Using a fluvial archive to place extreme flood sediment(dis)connectivity dynamics in context of a longer-term record  

作　　者：Kirstie Fryirs Chris Thompson Damian Gore 

机构地区：[1]School of Natural Sciences,Macquarie University,North Ryde,NSW,2109,Australia [2]Seqwater,117 Brisbane Street,Ipswich QLD,4305 Australia

出　　处：《International Journal of Sediment Research》2022年第4期447-456,共10页国际泥沙研究（英文版）

基　　金：supported by an ARC Linkage Grant (LP120200093) with industry partners DSITIA, Seqwater, and Lockyer Valley Regional Council。

摘　　要：The aim of this study was to establish the source and provenance of sediments deposited in a large floodplain sink during extreme floods in the Lockyer Creek catchment, Australia, in 2011 and 2013. We place the sediment source patterns in context of the longer-term record to determine whether coarsegrained sediment sources(i.e., very fine sand to very coarse sand) and the spatio-temporal pattern of(dis)connectivity have changed over time. We do this by matching the geochemical properties and age structure of a sediment profile located in a downstream floodplain sink to the elemental composition of source sediments. One hundred and fifty-seven sediment samples from 20 sites across the catchment are analysed using X-ray fluorescence(XRF) spectrometry to compare the elemental ratio composition of the downstream floodplain sink to its source materials. We use Optically Stimulated Luminescence(OSL)dating to determine the age structure of the sediments in the floodplain sink. The northern tributaries and parts of the Lockyer River trunk stream are the primary sources of coarse sediment. These areas are connected(coupled) to the lower trunk stream and floodplain sediment sink. Southern tributaries are largely disconnected(decoupled) and supply little sediment to the floodplain sediment sink. This pattern of sediment source contribution has remained similar over the last 6.8 ka at least. Sediment sources as observed in the 2011 flood have predominated over the mid-late Holocene whilst those in the 2013 flood are rare.

关 键 词：Sediment provenance GEOMORPHOLOGY Sediment source Sediment sink Lockyer Valley 

分 类 号：P333[天文地球—水文科学]