How does the growth of ship size increase the need for dredging?

In the context of civil engineering for harbors, the growth of ship size significantly increases the necessity for dredging to maintain navigable depths.1

Modern vessels, particularly larger ones, require greater water depth to remain afloat and avoid contact with the seabed, which could cause serious structural strain. As ships increase in size—specifically regarding their draft (the depth of the vessel below the waterline)—harbor approaches and berths must be deepened to accommodate them.23

Because silt and other materials naturally accumulate in harbor channels due to river flow and littoral drift, continuous maintenance dredging is required to prevent these deposits from obstructing navigation. The economic challenge is substantial, as the capital cost of harbor works often increases roughly in proportion to the cube of the deepest draft of the ships being accommodated. Consequently, engineers utilize advanced dredging equipment, such as suction dredges, to ensure waterways remain deep enough for modern maritime traffic.412