Estimation of beach erosion using Joint Probability analysis with a morphological model

Abstract

Resilience of a beach is often defined by return period (RP) of a designed storm. During extreme events some correlation exists between storm parameters, such as wave height (Hs) and surge (S), and these parameters are also stochastic in nature. Thus, numerous combinations of Hs and S occurs for the same level of RP. The objective of this study is to demonstrate if a same level of joint RP with different combination of Hs and S would produce similar beach erosion, considering wave directions and orientation of coastline. To achieve this, a non-directional Joint Probability (JP) of storm Hs and S is integrated with a morphological model. Three scenarios along a JP contour are selected and erosions are estimated. The selected JP scenarios are converted into a synthetic storm time-series for morphological simulations. The results demonstrated that JP with a high Hs and low S scenario produced more erosion than other scenarios under constant direction. Regarding wave direction, for the same Hs and S, the shore-normal wave direction produced highest erosion. Thus, shore-normal wave with high Hs and low S produces the highest erosion than other combinations. This study demonstrates the importance of consideration various JP and wave directions in assessing resilience of a beach.