The Tottori Sand Dunes, the largest area of natural sand dunes in Japan, is an important tourist attraction in the San’in Kaigan Geopark in western Japan. A sand fence has been emplaced to prevent blowing dune sand from damaging the environment and interfering with human activities; however, there has been no quantitative evaluation of its effectiveness. We collected imagery of the area around the sand fence from March to May 2021 with an unmanned aerial vehicle (UAV) and used the data to construct and analyze a time series of three-dimensional models via structure from motion (SfM) and multi view stereo (MVS) and geographic information system (GIS) techniques. We found that imagery collected on cloudy days and days when the sand surface had higher soil moisture yielded terrain models with superior accuracy. Moreover, after rectifying the UAV images using ground control points (GCP) and a total station, horizontal and vertical root mean squared errors were greatly improved to 0.018 ± 0.005 and 0.018 ± 0.007 m, respectively. We evaluated topographic and volumetric changes due to sand movement to and from the areas of sand fences by comparing successive elevation profiles of three cross sections of the study area. The results show that UAV photogrammetry can be used to accurately monitor topographic changes and sand movements and provide a basis for planning mitigation measures such as wind-blown sand prevention.

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