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    Wyświetlanie 1-3 z 3
    Tytuł:
    Modeling Soluble Contaminant Migration by Advection Process in Subsurface Water in the Eastern Niger Delta, Nigeria
    Autorzy:
    Ugbena, K. G.
    Tse, A. C.
    Akpokodje, Enuvie G.
    Powiązania:
    https://bibliotekanauki.pl/articles/1030673.pdf
    Data publikacji:
    2020
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Aquifer
    advective velocity
    conservative tracer
    migration
    soluble contaminant
    subsurface water
    Opis:
    The advective property of an aquifer in the Eastern Niger Delta was evaluated using a conservative tracer. Tracer migration was monitored in observation boreholes at various radial distances simultaneously. Particle size distribution analysis for the sand samples collected from the boreholes in the study site revealed aquifer composition to be predominantly fine sand (silt =13.42%, fine sand = 41.76%, medium sand = 36.71% and coarse sand = 8.09%) for the 8m depth sampled. This field tracer test thus, provides a definitive data on the simultaneous transport of a soluble contaminant and allows a quantitative appraisal of the advective property of the study site. The mean velocity determined 1.212×10-3 ms-1, represents the advective velocity of groundwater carrying the dissolved tracer substance. This is an indication of how soluble components of hydrocarbon will be transported in the study area. Modeling tracer migration by advection process to estimate where and when a soluble contaminant problem can first be noticed in an environmental matrix and its application in hydrological studies is an effective tool to address problems such as sustainability and uncertainty in groundwater resource system.
    Źródło:
    World Scientific News; 2020, 139, 2; 102-114
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Radial Flow Tracer Test to Investigate Coefficient of Transverse Dispersion in an Aquifer in the Eastern Niger Delta, Nigeria
    Autorzy:
    Ugbena, K. G.
    Akpokodje, Enuvie G.
    Tse, A. C.
    Powiązania:
    https://bibliotekanauki.pl/articles/1068620.pdf
    Data publikacji:
    2019
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Aquifer
    Niger Delta
    advective velocity
    contaminant
    longitudinal dispersion
    transverse dispersion
    Opis:
    The complex nature of flow dynamic of water at the subsurface makes it difficult to characterize directly the processes taking place in a porous medium. As a result, carrying out studies on the characteristics of contaminants at the subsurface often relies on indirect measurements of the parameters of the system. To overcome these difficulties and provide information on the subsurface, the continuous use of tracers in simulation studies to model hydrological characteristics at the subsurface has provided an important tool for understanding the flow and mixing dynamics of water resource systems. Results obtained from this radial flow tracer test shows coefficient of longitudinal and transverse dispersion of 2.104×10-3 m2s-1 and 1.54×10-3 m2s-1 respectively, longitudinal and transverse dispersivity of 1.73m and 1.27m respectively. Multidimensional transport in an aquifer involves both longitudinal and transverse dispersion in addition to advection process. Transverse dispersion in an aquifer spreads dissolved contaminant by molecular diffusion when flow velocity of groundwater is highly low. Initial concentration of dissolved contaminants at the point of release can produce an upstream spreading in a longitudinal transverse direction by molecular dispersion which is a diffusion-like process in an aquifer. Results obtained from tracer test can be used to characterize a site and for groundwater monitoring. Having basic knowledge of some physical processes taking place at the subsurface such as that produced from tracer test can also help in the design of environmental network to evaluate possible accidental migration of contaminants once it occur in aquifers and plan suitable mitigation actions to safeguard our water resource.
    Źródło:
    World Scientific News; 2019, 132; 233-243
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Using geoelectric soundings for estimation of hydraulic characteristics of aquifers in the coastal area of Lagos, southwestern Nigeria
    Autorzy:
    Fatoba, J.O.
    Omolayo, S.D.
    Adigun, E.O.
    Powiązania:
    https://bibliotekanauki.pl/articles/11667.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    geoelectrical parameter
    estimation
    hydraulic characteristics
    hydraulic parameter
    aquifer
    coastal area
    Lagos
    Nigeria
    Opis:
    Electrical resistivity investigation was carried out at Ibeju Lekki, Southwestern Nigeria. The thrust of this study is to determine the geoelectrical parameters of the shallow aquifer and estimate the hydraulic characteristics of this aquifer unit from the surface geophysics. The area falls within the Dahomey basin of the Nigeria sedimentary terrain. Twenty-one VES were conducted using Shlumberger array with a maximum half current electrode (AB/2) of 100 m giving total spread of 200 m. Data were interpreted using partial curve matching technique and assisted 1-D forward modeling with WINRESIST software. The qualitative interpretation revealed KQ curves (ρ1 < ρ2 > ρ3 > ρ4) and KH curve (ρ1 < ρ2 > ρ3 < ρ4). The geoelectric section generated from the results of the VES revealed a four geo-electric layers; these include topsoil with resistivity ranging from 213-5404 Ωm, dry sand with resistivity values vary from 301to 17178 Ωm, saturated sand with resistivity varying from 110 to1724 Ωm and sand (saline water content) with resistivity values of between 8 and 97 Ωm. The major aquifer in the area occurs at the third geoelectric layer. The depth to this aquifer is of between 0.7m and 6.0m and the layer thickness is between 0.2 m and 19.9 m. The hydraulic characteristics of the aquifer estimated from the geoelectric parameters reveal that the aquifer has porosity values of between 29.4 % and 57.7 %, protective capacities of between 0.00013 and 0.015 mhos, transverse resistance ranges from 345-18502 Ωm2, transmissivity values vary from 13 to 310 m2/day and hydraulic conductivity ranges from 0.8-65 m/day. The results show that the aquifer is characterized by high porosity and low protective capacities of overburden layers indicating that it is highly vulnerable to surface contamination. It has high transverse resistance, high transmissivity, and high hydraulic conductivity indicating that the aquifer can transmit water at higher rate and sustain the need of the community. This study has demonstrated the efficacy of surface geophysics in estimating hydraulic characteristics of an aquifer where pumping test data are not available and also to determine its vulnerability to surface contaminants.
    Źródło:
    International Letters of Natural Sciences; 2014, 06
    2300-9675
    Pojawia się w:
    International Letters of Natural Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-3 z 3

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