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Open Access International Journal of Water Research Volume 3 Issue 1 ISSN: 2694-4049 Review Article Estimating Aquifer Hydraulic Conductivity and Transmissivity for Parts of Oru LGA Imo State, Southeastern Nigeria Using Resistivity Data Agbodike I* Department of Physics, Imo State University Owerri, Nigeria

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Article History: This study focuses on determining the estimates of aquifer hydraulic conductivity and transmissivity for Received: 16 February, 2021 Accepted: 22 February, 2021 parts of Oru Area in Imo State of South Eastern Nigeria using data from surface electrical sounding. Published: 20 March, 2021 Eighteen vertical electrical sounding were made in the study area using a maximum Current electrode

separation of 1.0km.The Abem Tetrameter SAS 3000B was used in acquiring data while four metal stakes * Corresponding author: Agbodike were used as electrodes. The Schlumberger electrode configuration was adopted in the survey. The I, Department of Physics, Imo State University Owerri, Nigeria; Tel: unavailability of pumping test data in the area of study led to the use of diagnostic constants derived from +2348063841735; DOI: other areas but of similar geologic zone with the area of study to be used to estimate the aquifer hydraulic https://doi.org/10.36266/IJWR/119 conductivity and aquifer transmissivity of the area of study This manuscript shows that Aquifer transmissivity in this area varied from 158.765squared meter per day at Aji to 6668.584squared meter per

day at Akatta.. Also Aquifer hydraulic conductivity in the area varied from .2.327m/day at mgbidi to 89.956m/day in Akatta. These Characteristics are essential for the solution of several hydrological and hydrological problems within the area of study. In fact groundwater potential in this area depends on these aquifer characteristics. Keywords: Groundwater potential; Aquifer; Hydraulic conductivity; Transmissivity; Vertical electrical sounding

Copyright: © 2021 Agbodike I. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

aquiferous units and is measured in푚2/푑푎푦. According to Darcy’s Introduction law the fluid discharge 푄 is given by Aquifer hydraulic conductivity and transmissivity are part of the properties of an aquifer that control the movement, storage and 푄 = 퐾퐼퐴 extraction of underground water [1]. This paper estimates aquifer Where K is the hydraulic conductivity. I is the hydraulic gradient, A hydraulic conductivity and transmissivity for parts of Oru L.G.A is the cross-sectional area perpendicular to the direction of flow. in Imo State of southeastern Nigeria using data from surface Ohm’s law gives electrical soundings .Determination of these aquifer 퐽 = 휎퐸 characteristics is essential to the solution of several hydrological Where J is current density, and σ is the electrical conductivity which and hydrogeological problems. The determination of these is the reciprocal of the resistivity, р. For aquifer material having unit aquifer parameters is best made on the basis of data obtained from cross-sectional area and thickness h, the two fundamental laws can well pumping test data [2] However in the case of paucity of be combined to give; according to Niwas and Singhal [4] pumping test data these characteristics may be estimated using 퐾푆 푇 = 퐾휎푅 = = 퐾ℎ the da Dar-Zarrouk parameters from geophysical sounding. 휎 Estimation of aquifer hydraulic parameters using Da- Zarrouk Where T is the transmissivity, R is the transverse resistance of the parameters is well known and and has been extensively discussed aquifer, K is the hydraulic conductivity and S is the longitudinal by previous investigators Henriet [3] Niwas and Singhal [4] the conductance hydraulic conductivity (K) refers to the ability of a rock material It has also been shown by Niwas and Singhal [4] that in areas of to conduct fluids under a unit hydraulic gradient and is measured similar geologic setting and water quality, the product Kσ remains in m/day. K is generally estimated from the product of the aquifer fairly constant .Thus, the knowledge of K from some existing apparent resistivity and the diagnostic constant (diagnostic in the boreholes and of σ from VES sounding can be used to estimate Kσ sense that it is the only model parameter that is directly related to for the same geologic zone. Hence the aquifer hydraulic conductivity the subsurface) the diagnostic constant is the product of the and aquifer transmissivity for the entire area can be estimated Ijeh, measured hydraulic conductivity and aquifer conductivity Opara [6]. According to Opara et.al [5] in an article estimation of hydraulic A.I [5]. Aquifer transmissivity is defined as the product of parameters from Surface geo-electrical data; a case study of Orlu and hydraulic conductivity or permeability and thickness of the Environs, Imo river basin, Southeastern Nigeria. The mean Pubtexto Publishers | www.pubtexto.com 1 Int J Water Res

Citation: Agbodike I (2021). Estimating Aquifer Hydraulic Conductivity and Transmissivity for Parts of Oru LGA Imo State, Southeastern Nigeria Using Resistivity Data. Int J Water Res 3(1): 119 DOI: https://doi.org/10.36266/IJWR/119 diagnostic constants used for Benin formation was Benin formation, the sands and sandstones are coarse to fine grained and commonly of granular texture. The formation consists of friable 퐾휎 = 0.0118765 sand with intercalations of shale and clay lenses occurring Also according to the article Evaluation of the aquifer hydraulic occasionally at some depths (Short and Stauble) [10]. The formation characteristics from electrical sounding data in Imo River Basin, is partly estuarine, partly lagoon, partly deltaic and fluid, lacustrine South eastern Nigeria; the case study of Ogwashi-Asaba in origin Reymont, 1965. The sands and sandstone in this formation formation by Ijeh [6]. The mean diagnostic constants used for this are coarse grained, very granular, pebbly to very fine grained. They Ogwashi-Asaba formation was are either white in colour or yellowish brown. Hematite grains and 0.0102 + 0.0316 feldspars are also obtained. The shale are grayish brown, sandy to 퐾휎 = = 0.026 2 silty and contains some plant remains and dispersed lignite’s The Oru Area which is our study area is part of the Imo River (Reyment, [7] the formation has an average thickness of 600ft Basin. The northern part of the Oru Area is Ogwashi –Asaba (196.85m) Kogbe, [11]. Surface waters are not a major feature of the formation Agbodike [5]. Whereas other parts are Benin Oru Area. The Njaba and Obana rivers seem to be the only surface formation. In this research work due to unavailability of pumping waters in the area Agbodike, [12] the two formations are known to test data, the above stated diagnostic constants shall be used in have reliable groundwater that could sustain borehole production. the computation of the aquifer hydraulic conductivity and The high permeability of the coastal plain sands, the overlying transmissivity of the Study area. lateritic earth and the weathered top of this formation provide the Location and Geomorphology of the Study Area hydraulic conditions favoring aquifer formation in the study area. The copious rainfall that prevails in the area makes the aquifer The study area consists of some communities located within the prolific and continuously provides the ground water recharge. The Oru Area of Imo-State Nigeria. The increasing population in Oru geological map of the area is in (Figure 2). which is over two hundred and twenty nine thousand according to 1991 and 2006 national population census by national population commission owerri and consequent increasing demand for portable water prompted the present search for favorable groundwater potential zones in the area. Besides, this paper aims at providing a quantitative information about the ground water potential in this area so as to contribute to any future water resources management program for this region. The study area lies between longitude 6050E and 7000E and latitude 5050N and 5037N as shown in the location map of the Area as in (Figure 1). It covers a land mass of about 315 km2 South East Nigeria.

Figure 2: Geological map of the study Area. Data Acquisition and Interpretation Eighteen vertical electrical soundings were made in the study area using a maximum current electrode separation of 1.0km. The ABEM terrameter SAS 3000B was used in acquiring data while four metal stakes were used as electrodes. The schlumberger electrode configuration was adopted in this survey. In this array the current and potential electrode pairs have a common midpoint but the distances between adjacent electrodes differ significantly. For a schlumberger Figure 1: Location map of the study area. spread, the apparent resistivity computed from the measurement of Geology and Hydrogeology of the Area voltage, ∆V and the current I is given by the equation 푎2 푏 ∆푉 A study of the geology of Nigeria shows thatthe Oru Area is made 휌 = 휋 ( − ) 푎 푏 4 퐼 up of two geological formations; the Ogwashi-Asaba and the Benin formation which was formerly known as coastal plain Theoretically, the resistivity ρ, of a material is directly proportional sands Reymont, [7]. According to (Dessauvagie and Fayose [8]; to the potential difference ∆V and inversely proportional to the Whiteman [9]. Ogwashi-Asaba formation is characterized by induced current I 푉 alternation of clays and sands, grits and lignites. Reyment, [7] 휌 훼 suggested Oligocene-Miocene age for this formation. For the 퐼

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퐾푉 휌 = 퐼 Since 푉 푅 = 퐼 휌 = 퐾푅 Where K is the geometric factor, R is the resistance. The geometric factor K depends on the electrode separation. R is the resistance of the volume of ground between the potential electrodes. If V and I are measured in milli-volts and milli- amperes respectively and the distance of separations in meter, then the resistivity r is expressed in Ohm-meter. The apparent Figure 5: Sample of resistivity curve from the area. resistivity values obtained from the field were plotted against half the current electrode spacing (AB/2) on a bi-logarithmic graph for all the VES stations. The computer modeling delineated 6-7 geoelectric layers. The computer program RESIST designed and used in the National Geophysical Research Institute (NGRI) by Jupp and Vozoff [13], in Hyderabad India were employed in the interpretation of the VES data. The output of the Resist software comprises a best fit curve or computer modeled curve, a set of resistivity values with corresponding layer thickness, total probe depth and the fitting error in percentage. Some of the resistivity curves obtained in the area are plotted in (Figure 3), (Figure 4) and (Figure 5). (Table 1), (Table 2) [14-24]. Figure 6: Spatial distribution of aquifer hydraulic conductivity in the area.

Figure 3: Sample of resistivity curve from the area. Figure 7: Dimensional surface map of the aquifer hydraulic conductivity

distribution in the area.

Figure 4: Sample of resistivity curve from the Area.

Figure 8: Spatial distribution of aquifer transmissivity in the area.

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Figure 9: Dimensional surface map of the aquifer transmissivity distribution in the area.

Table 1: Aquifer Hydraulic Parameters of the Study Area Using Data from Surface Electrical Soundings according to Agbodike, (2019). Aquifer Aquifer Aquifer Transverse VES Resistivity Longitudinal Location Depth Thickness Conductivity Resistance NO (ohm-m) Conductances(mhos) (m) (m) Siemens (ohm-m2) 1 Ubachima 1 395 110 119 0.0025 47005 0.30126 2 Ubachima x2 317 92.4 79.3 0.00315 251381 0.25016 3 Umuokwe 313 96.4 68.8 0.00319 21534.4 0.21981 4 Oteru 470 200 140 0.00213 65800 0.2979 5 Umuowa 636 86 103 0.00157 65508 0.1619 6 Otulu 1 640 120 115 0.00156 73600 0.1796 7 Ubahazu 1 642 125 115 0.00156 73830 0.1791 8 Ubahazu 2 645 117 109 0.00155 70305 0.1689 9 Otulu 2 618 155 122 0.00162 75396 0.1974 10 Umuoji 221 164 123 0.00452 27183 0.55656 11 Mgbidi 1 196 205 90 0.0051 17640 0.4592 12 Mgbidi 2 1831 87 67 0.00055 122677 0.03659 13 Ibiaso Egbe 524 84 132 0.00191 69168 0.2519 14 Nempi 3934 81.6 63.5 0.00025 249809 0.1614 15 Akatta 3466 75 74 0.00029 256484 0.02135 16 Aji 557 27 24 0.00179 13368 0.04309 17 Ubulu 2915 36 69 0.00034 201135 0.02367 18 Akuma 96.5 39 41 0.01036 3956.5 0.42487

Table 2: Aquifer Hydraulic Parameters of the Study Area Using Data from Surface Electrical Soundings according to Agbodike, (2019).

Aquifer Hydraulic VES Resistivity Transmissivity Location kσ Conductivity Conductivity NO (ohm-m) M2/day Siemens m/day

1 Ubachima 1 395 0.01188 0.0025 558.255 4.633

2 Ubachima x2 317 0.01188 0.00315 2985.53 37.594 3 Umuokwe 313 0.01188 0.00319 255.753 3.717 4 Oteru 470 0.01188 0.00213 781.474 5.588 5 Umuowa 636 0.01188 0.00157 778.006 7.545 6 Otulu 1 640 0.01188 0.00156 874.11 7.592 7 Ubahazu 1 642 0.01188 0.00156 876.842 7.637 8 Ubahazu 2 645 0.01188 0.00155 834.977 7.663 Pubtexto Publishers | www.pubtexto.com 4 Int J Water Res

9 Otulu 2 618 0.01188 0.00162 895.441 7.349 10 Umuoji 221 0.01188 0.00452 322.839 2.623 11 Mgbidi 1 196 0.01188 0.0051 209.501 2.327 12 Mgbidi 2 1831 0.01188 0.00055 1456.97 21.741 13 Ibiaso Egbe 524 0.01188 0.00191 821.474 6.229 14 Nempi 3934 0.026 0.00025 6495.03 10.221 15 Akatta 3466 0.026 0.00029 6668.58 89.956 16 Aji 557 0.01188 0.00179 158.765 6.596 17 Ubulu 2915 0.026 0.00034 5229.51 75.777 18 Akuma 96.5 0.026 0.01036 102.869 2.508

11. Kogbe CA. Geology of Nigeria. Elizabeth publishing company Conclusion lagos. 1976. In this research work carried out in parts of Oru LGA in Imo 12. Agbodike C. Geoelectric exploration for groundwater in Oru State South eastern Nigeria, it has been shown that aquifer area of imo State of South-Eastern Nigeria. An M.Sc project transmissivity in this area varied from 158.765m2/day at Aji to submitted to school of postgraduate studies Abia State 6668.584 m2/day at Akatta. Also aquifer hydraulic conductivity university uturu. 2010; 134. in the area varied from 2.327m/day at mgbidi to 89.956m/day in 13. Jupp DLB, Vozoff K. Stable interactive methods for inversion Akatta. if geophysical data. Geophy. J. RAS 42957-9. 1975. References 14. Agbodike IIC, Igboekwe, Udeh MUI. Geophysical study of the weathered and near surface zone in parts of Oru area, Imo State, 1. Mbonu PDC, Ebeniro JO, Ofoegbu CO, Ekine AS. Nigeria, using seismic refraction method. 2018. Geoelectric Sounding for the determination of Aquifer 15. Borehole data from Imo State Ministry of Water Resources. characteristics In parts of the Umuahia area of Nigeria. 1991. 16. Breusse JJ. Modern geophysical methods for subsurface water 2. Ugada U. Hydrogeophysical evaluation of aquifer hydraulic exploration, Geophysics. 1963; 28. characteristics using surface geophysical data; a case study 17. Chilton PJ, Foster SSD. Hydrogeological characterization and of Umuahia and environs, Southeastern Nigeria. Arab water supply potentials of basement aquifers in tropical Africa. journal of geosciences. 2013. Hydrogeological journal. 1995. 3. Pulawaski B, Kurth R. Combined use of resistivity and 18. Kumar DJ, Ramadass G, Jagadish SV. Delineation of seismic refraction methods in groundwater prospecting in groundwater potential zones through electrical resistivity crystalline areas. Study project Kenya, Danida. 1977. parameters in hard rock terrain, osmania university campus, 4. Niwas, Singhal DC. Estimation of aquifer transmissivity hyderabad, telangana state India. IOSR journal of applied from Dar-Zarrouk parameters in porous media. Journal of geology and geophysic. 2015; 3:1-10. hydrogeology. 1981; 50: 393-399. 19. Igboekwe MU. Gurunadha VVS, Okwueze EE. Groundwater 5. Opara AI, et.al; Estimation of hydraulic parameters from flow modeling of Kwa Ibo river watershed, Southeastern surface Geoelectrical data; a case study of orlu and environs, Nigeria. John wiley and sons Ltd. 2005. imo river basin, southeastern nigeria, discovery nature 20. Okwueze EE. Preliminary findings of the groundwater resources journal. 2018; 12. potentials from a regional geoelectric survey of the obudu 6. Ekwe AC, Opara AI. Aquifer transmissivity from surface basement area, Nigeria Gjpas. calabar. 1996; 2: 201-211. geoelectrical data; a case study of owerri and environs 21. Oru population data 1991 and 2006. National population Southeastern Nigeria. Journal of the geological society of commission owerri. India. 2012. 22. Ugada U, Opara AI, Emberga TT, Ibim FD, Omenikoro AI, 7. Reyment RA. Aspects of Geology of Nigeria, Ibadan, Womuru EN. Delineation of shallow aquifers of Umuahia and Nigeria University of Ibadan. 1965. 145. environs,Imo- River Basin, Nigeria using Geo-Sounding data. J 8. Desavvagie TF, Fayose EA. Excursion A. cretaceous and water resources and protection, 2013; 5: 1097-1109. Tertiary rocks of Southern Nigeria. In: Dessavvagies TF, 23. Zohdy AAR. Groundwater exploration with schlumberger Whiteman AJ. (eds). African Geol. 1970; 659-66. sounding near jean, Neveda USGS. 1973; 66. 9. Whiteman A. Nigeria: Its petroleum geology, resources and 24. Zohdy AAR, Eaton GP, Mabey DR. Application of surface potential. Vol 1: Graham and Trotman. 1982; 382. geophysics to groundwater investigations U.S geol survey. 10. Short KC, Stauble AJ. Outline of geology of niger delta 1974. AAPG Bulletin. 1967; 51.

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