Connection number based risk evaluation method for watershed flood control engineering system using stochastic simulation and triangular fuzzy numbers

In order to deal with the risk evaluation problem of watershed flood control engineering system affected by many uncertainty factors, multivariate connection number expression of index samples and evaluation grade criterions of flood control engineering system was presented to describe hierarchy property and fuzziness of membership relation between index samples and evaluation grade criteria. A method of combining triangular fuzzy numbers with multivariate connection number theory was suggested to deal with the fuzzy evaluation grade criteria problem denoted by interval number in risk evaluation problem of watershed flood control engineering system. The discrepancy degree coefficients of connection number and evaluation index weights were expressed using triangular fuzzy numbers, then a connection number based risk evaluation method for watershed flood control engineering system using stochastic simulation and triangular fuzzy numbers, namely CN-SSTFN for short, was established using Monte-Carlo method. The research results show that various information of subjective and objective uncertainties in the risk evaluation process of watershed flood control engineering system can be comprehensively utilized using CN-SSTFN, its comprehensive evaluation results expressed by confidence intervals can provide more reliability information than that of the common evaluation methods, which can reflect practical conditions of the risk evaluation problem of watershed flood control engineering system affected by many uncertainty factors. The CN-SSTFN can be applied to comprehensive risk grade evaluation problems of different systems.