*6.2. Interruption of Continuous Longshore Sand Transport at the Sand Spit Tip*

In the Balili and Aringay River deltas, the sand supply downcoast was suspended until the sand supplied from the upcoast of the river deltas reaches downcoast, resulting in shoreline recession downcoast. Similarly, the shoreline downcoast of the sand spit retreated owing to the discontinuity in longshore sand supply at the tip of the sand spit at Santo Tomas. This is commonly observed around the tip of the sand spit. Noshi et al. [17] showed an example of the rapid development of a recurved sand spit around the south end of Phan Rang City in Vietnam. In their example, erosion occurred downcoast of the sand spit during the elongation period of the sand spit because of spatial imbalance in longshore sand transport at the tip of the sand spit. After the sand spit further elongated and connected the opposite shore, however, the sand supply by longshore sand transport along the shoreline of the sand spit was possible. In the area first eroded, sand was redeposited. The same phenomena were observed north of Pengambengan fishing port located in Bali Strait [18] and during the development of a barrier island in Nakatsu tidal flat [19].
