河流砾-砂过渡(GST)研究进展  

Overview of Research on Gravel-Sand Transition in Rivers

作　　者：张艺秋 胡修棉[1] ZHANG YiQiu;HU XiuMian(School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China)

机构地区：[1]南京大学地球科学与工程学院,南京210023

出　　处：《沉积学报》2022年第4期883-893,共11页Acta Sedimentologica Sinica

基　　金：第二次青藏高原科学考察(STEP)研究项目(2019QZKK0204)。

摘　　要：河流从上游山区流经下游宽阔地带时,所搬运物质在磨损和分选作用下逐步变细,当沉积物减小到中粗卵砾级别时(10~20 mm),会在相对短距离内(几倍河道宽度)快速转变为极粗砂(1~2 mm),这种粒度突变现象被称为砾—砂过渡(gravelsand transition,GST)。对河流砾—砂过渡进行了系统调研,介绍了其在河流中的基本特征;分析了砾—砂过渡的发生机理,包括粒度突变的外因假说、2~10 mm粒径空缺的内因解释,以及GST中加剧砾砂流动性差异的过程;也介绍了GST的空间普适性、其前后的河流转变和位置稳定性。GST的深入研究对于理解河流演化、泥沙运移、洪水风险管理、沉积物源分析具有重要意义。As rivers develop from upstream mountainous areas to a broad plain,the transported materials gradually become finer due to abrasion and sorting.However,once the particle size has been reduced to 10-20 mm(mediumcoarse pebbles),it abruptly changes within a relatively short distance(a few channel widths)to the size of very coarse sand(1-2 mm);that is,little or no material is present in the 2-10 mm range.This phenomenon is known as gravel-sand transition(GST).The present study summarizes reported research on GST in rivers,and introduces its basic behavior for typical rivers.Three possible GST mechanisms are then analyzed:the external hypothesis of grain size change;the internal explanation of the 2-10 mm gap in grain size;and the processes that increase the mobility of gravel and sand in GST.It also introduces the spatial universality of GST and river variation before and after GST,as well as the stability of location of the phenomenon.The gravel-sand transition is highly significant in the contexts of river evolution,sediment transport,flood risk management and sedimentary provenance analysis.

关 键 词：砾—砂过渡 河流沉积 粒度 沉积学 地貌学 

分 类 号：P512.2[天文地球—地质学]