摘要
河漫滩是洪水漫溢过自然堤而在河流两岸水流流速降低的地貌环境下所塑造的河流地貌单元,是洪水过程所形成的独特沉积体系,蕴含着大量的河流水文信息,但由于河流侧向摆动、河漫滩沉积速度较快等原因,造成河漫滩沉积环境变化较快,河漫滩沉积体系长期以来没有得到足够的重视。以鄱阳湖修河下游永修三角乡修河右岸的近现代河漫滩沉积序列为例,基于^(137)Cs比活度测试和事件性沉积建立时间标尺,依据粒度组份等指标,结合气象和水文观测数据,探究了器测以来河漫滩沉积体系对洪水事件的记录及记录特点。研究结果表明:较大洪水期间水动力不稳定、粒度较粗、分选差(或者好)、粒度跨度宽;该剖面揭示了1953年来16次较大洪水年份的14次,检出率高;平均粒径(μm)和SS(分选系数×粒径跨度)等指标对洪水事件的检出最好。这样揭示出来的洪水,可称为异常洪水,有别于基于滞水沉积所反演的极端洪水事件。研究在一定程度上能拓宽古洪水的研究内容与研究内涵。
A floodplain is a fluvial geomorphic unit formed by a flood that flows over the natural levee and below the river and is a unique sedimentary system formed by flood processes that contains a great deal of river hydrological information.However,because of the lateral sway of the river and the fast deposition rate of the floodplain,the sedimentary environment of the floodplain changes rapidly,which means that the floodplain sedimentary system has not been adequately studied for a long time.We examine the modern floodplain,on the right bank of the Xiu River in the triangle township of Yongxiu County,along the lower reaches of the river,as our case study.Testing the specific activity of 137 Cs to establish the time scale,based on particle size and combined with the meteorological and hydrological observation data,we explore the instrument for the floodplain depositional system of flood event records and record features.Study shows that during the larger floods with the hydrodynamic instability,coarse grain size,poor sorting(or good),and wide particle size span;This section reveals 14 larger flood years have occurred since 1953 with a high detection rate.The average particle size(μm)and SS(sorting coefficient×particle size span)are the best indicators for flood events.These floods can be called abnormal floods,which are different with extreme flood inversions based on stagnant water deposition.Therefore,to a certain extent,this study will broaden the content and connotation of the ancient flood research.
作者
连丽聪
凌超豪
李晓峰
曹向明
毛端谦
万智巍
贾玉连
牛文瑜
LIAN LiCong;LING ChaoHao;LI XiaoFeng;CAO XiangMing;MAO DuanQian;WAN ZhiWei;JIA YuLian;NIU WenYu(School of Geography and Environment,Jiangxi Normal University,Nanchang 330022,China;Key Laboratory of Poyang Lack Wetland and Research Ministry of Education,Nanchang 330022,China;Nanjing Institute of Geography and Limnology,Chinese Academy of Science,Nanjing 210008,China;University of Chinese Academy of Science,Beijing 100049,China)
出处
《沉积学报》
CAS
CSCD
北大核心
2019年第1期135-142,共8页
Acta Sedimentologica Sinica
基金
江西省重大生态安全问题监控协同创新中心项目(JXS-EW-00)
国家自然科学基金项目(41262007)
鄱阳湖湿地与流域研究教育部重点实验室(江西师范大学)开放基金(ZK2013003)~~
关键词
修河
异常洪水
河漫滩沉积
水文记录
粒度指标
Xiu River
abnormal flood events
floodplain sediments
hydrological records
granularity index
