Effects of recharge area and drainage system on ground water quality of Telkaif area/ north of Iraq

Drainage system and recharge area of the catchment area plays important role in recharging ground water aquifer, through infilteration of rain and runoff water to the ground water depending on the type of sediments cover, intensity of rainfall, slope and intensity of runoff. This study discuss the drainage system recharge and its effect on the concetration of the chemical constituents of ground samples, through the analysis of chemical and physical parameters of ground water samples of the studied area for two periods during the year 2007. The first period of sampling is on April 2007 where the ground water table is on the highest level, while the second period is on November 2007 where the ground water table is on the lowest level. The chemical parameters analyzed were pH, TDS, EC, TH, Ca, Mg, Na, K, HCO₃, SO₄, Cl and NO₃. Chemical parameters such as sodium percentage (Na%), Sodium adsorption ratio (SAR), Permeability Index (PI) and saturation index with respect to calcite and gypsum (SI) were calculated, based on the major cation and anions analysis of ground water samples. A notable variation in the chemical composition of ground water samples between the two analyses has attracted attention of the authors. An attempts is made to interpret the variation in the chemical composition of ground water and the cause of the variation by the interaction of ground water and host rocks in one hand and drainage system recharge and dissolution of surface pollutants during infilteration and percolation of rainwater in the other hand. The abundance of the major ions of the ground water samples (1, 2, 3, 4) is in the following order: Na > Ca > Mg > K = HCO₃ > SO₄ > Cl > NO₃, while the abundance of the major ions of the rest samples is in the following order: Ca > Na > Mg > K = SO₄ > HCO₃ > Cl > NO₃.