Morphodynamics of River Deltas in Response to Different Basin Water Depths: An Experimental Examination of the Grade Index Model
Morphodynamics of River Deltas in Response to Different Basin Water Depths: An Experimental Examination of the Grade Index Model
复制标题
不同流域水深响应的河流三角洲形态动力学：等级指数模型的实验检验
DOI：
10.1029/2019gl082483
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发表时间：
2019
影响因子：
5.2
通讯作者：
Naruse Hajime
中科院分区：
文献类型：
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作者：
Wang Junhui;Muto Tetsuji;Urata Kento;Sato Toshihiko;Naruse Hajime
流域水深(h)决定了河流三角洲的长期形态动力学，这体现在等级指数（Gindex）中。gindex是陆地泥沙分配与全部供给泥沙的体积-单位-时间比，可以作为无量纲的盆地水深（h*）的函数给出。水槽试验结果表明，gindexvalue越低（即当盆地水较深；h* > 1时），三角洲进积和三角洲平原沉积受到抑制，分流河道迁移和崩解发生的频率越低。当gini ~0（即极深盆地水；h*~+∞）时，三角洲既不能进退也不能后退，分流河道趋于稳定。等级指数模型有助于解释台湾东部黎武三角洲和黄河三角洲的形态动力学差异，它们分别是深水三角洲和浅水三角洲的自然例子。
Basin water depth (h) governs the long‐term morphodynamics of river deltas, which are embodied in the grade index (Gindex). TheGindex, a volume‐in‐unit‐time ratio of subaerial sediment allocation to the entire supplied sediment, can be given as a function of the dimensionless basin water depth (h*). Tank experiments reported herein reveal that delta progradation and deltaplain aggradation are suppressed and distributary channel migration and avulsion take place less frequently when theGindexvalue is lower (i.e., when the basin water is deeper;h*≫ 1). If theGindex~0 (i.e., extremely deep basin water;h*~+∞), the delta can neither prograde nor aggrade, and the distributary channels tend to stabilize. The grade index model helps explain the contrasting morphodynamics of the Liwu Delta (east Taiwan) and Yellow River Delta, as natural examples of deepwater and shallow‐water deltas, respectively.