“…Several ANN applications in groundwater and surface water hydrology have been recently published. In groundwater hydrology these include simulation of a numerical model in order to obtain results in less time with smaller computational effort (Arndt et al, 2005;Hani et al, 2006;Nikolos et al, 2008); estimation of aquifer parameters (hydraulic conductivity), using an inverse problem method where, using hydraulic head measurements, the aquifer parameters are calculated (Zio, 1997;Wosten et al, 2001;Garcia and Shigidi, 2006;Samani et al, 2007); forecasting spring outflow, combining a mathematical model that calculates input parameters of a neural network (Lallahem and Mania, 2003a); prediction of a flow field, which is still in initial level and combines a conventional numerical model with ANN in order to produce a map of the flow field (Benning et al, 2001); and prediction of contamination risk, based on conductance, precipitation, temperature, and pumping data (Kuo et al, 2004;Coppola et al, 2005a;Sahoo et al, 2006). In surface water hydrology the main implementation concerns catchment flow prediction for managing flood-risk or reservoir storage (Coulibaly et al, 2000;Aqil et al, 2007); rainfall runoff modeling, which can be either lumped or semi-distributed (Sajikumar and Thandaveswara, 1999;Lallahem and Mania, 2003b;Chen and Adams, 2006); and time series modeling, which in association with fuzzy logic has been applied for river flow modeling (Nayak et al, 2004).…”