Abstract. Developing a hydrological forecasting model based on past records is crucial to 23 effective hydropower reservoir management and scheduling. Traditionally, time series analysis and 24 modeling is used for building mathematical models to generate hydrologic records in hydrology 25 and water resources. Artificial intelligence (AI), as a branch of computer science, is capable of 26 analyzing long-series and large-scale hydrological data. In recent years, it is one of front issues to 27 apply AI technology to the hydrological forecasting modeling. In this paper, autoregressive 28 moving-average (ARMA) models, artificial neural networks (ANNs) approaches, adaptive 29 neural-based fuzzy inference system (ANFIS) techniques, genetic programming (GP) models and 30 support vector machine (SVM) method are examined using the long-term observations of monthly 31 river flow discharges. The four quantitative standard statistical performance evaluation measures, 32 the coefficient of correlation (R), Nash-Sutcliffe efficiency coefficient (E), root mean squared 33 error (RMSE), mean absolute percentage error (MAPE), are employed to evaluate the 34 performances of various models developed. Two case study river sites are also provided to 35 illustrate their respective performances. The results indicate that the best performance can be 36 obtained by ANFIS, GP and SVM, in terms of different evaluation criteria during the training and 37 validation phases. 38 39