秦皇岛全新世海岸的演化和现代海岸的保护

秦皇岛海岸东自山海关西至洋河口。经过六十年代与八十年代两个时期对岸带的调查与实验分析资料的对比,作者认为其全新世时期的发育演化分为四个阶段:1)距今七千年前的海退阶段,2)距今七千年至五千年的海进阶段,3)距今五千年至三千年的海退阶段,4)距今三千年来的海进阶段。本文还论述了海岸带现代侵蚀问题,认为遭受侵蚀的原因有:海面的上升,沿海河流建水坝和茌河床及岸带大量挖砂使海岸带泥沙供应减少。此外,还对海岸的保护提出了具体的建议。

Holocene Geomorphic Evolution and Problem of Protection of the Qinhuangdao Coastal Belt of China

The studied area includes the coastal belt from shanhaiguan in the east to the mouth of the Yanghe River in the west. After two periods of field surveys and laboratory work taken in the 1960's and 1980's, we come to the conclusion that the evolution of this coastal belt in the Holocene can be divided into the following stages; 1) Before 7000 Yr B. P. The climate was dry and cold as it had been in Late Pleistocene. River erosion was intense on a background of slow tectonic uplift, leading to aggradation of the off-shore area and extension of land. 2) 7000-5000 Yr B. P. Global warming of climate leading to sea-level rise across a distance of 1-4 km. Marine de posits overriding fluvial deposits with full development of barrier beach and lagoons. 3) 5000-3000 Yr B.P.The climate turned arid-cold again, a slight drop of sealevel and deposition of thin beds of alluvium. 4) 3000-900 Yr B. P. Appearance of laminated marine strata and beach ridges decreased in age toward the sea, hence, a regression of the sea toward the end of this period.At present, the coast is under marine erosion owing to an estimated annual sea-level rise of about 0.87 mm and building of water dams and digging sands from river beds, leading to decrease of sand supply to the coast. The sand beach at Beidaihe, a hot spot of tourism, has been shrinking. Urgent measures must be taken to forbid further digging of sands from the river beds.