Coastal Flood Hazard Analysis for Bandar Anzali Coast Considering Joint Probability of Significant Events

Communities accommodated along shorelines have always been under devastating threats from the sea/ocean such as coastal flooding. Mitigation planning against such threads demands a well understanding of the thread’s nature. In addition to the physical understanding, such planning is always based on statistical representation of the thread generating events. Coastal hazard analysis is the method of estimating such statistical representations based on the physics and time history of the events and so, it is the preliminary step toward hazard mitigation planning. Methods that combine contributing physical processes have weekly considered the dependence between the physical processes. Using proper joint probability statistical methods, rational combinations of events can be estimated on the ground of their history. Copula functions are a group of functions that generate such combinations. Estimating the marginal distribution of the events, Copula functions represent the joint probability of the events based on their historical joint occurrence. This method is used in this paper to derive the joint probability of storm surge and wave height for Bandar Anzali coasts. The ad-hoc method of superimposing the significant events is also pursued for comparison. The marginal distributions are chosen from GEV, Weibull, Gumble and Lognormal probability distributions. The model parameters are estimated using the Maximum Likelihood method, and the goodness of fit is evaluated using the Root Mean Square Error criterion. Deep water waves with return period of 20, 50 and 100 years in addition to the joint probability results are transferred to the beach using the spectral coefficient method. Considering wave setup and wave run up, the final inundation levels are estimated and the inundated regions are plotted.