Typhoon impact and recovery from continuous video monitoring : a case study from Nha Trang Beach, Vietnam

Nha Trang beach in Vietnam is regarded as one of the most beautiful beaches in the world. However, its degradation in recent years is a serious problem for its economic development. Understanding the mechanisms of shoreline evolution is thus part of an integrated management strategy of the area. In this study, the evolution of Nha Trang shoreline is investigated in detail with a high resolution (2Mp) and high frequency (2Hz) video camera system installed from May 2013 to present. The surfzone cross-shore profiles, shoreline positions and wave characteristics (height and period) extracted from the video data are calibrated with in-situ measurement from two field experiments (from 23/05 to 01/06 and 03/12 to 10/12 2013) and bathymetry measurement during the Haiyan typhoon event. The study shows a marked seasonal evolution of the Nha Trang shoreline with accretion from March to September and cumulated seasonal amplitude of about 15 m. The impact of Nari and Haiyan typhoons to the shoreline is also dramatic with changes of 4 to 8 in in each case. The recovery to individual events is fast, of the order of one and half month