Baltic Sea coastal erosion and underwater seabed dynamics

Marcin Skrzypek from the Maritime Office in Gdynia explains how underwater changes impact beaches and coastlines. He notes that the marine shore includes the underwater zone where waves interact with the seabed at depths of 12–14 meters, triggering sand movement that affects the condition of beaches and dunes.

Natural sandy ridges, or underwater reefs, act as obstacles that cause waves to break and lose energy before reaching the shore. However, when coastal zones narrow or the seabed drops off quickly, waves hit the shore with greater force. To manage this, maritime administration uses bathymetric measurements to monitor the seabed and plan protective works.

In the southern Baltic, sand is continuously moved along the coast by waves and currents. Factors such as wind direction changes, storms, and man-made structures can disrupt this transport, leading to sand shortages in certain areas. To combat this, authorities use artificial beach nourishment, known as refulacja. These insights were shared during the V Congress of Water Management and Flood Protection.