Variability of effective discharge for suspended sediment transport in a large semi-arid river basin
Variability of effective discharge for suspended sediment transport in a large semi-arid river basin
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DOI：
10.1016/j.jhydrol.2010.05.014
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发表时间：
2010-07
影响因子：
6.4
通讯作者：
Yuanxu Ma;H. Huang;Jiongxin Xu;G. Brierley;Z. Yao
中科院分区：
文献类型：
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作者：
Yuanxu Ma;H. Huang;Jiongxin Xu;G. Brierley;Z. Yao
本文根据1959 ~ 1969年的平均日径流量和平均日悬移质输沙量，分析了无定河流域3个地貌带（黄土丘陵沟壑区、黄土河谷区和风成沙区）的有效流量的变化规律。本文提出了一种改进的确定放电等级间隔的方法，即所有放电的标准差S的算术间隔相等，如S、0.75S、0.5S和0.25S。流域有效流量平均历时在两个黄土区主要为0.026%~ 3.16%（对应于大洪水），在风成沙区主要为18.75%~ 91.51%（对应于小流量或中等流量）。有效流量的平均流量持续时间显著地受类别间隔的大小以及水流和泥沙状况的特征的影响。以0.25S为最佳分级间隔，两个黄土区的平均有效流量历时约为0.026%（横山为0.104%），而风成沙区的平均有效流量历时在榆林和韩家峁分别为24.50%和52.66%。悬移质输移量直方图表明，悬移质输移量存在双峰主导流量，一个峰值出现在小流量范围内，另一个峰值出现在大洪水范围内。风成沙区的流域密度和比沙率较低，有效流量事件发生频率较高，悬移质泥沙浓度远低于黄土区相同流量事件所携带的泥沙浓度。与此相反，排水密度较高的两个黄土地区，不频繁的高浓度流产生高比泥沙产量。整个无定河流域的有效流量与平滩流量差异很大。
The variability of effective discharge is analysed for three geomorphological zones (gullied hilly loess, valley–hill loess and eolian sand) in the Wuding River basin, China, based on mean daily flow discharge and mean daily suspended sediment discharge from 1959 to 1969, a period when human disturbance in this catchment was less intensive. A modified approach to the determination of discharge class intervals is developed, framed in terms of equal arithmetic intervals of the standard deviation S for all the discharges, such as S, 0.75S, 0.5S, and 0.25S. The average flow duration of effective discharge in the river basin ranges primarily from 0.026% to 3.16% in the two loess regions (corresponding to large flood events), and from 18.75% to 91.51% in the eolian sand region (corresponding to low or moderate flows). The average flow duration of effective discharge is significantly influenced by the size of class intervals and by characteristics of the flow and sediment regime. Using the most appropriate class interval of 0.25S, the average flow duration of effective discharge is about 0.026% in the two loess regions (other than 0.104% at Hengshan), but in the eolian sand region it reaches 24.50% at Yulin and 52.66% at Hanjiamao, respectively. Histograms of suspended sediment transport indicate that there is a bimodal dominant discharge for suspended sediment transport, with one peak in the range of low flows and the other in the range of large floods. Drainage density and specific sediment yields are lower in the eolian sand region, where effective discharge events occur more frequently and suspended sediment concentration is much lower than that carried by events of the same discharge in the loess region. In contrast, drainage density is higher in the two loess regions, where infrequent hyperconcentrated flows generate high specific sediment yields. Effective discharge differs significantly from bankfull discharge across the whole Wuding River basin.