Hydrogeochemical investigation of Uyo and its environs
The study area, Uyo and its environs, is located in Akwa Ibom State, south-southern Nigeria and is bounded by latitudes 04° 56' 00" to 05° 07' 30"N and longitudes 007° 49' 30" to 008° 2' 00"E with an areal extent of 625km2 and is made up of extracts of 1:50,000 Sheets Ikot Ekpene, Uwet, Opobo and Calabar; namely, 331NW, 330NE, 323SW and 322SE. The Local Government Areas covered in the course of this study are Ibiono Ibom LGA, Ikono LGA, Itu LGA, Uruan LGA as well as Uyo LGA. \r\n\r\nThe objective of the project was to determine the distribution of physicochemical parameters and microbial loads in the water, which will be useful for the planning and sustainable management of surface and groundwater resources in the area.\r\n\r\nThe methods adopted for the project were geological mapping, geophysical studies, hydrogeological and hydrochemical mapping as well as hydraulic conductivity determination of the soil media within the study area. The hydrochemical and hydraulic conductivity were determined after conducting laboratory analyses on water and soil samples following standard laboratory procedures.\r\n\r\nThe study area is underlain by Tertiary to Recent continental fluviatile sands and clays of Benin Formation, also known as Coastal Plain sands. Geologically, the study area is composed of coastal sediments of sands/sandy clay, clayey sand, pebbly, clayey sand and minor clay. Conglomeratic bands occur at various horizons within the section (as shown in Plate 1). The sediments reflect continental environment of deposition. The rock units are generally porous, poorly sorted, loose and friable. The loose and friable nature of the upper part of the formation gave rise to gully erosion at various parts of the study area.\r\n\r\nFour main hydro-stratigraphic units were delineated within Uyo based on stratigraphic relation and lithology. These include upper, middle and lower sand aquifers, in increasing geologic age and depth of burial with the Imo shale aquitard separating the most extensive middle aquifer from the lower sand aquifer. The upper sand aquifer of the recent alluvium deposits and Pleistocene-Pliocene Benin Formation form the major aquiferous units in the study area. The deposits include lateritic sands, fine to medium-grained sands and dark grey carbonaceous muds.\r\n\r\nThe highest water elevation of 92m was recorded in the northern portion of the study area while the lowest elevation of -66m (66m below mean sea level) was recorded in the south. In the study area, the Groundwater flow displays a general north - south and easterly direction which is attributable the subsurface basins in the south and east respectively and likely responsible to the presence of swampy flood plain east of the study area. Hydrogeologically, widely spaced contour areas, as observed in Uyo and its environs, are very prolific in groundwater yield.\r\n\r\nThe water samples are predominantly earth-alkaline water species (Ca2+ and Mg2+) with predominantly Cl- and HCO3-. Analysis revealed that the relative abundance of the major cations is as such: Ca > Mg > Na+K, with the Ca being the most dominant cation in all the water samples analyzed. While the relative abundance of the major anions for the water samples is as such: Cl > HCO3 > SO4, with Cl being the most dominant anion.\r\n\r\nAccording the classification of Permeability based on Terzaghi and Peck (1967), the permeability of the soils in the study area ranged from Low Permeability to Medium Permeability, with Low Permeability being restricted to the eastern flank of the study area where the swamp exists, and which is characterized by clayey sand.\r\n\r\nGeophysical investigation using the electrical method (Vertical Electrical Sounding) revealed that the study area generally has fair to good groundwater yield, which can be tapped through borehole drilling predominantly for domestic and small-scale industrial uses. These aquifers are thin and are mainly recharged by precipitation, hence, may not support heavy industrial water needs. It is therefore paramount to probe in excess of 500m depth for probable high yield aquifers for such industrial use. The geophysical survey also revealed the presence of a deep-seated incision trending approximately north - south across the entire study area.\r\n\r\nThe physical and chemical parameters of the water samples conformed to international standards of potable water except for a few water samples having concentrations of certain constituents exceeding the WHO and NSDWQ maximum permissible limits in drinking water, which rendered the water in those localities unfit for human consumption unless treated. \r\n
Simple
- Date (Publication)
- 2019
- Presentation form
- Digital document
- Status
- Completed
- Keywords
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Geology, Groundwater contamination, Rock-water interaction, Water Level Elevation, Elemental Concentration.
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- Other constraints
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Internal only
- Denominator
- 50000
- Language
- English
- Topic category
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- Description
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Nigeria, Akwa Ibom State, Uyo
- Reference system identifier
- 4326
- Distribution format
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.doc
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.doc
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- Name of the resource
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Hydrogeochemical investigation of Uyo and its environs
- Description
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The study area, Uyo and its environs, is located in Akwa Ibom State, south-southern Nigeria and is bounded by latitudes 04° 56' 00" to 05° 07' 30"N and longitudes 007° 49' 30" to 008° 2' 00"E with an areal extent of 625km2 and is made up of extracts of 1:50,000 Sheets Ikot Ekpene, Uwet, Opobo and Calabar; namely, 331NW, 330NE, 323SW and 322SE. The Local Government Areas covered in the course of this study are Ibiono Ibom LGA, Ikono LGA, Itu LGA, Uruan LGA as well as Uyo LGA. \r\n\r\nThe objective of the project was to determine the distribution of physicochemical parameters and microbial loads in the water, which will be useful for the planning and sustainable management of surface and groundwater resources in the area.\r\n\r\nThe methods adopted for the project were geological mapping, geophysical studies, hydrogeological and hydrochemical mapping as well as hydraulic conductivity determination of the soil media within the study area. The hydrochemical and hydraulic conductivity were determined after conducting laboratory analyses on water and soil samples following standard laboratory procedures.\r\n\r\nThe study area is underlain by Tertiary to Recent continental fluviatile sands and clays of Benin Formation, also known as Coastal Plain sands. Geologically, the study area is composed of coastal sediments of sands/sandy clay, clayey sand, pebbly, clayey sand and minor clay. Conglomeratic bands occur at various horizons within the section (as shown in Plate 1). The sediments reflect continental environment of deposition. The rock units are generally porous, poorly sorted, loose and friable. The loose and friable nature of the upper part of the formation gave rise to gully erosion at various parts of the study area.\r\n\r\nFour main hydro-stratigraphic units were delineated within Uyo based on stratigraphic relation and lithology. These include upper, middle and lower sand aquifers, in increasing geologic age and depth of burial with the Imo shale aquitard separating the most extensive middle aquifer from the lower sand aquifer. The upper sand aquifer of the recent alluvium deposits and Pleistocene-Pliocene Benin Formation form the major aquiferous units in the study area. The deposits include lateritic sands, fine to medium-grained sands and dark grey carbonaceous muds.\r\n\r\nThe highest water elevation of 92m was recorded in the northern portion of the study area while the lowest elevation of -66m (66m below mean sea level) was recorded in the south. In the study area, the Groundwater flow displays a general north - south and easterly direction which is attributable the subsurface basins in the south and east respectively and likely responsible to the presence of swampy flood plain east of the study area. Hydrogeologically, widely spaced contour areas, as observed in Uyo and its environs, are very prolific in groundwater yield.\r\n\r\nThe water samples are predominantly earth-alkaline water species (Ca2+ and Mg2+) with predominantly Cl- and HCO3-. Analysis revealed that the relative abundance of the major cations is as such: Ca > Mg > Na+K, with the Ca being the most dominant cation in all the water samples analyzed. While the relative abundance of the major anions for the water samples is as such: Cl > HCO3 > SO4, with Cl being the most dominant anion.\r\n\r\nAccording the classification of Permeability based on Terzaghi and Peck (1967), the permeability of the soils in the study area ranged from Low Permeability to Medium Permeability, with Low Permeability being restricted to the eastern flank of the study area where the swamp exists, and which is characterized by clayey sand.\r\n\r\nGeophysical investigation using the electrical method (Vertical Electrical Sounding) revealed that the study area generally has fair to good groundwater yield, which can be tapped through borehole drilling predominantly for domestic and small-scale industrial uses. These aquifers are thin and are mainly recharged by precipitation, hence, may not support heavy industrial water needs. It is therefore paramount to probe in excess of 500m depth for probable high yield aquifers for such industrial use. The geophysical survey also revealed the presence of a deep-seated incision trending approximately north - south across the entire study area.\r\n\r\nThe physical and chemical parameters of the water samples conformed to international standards of potable water except for a few water samples having concentrations of certain constituents exceeding the WHO and NSDWQ maximum permissible limits in drinking water, which rendered the water in those localities unfit for human consumption unless treated. \r\n
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- Statement
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Inserted in the reports are the following maps (1:50,000): Location map, SRTM map, Drainage & Accessibility map, Geological map, Water Table Elevation Contour map, pH values map, Permeability map, Concentration maps of Total Dissolved Solids, Nitrate, Iron, Salinity, Total Hardness, Dissolved Oxygen, Biochemical Oxygen Demand, and Chemical Oxygen Demand.