6000年来我国低平海岸线的冲淤变化及其对海岸带开发的影响

Study on Low Coast Changes in the Past 6000 Years in China and Their Impacts on the Coastal Zone Exploitation

自约 6ka前我国海岸轮廓形成以来 ,海岸线主要呈淤进状态。在距今 6～ 3ka前 ,因黄河等河流泥沙主要填淤平原洼地 ,岸线稳定微涨 ;在距今约 3ka至 2 0世纪 60年代 ,河流以巨量泥沙使海岸线 ,尤其是低平的平原海岸线迅速外移 ;最近 30 a来 ,因为黄河等河流入海水沙大量减少 ,造成目前除行水河口处淤涨外 ,多数岸段转为侵蚀或稳定 ,且被侵蚀岸线有逐渐扩大的趋势。这种变化导致了新淤土地的减少 ,也破坏了原有的沙滩、湿地资源 。

The coastline has been mainly in gradual aggradation since the contour of Chinese coast was formed about 6 ka ago. The rivers, such as the Yellow River, mainly deposited their sediments in the depression areas during 6~3 kaB.P.,so the coastline could approximately keep stable during that period.The coastline, especially the plain coastline,expanded seaward during 3000~30 aB.P. because a large volume of alluvial sediments deposited in the coastal areas. Because of the drastic reduction of river discharge and sediment supply, most of coasts, except the esturine coasts, have turned to be eroded or stable since the 1960s, and the eroded coastlines have a tendency to increase nowadays. This kind of change causes the reduction of new coastal lands silted up by rivers and the destruction of beach and wetland resources. Measures should be taken to reduce the losses caused by coast erosion.