Evaluating the Sand-Trapping Efficiency of Sand Fences Using a Combination of Wind-Blown Sand Measurements and UAV Photogrammetry at Tottori Sand Dunes, Japan

Abstract

Fences are commonly used in coastal regions to control wind-blown sand. Sand-trapping fences and sand-stabilizing fences have been installed at the Tottori Sand Dunes, Tottori Prefecture, Japan, to prevent damage by wind-blown sand; however, the effectiveness of these fences has not previously been quantitatively evaluated. This study analyzed the effects of sand fences on sand trapping using field observations of blown-sand flux and unmanned aerial vehicle (UAV) photogrammetry. The estimated total blown-sand flux in the near-ground surface observed inside and outside the sand fences indicated that wind-blown sand was effectively trapped by the sand fences at wind speeds lower than 17 m s−1, reducing sand flux by more than 80%. The UAV photogrammetry results demonstrated that large amounts of sand were transported from the dune to the fenced area during March and April, and sand initially accumulated on the lee side of the sand-trapping fences, forming a new foredune. Sand accumulated on the existing foredune during April and May, and the vertical accretion around the foredune was two to four times the sand deposition within the sand-stabilizing fences. This indicated the effectiveness of sand-trapping fences for controlling wind-blown sand; however, their efficiency was reduced as they were gradually buried, with sand being trapped by the sand-stabilizing fences.

Using dune restoration on an urban beach as a coastal resilience approach

“…The net accumulation of sand we observed was largely associated with the perimeter fence and the incipient foredune ridge. Sand fencing is a common restoration method of accreting wind-blown sand (Itzkin et al, 2019;Liu et al, 2023). The DEM also showed accumulation of sand across the southern half of the site, trapped by the sand fence, which conformed with the predominant wind direction.…”

“…The 1.2-hectare area of a heavily groomed beach was passively restored by installing sand fencing around three sides of the site, (leaving the oceanward edge open) and adding native dune plant seeds in December 2016. Sand fencing is known totrap and accrete sand (Itzkin et al, 2019;Liu et al, 2023). Grooming was restricted to approximately 4-5 m outside of the fenced area.…”