Monitoring of Sea State and Surface Currents in Rural Coastal Areas

Rural coastal areas are among the most poorly monitored environments, despite being highly exposed to marine hazards, climate variability, and increasing anthropogenic pressure. Limited accessibility, the absence of permanent infrastructures, and high operational costs often prevent the deployment of conventional in situ monitoring instruments, leading to significant observational gaps in the estimation of sea state parameters and surface current dynamics. Developing sustainable and low-impact observational strategies is therefore crucial to improve environmental monitoring and risk awareness in these marginal coastal regions [1].

Satellite-based remote sensing systems provide valuable large-scale observations of ocean dynamics. However, their low revisit time and reduced performance in nearshore and shallow-water environments limit their effectiveness along rural coastlines. As a result, increasing attention has been devoted to sensing technologies operating at local scales and closer to the sea surface, including radar and video-based monitoring systems. Among radar-based solutions, short range (SR) K-band systems are particularly suited for this purpose. Their compact size, low power emissions, high temporal resolution, and sensitivity to short surface waves make them ideal for monitoring coastal and semi-enclosed environments. Moreover, recent developments in portable K-band radar prototypes enable rapid and non-invasive deployment in remote coastal areas, without the need for permanent installations [2], [3].

With regard to video monitoring, small unmanned aerial systems equipped with lightweight optical cameras have attracted considerable interest as highly flexible and cost-effective tools for rapid data acquisition in hard-to-reach areas, such as rocky coastlines, wetlands, river mouths, and sparsely populated shores [4], [5].

Within this framework, this contribution reviews the results of lightweight portable SRK-band radar for sea monitoring and presents an innovative signal processing strategy for extracting quantitative information on sea state parameters and surface current fields from drone-based optical camera. Both the considered technologies are useful for nearshore zone, where other observational systems are often unreliable or unavailable.

[1] P. Neill and M. R. Hashemi, “In situ and remote methods for resource characterization,” in E-Business Solutions, Fundamentals of Ocean Renewable Energy, S. P. Neill and M. R. Hashemi. New York, NY, USA: Academic, 2018, pp. 157–191.

[2] Ludeno, G.; Catapano, I.; Soldovieri, F.; Gennarelli, G. Retrieval of sea surface currents and directional wave spectra by 24 GHz FMCW MIMO radar. IEEE Trans. Geosci. Remote Sens. 2023, 61, 5100713.

[3] Ludeno, G.; Antuono, M.; Soldovieri, F.; Gennarelli, G. A Feasibility Study of Nearshore Bathymetry Estimation via Short-Range K-Band MIMO Radar. Remote Sens. 2024, 16, 261

[4] Streser, R. Carrasco, and J. Horstmann, “Video-based estimation of surface currents using a low-cost quadcopter,” IEEE Geosci. Remote Sens. Lett., vol. 14, no. 11, pp. 2027–2031, Nov. 2017.

[5] Solodoch, Y. Toledo, V. Grigorieva and Y. Lehahn, "Retrieval of Surface Waves Spectrum From UAV Nadir Video," IEEE Trans. Geosci. Remote Sens., vol. 63, pp. 1-14, 2025, Art no. 4201914, doi: 10.1109/TGRS.2025.3536378.