Regional Wave Transformation and Associated Shoreline Evolution in the Red River Delta, Vietnam

Abstract

Several stretches of shoreline in the Red River Delta, Vietnam, are suffering from severe erosion, especially an area in the southern part of the delta known as Hai Hau Beach. Commonly found explanations for this erosion is the construction of a large dam upstream the Red River Delta and the closing of a river branch that used to supply sediment to the beach. However, in this study it is shown that the prevailing wave climate during the winter monsoon in combination with the complex topography of the delta create longshore transport gradients that promotes erosion at Hai Hau Beach. A newly developed two-dimensional random wave transformation model based on the mild slope equations was employed for a 20-year long time series of hindcast waves to compute representative nearshore wave properties for the Red River Delta shoreline. These properties were utilized to compute the longshore sediment transport rate along the delta from which shoreline evolution was inferred.