陈进军,
胡小飞,,
苏航,
陈颖,
张建
兰州大学资源环境学院, 西部环境教育部重点实验室, 甘肃 兰州 730000
基金项目: 国家自然科学基金项目（批准号：41471009和41571003）资助
详细信息
作者简介: 陈殿宝, 男, 30岁, 博士研究生, 第四纪地质学专业, E-mail:chendb13@lzu.edu.cn
通讯作者: 胡小飞, E-mail:feixhu@lzu.edu.cn
中图分类号: P512.2;P534.63收稿日期:2017-12-28
修回日期:2018-04-12
刊出日期:2018-11-30
Characteristics and analysis on the sediment grain size along the Liyuan River on the north piedmont of the Qilian Shan
Chen Dianbao,Chen Jinjun,
Hu Xiaofei,,
Su Hang,
Chen Ying,
Zhang Jian
Key Laboratory of Western China's Environmental System(Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, Gansu
More Information
Corresponding author: Hu Xiaofei,E-mail:feixhu@lzu.edu.cn
MSC: P512.2;P534.63--> Received Date: 28 December 2017
Revised Date: 12 April 2018
Publish Date: 30 November 2018
摘要
摘要:对河流沉积物粒径顺流变小这一现象的解释经历了从磨损到选择性沉积的转变，并发现混合粒径沉积物在搬运中会伴随有"隐藏效应"，水力分选作用会随"隐藏效应"的增强而减弱；另外，河流河床经常会发生由砾质向砂质的过渡，这与砂含量增加及砾石与砂在临界起动力上产生的分化相关。这些理论都需要大量的野外观测进行论证。文章以祁连山北麓发育的梨园河为例，以河道水力学参数和河床沉积物粒径为主要研究对象，对梨园河现代河床沉积物粒径向下游变化的特征及其影响因素进行分析。分析结果显示：选择性沉积是梨园河沉积物粒径向下游逐渐变小的主要原因；砂含量向下游的增加导致河床对砾石的水力分选作用发生重要转变，并伴随砾质河床向砂质河床过渡；梨园河上半段的水力分选作用要比下半段强，这与"隐藏效应"向下游的增加有关；上半段的沉积速率比下半段的高，导致上半段沉积物粒径向下游变小的趋势更为显著。
关键词: 梨园河/
沉积物粒径/
水力分选/
水力学参数
Abstract:The phenomenon of downstream fining of river sediment grain-size has been analyzed by a large number of studies. Predominant explanations of the phenomenon have changed from abrasion to selective deposition. Studies found that mixtures of sediment can lead to "Hiding effects" in the process of sediment transport, and that hydraulic sorting effects on sediment will decrease along with increasing "Hiding effects". Rivers often exhibit the phenomenon of gravel-sand transition, which is relevant to the segregation in the threshold entrainment stress between gravel and sand. The analysis of fluvial sediment mass balance shows that fluvial sediment architecture is governed by the spatial distribution of sediment volume. Allogenic factors, such as sediment supply and tectonic subsidence, mainly exert influence on the spatial distribution of deposition, and then indirectly influence the fluvial sediment architecture. This paper takes the Liyuan River, which developed in the north foot of the Qilian Shan, as an example, to examine the river hydraulic parameters and sediment grain-size, and then to analyze the characteristics of downstream variation of sediment grain-size and the influence factors. The analysis results suggest:selective deposition is the dominating driver of downstream fining of sediment grain-size in the Liyuan River; the downstream increase in sand content lead to the transformation of gravel sorting in the gravel-sand transition; hydraulic sorting effects in 0~26 km reach is stronger than that in 26~50 km reach, which is relevant to the "Hiding effects" that increasing downstream; the deposition rate in 0~26 km reach is higher than that in 26~50 km reach, that is the reason why the downstream fining tendency of river sediment grain-size in 0~26 km reach is more clear than that in 26~50 km reach, besides, the hydraulic sorting is also responsible for the differences in downstream fining tendency of river sediment grain-size between the two reaches.
Key words:Liyuan River/
sediment grain-size/
hydraulic sorting/
hydraulic parameters
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