Determination of longshore sediment transport for Cua Dai beaches, Quang Nam province

Abstract

    Coastal erosion along the beaches near Cua Dai estuary (Hoi An, Quang Nam province) has occurred for years which is governed by wave induced longshore sediment transport. There have been few estimations of longshore sediment transport for the area but mostly based on wave data collected for some short periods which are not well presenting the wave climate of the area. This paper presents new results on wave induced longshore sediment transports along the beaches based on measured data and longterm deepwater waves from 1997 to 2010 using Soulsby - Van Rijn (1997) method. The wave data show the prevailing wave direction is ENE which occurred for more than 50% of time. Due to this, the longshore sediment transports are mainly due to the prevailing waves during the Northeast monsoon season. The estimated net longshore sediment transport along the northern coast of the estuary is about 2.7 to 3.0 million cubic meters per year to the north. The net longshore sediment transport along the southern coast is about 1.4 to 1.6 million cubic meters per year to the south. The increment of the net longshore sediment transport along the coastal section from 1 to 3 kilometers north of the estuary is the major cause of severe coastal erosion in this section.