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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Lateral erosion of the Sacramento River, California (1942-1999), and responses of channel and floodplain lake to human influences
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Lateral erosion of the Sacramento River, California (1942-1999), and responses of channel and floodplain lake to human influences

机译：加利福尼亚萨克拉曼多河的横向侵蚀（1942-1999），以及河道和漫滩湖对人类影响的响应

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摘要

This study focused on a spatial and temporal analysis of the active channel and associated floodplain lakes using aerial photographs spanning five decades (1942, 1962, 1985, 1999) over a 140km long reach of the Sacramento. Planimetric changes were analysed longitudinally and temporally to highlight the spatial structures and their evolution through time. The results underline complex changes and space-time pattern in bank erosion, channel length and active channel width. The bank erosion and also channel lengthening were higher between 1962 and 1985 than in the two periods studied before and after. Active channel width significantly decreased from 1942 to 1999; partly progressively from upstream to downstream with local widening whatever the studied periods. Similarly the floodplain lakes observed before 1942-1962 were significantly different in size and geometry from those which appeared during the most recent period. The creation of lakes is less frequent after the 1940s, with a secondary peak of occurrence during the 1962-1985 period. The interpretation of these changes is complex because of various human pressures acting over different time scales (bank protection, flow diversion, sediment starvation, land-use changes) and various natural influences (flood sequences through out the period, geological setting). The findings are discussed by comparison with previous work, and highlight the important effect of dam impact on peak flow and sediment starvation modifying longitudinally hydraulic conditions within the channel, but also the increase in riprap protection which induced change in bank erosion, channel planimetry and floodplain lake characters (geometry, frequency of renewal). Variation in flood intensities is also observed as having positive effects on the bank erosion pattern. Secondarily, land-use changes also controlled bank erosion intensity.
机译：这项研究的重点是使用跨越萨克拉曼多（Sacramento）140公里长的五十年（1942，1962，1985，1999）的航空照片对活动河道和相关的漫滩湖进行时空分析。纵向和时间上分析了平面变化，以突出空间结构及其随时间的演变。结果强调了河岸侵蚀，河道长度和有效河道宽度的复杂变化和时空格局。在1962年至1985年之间，河岸侵蚀和河道加长程度高于前后研究的两个时期。有效通道宽度从1942年到1999年显着减少;无论研究的时间长短，部分从上游到下游逐步进行，局部扩大。同样，在1942年至1962年之前观察到的洪泛区湖泊的大小和几何形状与最近时期出现的湖水明显不同。在1940年代后，湖泊的创建频率降低了，在1962-1985年期间出现了第二高峰。这些变化的解释很复杂，因为各种人为压力作用于不同的时间尺度（河岸保护，分流，沉积物饥饿，土地利用变化）以及各种自然影响（整个时期的洪水序列，地质环境）。通过与以前的工作进行比较来讨论这些发现，并强调了大坝冲击对峰值流量和沉积物饥饿的重要影响，从而改变了河道内的纵向水力条件，同时还增加了护堤保护，从而引起了河岸侵蚀，河道平面度和洪泛区的变化。湖泊特征（几何形状，更新频率）。还观察到洪水强度的变化对河岸侵蚀模式具有积极影响。其次，土地利用变化也控制了河岸侵蚀强度。

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