“…The PSO is a population-based optimization technique introduced by Eberhart and Kennedy (1995), motivated by collective and social behavior of bird flocking or fish schooling (Parsopoulos and Vrahatis, 2002). PSO has been successfully applied in various water resources problems such as basin-scale optimal water allocation (Shourian et al, 2008a(Shourian et al, ,2008bMousavi and Shourian, 2010b), optimal hydropower systems design and operation (Mousavi and Shourian, 2010a), multi-objective reservoir operation (Kumar and Reddy, 2007;Reddy and Kumar, 2007a;Baltar and Fontane, 2008) and storm water network design (Afshar, 2008).…”