Downstream effects of dams on alluvial rivers.
Downstream effects of dams on alluvial rivers.
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DOI：
10.3133/pp1286
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
G. P. Williams;M. Wolman
中科院分区：
文献类型：
--
作者：
G. P. Williams;M. Wolman
本研究描述了建在冲积河上的21座水坝的平均河床高程、河道宽度、河床物质大小、植被、水量和下游泥沙负荷的变化。大多数被研究的水道位于半干旱的美国西部。大坝总体上降低了洪峰，但在其他方面，各河流的坝后水量特征有所不同。在大坝下游数百公里范围内，泥沙浓度和悬浮荷载显著降低；大坝建成后，一些河流的年泥沙负荷与大坝下游任何地方的大坝建成前的负荷不相等。在研究的287个截面中，床层退化从可忽略到约7.5米不等。一般来说，大多数退化发生在大坝关闭后的头十年或二十年。随着降解的进行，床上物质最初变粗，但这种模式在以后的几年中可能会改变。在大坝下游河段，河道宽度可以增加、减少或保持不变。尽管有很大的变化，河床高程和河道宽度的横断面随时间的变化通常可以用简单的双曲方程来描述。方程系数需要根据经验确定。在大坝下游的河段，河岸植被通常会增加，这可能是因为峰值流量的减少。文献120篇，图表49张，表格14张。«少
This study describes changes in mean channel-bed elevation, channel width, bed-material sizes, vegetation, water discharges, and sediment loads downstream from 21 dams constructed on alluvial rivers. Most of the studied channels are in the semiarid western US. Flood peaks generally were decreased by the dams, but in other respects the post-dam water-discharge characteristics varied from river to river. Sediment concentrations and suspended loads were decreased markedly for hundreds of kilometers downstream from dams; post-dam annual sediment loads on some rivers did not equal pre-dam loads anywhere downstream from a dam. Bed degradation varied from negligible to about 7.5 meters in the 287 cross sections studied. In general, most degradation occurred during the first decade or two after dam closure. Bed material initially coarsened as degradation proceeded, but this pattern may change during later years. Channel width can increase, decrease, or remain constant in the reach downstream from a dam. Despite major variation, changes at a cross section in stream bed elevation and in channel width with time often can be described by simple hyperbolic equations. Equation coefficients need to be determined empirically. Riparian vegetation commonly increased in the reach downstream from the dams, probably because of the decrease in peakmore » flows. 120 references, 49 figures, 14 tables.« less