Evaluation of water quality of Kizilirmak River (Sivas/Turkey) using geo-statistical and multivariable statistical approaches

Groundwater and surface water qualities are evaluated using geographic information system (GIS)-based geo-statistical and multivariable statistical methods. This research aims to investigate the water quality of Kizilirmak River, that remain within the provincial boundaries of Sivas, using geo-statistical and multivariable statistical methods, and to provide the water quality map of Kizilirmak River. In this regard, surface water samples from 28 surface water quality monitoring stations were analysed for wet and dry seasons. The hydro-chemical properties of surface water quality were determined, and the water quality index was evaluated for each station. Spherical, exponential and Gaussian models were determined as the best semi-variogram models according to the minimum root mean square error values and the cross-validation method. The final water surface quality map of Kizilirmak River was obtained by weighted superposition of the spatial distribution maps of the surface water quality parameters which were obtained by the geo-statistical method. The correlations between the surface water quality parameters were determined using multivariable statistical analysis methods such as correlation analysis and factor analysis (principal component analysis). The surface water quality in the study area was categorized as excellent, good, poor and very poor. The water quality of Kizilirmak River's portion near Sivas city centre and in the South of the province did not meet the standards for drinking water purposes. This research provides the surface water quality map of the study area by use of GIS-based statistical methods.