CHANNEL EVOLUTION IN MODIFIED ALLUVIAL STREAMS.
CHANNEL EVOLUTION IN MODIFIED ALLUVIAL STREAMS.
复制标题
改良冲积流中的河道演化。
DOI：
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发表时间：
1987
期刊：
影响因子：
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通讯作者：
C. Hupp
中科院分区：
文献类型：
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作者：
A. Simon;C. Hupp
田纳西州西部冲积河道的改造增加了沿主干和支流的能量条件，并启动了纵向河道调整。河床水位的变化是施加扰动的大小和程度以及调节河段在河网中的位置的函数。用简单的功率方程来描述河床退化。计算的指数定义了随时间下降的幅度，并随着距离最大扰动区域上游的距离非线性下降。退化过程过度调节后，AMD下游河段和上游河段立即开始退化。沉降速率随离AMD下游距离的增加而线性增加，可以通过局部降解速率来估计。在退化之后，大量的浪费使河道变宽，并在沉积阶段继续扩大。来自黄土的银行材料的管道增加了银行的内部不稳定，从而提高了银行的失败率。河岸轮廓的发展是根据三个动态和可观察的表面来定义的：(a)垂直表面（70至90度），(b)上岸（25至50度），以及(c)泥沼线（20至25度）。通过低角度滑坡和河流改造的额外平坦化，泥沼线发展起来，是河岸植被和稳定的河岸条件重建的初始地点。通过对河床水平趋势的量化和对岸坡发育的定性阶段的认识，建立了扰动河道中河道演化的六步半定量模型。
Modification of alluvial channels in western Tennessee has created increased energy conditions along main stems and tributaries and initiated longitudinal channel adjustment. Changes in bed level are functions of the magnitude and extent of the imposed disturbance and the location of the adjusting reach in the fluvial network. Streambed degradation is described by simple power equations. Computed exponents define the magnitude of downcutting with time and decrease nonlinearly with distance upstream from the area of maximum disturbance (AMD). Aggradation begins immediately in reaches downstream of the AMD and in upstream reaches after overadjustment by the degradation process. Aggradation rates increase linearly with distance downstream from the AMD and can be estimated from local degradation rates. Channel widening by mass wasting follows degradation and continues through aggradational phases. Piping in the loess-derived bank materials enhances bank failure rates by internally destabilizing the bank. Development of the bank profile is defined in terms of three dynamic and observable surfaces: (a) vertical face (70 to 90 degrees), (b) upper bank (25 to 50 degrees), and (c) slough line (20 to 25 degrees). The slough line develops through additional flattening by low-angle slides and fluvial reworking and is the initial site at which riparian vegetation and stable bank conditions are reestablished. A six-step, semiquantitative model of channel evolution in disturbed channels was developed by quantifying bed level trends and recognizing qualitative stages of bank slope development.