Annual Journal of Civil Engineering in the Ocean Vol.38
THE VOLUME OF WIND-BLOWN SAND GENERATING FROM THE SWASH ZONE ESTIMATED FROM BEACH TOPOGRAPHIC CHANGES
2022 Volume 78 Issue 2 Pages I_97-I_102
Details
2022 Volume 78 Issue 2 Pages I_97-I_102
In the windy season (from the mid-December to the early March) when wind-blown sand generates, beach topography surveys by the Terrestrial Laser Scanner (TLS survey) and the Unmanned Aerial Vehicle (UAV survey) were carried out 4 years at the Hiyoriyamahama beach on the west coast of Niigata. Accurate TLS survey makes it possible to calculate reliable sand volume.
From the sand budget analysis of the beach topography, it became possible to confirm the fact of the generation of wind-blown sand from the swash zone and to estimate its volume. The amount of sand blown off from the swash zone during a winter season ranged from approximately 1.6 to 2.5 m3/m. In a particular area where is named the Second District by the beach management office, the volume of blown sand estimated from the accumulated sand volume around the fences installed at the land side edge of the beach was 4.6 m3/m in 2016 and 7.5 m3/m in 2017, respectively. The ratios of the volume generated from the swash zone and the volume estimated at the land side edge were 2.27 / 4.6 =0.49 in 2016，and 3.66/7.5=0.49 in 2017, respectively. It results that approximately 50% of blown sand is generated from the run-up zone. The width of the swash zone was about 20m to 40m. The maximum run-up height read from the topographical data was roughly in match up with the value estimated by the revised imaginary slope method.
