Exploring the Optimal Scale of Coastal Reclamation Activities Based on an Environmental Capacity Assessment System: A Case Study in Haizhou Bay, China

With the acceleration of urbanization, the demand for land due to urban large-scale construction and development is increasing. Coastal reclamation (CR) is a prevailing approach to tackle the contradiction between coastal land shortage and the growing demand for living space for human beings. Enormous social and economic benefits are derived from CR, while at the same time bringing a series of environmental problems. Since the beginning of the 21st century, this oceanic-oriented development has become more frequent. Therefore, the considerable economic and ecological trade-offs of reclamation activities must be analyzed to enable targeted land use decisions. By comprehensively evaluating the natural conditions of the sea area, including geology, topography, hydrology, ecology, and social and economic conditions, this study established an environmental capacity assessment system (ECAS) based on water environmental capacity for assessment of the potential environmental impact resulting from CR. According to the water quality status and positions of CR in Haizhou Bay, the environmental capacities of four major pollutants were calculated to forecast the suitable area of CR. The results indicated that these reclamation projects had notable negative effects on the environmental capacity of the four major pollutants. The order of pollutants according to their harm on seawater quality is: PO4-P > NH4-N > NOX-N > COD. In three reclamation alternative scenarios, scenario 3 led to the minimum negative impacts on the environmental capacity, scenario 2 followed, and scenario 1 had the worst result. Hence, scenario 3 was the optimal reclamation scenario, under which the suitable area of CR in Haizhou Bay was found to be 83 km(2). This study provides a scientific reference for the effective management of coastal reclamation and future environmental impact research when new CR is proposed, as well as sustainable urban development.