Channel deposition induced by bank erosion in response to decreased flows in the sand-banked reach of the upstream Yellow River
Channel deposition induced by bank erosion in response to decreased flows in the sand-banked reach of the upstream Yellow River
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DOI：
10.1016/j.catena.2013.01.007
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发表时间：
2013-06
期刊：
影响因子：
6.2
通讯作者：
W. Ta;X. Jia;Haibing Wang
中科院分区：
文献类型：
--
作者：
W. Ta;X. Jia;Haibing Wang
沙滩河流由于滩面阻力小，侧向冲刷严重。在大多数天然河流中，洪水流量会导致高的横向河道侵蚀率，并导致悬浮泥沙负荷增加;然而，我们的研究表明，低流量也会导致高的横向河道侵蚀率。利用1962年、1982年、1991年和2000年黄河库布齐沙漠河段113个河道断面的剖面数据，我们发现尽管流量减少了58%，但横向河道侵蚀率保持相对恒定，为0.6 - 0.67 × 108tyr-1，并导致了独特的岸-道泥沙输移（BCST）的发展。这BCST过程，结合减少流量，导致悬浮泥沙流出量减少了30%，增加了泥沙在河道中的沉积，并提供了一个机制的河道调整，以减少流量在沙洲河流。我们的研究结果还表明，这种高的横向河道侵蚀率约占总测量沉积率的64%，在1982 - 2000年的河道收缩期，平均高达0.90 - 1.15 <$108 tyr-1。即使在1962 - 1982年的河道拓宽期，横向冲刷也造成了约0.41 × 108t的泥沙淤积。河道冲刷是河道泥沙的重要来源，是造成河道横向移动的主要原因，因此，河道固岸应成为河道治理和防洪的重点。
Sand-banked rivers are characterized by severe lateral channel erosion due to weak bank resistance. High lateral channel erosion rates occur in most natural rivers in response to flood flows and contribute to increased suspended sediment loadings; however, evidence from our study shows that low flows also cause high lateral channel erosion rates in sand-banked rivers. Using the profile data of 113 channel cross-sections taken in 1962, 1982, 1991 and 2000 in the Kubq desert reach of the Yellow River, we show that the lateral channel erosion rate remained relatively constant of 0.6–0.67∗108tyr−1despite flow decreases of 58% and led to the development of a unique bank-to-channel sediment transfer (BCST). This BCST process, in combination with the decreased flow which caused suspended sediment effluxes to decrease by 30%, enhanced sediment deposition in the channel and provided a mechanism of channel adjustment to decreased flow in sand-banked rivers. Our results also show that this high lateral channel erosion rate accounted for about 64% of the total measured sediment deposition rates, which showed, on average, to be as much as 0.90–1.15∗108tyr−1in the channel shrinkage period of 1982–2000. Even in the channel widening period of 1962–1982, the lateral channel erosion was also found to cause about 0.41∗108t of sediment deposition in the channel annually. As the lateral channel erosion is a substantial sediment source of river sediments and leads to lateral channel shifts for sand-banked rivers, channel bank stabilization should be a priority in river management and flood control in sand-banked rivers.