Abstract
Shoreline change rate has been used to discuss the distribution of sand input from the Thu Bon River. According to the rate of shoreline change, the asymmetric distribution of sediment input from the river at the Cua Dai River mouth, Vietnam has been revealed. Transporting of sediment to the north by wave-driven longshore currents together with asymmetric distribution of sand supplied from Thu Bon River has been causing severe erosion on the left beach of the Cua Dai River mouth. In the future, more detailed analysis will be carried out by accumulating wave data in order to quantify the mechanism of this asymmetric behavior of sediment and resulting morphology change around the Cua Dai River mouth.