Small Unmanned Aerial Vehicles in coastal areas: lessons learned from applications in Liguria, NW Mediterranean.

Abstract:

In 2013 we started to apply small UAVs to the study of coastal areas in Liguria, NW Mediterranean Sea. In this region monitoring coastal evolution and the impact of sea storms is a primary administrative need, as a large part of the economic income derives from summer tourism.

In two years, we accumulated almost 200 hours of flight with two different UAVs, a professional-grade Mikrokopter Okto and a consumer-grade Phantom DJI. We used photogrammetric and orthorectification techniques to obtain Digital Elevation Models (DEMs) and orthophotos of different beaches in the region.

Data from UAVs allowed us to answer several questions. What is the accuracy of DEMs obtained from UAVs in low-relief areas such as beaches? What are the problems encountered in the photogrammetric procedure near the shoreline? Are the results obtained with consumer-grade UAVs comparable to those obtained with professional-grade ones?

Aside from these technical questions, we used the data obtained from UAVs for different local studies aimed at giving management tools to the local administrations. We used the cloudpoint obtained from DEMs and the orthophotos to set up a runup modelling chain, to detect short-term changes in the coastal zone, and to give a first estimate of the debris deposited on the beach after a major storm.

As stated by Watts et al., 2012 (Remote Sensing 4, 1671-1692) the application of Unmanned Aerial Vehicles and photogrammetry techniques in earth sciences is flourishing, and has the potential to revolutionize the study of geomorphology. Surely, UAVs opened new research perspectives for our group, which has been actively working on coastal changes in Liguria for almost 25 years.