Managing industrialised coastal fine sediment systems

Abstract

A high level of concern surrounds the management of industrialised muddy coasts and estuaries. Many centuries of apparently desirable alterations, such as hard defences, training walls and groynes, aided by traditional dredging and disposal, are today recognised as having associated disadvantages. The port and shipping industry is the principal facilitator of world trade, but the trends in its development place ever-increasing strains on conventional methods of management. In particular, inadequacies in “water-side” technologies are constraining the demands of modern societies. The present paper reviews a number of emerging self-sediment engineering technologies to manipulate intertidal zones, many of which are finding wide acceptance by practitioners, although many of these were first used some time ago: salt marsh inducement, set-back, tidal flat regeneration, etc. all have their place. A far greater challenge, and one less readily accepted, is attached to generic Sediment Management Systems for the subtidal zone. A range of more economic, more environmentally desirable methodologies to manage fine sediment for the ports and shipping industry are now well-proven: Auto-flushing, Entrance Flow Optimisation, and various manifestations of the Nautical Depth concept. Although for the moment these apply narrowly to ports, it is shown that they readily have a wider application to the management of whole systems. The technologies and their costs and benefits are herein set out. Bearing in mind that these technologies are well-proven, their wider adoption has now become a “people issue”. The environmental benefits of these methods are also discussed. A challenge facing our highly specialised society is that, in the optimal case, aspects of marine physics, chemistry and microbiology must all be carefully manipulated at the same time. Notably, no port in the world currently has a sediment management plan suited to the modern era.