Sand spit morphological evolution at tidal inlets by using satellite images analysis: Two case studies in Vietnam

Abstract

This paper presents the long-term morphological changes of the sand spits at the Ken Inlet in Ha Tinh Province and Phan Inlet in Binh Thuan Province, Vietnam. The analysis results show that the sand spit morphology at Ken Inlet was drastically changed before the completion of the Da Bac sluice gate construction in 1992, after that the sand spit elongation rate became stable at a rate of about 68 meters per year. Meanwhile, the sand spit at Phan Inlet was breached three times during the winter months of 1990-1991, 1998-1999 and 2014-2015. Moreover, the results of remote sensing image analysis also show that after the sand spit have been breached, it continued elongating at a relatively stable rate of 170÷200 meters per year. Based on the analytical model by Kraus (1999) for predicting the sand spit elongation, the estimated long-shore sediment transport rates of Phan Inlet and Ken Inlet are 145,000 m3/year and 133,500 m3/year, respectively. These longshore sediment transport rates are a main contribution for the sand spit elongation in these study areas. Keywords: sand spits; tidal Inlet; breaching; elongation; Landsat images; Google Earth images.