwater resources are the main sources of drinking water for populations and livestock. The study area is located in south-eastern Mauritan...In Mauritanian, 4/5 of the territory is subject to an arid climate, where groundwater resources are the main sources of drinking water for populations and livestock. The study area is located in south-eastern Mauritania and in the western part of the Taoudenni Transboundary Basin. A better knowledge of the hydrogeological system to ensure a sustainable and rational management is necessary for this vulnerable water resource. This pioneering study, based on the compilation of hydrogeological, geochemical and isotopic data, aims to characterize the hydrodynamics and recharge of this one layer aquifer system, composed of Aioune infracambrian sandstone. The piezometric surface exhibits relatively the same morphology of the soil topography, and computed effective velocity is 94 m/yr (Northeast area), and the direction of flow is generally from cliff to plains area. The chemical data show water types evolving between two poles namely the HCO3-Ca/Mg pole (low mineralized), and the Cl-Ca/Na pole;these waters are characterized by a high vulnerability to pollution, especially at shallow depth area (Douerare, Aioune). The dissolution of bicarbonate and evaporate minerals is likely the main source of mineralization. The isotopic tool used to support comprehension of the system functioning, evidences a local indirect recharge water localized at the cliff or Wadi zones. The age of the waters ranges from the present to 1060 year. The recharge rate calculated by 14C and the chloride masse balance is respectively 0.4 to 5 mm/year. This recharge compared to the water pumping rate is lower and hence this imbalance is likely the cause of water shortages particularly during summer season period.展开更多
The Dallol Maouri is a valley of an ancient tributary of the Niger River. The groundwater in this area of the upper Dallol Maouri is little known because of the weakness of the data. The purpose of this study is to ma...The Dallol Maouri is a valley of an ancient tributary of the Niger River. The groundwater in this area of the upper Dallol Maouri is little known because of the weakness of the data. The purpose of this study is to make a hydrodynamic characterization of the water table of the upper dallol Maouri by piezometric approach. A piezometric monitoring network made up of 65 points (54 wells and 11 piezometers) was set up. Six (6) piezometric measurement campaigns were carried out from June 2018 to June 2021. The piezometric survey is carried out once every six months: in January and June corresponding respectively to the high and low water period. The results show that the water table is multi-layered in places with a combination of alluvial and Continental Terminal 3 (CT3) aquifers, or perched aquifers and inferoflux aquifers around permanent ponds. The flow direction of the Continental Terminal 3 (CT3) aquifer is mainly North-East/South-West. The piezometric levels are around 219 m (in the South-West part) and 281 m (in the North-East part). The hydraulic gradient varies from 0.018‰ to 1.83‰. The recharge zones are located in the outcrop zone of the aquifer and in the valleys. A lack of recharge is observed on the plateaus despite the presence of numerous permanent ponds. The recharge coefficient in 2020 is estimated at 25% of the total rainfall recorded.展开更多
This study aims to make a hydrogeological characterization of the aquifers of the Continental Terminal and the Oligo-Miocene.To do so,an analysis is conducted on the basis of hydrogeological parameters from 172 boreho...This study aims to make a hydrogeological characterization of the aquifers of the Continental Terminal and the Oligo-Miocene.To do so,an analysis is conducted on the basis of hydrogeological parameters from 172 boreholes,10 of which are used for groundwater levels and flows analysis.The results of the statistical analysis of the hydrogeological parameters show that the average flow rate is 42.29 m^(3)/h,the average specific flow rate is 5.96 m^(3)/h/m,and the average transmissivity is 0.024 m^(2)/s.These values highlight the high productivity of aquifers from the Continental Terminal and the Oligo-Miocene.The results of piezometry showed that water flows from the south center to the northwest of Tambacounda where the largest depression is located and could even be the outlet of the system.The groundwater fluctuations between low water level and high water level seasons reveal a rise in the piezometric surface of the aquifers at the scale of the study area.展开更多
Since the 50s, many changes are observed in the climate of the globe, the warming of the atmosphere and the ocean, the decrease in the extent of snow and ice, and rising sea levels. In addition to the demographic pres...Since the 50s, many changes are observed in the climate of the globe, the warming of the atmosphere and the ocean, the decrease in the extent of snow and ice, and rising sea levels. In addition to the demographic pressure, the Maghreb countries are suffering from the drought, which accentuates the phenomenon of desertification and soil erosion, as well as their salinity, which leads to the salinization and depletion of water resources. In Morocco, the climate change leads to the erosion of the soil under the effect of desertification resulting in siltation of reservoirs and the increased salinization of soil and water resources. The Essaouira basin, which is the subject of this study, is located at the Western extremity of the High Atlas to the Southeast of the Essaouira city;between 31°20' to 31°30'N and between 9°00' to 9°46'W. The basin is characterized by a semi-arid climate with average annual rainfall of around 300 mm·year<sup>-1</sup> and an average temperature of 20°C. Considering the importance of the aquifer in Essaouira in the supply of the region's groundwater, a study was conducted to assess quantitatively and qualitatively the impact of climate change on water resources in this area. The aquifers present in this region are one of cenomano-turonian upstream and plio-quaternary downstream, separated by the diaper of Tidzi. A piezometric map of the basin was made (1990-2009) and the hydrochemical method of the waters shows that they present a facies Na-Cl with an electrical conductivity ranging from 700 to 7000 μs/cm. The isotopic tracers like <sup>18</sup>O, <sup>2</sup>H, <sup>3</sup>H and <sup>14</sup>C were analyzed to determine the age of groundwater, and a right local meteoric close to the right meteoric world characterizing the precipitation of oceanic origin has been determined. The Essaouira basin turns out to be very vulnerable and sensitive to climate change because its recharge is entirely dependent on the rainwater. These results should be taken in consideration for the future water management in the region.展开更多
This study aims to identify from geo-electrics the areas favorable to the in-stallation of drinking water supply(AEP)drilling in the sub-prefecture of Gbangbégouiné-Yati in order to contribute to a better di...This study aims to identify from geo-electrics the areas favorable to the in-stallation of drinking water supply(AEP)drilling in the sub-prefecture of Gbangbégouiné-Yati in order to contribute to a better distribution and manage-ment of water tables in the Department of Man.To achieve these objectives,pi ezometric maps and electrical resistivity maps were produced to understand the functioning of groundwater and to have the imaging of the subsoil.The piezometric maps revealed a regressive trend in the water level in the period from February 2024 to April 2024 and flow towards the lowlands in the north and,more mainly,in the east.Electrical resistivity imaging reveals three types of formations:conductive formations(resistivities between 100 and 1000 Ohm.m),medium resistivity formations(1000 to 3200 Ohm.m),and resistive formations(3200 to 6000 Ohm.m).Low resistivity formations likely to contain water in this locality are located between depths of 40 m and 50 m.展开更多
The present study was carried out in Douala megacity of Cameroon to highlight suitable aquifer that could be exploited by population or municipality authorities,to promote access to safe potable water and avoid or red...The present study was carried out in Douala megacity of Cameroon to highlight suitable aquifer that could be exploited by population or municipality authorities,to promote access to safe potable water and avoid or reduce water borne deseases.Specifically,this study aimed to assess structure of Quaternary-Mio-Pliocene aquifer and its potentiality and vulnerability distribution,within Tongo-Bassa watershed through piezometry and geoelectrical survey.Then,29 wells were assessed by piezometric study both in wet and rainy season,while thirty-two(32)vertical electrical sounding were performed through geohydraulic parameters(Permeability,Porosity,Transmissivity,Longitudinal Conductance and Hydraulic resistance).Piezometric survey in shallow aquifer globally show a convergent flow(from South East to North West direction)to defined outlet and this masks heterogeneities of flowing from wet to dry season.Vertical electrical soundings inversion revealed 10(HK,KH,HA,HKH,H,K,AK,QH,KQ,HKQ)curves types which confirm lithological heterogeneities.Borehole lithologs correlated to geoelectric section allow distinguishes unconfined and semi-confined/confined aquifers exploited by population.Unconfined aquifer with depth less than 28 m,fairly adapted for local level with limited consumption for private water supply(0.02<Tr<14.67 m^(2)/day)show that 87.87%of the area are more vulnerable(−0.58<Log C<0.96).Semi-confined/confined aquifers with depth less than 70 m,with good groundwater potential(0.50<Tr<42.05 m^(2)/day)adapted for groundwater supply that municipality authorities can exploit to manage groundwater development in Douala Sedimentary Basin,show that only 39.39%of the area are vulnerable(0.29<Log C<0.95).展开更多
文摘Groundwater is naturally protected against pollution through its filter layer which is the soil. However, the development of human activities, including the use of chemicals, gradually reduces the purifying action of this layer. It is therefore essential to develop strategies for a better management of this precious resource. The general objective of this work is to establish the piezometry of the aquifer of the Continental Terminal in the borehole fields of Godomey and Ouedo to improve the delineation of protection perimeters around the boreholes of Ouedo. The study was conducted using three methods that were the FCR method, the infiltration method and the method of Krijgsman and Lobo-Ferreira. The exploitation of the piezometric map enabled to obtain the hydraulic gradient of 0.165%. The radii of immediate protection’s perimeters (PPI) range from 55.653 m to 99.755 m. The retained close protection’ perimeters (PPR) and remote protection’s perimeters (PPE) have an ellipsoidal shape. Their upstream radii range from 220.72 m to 390 m for PPR and from 356.52 m to 659.52 m for PPE;the downstream radii range from 213.06 m to 387.25 m for PPR, and from 321.28 m to 603.97 m for PPE;the radii perpendicular to the flow direction to the right of each borehole vary from 212.58 m to 381.16 m for PPR, and from 336.11 m to 602.67 m for PPE. Probable risks identified for groundwater contamination in these protection areas are the discharge of domestic waste water, solid wastes and the use of chemical fertilizers and pesticides in farming practices.
文摘Hydrogeological modeling is an interesting and widely-used approach to improving our understanding of groundwater,both to test existing hypotheses on the behavior of hydrosystems and to predict their responses to various natural or man-made problems.Today,software such as Leapfrog Geo offers the possibility of building a 3D geological model with a more accurate representation of the subsurface.Statistical tools such as ordinary kriging can be used to simulate the spatial distribution of groundwater.These modeling approaches were combined to improve knowledge of the groundwater flow context within three massifs on the island of Grande Comore.The delineation of the 3D geometry of litho-stratigraphic units has enabled a more detailed conceptualization of groundwater flows in a complex volcanic environment.Piezometric interpolations were used to validate aquifer geometry.It has been demonstrated that an implicit geological model coupled with piezometry can provide very interesting information on the hydrogeological configuration of a volcanic massif.In the Karthala and Badjini massifs,the respective confined and semi-confined configurations of the aquifers are observed,with thicknesses that progressively decrease with distance from the coast.In the Grille massif,on the other hand,the aquifer configuration is unconfined,with thickness increasing with distance from the coast.In all three massifs,the flow of water in the underground hydrosystems is from the central part towards the coast,naturally following the geological configuration of the ground.It should be noted that the absence of data in the central parts of the massifs still leaves uncertainties about the geometry in these parts of the aquifers.However,the models that have been established provide valid hypotheses for characterizing the hydrogeological configuration at the scale of each massif.
文摘in arid and semi-arid areas, artificial recharge is a key technology in groundwater resources management, and a reliable estimate of artificial recharge is necessary to its sustainable development. Several methods are available to estimate the artificial recharge; however, most of them require field data or model parameters, thus limiting their applications. To overcome this limitation, we presented an analytical method to estimate the artificial recharge through monitoring the water release by piezometer and analysing the controlling factors of the artificial recharge from a hill dam in Tunisia. A total of 97 measurements of water flow in the streambed recorded from 4 gauging stations were analysed. Results indicated that the average infiltration velocity ranged from 0.043 to 0.127 m/d and the infiltration index varied from 7.6 to 11.8 L/（s.km）. Pearson＇s correlation coefficient analysis shows that the infiltration index, the stream gradient, the thickness of unsaturated zone, the number of infiltration pond, the stream geometry, and the water flow rate were found to be the main factors in determining the infiltration. The high correlation coefficients （0.908 for the number of infiltration pond and 0.999 for the stream geometry） mean that the number of infiltration pond and the stream geometry are the most influential factors. Time variations of groundwater level were used to analyze the recharge effects on the piezometry of aquifer. The analysis showed that during the artificial recharge, the water table increased at a rate of 5 mm/d and that the increase was limited to the area surrounding the recharge site. Based on the results of the study, building infiltration ponds along streambed and improving the potential of rainwater harvesting over the study area are recommended.
文摘In Mauritanian, 4/5 of the territory is subject to an arid climate, where groundwater resources are the main sources of drinking water for populations and livestock. The study area is located in south-eastern Mauritania and in the western part of the Taoudenni Transboundary Basin. A better knowledge of the hydrogeological system to ensure a sustainable and rational management is necessary for this vulnerable water resource. This pioneering study, based on the compilation of hydrogeological, geochemical and isotopic data, aims to characterize the hydrodynamics and recharge of this one layer aquifer system, composed of Aioune infracambrian sandstone. The piezometric surface exhibits relatively the same morphology of the soil topography, and computed effective velocity is 94 m/yr (Northeast area), and the direction of flow is generally from cliff to plains area. The chemical data show water types evolving between two poles namely the HCO3-Ca/Mg pole (low mineralized), and the Cl-Ca/Na pole;these waters are characterized by a high vulnerability to pollution, especially at shallow depth area (Douerare, Aioune). The dissolution of bicarbonate and evaporate minerals is likely the main source of mineralization. The isotopic tool used to support comprehension of the system functioning, evidences a local indirect recharge water localized at the cliff or Wadi zones. The age of the waters ranges from the present to 1060 year. The recharge rate calculated by 14C and the chloride masse balance is respectively 0.4 to 5 mm/year. This recharge compared to the water pumping rate is lower and hence this imbalance is likely the cause of water shortages particularly during summer season period.
文摘The Dallol Maouri is a valley of an ancient tributary of the Niger River. The groundwater in this area of the upper Dallol Maouri is little known because of the weakness of the data. The purpose of this study is to make a hydrodynamic characterization of the water table of the upper dallol Maouri by piezometric approach. A piezometric monitoring network made up of 65 points (54 wells and 11 piezometers) was set up. Six (6) piezometric measurement campaigns were carried out from June 2018 to June 2021. The piezometric survey is carried out once every six months: in January and June corresponding respectively to the high and low water period. The results show that the water table is multi-layered in places with a combination of alluvial and Continental Terminal 3 (CT3) aquifers, or perched aquifers and inferoflux aquifers around permanent ponds. The flow direction of the Continental Terminal 3 (CT3) aquifer is mainly North-East/South-West. The piezometric levels are around 219 m (in the South-West part) and 281 m (in the North-East part). The hydraulic gradient varies from 0.018‰ to 1.83‰. The recharge zones are located in the outcrop zone of the aquifer and in the valleys. A lack of recharge is observed on the plateaus despite the presence of numerous permanent ponds. The recharge coefficient in 2020 is estimated at 25% of the total rainfall recorded.
文摘This study aims to make a hydrogeological characterization of the aquifers of the Continental Terminal and the Oligo-Miocene.To do so,an analysis is conducted on the basis of hydrogeological parameters from 172 boreholes,10 of which are used for groundwater levels and flows analysis.The results of the statistical analysis of the hydrogeological parameters show that the average flow rate is 42.29 m^(3)/h,the average specific flow rate is 5.96 m^(3)/h/m,and the average transmissivity is 0.024 m^(2)/s.These values highlight the high productivity of aquifers from the Continental Terminal and the Oligo-Miocene.The results of piezometry showed that water flows from the south center to the northwest of Tambacounda where the largest depression is located and could even be the outlet of the system.The groundwater fluctuations between low water level and high water level seasons reveal a rise in the piezometric surface of the aquifers at the scale of the study area.
文摘Since the 50s, many changes are observed in the climate of the globe, the warming of the atmosphere and the ocean, the decrease in the extent of snow and ice, and rising sea levels. In addition to the demographic pressure, the Maghreb countries are suffering from the drought, which accentuates the phenomenon of desertification and soil erosion, as well as their salinity, which leads to the salinization and depletion of water resources. In Morocco, the climate change leads to the erosion of the soil under the effect of desertification resulting in siltation of reservoirs and the increased salinization of soil and water resources. The Essaouira basin, which is the subject of this study, is located at the Western extremity of the High Atlas to the Southeast of the Essaouira city;between 31°20' to 31°30'N and between 9°00' to 9°46'W. The basin is characterized by a semi-arid climate with average annual rainfall of around 300 mm·year<sup>-1</sup> and an average temperature of 20°C. Considering the importance of the aquifer in Essaouira in the supply of the region's groundwater, a study was conducted to assess quantitatively and qualitatively the impact of climate change on water resources in this area. The aquifers present in this region are one of cenomano-turonian upstream and plio-quaternary downstream, separated by the diaper of Tidzi. A piezometric map of the basin was made (1990-2009) and the hydrochemical method of the waters shows that they present a facies Na-Cl with an electrical conductivity ranging from 700 to 7000 μs/cm. The isotopic tracers like <sup>18</sup>O, <sup>2</sup>H, <sup>3</sup>H and <sup>14</sup>C were analyzed to determine the age of groundwater, and a right local meteoric close to the right meteoric world characterizing the precipitation of oceanic origin has been determined. The Essaouira basin turns out to be very vulnerable and sensitive to climate change because its recharge is entirely dependent on the rainwater. These results should be taken in consideration for the future water management in the region.
文摘This study aims to identify from geo-electrics the areas favorable to the in-stallation of drinking water supply(AEP)drilling in the sub-prefecture of Gbangbégouiné-Yati in order to contribute to a better distribution and manage-ment of water tables in the Department of Man.To achieve these objectives,pi ezometric maps and electrical resistivity maps were produced to understand the functioning of groundwater and to have the imaging of the subsoil.The piezometric maps revealed a regressive trend in the water level in the period from February 2024 to April 2024 and flow towards the lowlands in the north and,more mainly,in the east.Electrical resistivity imaging reveals three types of formations:conductive formations(resistivities between 100 and 1000 Ohm.m),medium resistivity formations(1000 to 3200 Ohm.m),and resistive formations(3200 to 6000 Ohm.m).Low resistivity formations likely to contain water in this locality are located between depths of 40 m and 50 m.
文摘The present study was carried out in Douala megacity of Cameroon to highlight suitable aquifer that could be exploited by population or municipality authorities,to promote access to safe potable water and avoid or reduce water borne deseases.Specifically,this study aimed to assess structure of Quaternary-Mio-Pliocene aquifer and its potentiality and vulnerability distribution,within Tongo-Bassa watershed through piezometry and geoelectrical survey.Then,29 wells were assessed by piezometric study both in wet and rainy season,while thirty-two(32)vertical electrical sounding were performed through geohydraulic parameters(Permeability,Porosity,Transmissivity,Longitudinal Conductance and Hydraulic resistance).Piezometric survey in shallow aquifer globally show a convergent flow(from South East to North West direction)to defined outlet and this masks heterogeneities of flowing from wet to dry season.Vertical electrical soundings inversion revealed 10(HK,KH,HA,HKH,H,K,AK,QH,KQ,HKQ)curves types which confirm lithological heterogeneities.Borehole lithologs correlated to geoelectric section allow distinguishes unconfined and semi-confined/confined aquifers exploited by population.Unconfined aquifer with depth less than 28 m,fairly adapted for local level with limited consumption for private water supply(0.02<Tr<14.67 m^(2)/day)show that 87.87%of the area are more vulnerable(−0.58<Log C<0.96).Semi-confined/confined aquifers with depth less than 70 m,with good groundwater potential(0.50<Tr<42.05 m^(2)/day)adapted for groundwater supply that municipality authorities can exploit to manage groundwater development in Douala Sedimentary Basin,show that only 39.39%of the area are vulnerable(0.29<Log C<0.95).
