Study On Coastal Erosion Of Beach-coral System And Its Adaptive Management

Beach-coral reef system is common coastal morphologic cell in tropical zone, which distributes extensively in the area of South China Sea. Global climate change and human activities are inducing more and more erosion along coral reef coasts. Based on the repeated surveys of typical coral reef coasts and combined with previous researches, this paper studied morphodynamic process of beach-coral reef system, its distribution and erosion characteristics. And the erosion causes were discussed to consider the adaptive management of erosion of coral reef coasts in China. The main conclusions are as follows:(1) Morphodynamic process of beach-coral system: The seasonal change of beaches on coral reef coasts is evident. It is characterized by narrow and steep beach face, deposition in backshore and coarser sediments in summer season than that in winter season. Coral reefs can provide effective protection for adjacent beaches by improving its adaptability and stability. The characteristics of the storm-effects on beach-coral reef system are controlled by wave dissipation of reefs and sediment buffering of beaches.(2) Erosion characteristics of beach-coral coasts: Because the natural protecting barrier composed of corals prevents and mitigates coastal damage, the erosion of coral coasts(fringing reef) is implicit or unobvious in China. The mutual response between the intensity of coastal erosion and the destruction of coral reefs is remarkable. The coast might changes from recessive slow-erosion to dominant explosive-erosion with the increase of destruction of corals. The erosion of coral reef coasts is controlled by both the morphodynamic process of coasts and the ecological process of corals, which can be divided into three stages: embryonic, recessive and explosive period.(3) Erosion causes of coral reef coasts: It includes both ecological factors of coral reefs and mophodynamic factors of coasts. Some causes have unique behaviors on coral reef coasts, and response in different spatial and temporal scale. The negative effects of sea level rise, storm and enormous waves would be decreased. However, coral reef coasts would be sensitive to the climate, and induce faster and more serious reactions.(4) Adaptive management of coral reef coasts: As an significant two-in-one approach of coordinating problems between corals and coasts, the adaptive management should take account of complexity of beach-coral reef system and uncertainty of coastal erosion. The management framework and self-adjust of strategy adaptively based on long term continuous monitoring are key issues of adaptive management.