Investigation of priorities in water quality management based on correlations and variations Hülya Boyacıog ˘lu a,⇑ , Vildan Gündogdu b , Hayal Boyacıog ˘lu c a Dokuz Eylul University, Faculty of Engineering, Department of Environmental Engineering, Tinaztepe Campus, Buca, 35160 Izmir, Turkey b Ege University, Faculty of Fisheries, Bornova, 35100 Izmir, Turkey c Ege University, Faculty of Science, Department of Statistics, Bornova, 35100 Izmir, Turkey article info Keywords: Canonical correlation Cluster analysis Sensitivity analysis Water quality index abstract The development of water quality assessment strategies investigating spatial and temporal changes caused by natural and anthropogenic phenomena is an important tool in management practices. This paper used cluster analysis, water quality index method, sensitivity analysis and canonical correlation analysis to investigate priorities in pollution control activities. Data sets representing 22 surface water quality parameters were subject to analysis. Results revealed that organic pollution was serious threat for overall water quality in the region. Besides, oil and grease, lead and mercury were the critical variables violating the standard. In contrast to inorganic variables, organic and physical-inorganic chemical param- eters were influenced by variations in physical conditions (discharge, temperature). This study showed that information produced based on the variations and correlations in water quality data sets can be helpful to investigate priorities in water management activities. Moreover statistical techniques and index methods are useful tools in data – information transformation process. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Surface waters are the most vulnerable sources to pollution due to their easy accessibility for wastewater disposal. Both the natural processes as well as the anthropogenic influences together deter- mine the quality of surface water (Singh et al., 2004; Simeonov et al., 2003). Water quality can be thought as a measure of suitability of water for a particular use based on selected physical, chemical, and biological characteristics (USGS, 2001). During the last dec- ades, river water quality monitoring by measurement of quality parameters has been increasing. Creating a water quality monitor- ing system with appropriate efficiency and to extract useful infor- mation from complex data sets may require application of multivariate statistical tools due to multivariate nature of the eco- logical systems. The application of multivariate techniques (cluster analysis-CA, canonical correlation analysis-CCA, etc.) offers better understanding of water quality and ecological status of the studied systems. Moreover, water quality indices, which have been formu- lated all over the world can easily judge out the overall water qual- ity within a particular area promptly and efficiently. These methods allow identification of the possible factors influencing the water systems. Therefore they are valuable tools for reliable management of water resources as well as rapid solutions on pol- lution problems (Noori et al., 2010; Simeonov et al., 2003; Spanos et al., 2007; Bharti and Katyal, 2011; Horton, 1965). The research aimed: (1) to calculate water quality index-WQI to interpret overall water quality instead of evaluating variable-by- variable basis, (2) to examine parameter contribution to index score and sensitivity of the variables and (3) to analyze strength of the relationship between ‘‘physical’’ and ‘‘water quality’’ param- eters. The overall objective was to investigate priorities in water quality management practices in the case of Gediz River Basin, Turkey. 2. Study area The Gediz River Basin is one of the most important agricultural areas in the western part of Turkey (see Fig. 1). Gediz River with about 401 km length and 17,200 sq km drainage area flows from east to west into the Aegean Sea just north of Izmir (MoEF, 2008). The basin approaches a total population of 2 million. The re- gion has hot dry summers, cool winters and average annual rainfall amount is 500–530 mm (Loon et al., 2007). The primary issues in the basin are water shortage, competing use, and high levels of pol- lution, etc. The major water pollutant sources are point (untreated wastewater discharges from organized industrial districts and municipal sewage treatment plants) and diffuse sources (mainly runoff from agricultural, forest areas, and domestic–industrial 0025-326X/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.marpolbul.2013.01.010 ⇑ Corresponding author. Tel.: +90 232 3017135; fax: +90 232 4531143. E-mail addresses: hulya.boyacioglu@deu.edu.tr (H. Boyacıog ˘lu), vildangundogdu@ yahoo.com (V. Gündogdu), hayal.boyacioglu@ege.edu.tr (H. Boyacıog ˘lu). Marine Pollution Bulletin xxx (2013) xxx–xxx Contents lists available at SciVerse ScienceDirect Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul Please cite this article in press as: Boyacıog ˘lu, H., et al. Investigation of priorities in water quality management based on correlations and variations. Mar. Pollut. Bull. (2013), http://dx.doi.org/10.1016/j.marpolbul.2013.01.010