Comparative Analysis of the Unmanned Aerial Vehicles and Terrestrial Laser Scanning Application for Coastal Zone Monitoring

The shallow sandy shores of the tideless sea are regularly affected by storm activity. Foredune ridge is a natural and anthropogenic object, a natural protective barrier that protects ecosystems and populated areas from the effects of dangerous hydrometeorological phenomena such as storm surges and wind-sand flux. In the course of impact of dangerous hydrometeorological phenomena, the foredune ridge integrity is disturbed, the composing material is washed away thus forming breakthroughs. Monitoring of the foredune state is an important stage in maintaining its condition and also provides an empirical basis for predicting the impact of hazardous events. The use of ground-based laser scanning technology as well as digital photogrammetry for the study of sensitive coastal zones is justified for these purposes. In this article, we compare the results of calculating the dynamics of the beach sand material and advance them according to the results of ground-based laser scanning and digital photogrammetry. Comparability is provided by high-density clouds of ground-scan points and digital photogrammetry in a single coordinate reference. Two sections of the sensitive coastal zone of the Curonian Spit (Russian sector of the South-Eastern Baltic) have been explored in advance. A comparison of the applicability of means for obtaining digital elevation models to evaluate the dynamics of sand material has been made. In comparison with TLS, the use of UAV with the SfM algorithm is limited to post-storm surveys, since the final accuracy does not provide for reliable lithodynamic studies due to the small scale of processes comparable to measurement errors.