اصلاح آنالیز توسط شاخص کیفیت آب با استفاده از روش های تصمیم گیری چند معیاره Modifying the analysis made by water quality index using multi-criteria decision making methods

1. Introduction Groundwater is among the vital water resources on the earth planet, being exploited for fundamental uses such as drinking, agriculture and industry (Wu and Sun, 2016; Li et al., 2016; Chitsaz and Azarnivand, 2016; Jamshidzadeh and Mirbagheri, 2011). Rainfall penetration through the soil and stones on the ground surface is the most important source of groundwater provision. This water resource accompanied by water penetration of rivers/lakes as well as artificial recharge of groundwater and reused waste waters are the major sources for augmentation of groundwater resources (Adetunde et al., 2011). In general, population growth and the expansion of urbanization as the chief cause of agriculture and industry evolution gave rise to instability of aquifers (Krishan et al., 2016). Moreover, the exponential rise of population and over exploitation of groundwater resources has ended in quality degradation of groundwater (Pophare et al., 2014). In particular, just like the quantity, quality of groundwater should be taken into a serious consideration (Aghazadeh and Asghari-Moghadam, 2010). Considering this fact that, artificial recharge, environmental rainfall, ground water penetration and groundwater geo-chemical reactions might influence the quality of groundwater (Vasanthavigar et al., 2010), its pollution would threaten human’s health, economic development and social welfare (Milovanovic, 2007). Several factors and methods have so far, been innovated to present water quality parameters. Among all, Water Quality Index (WQI) is appreciated as a prominent factor for classification and quality management of groundwater (Hosseini-Moghari et al., 2015). In order to evaluate the quality of drinking water in Sabalan aquifer eas a volcanic region- Mosaferi and his colleagues (Mosaferi et al., 2015) put WQI into practice using 7 qualitative parameters. In addition, Sadat-Noori et al. (2013) performed zoning of adequate regions for drinking exploitations in Saveh-Arak plane. While having a positive effect on the qualitative assessment of groundwater resources, WQI is expected to entail drawbacks. Lermontov et al. (2009) stated that classifications which are adopted from this index would generate inflexible and definite results. Moreover, Dahiya et al. (2007) explained that this analysis, in some cases, presents unreliable consequences. For instance, based on the analysis made by WQI, the quality of water has been reported to be adequate for drinking purposes, while assessed to be inadequate for agriculture using Wilcox diagram. Such an assumption should be considered a genuine contradiction as sensitivities to drinking water is remarkably higher compared to the water used in agriculture. In line with the above elucidation, Multicriteria decision making methods were recommended in order to avoid conflicts in the qualitative classification of samples.