engleski

Autonomous Vehicles Mapping Plitvice Lakes National Park, Croatia

Plitvice Lakes National Park is the largest national park in Croatia as well as the oldest one dating back to 1949. It was put on the UNESCO World Heritage List in 1979 due to the unique physico-chemical and biological conditions that have led to the creation of 16 named and several smaller unnamed lakes which are cascading one into the next. Previously conducted scientific research proved that the increased amount of dissolved organic matter (pollution) stops the travertine processes on Plitvice Lakes. Thus this complex, dynamic but also fragile geological, biological and hydrological system needed a comprehensive limnological survey. Thirteen out of sixteen named lakes were firstly recorded from air by an unmanned aerial vehicle mounted with a survey grade GPS and a full frame high resolution camera. These recordings were used to generate a georeferenced high resolution orthophoto on which the following surveys by a multibeam sonar depended. It is important to note that this was the first time that these lakes were ever surveyed by multibeam sonar technology as well as by such high resolution camera. Due to the fact that these thirteen lakes are hard to reach and often too shallow for a boat-mounted sonar, a specialized autonomous surface vehicle was developed. The lakes were recorded by the autonomous surface vehicle mounted with a multibeam sonar to create detailed bathymetric models of the lakes. The missions were planned for the surface vehicle based on the orthophoto from the preliminary studies. A detailed description of the methodology applied to survey different lakes is described in details herein. Moreover, the resulting high resolution bathymetric maps are presented and analyzed together with an overview of average, maximum depths and number of data points. Numerous interesting depressions, which are phenomena in line with Plitvice Lakes' previous studies, are noted at lakes' beds and their cause is discussed. This study goes to show the huge potential of remote sensing technologies integrated onto autonomous vehicles in terms of much quicker surveys, a few orders of magnitude of data points more compared to the manual surveys from a few decades ago, as well as data accuracy, precision, and georeferencing.

autonomous surface vehicle ; unmanned aerial vehicle ; multibeam sonar ; bathymetry ; photogrammetry

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