《Soil & Water Conservation》杂志刊登“利用湖泊沉积率量化流域水土流失防治的有效性”

作者：D.G. Wren, G.R. Davidson

刊物：Journal of Soil & Water Conservation，2011年，66卷5期

关键词： 保持；侵蚀控制；湖泊；沉积；铅—210；铯—137

摘要：侵蚀控制方法有效性的难以衡量，阻碍了管理实践的发展，妨碍了随着时间的推移对水土流失控制结构的价值进行准确评估。在某一地区，尤其是存在沟壑侵蚀的地区，表面侵蚀会有很大差异，并且河流泥沙具有极高的可变性，这一特性阻碍了使用河流中输移的泥沙来对侵蚀进行量化。当流域水流汇入湖泊，由累积泥沙沉积量可能得出关于历史沉积率的信息，而历史沉积率可用于评估先前侵蚀控制措施的有效性。本研究以密西西比河冲积河漫滩的5个天然牛轭湖中的泥沙沉积物为研究对象，采用铅-210的衰变率和炸弹脉冲衍生铯-137，推定沉积物的年代，目的是研究由于管理实践导致的沉积率和侵蚀减少量变化的相关趋势。研究结果发现，放射性同位素定年方法与已知的管理实践的实施相一致，是最好的使用方法。沉积率随时间的变化发展很短，比如有检测到12年的。与相对较小的湖泊相比，较大的湖泊沉积率变化较小。

Using lake sedimentation rates to quantify the effectiveness of erosion control in watersheds

Authors: D.G. Wren, G.R. Davidson

Journal: Journal of Soil & Water Conservation, 2011, 66(5)

Keywords: conservation; erosion control; lake; sedimentation; lead-210; cesium-137

Abstract：The effectiveness of erosion control methods is difficult to measure, hampering the development of management practices and preventing accurate assessment of the value of erosion control structures over time. Surface erosion can vary widely over an area, particularly if gully erosion is present, and the use of sediments transported in streams for quantifying erosion is hindered by the highly variable nature of fluvial sediment loads. When a watershed drains into a lake, accumulated sediments have the potential to yield information about historic rates of sedimentation that can be used to evaluate the effectiveness of previous erosion control measures. In the present study, sediments from five natural oxbow cutoff lakes in the Mississippi River alluvial floodplain were dated using lead-210 decay rates and bomb-pulse derived cesium-137 with the goal of relating trends in sedimentation rate to reductions in erosion due to management practices. It was found that the radioisotope dating methods were best used in concert with known dates for implementation of management practices. Changes in sedimentation rate over time frames as short as 12 years were detectable. Larger lakes showed smaller changes in sedimentation rate relative to smaller lakes.

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