An improved short-term swash zone beach profile change model focusing on berm formation and erosion

Abstract

A short-term swash zone beach profile change model focusing on berm formation and erosion proposed by Suzuki and Kuriyama (2010) was improved. The model was developed using a 2.5-year data set of beach profiles and offshore waves observed at the Hasaki coast, Ibaraki, Japan, facing the Pacific Ocean. The distributions of cross-shore sediment transport rate for berm formation and erosion were determined using the curve slopes at the inflection points. The curve slopes for berm formation and erosion were estimated by using the wave energy flux, and the product of the wave height of long-period wave and berm height, respectively. The investigation area was set from the maximum wave run-up position to the shoreline position at the mean tide level. The both models were applied to the calculation of the beach profile change for three months, which results were compared with observed data. It is found that the present model well predicts not only the shoreline change, but also the beach profile change, including the berm formation and erosion. The correlation coefficient (R) of shoreline position at the high tide level between the numerical results and observed data is 0.70, which is 0.37 higher than the previous model. Also, the averaged correlation coefficient of shoreline positions at five different ground elevations is R = 0.73