The imperfection and fuzziness affecting the water quality risk due to the random uncertainty and fuzzy uncertainty are analyzed. The risk of water quality in water environment system is regarded as a fuzzy event to establish the fuzzy probabilistic model for calculating the risk rate to check if the water quality is exceeding the standard. The concept of information entropy of fuzzy event is introduced to assess the credibility of the selected characteristic value of the membership function, and then the relationship between characteristic value of membership function and risk rate is describ...
