2021. April 24.
River navigation is most eco-friendly mode of transportation because of low relative fuel consumptions, and thus CO2 emissions. However, ships also have serious impacts on the aquatic ecosystem through various mechanisms. Most of the relevant issues are related to the hydrodynamic impacts of ship induced waves (Gabel et al., 2017), so any method that helps with the study of these waves is welcome.
Field measurement and numerical modeling are available to analyze the general features of ship induced waves as they impact the river banks (e.g., Fleit et al., 2019). The quantification of the initial wave wake close to the ships using conventional fixed instruments, on the other hand, still constitutes a challenge. The rapid developments in unmanned aerial vehicles (UAVs or drones), video sensors and the related processing methods offer cheap and fast surveys for a wide range of engineering and scientific applications. The airborne video-based study of ship induced waves seems a promising domain to use the newest technologies.
We will test a computer algorithm that can automatically derive the direction and wavelength of the waves from a downward-looking airborne video that follows the ship. The method, coded in Matlab, applies a two-dimensional Fourier transform of the pixel intensities in small image blocks.
An interested student will perform airborne video recordings of ship induced waves on the Danube and apply/adapt the image processing algorithm for deriving the spatial distribution of wavelength and propagation direction. It is hoped that the results will help us understand the connections between ship parameters (e.g., shape, width, draft, velocity, direction etc.) and the generated wave patterns in real-life conditions.
References
Gabel F., Lorenz S., Stoll S. (2017) Effects of ship-induced waves on aquatic ecosystems. Science of the Total Environment, 601-602:926–939.
Fleit G., Baranya S., Krámer T., Bihs H., Józsa J. (2019) A practical framework to assess the hydrodynamic impact of ship waves on river banks. River Research and Applications 35:1428-1442.