Representative Coastal Erosion Processes And Controlling Factors

Coastal erosion is one of the marine disasters threatening the social activities, properties and safety of people in the coastal zone, especially at muddy coast and sandy coast. Coastal erosion is the result of natural factors and human activities in the coastal zone.Taking muddy coast of Yellow River delta and sandy coast of South Shangdong for examples, the author discusses the controlling factors of coastal erosion and analyzes the existing data with quantitative methods, basing on the researches of predecessors.Various factors are included in the coastal erosion processes, any factors causing unbalance of coastal material budgets have a potential impact on the coastal erosion. Natural factors include such as global sea-level rise, storm waves, land subsidence and decrease of sand supply from land. Human activities impact include sand mining from coastal zone, river daming and coastal engineering. These natural and anthropic factors mutually enforce and constraint each other, jointly cause coast erosion. Decrease of sediment supplies from rivers is the main source of coastal budget unbalance and coastal erosion. Sea-level rise causes the shoreline recession slowly and continuously, and its effect will increase with the acceleration of sea-level rise in the future. The effect of human activities acts dominantly and rapidly on a regional scale.The coastline of Yellow River Delta has changed remarkably. Decrease in sediments discharge from the Yellow River due to decrease of rainfall and daming on the rivers is a direct cause of coastal erosion over the study period. The slowing-down of delta erosion after year 2000 is attributed to the coastal defense enforcement, such as dikes along the vast coastline. The purpose of this thesis is to discuss the controlling factors impact on shoreline change of Yellow River Delta. The sandy coast of the South Shangdong were under erosion since 1970s and shoreline retreated sharply since 1980s. Decrease in sediment supplies from the rivers and sand dredging in the foreshore are the main reasons for coastal erosion. Coastal erosion is intensified by ocean dynamic, whilst decrease in sediment supply from rivers, sea-level rise and sand dredging on the foreshore provide the material potentials. The purpose of this study is to analyes the processes and the factors according to historical measured data.According to the current coastline erosion state, analysis and discussion on the effects of different factors and suggestion to the solution and strategy to prevent the coast from erosion are making great sense on coastal development and protection.For muddy coast, we can protect them by building coastal engineering such as breakwater and dikes, and taking biological means. The sandy coast could be protected by sand nourishment, one of the nature-friendly methods besides coastal hard defense engineering. Various methods can be combined together to make the best outputs.