Dredged marine sediments, which are traditionally discarded by open sea disposal, have historically been one of the main marine pollution sources. It is therefore of great value to investigate the beneficial use of these sediments for coastal ecological engineering applications. Recognizing the importance of this beneficial utilization, some countries have been conducting research in this field for up to 40 years. Linked with this, the practice of ecological engineering has a history of more than 100 years worldwide, with demonstration projects distributed along the Atlantic and Pacific coastal zones, and in estuary wetlands. This paper reviews the current research trends and synthesizes engineering application cases worldwide, aiming to provide guidance for dissemination of this technology in China.
The main functions of ecological engineering with placement of dredged marine sediments are summarized as follows: (1) Stabilize and nourish subsiding and eroding coastal wetlands. Coastal wetlands in many areas are deteriorating due, in part, to sediment depletion, subsidence and sea level rise. The ecological engineering efforts using dredged marine sediments provide a potential alternative to ameliorate these effects, and to help restore and nourish coastal ecosystems. (2) Restore the deteriorated wetlands. Dredged materials can be used as a substantial substrate to restore the coastal wetlands in formerly diked lands drained for agriculture and other purposes. The potential use of dredged materials includes enhancing the sediment budget at low elevations, reintroduction of tidal effects, and improving the geomorphology of the marsh plant forms. (3) Create artificial ecological islands. Artificial islands may be created with dredged marine materials, and different types of habitats are developed with various elevations to provide nesting and refuge habitats for birds and other wildlife. Historically, many dredged material islands originally created based simply as a convenient placement option have developed naturally into productive and valuable wildlife habitat, supporting abundant biodiversity and various habitats.
Based on the accumulated information, which includes the most environmentally sound and technically feasible options for dredged material placement in modern ports and harbors, and taking into account the oceanic industry and the environmental challenges of China, this study discusses the potential applications of dredged marine sediments for coastal engineering. The summarized information from these global experiences provides potential opportunities to combine dredged marine materials treatment with coastal ecological engineering, guaranteeing the sustainable development of the marine industry. The main purpose of this study is to provide an alternative solution to the contradiction between the oceanic economic development and coastal wetlands ecological and environmental protection.