FIELD EXPERIMENT OF CONTROLLING LONGSHORE SAND TRANSPORT USING STONE GROIN IN SANBYAKKEN REGION IN NAKATSU TIDAL FLAT

Abstract

A field experiment on sand back passing was carried out in Sanbyakken Region in Nakatsu tidal flat in Oita Prefecture. 3600 m3 of sand was dredged at the tip of the sand spit, which causes the closure of the Kakise River mouth, and such sand was transported to the west end of the sand spit. To prevent sand from rapidly returning to the tip of the sand spit, a 24-m-stone groin was experimentally installed at the middle of the sand spit. The effect of controlling longshore sand transport was investigated. Aerial photographs were taken four times during the monitoring period. The stone groin had a mild effect on the shoreline changes compared with that of the ordinary groin because of short length and low crown height.