Groins and submerged breakwaters – new modeling and empirical experience

The relationship between the effectiveness of groins and their technical condition was studied. The supporting role of groins in artificial shore nourishment was tested using the theoretical modeling of hydrodynamic and morphodynamic processes in the nearshore zone. This modeling scheme was developed as to represent the actual coastal situation occurring on the shores of the Hel Peninsula (the Gulf of Gdańsk, the southern Baltic Sea). Based on the results of computations and the results of field observations, recommendations were prepared on the design and maintenance of groins. The second part of the paper is devoted to submerged breakwaters. The theoretical modeling of wave-current fields near the segmented submerged breakwaters led to the determination of coefficients of wave transmission and rip current velocities, which finally yielded a piece of design advice. In all numerical simulations, the Delft3D software was used.