ABSTRACT
Osiberu, O.A.; Choi, J.-W.; Garcia, V.G.; Su, H.; Semenitari, A.G., and Ren, J., 0000. Effects of vegetation and wind on assessing spatial and temporal coastal dune changes using uncrewed aerial vehicle and total station surveys.
The effectiveness of uncrewed aerial vehicle (UAV) surveys in monitoring coastal topographical change has focused on parameters such as terrain slope, flight altitude, and equipment used; however, only a few have examined the effect of vegetation and very few on the effect of wind, suggesting a knowledge gap. Dense vegetation can pose challenges to line-of-sight measurements and wind may affect the stability and accuracy of survey instruments, so this study focused on analyzing the effects of vegetation (monocotyledon and dicotyledon plants) and wind on data collection using UAV and total station surveys. From December 2022 to April 2023, vegetation, elevation, and wind data were collected in two mitigated areas of South Padre Island, Texas. Digital elevation models were developed, topographic profiles were extracted, dune volumes were analyzed, and errors between the two surveying methods were evaluated. Results show significant differences in the vegetation densities over time for the dicotyledon species and across all study areas for monocotyledon and dicotyledon plants. Digital elevation models generated by total station and UAV surveys appear to fairly agree. The topographic profiles obtained from both methods show high similarities. The migration and movement of sand and the change of the dune morphology over time were observed. The elevation errors estimated between the two surveys are 5%–10% of average percentage errors, 0.26–0.87 m of root mean square error, and 0.19–0.54 m of mean absolute difference, respectively. Dune growth was observed based on the total dune volumes estimated, with relative errors of 4%–24% between the two methods. A strong correlation between the elevation measurement errors and wind speed was observed; however, the correlations between vegetation and elevation errors in UAV surveys were found to be weak. Results presented here have significant implications for restoration projects planning, implementation, and monitoring along the Texas Gulf Coast.
