The importance of streambank erosion to watershed-scale sediment export is being increasingly recognized. However few studies have quantified bank erosion and watershed sediment flux at the basin scale across temporal and spatial scales. In this study we evaluated the spatial distribution, extent, and temporal frequency of bank erosion in the 5218 ha Walnut Creek watershed in Iowa across a seven year period. We inventoried severely eroding streambanks along over 10 km of stream and monitored erosion pins at 20 sites within the watershed. Annual streambank recession rates ranged from 0.6 cm/yr during years of hydrological inactivity to 28.2 cm/yr during seasons with high discharge rates, with an overall average of 18.8 cm/yr. The percentage of total basin export attributed to streambank erosion along the main stem of Walnut Creek ranged from 23 to 53%. Large variations in individual site, annual rates and percentage of annual load suggested that developing direct relationships between streambank erosion rates and total sediment discharge may be confounded by the timing and magnitude of discharge events, storage of sediments within channel system and the remobilization of eroded material.
展开▼
机译：河岸侵蚀对流域规模的沉积物出口的重要性日益得到认可。然而，很少有研究量化流域范围内跨时空尺度的河岸侵蚀和流域沉积物通量。在这项研究中，我们评估了爱荷华州5218公顷核桃溪流域7年间河岸侵蚀的空间分布，程度和时间频率。我们清查了沿河10公里以上的侵蚀严重的河岸，并监测了流域内20个地点的侵蚀针脚。年河岸退缩率的范围从无水活动年的0.6 cm / yr到高出水率的季节的28.2 cm / yr，总体平均为18.8 cm / yr。流域沿核桃溪主干流侵蚀造成的流域总出口百分比在23％至53％之间。各个地点，年率和年负荷百分比的巨大差异表明，河床冲刷率与总沉积物排放之间发展的直接关系可能与排放事件的时间和大小，河道系统内沉积物的存储以及侵蚀物质的迁移有关。 。
展开▼
