Reconstruction of flood events over the last 150 years in the lower reaches of the Changjiang River

• 来源期刊: 科学通报(英文版)
• 学科: 地球科学
• 关键词: 洪水事件 长江下游 柱状沉积物 地球化学测量 平均晶粒尺寸 概率累积曲线 地表侵蚀 长江中下游
• 年，卷（期）: 2010,（21）
• 所属期刊栏目: ARTICLES
• 页码范围: 2268-2274
• 页数: 7页
• 分类号: P467 TV147
• 语种: 英文

摘要

The reconstruction of paleofloods in the Holocene has become one research highlight for the present global change study.The core sediments from one newly-emerged bar in the lower Changjiang River(Yangtze River)mainstream were collected for grain size and organic elemental measurements,with aim to reconstruct the flood events over the past 150 years.Major grain size parameters such as mean grain size,probability cumulative curve and C-M diagram of the core sediments clearly indicate the flood event deposition.Furthermore,the TOC/TN ratios in the sediments can indicate flood events considering that during the flash floods,strong surface erosion in the upper and lower reaches of the Changjiang River can transport a large amount of undecomposed plant debris and organic components with relatively low C/N ratios into the lower mainstream.Based on 210Pb dating and sedimentary geochemical results,the research profile recorded several large floods happened from 1850 to 1954,which agrees well with the historical documents and hydrological observations.Interesting to note that the flood events since the 1960s cannot be distinctly recognized on the basis of sediment grain size and organic elemental compositions of the profile,which mainly reflects the intensive human activities over the last fifty years,especially condense dam construction,have significantly changed the characters of suspended sediment into the lower mainstream.