海洋地质与第四纪地质2025，Vol.45Issue(2)：31-42,12.DOI:10.16562/j.cnki.0256-1492.2024022902
2020年特大洪水期间长江水下三角洲沉积物沉积特征
Depositional characteristics of sediments in the Changjiang River subaqueous delta during the catastrophic flood in 2020
摘要
Abstract
Catastrophic floods in large rivers exert significant influences on the sedimentary environment in the estuarine region.However,viewpoints of sedimentary characteristics of the paleoflood in the estuarine delta is controversial.Therefore,it is necessary to understand the sedimentary characteristics of modern flood.The whole Changjiang River basin suffered from a catastrophic flood in 2020.Sixteen sediment cores in the Changjiang subaqueous delta were collected during the flood period.Grain size and organic index(TOC,TN)were measured.The result indicates that the flood layers is 3～21 cm thick,the average TOC and TN is 0.59%and 0.077%,respectively,which is higher than that of lower part deposit.The mean grain size of the flood layers(13.23µm)is finer than that of the lower part deposits(13.87µm).The end-member modelling analysis indicated that the finest populations(EM1)were originated from the 2020 flooding.Comparing the EMs of 2020 flood deposits with grain size characteristics of flood deposits in previous studies,we found that the 2020 flood sediments were finer than the lower part non-flood deposits,but coarser than the previous flood sediments,which is different from the common view that the paleoflood deposits are characterized by coarser sediments.We believed that this difference was due to(1)human activities(e.g.dam construction)in the river basin,by which more coarse sediment were trapped within the dam;(2)the weakened erosion in middle and lower reaches of river channels;and(3)the subaqueous delta by ocean dynamic erosion.This study is beneficial for the reconstruction of long-term paleoflood events sequences and the interpretation of extreme event deposition in the estuarine region.关键词
特大洪水/沉积特征/人类活动/长江水下三角洲Key words
extreme flood/sedimentary characteristic/human activities/Changjiang River subaqueous delta分类
海洋学引用本文复制引用
李明宸,闫粟,公力维,王雪晨,耿润玉,徐润喆,周亮,汪亚平,沈治雄..2020年特大洪水期间长江水下三角洲沉积物沉积特征[J].海洋地质与第四纪地质,2025,45(2):31-42,12.基金项目
国家自然科学基金项目"海南岛南部海岸风暴巨砾沉积揭示的风暴强度"(41706096),"长江流域两千年以来入海水沙通量变化及其对河口-陆架泥质沉积体系发育和演化的影响"(41776048),"海岸风暴频率-强度关系的沉积记录分析"(41530962),"The magnitude and frequency of extreme late Holocene flooding in the middle Yangtze River and their climatic and anthropogenic forcing"(42250610211) （41706096）
上海市教育委员会科研创新项目"长江三角洲蓝图重绘的基础科学问题研究"(2019-01-07-00-05-E00027) （2019-01-07-00-05-E00027）
江苏省研究生科研与实践创新计划项目"长江口历史水道变迁和特大洪水事件的沉积记录"(KYCX22_2787) （KYCX22_2787）
江苏省高等学校大学生创新创业训练计划"长江水下三角洲历史特大水文事件沉积的识别"(202110320121Y) （202110320121Y）
