Author(s): Rongyao Ji; Yongjun Lu; Xianlin Luo; Liqin Zuo
Linked Author(s): Yongjun Lu
Keywords: Barrier-lagoon；formation；recent evolution；human activities；BoHe
Abstract: A typical barrier-lagoon system, namely Bohe, is located in the west of Guangdong Province, China. During the period of 1932 ~ 2000, the total area of this lagoon system was reduced by 45. 3% . One of the main factors affecting the recent evolution of the barrier- lagoon system is human activities in the coastal zone, such as large-scale tidal flat inning, aquacultures, construction of ports and docks, and sand mining, which have accelerated the barrier erosion and lead to the rapid reduction of lagoon area. Based on the borehole data and the technique of 14C dating, two distinctive sedimentary sequences were found in the Bohe lagoon area, the upper formed in the Holocene Epoch and the lower formed in the lateEpipleistocene Epoch. According to analysis of deposition sequences and sedimentary setting, the main evolution stages of the Bohe barrier-lagoon system can be indicated, which are: (a) 33000~18000 BP, with the rapid rise of sea level, the old Bohe valley was submerged and the lagoon system was formed for the first time; (b) 17000 BP, as the sea level dropped, the lagoon sediment was exposed in the air and was subject to weathering, and the barrier-lagoon system was substantially destroyed; (c) 17000~6000 BP, with another rise of sea level, the barriers and the lagoon deposits developed again and the basic outline of the modern coast was formed; (d) 6000~2000 BP, after the sea level stabilized, the barriers migrated seaward rapidly with rich sand supply, and the modern barrier-lagoon system came into being; (e) in recent times, with a slight rise of sea level and intensified human activities, the barrier costal erosion has been increased and the evolution process of the barrier-lagoon system are accelerated.
Year: 2007