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Description
The coast and the nearshore is a resource of extremely high value to the Baltic States and a location of major conflict of interests by different user groups. It is an important ecosystem that supports human wellbeing, incl. providing food and recreational opportunities. It also has an important commercial function, supporting trade, the movement of people, and recreation through the beaches, ports and marinas. It is the buffer between land and sea, with coastal erosion and integrity of the nearshore ecosystem being a particular concern.
This research brings together specialists from Tallinn University of Technology, Latvian Institute of Aquatic Ecology, Klaipeda University and Norwegian University of Science and Technology, each with their own internationally recognized expertise, to provide solutions to the current and future problems that already and will affect how we use coastal resources.
The major source of energy to the nearshore are waves. Many of the problems we experience (such as erosion and port siltation) relate to how sediment (mainly gravel, sand and mud) is moved. Much current knowledge comes from open ocean and cannot be directly applied to very different conditions of the Baltic Sea. This research will provide environmentally friendly solutions to coastal problems in ways that very specifically account for the wave, water level and sediment conditions in the eastern Baltic Sea and are transferable for all similar water bodies.
This is accomplished using i) data and knowledge that we currently have to provide much better and higher resolution knowledge about waves than are presently available, ii) by measuring sediment transport using novel sensors developed at TalTech, iii) by applying the new knowledge to examine how the interactions of waves and sediment impact the natural shores and coastal structures, and iv) provide tools so that coastal managers can make use of the knowledge produced to estimate how vulnerable are single coastal sections.
Summary of project results
We have i)considerably progressed the knowledge of functioning of sedimentary shores of the Baltic Sea and typical and extreme properties of its drivers, from wave and water level extremes up to transport of adverse items, ii)developed several tools to estimate the vulnerability of these shores and to identify dangers to their functioning, iii)reached a detailed description of wave climate and wave-driven impacts in the Gulf of Finland and Gulf of Riga, iv)verified it against measurements, v)shown that the loss of sea ice will increase pressure on the shores, and vi)developed a technique to identify ships from recordings of their waves.
Properties of meteotsunami‑like oscillations are quantified for the Port of Klaipėda. Intriguingly, storm waves always directly enter the Port of Ringsu (Ruhnu) because of refraction. Options for its re-design were created based on advanced phase-resolved wave models.
Near-bottom velocities were measured with unprecedented resolution in the Gulf of Riga using novel devices called hydromasts. A Hall effect sensor-based device was developed and validated to estimate surface flow properties. The properties of plastic pollution were established on 24 Latvian beaches. The technique of Lagrangian coherent structures for its prediction was tested.
An unusual pattern of sediment transport that stabilizes beaches of northern Estonia was identified. The impact of pressures on coastal dynamics and morphology was quantified for the coasts of Lithuania. A method to estimate economic and environmental feasibility of marine wind parks was developed for the Baltic Sea. It is shown that manifestations of climate change have led to complicated patterns of reactions of its shores.
We recalculated wave climatology at high resolution ~500 m along relatively straight sections of the shore and down to ~250 m in segments with complicated geometry and linked the results with reflections of changing wind patterns on wave properties.
We substantially refined extreme water level risk mapping (incl. wave-driven set-up) for the entire study area or longer segments, and for shorter segments at a higher resolution.
We performed wave and nearbed water movement field studies, and developed sediment transport models for the eastern Baltic shoreline. This is a major step towards specification how much sediment is REALLY being transported along the Baltic Sea shores. Results of a detailed analysis of simulated vs observed sediment transport are in the stage of submission, and will definitely improve models for wider application. With design, we focused on the Port of Ringsu that experiences problems. An efficient wave model REEF3D::FNPF using a 3D Navier-Stokes solver with two-phase approach was developed and tuned for the Baltic Sea, and used for detailed analysis of hydrodynamic loads on the Port of Ringsu.
In the light of the results of the above, we have remapped coastal risk and vulnerability using multi-criteria evaluation methods and provided examples of tools to enable improved management and more efficient use of resources.
The output, in particular the decision support tools, fills a major gap in understanding the coasts and improves our ability to properly use coastal resources. It provides essential new knowledge for coastal management and planning for single users and coastal communities.
The outcome supports informed decision-making on the use of the coastal zone and its resources and provides improved estimates of vulnerability and exposedness from single coastal segments to country scale and even worldwide via recommendations to the UN.
The developed knowledge has been shared between all teams, implemented into their research routine, and massively communicated to scientific community and society.
Summary of bilateral results
While the Baltic partners have enough competence in phase-averaged wave models, wave climate and related extremes, much of the properties of local hydrodynamic loads is still not resolved by these methods. The specific and irreplaceable in the Baltic States contribution of the donor project partner NTNU addressed calculations of local wave loads in high resolution. NTNU provided specific competence in high-resolution simulations of wave propagation, breaking, reflection, loads to the seabed and overtopping, using detailed 3D wave models for a selection of beaches and specific infrastructure (small harbors, groins, local revetments). Together with high-resolution measurements, doing so has potential to lead to a substantial progress in understanding sediment entrainment into transport, transport itself and local loads to various structures, included (re)calculations of the local redistribution of sediment around.The collaboration led to massive improvement of knowledge, not achievable by any of the single teams, about the functioning of the system of sedimentary shores of the eastern Baltic Sea, properties of extreme hydrodynamic loads in the area in terms of waves (both in local, country-wide and regional context), wave climate, wave set-up, wave-shore interaction, structural properties of sedimentary systems, and the options and needs for decision support systems in the entire region.These achievements have a number of direct applications (such as specification of ship properties based on multi-point recordings of ship wave presented to the United Nations; see Introducing the research to the public, or in-depth understanding of specific features of coastal processes in the Baltic Sea). The joint use of wave simulations from the basin scale down to ~1 m in the harbor interior made it possible to develop optimal solutions for a small harbor in an extremely complicated wave environment as a joint effort of the donor and Taltech teams.