A trigger-tube tracer dilution technique for determining Darcy and apparent velocities of groundwater in dug wells: A case study on phreatic aquiferous formation in Bamenda-Cameroon
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摘要
The need to understand flow within aquiferous formations for a complete evaluation of groundwater resource and quality control prompts the determination of groundwater velocities through well dilution technique. Well dilution techniques utilize tracer solutions after establishing an initial homogenous condition to monitor the flow rate of ambient groundwater into the wells. Application of dilution techniques in wells makes it feasible to determine the velocities of groundwater in the aquiferous formation surrounding the well. In this study, a simple trigger-tube tracer dilution technique was employed to determine the Darcy and apparent velocities of groundwater in the phreatic aquiferous formation in Bamenda, Cameroon. Eighteen(18) hand dug-wells at different locations within Bamenda were sampled by utilizing sodium chloride(NaCl) as the conservative tracer. Field estimates of groundwater flow velocities in the phreatic aquiferous formation in Bamenda reveal Darcy's groundwater velocity in the range of 0.39 m/d at Nacho to 130.64 m/d at Foncha Street and apparent velocity in the range of 0.78 m/d at Nacho to 277.86 m/d at Foncha Street. The immense variations in the velocities of groundwater indicate that the groundwater flows at different rates and directions within the aquiferous formation in Bamenda, possibly due to variations in their hydraulic conductivities. Moreover, the spatial variations in the formation types, facies changes, thickness, and layering of the aquiferous formation also contribute to the variation of velocities. Areas with low groundwater velocities are associated with a lower contaminant transport rate when compared to areas with high groundwater velocities. The findings of this study are important for assessing the rates of pollutant movement in the subsurface, as well as the effectiveness and efficacy of the trigger-tube technique in evaluating the hydraulic properties of aquiferous formations.
The need to understand flow within aquiferous formations for a complete evaluation of groundwater resource and quality control prompts the determination of groundwater velocities through well dilution technique. Well dilution techniques utilize tracer solutions after establishing an initial homogenous condition to monitor the flow rate of ambient groundwater into the wells. Application of dilution techniques in wells makes it feasible to determine the velocities of groundwater in the aquiferous formation surrounding the well. In this study, a simple trigger-tube tracer dilution technique was employed to determine the Darcy and apparent velocities of groundwater in the phreatic aquiferous formation in Bamenda, Cameroon. Eighteen(18) hand dug-wells at different locations within Bamenda were sampled by utilizing sodium chloride(NaCl) as the conservative tracer. Field estimates of groundwater flow velocities in the phreatic aquiferous formation in Bamenda reveal Darcy's groundwater velocity in the range of 0.39 m/d at Nacho to 130.64 m/d at Foncha Street and apparent velocity in the range of 0.78 m/d at Nacho to 277.86 m/d at Foncha Street. The immense variations in the velocities of groundwater indicate that the groundwater flows at different rates and directions within the aquiferous formation in Bamenda, possibly due to variations in their hydraulic conductivities. Moreover, the spatial variations in the formation types, facies changes, thickness, and layering of the aquiferous formation also contribute to the variation of velocities. Areas with low groundwater velocities are associated with a lower contaminant transport rate when compared to areas with high groundwater velocities. The findings of this study are important for assessing the rates of pollutant movement in the subsurface, as well as the effectiveness and efficacy of the trigger-tube technique in evaluating the hydraulic properties of aquiferous formations.
The need to understand flow within aquiferous formations for a complete evaluation of groundwater resource and quality control prompts the determination of groundwater velocities through well dilution technique. Well dilution techniques utilize tracer solutions after establishing an initial homogenous condition to monitor the flow rate of ambient groundwater into the wells. Application of dilution techniques in wells makes it feasible to determine the velocities of groundwater in the aquiferous formation surrounding the well. In this study, a simple trigger-tube tracer dilution technique was employed to determine the Darcy and apparent velocities of groundwater in the phreatic aquiferous formation in Bamenda, Cameroon. Eighteen(18) hand dug-wells at different locations within Bamenda were sampled by utilizing sodium chloride(NaCl) as the conservative tracer. Field estimates of groundwater flow velocities in the phreatic aquiferous formation in Bamenda reveal Darcy's groundwater velocity in the range of 0.39 m/d at Nacho to 130.64 m/d at Foncha Street and apparent velocity in the range of 0.78 m/d at Nacho to 277.86 m/d at Foncha Street. The immense variations in the velocities of groundwater indicate that the groundwater flows at different rates and directions within the aquiferous formation in Bamenda, possibly due to variations in their hydraulic conductivities. Moreover, the spatial variations in the formation types, facies changes, thickness, and layering of the aquiferous formation also contribute to the variation of velocities. Areas with low groundwater velocities are associated with a lower contaminant transport rate when compared to areas with high groundwater velocities. The findings of this study are important for assessing the rates of pollutant movement in the subsurface, as well as the effectiveness and efficacy of the trigger-tube technique in evaluating the hydraulic properties of aquiferous formations.
引文
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A A Cronin,N Breslin,et al.2006.Monitoring source and domestic water quality in parallel with salinity risk identification in northern Mozambique to prioritise protection interventions.Journal of Water and Health,4(3):333-345.
A Auippa,S Bellomoa,et al.2003.Natural and anthropogenic factors affecting groundwater quality of an active volcano(Mt.Etna,Italy).Applied Geochemistry,18(6):863-882.
AchoChi.1998.Human interference and environmental instability:Addressing the environmental consequences of rapid urban growth in Bamenda,Cameroon.Environment and Urbanization,10(2):161-174.
A E Van Wyk,Y Xu,et al.2000.Utilization of tracer experiments for the development of rural water supply management strategies for secondary aquifers.Water Research Commission of South Africa Report,Pretoria,South Africa.
A F Takounjou,D Kuitcha,et al.2013.Assessing groundwater nitrate pollution in Yaoundé,Cameroon:Modelling Approach.World Applied Sciences Journal,23(3):333-344.
A Magha,M T Awah,et al.2015.Physicochemical and bacteriological characterization of spring and well in Bamenda III(NW Region,Cameroon).American Journal of Environmental Protection,4(3):163-173.
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D Kuitcha,K B V Kamgang,et al.2008.Water supply,sanitation and health risk in Yaoundé,Cameroon.African Journal of Environmental Science and Technology,2(11):379-386.
D M Gountié,E Njonfang,et al.2012.Dynamic and evolution of the Mounts Bambouto and Bamenda calderas by study of ignimbritic deposits(West-Cameroon,Cameroon Line).Syllabus Rev,3:11-23.
E Tanawa,H B D Tchapnga,et al.2002.Habitat and protection of water resources in suburban areas in African Cities.Building and Environment,37(3):269-275.
G T Mafany,W T Fantong,et al.2006.Quality of groundwater in Cameroon and its vulnerability to pollution.In:Xu Yongxin,Brent U(eds)groundwater pollution in Africa.Taylor and Francis(Balkema),The Netherlands,47-55.
J Ndjama,K B V Kamgang,et al.2008.Water supply,sanitation and health risks in DoualaCameroon.African Journal of Environmental Science and Technology,2(12):422-429.
J P Nzenti,B Abaga,et al.2011.Petrogenesis of perealuminius magmas from the AkumBamenda massif,Pan African fold belt,Cameroon.International Geology Review,53(10):1121-1149.
J R Mache,A Nyoja,et al.2013.Smectite clay from the Sabga deposit(Cameroon):Mineralogical and physiochemical properties.Clay Minerals,48(3):499-512.
J Stibinger.2004.Examples of determining the hydraulic conductivity of soils:Theory and applications of selected basic methods.University Handbook on Soil Hydraulics.Published by Faulty of Environment,Jan Evangelista University in Uste'n.Labem.
M J Wirmvem,T Ohba,et al.2013.Hydrochemistry of shallow groundwater and surface water in the Ndop Plain,North West Cameroon.African Journal of Environmental Science and Technology,7(7):518-530.
M J Wirmvem,T Ohba,et al.2014.Hydrochemical and isotopic characterization of groundwater in the Ndop Plain,Northwest Cameroon:Resilience to seasonal climatic changes.Environmental Earth Sciences,72(9):3585-3598.
M Pitrak,S Mares,et al.2007.A simple borehole dilution technique to measure horizontal groundwater flow.Groundwater,45(1):98-92.
P Kamgang,E Njonfang,et al.2010.Petrogenesis of a silicic magma system:Geochemical evidence from Bamenda Mountains,NWCameroon,Cameroon Volcanic Line.Journal of African Earth Sciences,58(2):285-304.
R A Akoachere,G Van Tonder,2011.The Trigger-Tube:A new apparatus and method for mixing solution for injection test in boreholes.Water SA,37(2):139-146.
R A Akoachere,Y M Ngwese.2007.Darcy and apparent velocities of groundwater in Phreatic aquiferous formations in Kumba Cameroon:Determined by use of Trigger-Tube tracer test method in Dug Wells.Journal of Hydrogeology and Hydrological Engineering,6(1):1-6.
S Morin.1988.Les dissymétries fondamentales des hautes terres de l'Ouest-Cameroun et leurs conséquences sur l'occupation humaine:Exemple des monts Bambouto.L'homme et la montagne tropicale.Sepanrit ed.Bordeaux,49-51.
S R H Worthington,C Smart,W W Ruland.2002.Assessment of groundwater velocity to the municipal wells at Walker at Walkerton.Canadian Geotechnical Society,1081-1086.
S S Kometa,N R Akoh.2012.The hydrogeomorpological implication of urbanization in Bamenda,Cameroon.Journal of Sustainable Development,5(6):64-73.
T D Keleko,J M Tadjou,et al.2013.Groundwater investigation using geoelectrical method:Acase study of the Western Region of Cameroon.Journal of Water Resource and Protection,5(6):633-641.
A A Cronin,N Breslin,et al.2006.Monitoring source and domestic water quality in parallel with salinity risk identification in northern Mozambique to prioritise protection interventions.Journal of Water and Health,4(3):333-345.
A Auippa,S Bellomoa,et al.2003.Natural and anthropogenic factors affecting groundwater quality of an active volcano(Mt.Etna,Italy).Applied Geochemistry,18(6):863-882.
AchoChi.1998.Human interference and environmental instability:Addressing the environmental consequences of rapid urban growth in Bamenda,Cameroon.Environment and Urbanization,10(2):161-174.
A E Van Wyk,Y Xu,et al.2000.Utilization of tracer experiments for the development of rural water supply management strategies for secondary aquifers.Water Research Commission of South Africa Report,Pretoria,South Africa.
A F Takounjou,D Kuitcha,et al.2013.Assessing groundwater nitrate pollution in Yaoundé,Cameroon:Modelling Approach.World Applied Sciences Journal,23(3):333-344.
A Magha,M T Awah,et al.2015.Physicochemical and bacteriological characterization of spring and well in Bamenda III(NW Region,Cameroon).American Journal of Environmental Protection,4(3):163-173.
A S Neba,1999.Modern geography of the Republic of Cameroon(3rd Ed).Neba Publishers,Bamenda,235.
B Ousmane,A Daddy,et al.2006.Groundwater contamination in the Niamey urban area,Niger.Groundwater pollution in Africa.Taylor and Francis(Balkema),The Netherlands,169-179.
D Kuitcha,K B V Kamgang,et al.2008.Water supply,sanitation and health risk in Yaoundé,Cameroon.African Journal of Environmental Science and Technology,2(11):379-386.
D M Gountié,E Njonfang,et al.2012.Dynamic and evolution of the Mounts Bambouto and Bamenda calderas by study of ignimbritic deposits(West-Cameroon,Cameroon Line).Syllabus Rev,3:11-23.
E Tanawa,H B D Tchapnga,et al.2002.Habitat and protection of water resources in suburban areas in African Cities.Building and Environment,37(3):269-275.
G T Mafany,W T Fantong,et al.2006.Quality of groundwater in Cameroon and its vulnerability to pollution.In:Xu Yongxin,Brent U(eds)groundwater pollution in Africa.Taylor and Francis(Balkema),The Netherlands,47-55.
J Ndjama,K B V Kamgang,et al.2008.Water supply,sanitation and health risks in DoualaCameroon.African Journal of Environmental Science and Technology,2(12):422-429.
J P Nzenti,B Abaga,et al.2011.Petrogenesis of perealuminius magmas from the AkumBamenda massif,Pan African fold belt,Cameroon.International Geology Review,53(10):1121-1149.
J R Mache,A Nyoja,et al.2013.Smectite clay from the Sabga deposit(Cameroon):Mineralogical and physiochemical properties.Clay Minerals,48(3):499-512.
J Stibinger.2004.Examples of determining the hydraulic conductivity of soils:Theory and applications of selected basic methods.University Handbook on Soil Hydraulics.Published by Faulty of Environment,Jan Evangelista University in Uste'n.Labem.
M J Wirmvem,T Ohba,et al.2013.Hydrochemistry of shallow groundwater and surface water in the Ndop Plain,North West Cameroon.African Journal of Environmental Science and Technology,7(7):518-530.
M J Wirmvem,T Ohba,et al.2014.Hydrochemical and isotopic characterization of groundwater in the Ndop Plain,Northwest Cameroon:Resilience to seasonal climatic changes.Environmental Earth Sciences,72(9):3585-3598.
M Pitrak,S Mares,et al.2007.A simple borehole dilution technique to measure horizontal groundwater flow.Groundwater,45(1):98-92.
P Kamgang,E Njonfang,et al.2010.Petrogenesis of a silicic magma system:Geochemical evidence from Bamenda Mountains,NWCameroon,Cameroon Volcanic Line.Journal of African Earth Sciences,58(2):285-304.
R A Akoachere,G Van Tonder,2011.The Trigger-Tube:A new apparatus and method for mixing solution for injection test in boreholes.Water SA,37(2):139-146.
R A Akoachere,Y M Ngwese.2007.Darcy and apparent velocities of groundwater in Phreatic aquiferous formations in Kumba Cameroon:Determined by use of Trigger-Tube tracer test method in Dug Wells.Journal of Hydrogeology and Hydrological Engineering,6(1):1-6.
S Morin.1988.Les dissymétries fondamentales des hautes terres de l'Ouest-Cameroun et leurs conséquences sur l'occupation humaine:Exemple des monts Bambouto.L'homme et la montagne tropicale.Sepanrit ed.Bordeaux,49-51.
S R H Worthington,C Smart,W W Ruland.2002.Assessment of groundwater velocity to the municipal wells at Walker at Walkerton.Canadian Geotechnical Society,1081-1086.
S S Kometa,N R Akoh.2012.The hydrogeomorpological implication of urbanization in Bamenda,Cameroon.Journal of Sustainable Development,5(6):64-73.
T D Keleko,J M Tadjou,et al.2013.Groundwater investigation using geoelectrical method:Acase study of the Western Region of Cameroon.Journal of Water Resource and Protection,5(6):633-641.