The present study attempts to define the relationship between groundwater flow systems and the distribution of chemical facies with the aid of Geographical Information System (GIS). The study also identifies the different geochemical processes responsible for the chemical evolution of groundwater chemistry. Analytical results of 23 groundwater samples reveal mean values of cations as Na⁺ (84.2 mg/l), K⁺ (4.2 mg/l), Ca²⁺ (27 mg/l), Mg²⁺ (11.5 mg/l) and Fe²⁺ (0.6 mg/l). The anion mean values are HCO₃<sup style="margin-left:-7px;">– </sup> (4.5 mg/l), SO₄<sup style="margin-left:-7px;">2– </sup> (3.7 mg/l), Cl^– (22.5 mg/l) and NO₃<sup style="margin-left:-7px;">– </sup> (2.2 mg/l). Based on mean values, the cations are in order of abundance as Na⁺ > Ca²⁺> Mg²⁺ > K⁺ > Fe²⁺ while the anions reveal order of abundance as Cl^– > HCO₃<sup style="margin-left:-7px;">– </sup> > SO₄<sup style="margin-left:-7px;">2– </sup> > NO₃<sup style="margin-left:-7px;">– </sup>. The geographical information system (GIS) using Inverse Distance Weighted (IDW) delineate two groundwater zones into: Ca-Mg-SO₄-Cl and Na-SO₄-Cl water types. The Ca-Mg-SO₄-Cl constitutes about 35% of the chemical facies and its evolutionary trend is due to simple hydrochemical mixing between Ca-Mg-HCO₃ and Na-SO₄-Cl facies and reverse cation exchange. The Na-SO₄-Cl facies constitutes about 65% of the chemical facies and represents fossil groundwater. The Ca-Mg-SO₄-Cl facies is dominant in the recharge areas while Na-SO₄-Cl facies prevails in discharge areas. Rock-water interaction diagrams indicate precipitation induced chemical weathering along with dissolution of rock-forming minerals. The scattered plots among ions revealed geochemical processes as carbonate weathering, silicate weathering, cation exchange and sulphate reduction. HCA identified effects of rock-water interaction and anthropogenic effects as responsible for the modification of groundwater chemistry in the area

The rocks of the Jos-Bukuru area in North Central Nigeria is characterized by negative and positive gravity residual anomalies ranging from -25 to +20 mGals. Lineaments were extracted from the gravity residual anomaly map for the purpose of assessing the groundwater resources in the area. The region is marked by more than one set of lineaments, each with its distinctive orientation and probably spacing. Lineaments shorter than 20 km in length are shallow structures suitable for this exercise because of their importance in groundwater recharge, transmission and discharge. In a bin size of 15˚ one major and one minimum striking directions between 000˚ and 030˚ were obtained. The major type lies between 000˚ and 015˚, while the minimum one is oriented within the 015˚ and 030˚ direction. These directions correspond to the stress axis of the essentially north-south trending geological structures of Nigeria. Invasions of mineralizing fluids might had sealed some of the joints and other fractures, however where the open spaces are not sealed, weathering and erosion widen and deepened the joints paving routes for surface water flows and direct seepage into the underlying strata. On the lineament density and lineament intersection maps the closures suggest probable discontinuity of the aquifer units. On this basis of the lineament density and the lineament intersection results, the area was divided into three hydrogeological zones. Site 1 is considered most favourable for water well development, while site 3 may result in low yields or even in abortive water wells.

Karlahi is largely underlain by granites and migmatites gneiss of the Adamawa Massif. The area lies west of Benue Trough and east of Cameroon volcanic line. The aim of this paper is to determine hydraulic properties of water bearing layer using parameters derived from Dar-Zarrouk equation and characterized them into groundwater potential zones. The resistivity values of the weathered and slightly weathered layers which make up the water bearing layers were added and an average was taken and used as the resistivity of the water bearing formation in computation of Dar-Zarrouk parameters in Karlahi area. The values of resistivity of water bearing formation ranged from 18 to 4963 Ωm with an average resistivity value of 549 Ωm and the thickness of the water bearing formation ranges from 21 to 32 m with an average thickness of 24.5 m. Conductivity values range from 0.000201 to 0.05509 (σ) while the longitudinal conductance range from 0.00483 to 1.2363 Ω-1, the transverse resistance ranges from 407 to 123504.3 Ωm2. The hydraulic conductivity and transmissivity values range from 0.14 to 25.87 m/day and 3.28 to 580.4 m2/day respectively. The longitudinal conductance values in Karlahi area revealed poor to good with an average longitudinal conductance value that is moderate. High transverse resistance values are located in the central and southern part of Karlahi area while low values are located in the eastern part. The spatial distribution map of transmissivity in the area revealed moderate to high transmissivity values in the north central part and a negligible to low transmissivity in southern part, extreme northeastern part. The groundwater potential map of Karlahi area shows negligible to weak potential groundwater zones in SW and SE, moderate potential in the central to northern part of Karlahi area.

The Mubi-Hong area constitutes part of the northeast basement complex of Nigeria and has experienced tectono-metamorphic deformation distinguished into D1, D2 and D3 events. The resultant effect is production of varied ductile and brittle structures (faults, folds, mineral stretching and foliation) which trends mostly in NNW-SSE direction, with other components NNE-SSW and NE-SW. Deformation and metamorphism in the area can be described as being progressive as indicated by the varied nature of synclinal-anticlinal folds. The tensile tectonism is also responsible for the structures and subsequent emplacement of large volumes of granitoids during Pan-African (600+150Ma). A Multi directional orientation of brittle, planar and linear structures in the area suggests that the area have undergone polyphase deformation similar to those in other parts of the Nigerian basement complex.

The combination of Self Potential (SP), Electromagnetic (EM) and Resistivity profiling methods in Gwoza has resulted in the delineation of conductive zones suspected to be sulfide mineralization in the area. Mineralization potentials of -201 mV on the profile AA', -250.2 mV on the profile BB' and -203 mV on the profile CC' respectively have been observed. Correspondingly, both the vertical coil and the horizontal coil readings of the EM anomalies on the profiles AA', BB' and CC' also show significant negative anomalies across the delineated conductive zones. Three resistivity profiles DD', EE' and KK' have also shown very low resistivity values across the said conductive zones. These conductive zones have been established as sulfide mineralization within faults in this work. The recovery of chalcopyrite samples from a hand-dug well close to the delineated conductive zone of the profile BB' tends to lend credence to the interpretation in this study.