人类活动对中国北部海岸带地貌和沉积作用的影响

HUMAN IMPACT ON THE COASTAL MORPHOLOGY AND SEDIMENTATION OF NORTH CHINA

本文根据现代地学方法和历史资料,论证了人类活动对中国北部海岸带大型海岸地貌和沉积体直接和间接的影响。

This paper discusses major coastal landforms and sedimentation affected directly or indirectly by human activities:(1)The coastal plain of Ncrth diangsu and its associated subaqueous delta of the abandoned Huanghe River were the direct result of human diversion of the Huanghe River south- wards between 1128 and 1854 AD.(2)The present Huanghe River delta is river-dominated and micro-tidal,but has an arcuate form due indirectly to man's cultivation of the Loess Plateau and the huge sediment load(1.1 billi- on tons per annum)resulting from accelerated erosion. Accumulation rate of the Bohai Sea is also greatly affected by human activity.Detailed analysis of historical data shows that during the last 5,000 years,the Huanghe River did not flow into the Bohai Sea for 758 years and annual sediment input into the Bohai Sea reached 1.1 billion tons for only 840 years.These data together with coring and shallow seismic profiling data seem to indicate that the accumulation rate of the Bohai Sea averages about 0.6-0.7m/ka in the Holocene. Man is a geological agent.This paper illustrates the enormous scale of human impact on morphology and sedimentation of the coastal zone and shows that river and sea form an integrated system,the study of whcih should receive more attention from geo-scientists.