“…For example, principal component analysis (PCA) has been used to determine the main variables that affect eutrophication processes from a wide number of water quality parameters including TN, TP, oxygen, Chl-a, Secchi depth, phosphate, nitrate, nitrite, and ammonia (Lundberg et al, 2005;Primpas et al, 2010); Cluster analysis (CA) has been used to classify waters into the three eutrophication statuses including the oligotrophic, mesotrophic, and eutrophic state using several variables (Chl-a, phosphate, nitrate, nitrite, and ammonia) (Stefanou et al, 2000;Primpas et al, 2008); Discriminant factor analysis (DFA) has been used to identify different variables (nitrate, phosphate, Chl-a, DO, turbidity and temperature) that can differentiate sampling sites and to group them according to their eutrophication conditions (Tsirtsis and Karydis, 1999;Pinto et al, 2012); Artificial neural network (ANN) mode has been used for prediction of eutrophication conditions with reasonable accuracy by a wide range of variables (TP, TN, COD, the Secchi disk depth, DO and Chl-a) (Jiang et al, 2006;Kuo et al, 2007). Support vector machine (SVM) (Vapnik, 1995) is a promising power approach used to reflect the nonlinearity between responsive indicator and input variables using stochastic error minimization approaches (Zhou et al, 2016a) and is an effective tool to predict values from a wide variety of environmental fields (Ribeiro and Torgo, 2008;Farfani et al, 2015;Kisi et al, 2015). The grid search (GS) algorithm is straight forward to determine the optimized parameter values for the SVM (Sajan et al, 2015;Gao and Hou, 2016).…”