Overtopping risk analysis of existing dikes bases on Bayes method and measured annual highest flood water level

A fuzzy test method for distribution probability model of measured annual highest flood water level is proposed, using the distribution as a prior distribution, statistical parameters of the probability model can be future upheld and renewed by post-check parameters which the Bayes method be used. In an example, using K-S test method and the fuzzy test method, the highest measured flood water levels in 58 years at a city hydrological station of the Yangtze River downstream is used as the statistic sample, the distribution pattern of annual highest water level are tested. It is found that the normal distribution is more approachable actual situation by the fuzzy test method. Then, the distribution parameters of the probability model are amended using the small sample of the measured highest flood water level of last 10 years. The proposed calculating method of renewed probability model and parameters for distribution of the annual highest water level in this paper can affords a theory method for heightening design plan decision of existing dikes. Using measured annual highest flood water levels of the hydrological station at the city, the failure probability of overtopping model of a dike under the different floodwater standard is analyzed.