Author(s)

Ahmed Nur, Jackson M. Ishaku, Solomon N. Yusuf

Department of Geology, Modibbo Adama University of Technology, Yola, Nigeria.
Department of Geology, University of Maiduguri, Maiduguri, Nigeria.

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^– (4.5 mg/l), SO₄^2– (3.7 mg/l), Cl^– (22.5 mg/l) and NO₃^– (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^– > SO₄^2– > NO₃^– . 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.

Groundwater; Chemical Facies; GIS; Rock-Water Interaction; Cations and Anions

A. Nur, J. Ishaku and S. Yusuf, "Groundwater Flow Patterns and Hydrochemical Facies Distribution Using Geographical Information System (GIS) in Damaturu, Northeast Nigeria," International Journal of Geosciences, Vol. 3 No. 5, 2012, pp. 1096-1106. doi: 10.4236/ijg.2012.35111.