Land-ocean-human interactions in intensively developing coastal zone: Demonstration of case studies

Land-Ocean-Human (L-O-H) interactions in intensively developing coastal zones are demonstrated using four case studies in the western Bohai Sea, China. Three aspects of L-O-H interactions are discussed: 1. Coastlines are the result of Land-Ocean (L-O) interactions, but human activities have changed many coastlines from natural to artificial. In recent years, sea reclamation projects have moved the land and its coastline towards the sea, leading to hydrodynamic changes and affecting both the topography and sediment-erosion dynamics in western Bohai Bay (case study 1). 2. Estuaries are key areas for L-O interactions; river sediments, together with ocean power, shape the topography of the estuarine delta, while river nutrients impact offshore biological productivity. However, due to irrigation and reservoir construction up-stream, runoff and sediments have decreased resulting in increased coastal erosion in the Yellow River Delta (case study 2). Rivers carry industrial and agricultural point and non-point source pollution into the sea, causing marine pollution in Jinzhou Bay (case study 3). 4. Sea-level rise caused by global climate change enhances the role of the ocean. At a local scale, in Binhai New Area, sea-level change is also influenced by vertical land movement along with some land subsidence caused by over-exploitation of groundwater. Rising sea levels exacerbate storm surges and floods, and increase the risk of socio-economic and ecological impacts (case study 4). Because of rapid economic growth in Chinese coastal areas, L-O-H interactions have become the most significant factors changing natural and artificial environments. If the coastal zone is to be developed sustainably, human activities must be regulated.