Analysis of embayed beach planform stability in Danang, Vietnam

Anh Do, Marcel Stive, Ronald Brouwer, Sierd de Vries

Thursday 2 july 2015

17:00 - 17:15h at Mississippi (level 1)

Themes: (T) Sediment management and morphodynamics, (ST) Morphodynamics of estuaries and coastal areas

Parallel session: 13A. Sediment - Coast

This study presents an analysis of the planform stability of the complex embayed beach system of Da Nang Bay, central Vietnam. As a result of the intensification of extreme weather conditions and human activities in this area (e.g. land reclamation, river damming, and coastal structures), coastal safety as well as economic and ecological values are under pressure. In order to anticipate future changes in the system, it is important to understand the morphological stability of the beaches in Da Nang Bay. To obtain more insight into the hydrodynamics and morphodynamics of embayed beaches, we first employed the simple parabolic bay shape equation (PBSE) to determine the empirical morphological stability of the beaches: stable, dynamic equilibrium, natural reshaping or unstable. It was found that the predicted planform stability of the beaches in Da Nang Bay does not correspond to the observed behavior. It is hypothesized that the discrepancies between predicted and observed behavior of the embayed beaches in Da Nang Bay could possibly be attributed to a) the seasonal availability of sediment from the two rivers discharging in Da Nang Bay and b) the seasonality of the dominant wave direction that mainly determines the planform stability resulting from the PBSE. The aim of this study focuses on point b) and is twofold: 1) to obtain more insight into the planform stability of the beaches in Da Nang Bay by applying a more advanced model to predict, the wave climate and 2) to investigate seasonal variations in dominant wave direction affect the planform stability.