Optimized Harbor Basins

Major progress in enhancing port operating efficiency, for example in the container shipping industry, has been made in recent years in respect of vessels and "landside" handling refinements. This presentation complements these developments and relates to optimising "waterside" performance of blind-ending basins. Basins may be created by either building breakwaters seawards from a straight coast or by digging into alluvial deposits along channel margins. They provide safe-harbouring from the most severe wave and water current stresses, ice loading, etc., and are consequently a commonly-resorted-to feature all round the world. However, the entrances to blind-ending basins in silt-laden waters are the site of a "conflict of interests". In order to provide free and safe access, these entrances must be wide. In contrast, the wider the entrance the greater is the opportunity for sediment to be input and deposited. Even in low turbidity systems, such harbour basins often have a high siltation rate. Intrinsic characteristics of flow and water/sediment exchange lead to a high fraction of input material being deposited in the basin entrance, where it can rapidly form a shoal and an impediment to navigation. In basins adjacent to industrialised areas, the sediment deposited is often the finest grained and most severely contaminated. It is consequently expensive to dredge, treat and dispose of such material.