Sediment budget analysis of slope–channel coupling and in-channel sediment storage in an upland catchment, southeastern Australia
Sediment budget analysis of slope–channel coupling and in-channel sediment storage in an upland catchment, southeastern Australia
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澳大利亚东南部高地流域斜坡-河道耦合和河道内沉积物储存的沉积物收支分析
DOI：
10.1016/j.geomorph.2008.03.004
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发表时间：
2008
期刊：
影响因子：
3.9
通讯作者：
D. Dragovich
中科院分区：
文献类型：
--
作者：
H. Smith;D. Dragovich
坡槽耦合和槽内泥沙淤积是影响流域泥沙输移的重要因素。沉积物预算提供了一个适当的手段来评估这些因素的作用，通过量化的集水区沉积物转移系统的各个组成部分。在这项研究中，在澳大利亚东南部的一个1.64平方公里的沟壑高地集水区开发了一个精细（<63 µm）的沉积物预算。采用了一种基于过程的方法，包括详细监测山坡和河岸侵蚀，河道变化，悬浮泥沙输出结合USLE的山坡侵蚀估计和泥沙来源追踪使用137 Cs和210 Pbex。从这些数据集开发的沉积物预算表明，渠道银行占总沉积物输入的估计80%。谷底和河道内沉积物储存占输入量的53%，其余47%从集水区出口排出。估计山坡泥沙输入渠道低（5.7吨）的研究期间相比，渠道银行输入（41.6吨）。然而，估计有56%的侵蚀山坡沉积物到达渠道，这表明更大的水平，这两个子系统之间的耦合比沉积物源输入的比较明显。显然，对流域产沙量变化的解释在很大程度上取决于响应降雨和流量模式的渠道中沉积物供应和储存的动态。这反映在各个测量间隔的沉积物输送比（SDR）中，范围从1%到153%。在低降雨量期间，银行沉积物供应减少，但正在进行从陆上过程输送沉积物到渠道，导致在渠道床上的净积累，流量不足，运输这种材料的集水出口。在第一年监测的春季高流量期之后，在此期间提供给渠道的沉积物被移除，并且估计自研究期开始以来，72%的沉积物累积在渠道床上。鉴于储存和交付的季节性和干旱性变化，监测期可能对总体特别提款权产生重要影响。在这些研究结果的基础上，本研究突出了潜在的重要性，沉积物动力学的渠道，以确定当代产沙量在澳大利亚东南部的小沟壑高地集水区。
Slope–channel coupling and in-channel sediment storage can be important factors that influence sediment delivery through catchments. Sediment budgets offer an appropriate means to assess the role of these factors by quantifying the various components in the catchment sediment transfer system. In this study a fine (<63 µm) sediment budget was developed for a 1.64-km2gullied upland catchment in southeastern Australia. A process-based approach was adopted that involved detailed monitoring of hillslope and bank erosion, channel change, and suspended sediment output in conjunction with USLE-based hillslope erosion estimation and sediment source tracing using137Cs and210Pbex. The sediment budget developed from these datasets indicated channel banks accounted for an estimated 80% of total sediment inputs. Valley floor and in-channel sediment storage accounted for 53% of inputs, with the remaining 47% being discharged from the catchment outlet. Estimated hillslope sediment input to channels was low (5.7 t) for the study period compared to channel bank input (41.6 t). However an estimated 56% of eroded hillslope sediment reached channels, suggesting a greater level of coupling between the two subsystems than was apparent from comparison of sediment source inputs. Evidently the interpretation of variability in catchment sediment yield is largely dependent on the dynamics of sediment supply and storage in channels in response to patterns of rainfall and discharge. This was reflected in the sediment delivery ratios (SDR) for individual measurement intervals, which ranged from 1 to 153%. Bank sediment supply during low rainfall periods was reduced but ongoing from subaerial processes delivering sediment to channels, resulting in net accumulation on the channel bed with insufficient flow to transport this material to the catchment outlet. Following the higher flow period in spring of the first year of monitoring, the sediment supplied to channels during this interval was removed as well as an estimated 72% of the sediment accumulated on the channel bed since the start of the study period. Given the seasonal and drought-dependent variability in storage and delivery, the period of monitoring may have an important influence on the overall SDR. On the basis of these findings, this study highlights the potential importance of sediment dynamics in channels for determining contemporary sediment yields from small gullied upland catchments in southeastern Australia.