Risk Assessment of Dike Based on Risk Chain Model and Fuzzy Influence Diagram

For the risk assessment of flood defense, a comprehensive understanding of risk factors affecting dike failure is essential. Traditional risk assessment methods are mostly based on experts’ experience and focus on just one type of failure mode of flood defensive structures. The risk resources, including the analytical factors and non-analytical factors, were summarized firstly according to the general experience of dikes. The uncertainty of the resources that affect dike safety can be quantified by membership degree. Hence, a fuzzy influence diagram based on fuzzy mathematics was proposed to assess the safety of the dikes. We evaluated the multi-failure modes at the same time by a fuzzy influence diagram. Taking a dike as an example, the expected value of the dike failure was 6.25%. Furthermore, the chance of damage to this dike was “very unlikely” according to the descriptive term of the Intergovernmental Panel on Climate Change (IPCC). The evaluation result was obtained as a probabilistic value, which enabled an intuitive perception of the safety of the dikes. Therefore, we provided some reasonable suggestions for project management and regular maintenance. Since the proposed method can account for uncertainties, it is well suited for the risk assessment of dikes with obvious uncertainties.