A geophysical investigation was carried out to characterize aquifer parameters and assess the groundwater condition in Abak, southern Nigeria. Vertical electrical sounding (VES) was carried out using Schlumberger conf...A geophysical investigation was carried out to characterize aquifer parameters and assess the groundwater condition in Abak, southern Nigeria. Vertical electrical sounding (VES) was carried out using Schlumberger configuration in 10 locations within the area. Both manual and computer interpretation of the resistivity data reveals three to four geoelectric units (laterite topsoil, medium-grained sand, coarse-grained sand, and sandy clay sand) which agrees with the lithologic log from existing boreholes. The aquifer layer was identified along the third formation with resistivity values ranging from 1239 - 5719 Ωm and aquifer depth ranging from 30.2 - 54.8 m. The aquifer thickness ranged from 24.2 - 43.7 m. Hydraulic conductivity ranged from 0.1206 m/day - 0.5026 m/day with an average value of 0.29403 m/day. Formation factor ranged from 14.55 - 16.64. Porosity ranged from 15.98% - 22.40%, with an average value of 19.64%. The aquiferous zone falls within the medium/coarse-grained sand. The aquifer is shallow, unconfined, and prolific with a little overburden formation of 13.5 m. The area shows good prospects for groundwater development.展开更多
In this work, seismic refraction was used to obtain elastic properties (shear modulus (μ), Young modulus (E), Bulk modulus (K) and lithological information in Uyo and its environ as an aid to engineering foundation. ...In this work, seismic refraction was used to obtain elastic properties (shear modulus (μ), Young modulus (E), Bulk modulus (K) and lithological information in Uyo and its environ as an aid to engineering foundation. Using seismic refraction method, the top and weathered layer of the engineering foundation in the study area was investigated to determine the elastic parameters of top soil and also assess the strength of engineering foundation based on the parameter distribution. A 24-channel signal enhancement seismograph, geophones, sledge hammer and a metal plate (source) for generating seismic waves were used. The study area lies between latitudes 4˚45' and 5˚15'N and between longitudes 7˚45' and 8˚30'E in the Niger Delta region of southern Nigeria. Geologically, the area is located in the Tertiary to Quaternary Coastal Plain Sands (CPS) (otherwise called the Benin Formation) and Alluvium environments of the Niger Delta region of southern Nigeria. Shear Modulus had average values of 0.43 × 10<sup>8</sup> N/m<sup>2</sup> and 1.40 × 10<sup>8</sup> N/m<sup>2</sup> for layers 1 and 2 respectively. The average values of the Young Modulus for layers 1 and 2 were determined as 2.32 × 10<sup>8</sup> N/m<sup>2</sup> and 3.84 × 10<sup>8</sup> N/m<sup>2</sup> respectively. The average values of the bulk Modulus for layers 1 and 2 were estimated as 1.52 × 10<sup>8</sup> N/m<sup>2</sup> and 4.93 × 10<sup>8</sup> N/m<sup>2</sup> respectively.展开更多
In recent years there has been serious concern on the deteriorating groundwater quality due to the activities of man. Geographic Information System (GIS), a high performance computer based tool is playing a critical r...In recent years there has been serious concern on the deteriorating groundwater quality due to the activities of man. Geographic Information System (GIS), a high performance computer based tool is playing a critical role in water resource management and pollution study. In this work, the GIS software was used to analyze the effects of various data layers (topographic slope, groundwater table variation, soil porosity and land use activities) on the distribution of groundwater pollution in the Nigerian city of Uyo. Spatial variability map of different groundwater quality parameters were generated using interpolation operation in the software. A good correlation exists between some of the pollution indicators (total dissolved solids, TDS and conductiveity, CN, 0.8;chloride and TDS, 0.17 as well as TDS and sulphate, 0.23). The results of spatial variability maps of different groundwater quality parameters indicate an increase in the percentages of pollution levels during the last five years. Cross operation was also used to explain the effects of various data layers viz. topographic slope, groundwater slope, depth to groundwater layer and land use activities on the distribution of groundwater pollution.展开更多
文摘A geophysical investigation was carried out to characterize aquifer parameters and assess the groundwater condition in Abak, southern Nigeria. Vertical electrical sounding (VES) was carried out using Schlumberger configuration in 10 locations within the area. Both manual and computer interpretation of the resistivity data reveals three to four geoelectric units (laterite topsoil, medium-grained sand, coarse-grained sand, and sandy clay sand) which agrees with the lithologic log from existing boreholes. The aquifer layer was identified along the third formation with resistivity values ranging from 1239 - 5719 Ωm and aquifer depth ranging from 30.2 - 54.8 m. The aquifer thickness ranged from 24.2 - 43.7 m. Hydraulic conductivity ranged from 0.1206 m/day - 0.5026 m/day with an average value of 0.29403 m/day. Formation factor ranged from 14.55 - 16.64. Porosity ranged from 15.98% - 22.40%, with an average value of 19.64%. The aquiferous zone falls within the medium/coarse-grained sand. The aquifer is shallow, unconfined, and prolific with a little overburden formation of 13.5 m. The area shows good prospects for groundwater development.
文摘In this work, seismic refraction was used to obtain elastic properties (shear modulus (μ), Young modulus (E), Bulk modulus (K) and lithological information in Uyo and its environ as an aid to engineering foundation. Using seismic refraction method, the top and weathered layer of the engineering foundation in the study area was investigated to determine the elastic parameters of top soil and also assess the strength of engineering foundation based on the parameter distribution. A 24-channel signal enhancement seismograph, geophones, sledge hammer and a metal plate (source) for generating seismic waves were used. The study area lies between latitudes 4˚45' and 5˚15'N and between longitudes 7˚45' and 8˚30'E in the Niger Delta region of southern Nigeria. Geologically, the area is located in the Tertiary to Quaternary Coastal Plain Sands (CPS) (otherwise called the Benin Formation) and Alluvium environments of the Niger Delta region of southern Nigeria. Shear Modulus had average values of 0.43 × 10<sup>8</sup> N/m<sup>2</sup> and 1.40 × 10<sup>8</sup> N/m<sup>2</sup> for layers 1 and 2 respectively. The average values of the Young Modulus for layers 1 and 2 were determined as 2.32 × 10<sup>8</sup> N/m<sup>2</sup> and 3.84 × 10<sup>8</sup> N/m<sup>2</sup> respectively. The average values of the bulk Modulus for layers 1 and 2 were estimated as 1.52 × 10<sup>8</sup> N/m<sup>2</sup> and 4.93 × 10<sup>8</sup> N/m<sup>2</sup> respectively.
文摘In recent years there has been serious concern on the deteriorating groundwater quality due to the activities of man. Geographic Information System (GIS), a high performance computer based tool is playing a critical role in water resource management and pollution study. In this work, the GIS software was used to analyze the effects of various data layers (topographic slope, groundwater table variation, soil porosity and land use activities) on the distribution of groundwater pollution in the Nigerian city of Uyo. Spatial variability map of different groundwater quality parameters were generated using interpolation operation in the software. A good correlation exists between some of the pollution indicators (total dissolved solids, TDS and conductiveity, CN, 0.8;chloride and TDS, 0.17 as well as TDS and sulphate, 0.23). The results of spatial variability maps of different groundwater quality parameters indicate an increase in the percentages of pollution levels during the last five years. Cross operation was also used to explain the effects of various data layers viz. topographic slope, groundwater slope, depth to groundwater layer and land use activities on the distribution of groundwater pollution.
