The multi-improved probabilistic fuzzy models calculate the weights by overweight method,information entropy and analytic hierarchy process. The water quality of the Yellow River in the western region of Northern China was assessed by the models based on the monitoring data of six national monitoring sections during 2003 to 2013. Probabilistic fuzzy model uses the probability to calculate pollutant concentrations and the membership degrees to describe the boundaries of water quality level. The model has a b...