Evaluation of geogenic and anthropogenic impacts on spatio-temporal variation in the quality of the drinking water sources under the impact of land-use and land-cover: A case study of the Erbil Central Sub-Basin, Iraq

The study area, Erbil Central Sub-Basin, is located within the foothill zone in the stable shelf tectonic unit of Iraq (northern Iraq) on the Arabian plate. Recently, groundwater demand has increased significantly due to insufficient surface water resources for agricultural, industrial, and domestic water uses depending on ever-increasing socio-economic development and population in the study area. Sampling studies were carried out in two different periods, May 2020 (wet season) and September 2020 (dry season), to determine the water quality in water resources located throughout the sub-basin. For this purpose, a total of 30 samples, including 27 groundwater wells, and 3 wastewater samples from channels, were collected and analyzed. The general hydrochemical analysis indicates that overall well water quality is suitable for drinking purposes except where elevated NO₃, COD, and BOD5 concentrations are found. Most trace metal analysis results (except for Fe) in wells and wastewater channels show that they are below the permissible limits (0.3 mg/L) from IQWS (2010) and WHO guidelines (2011). The results of the factor analysis for the wet and dry season hydrogeochemical indicate that the first five and six-component extracted have eigenvalues>1 and correspond to approximately 94.844 and 96.26 % of the total variance, respectively. The factor analysis indicated that groundwater quality in the wet and dry season are significantly associated with anthropogenic pollution sources such as leaching from soil layers, cesspools wastes, industrial wastes, and agriculture activities rather than natural, geogenic processes such as reverse ion exchange, the weathering of carbonate minerals from geologic formations outcropping throughout the Erbil Central Sub-Basin.