Long-term morphological change of the Cua Dai river mouth, Hoi An: part 2 relationship between changing of river mouth morphology and shoreline erosion

Abstract

In Part 1 of this study, the long-term evolution of morphology of Cua Dai River mouth and adjacent sandy beaches was investigated based on the result of Landsat image analysis. The dramtical shifting to the south of river mouth has been pointed out. In Part 2, that shifting process and relevant phenomenon are studied. The shifting southward (about 250m) was corresponding to the period with elongation of sandspit on the left after welding from offshore sandbar. The tip of cuspate shoreline on the right side was also observed to move to the south in the same period. The shifting to south of river channel diverting more sediment deposit on the right side of the river mouth, resulting in the erosion of the Cua Dai Beach on the left side became more serious. Countermeasure, which diverts more sediment going to the left side, is highly required. Detailed effectiveness and magnitude of this structure can be evaluated based on numerical simulation