IMT Lille Douai, Univ. Lille, EA 4515, LGCgE, Civil Engineering and Environmental Department, F-59000 Lille, France; MINES ParisTech, PSL Research University, Center of Geosciences, 35 rue Saint-Honoré, 77305 Fontainebleau Cedex, France.
IMT Lille Douai, Univ. Lille, EA 4515, LGCgE, Civil Engineering and Environmental Department, F-59000 Lille, France.
Sci Total Environ. 2019 Jun 10;668:457-469. doi: 10.1016/j.scitotenv.2019.02.458. Epub 2019 Mar 1.
Since a few years, land use management aims to reduce and control water erosion processes in watersheds but there is a lack of quantitative information on the contribution of the sources of transported sediment. This is most important in agricultural areas where soils are sensitive to erosion. The geology of these areas is often characterized by large expanses of relatively homogeneous quaternary silts. The possibility of distinguishing the sources of erosion according to their geological substratum is thus very delicate. This information is important because its lack can lead to the mis-implementation of erosion control measures. To address this request, a confluence-based sediment fingerprinting approach was developed on the Canche river watershed (1274 km; northern France), located in the European loess belt, an area that is affected by diffuse and concentrate erosion processes. Suspended particulate matter was collected during five seasonal sampling campaigns using sediment traps at the outlet of each tributary and confluence with the main stream of the Canche river. The final composite fingerprint was defined using physico-chemical and statistical analyses. The best tracer parameters for each tributary were selected using stepwise discriminant function analyses. These parameters were introduced into a mass balance mixing model incorporating Monte-Carlo simulations to represent the uncertainty. Estimates of the overall mean contributions from each tributary were quantified at different temporal scales. The annual sediment flux tributaries contributions range from 3 to 22% at the outlet of the Canche river, and annual sediment flux range from 0.87 to 40.7 kt yr. The Planquette and the Créquoise tributaries appear to be those producing the largest sediment flux. In contrast, tributaries with the highest number of erosion control on their area exhibit the lowest values of sediment flux. Our results indicate a positive impact of recent land management policies in the Canche river watershed.
几年来，土地利用管理旨在减少和控制流域的水蚀过程，但对于输移泥沙的来源的贡献缺乏定量信息。在土壤容易受到侵蚀的农业区，这一点尤为重要。这些地区的地质通常以大面积相对均匀的第四纪粉土为特征。因此，根据其地质基底区分侵蚀源的可能性非常微妙。由于缺乏这种信息，可能会导致侵蚀控制措施的错误实施。为了满足这一要求，在位于欧洲黄土带的坎什河流域（1274 公里；法国北部）开发了一种基于汇流的泥沙示踪方法。该流域受到弥散和集中侵蚀过程的影响。在五个季节性采样期间，使用沉积物陷阱在每个支流的出口处和与坎什河干流的汇合处收集悬浮颗粒物。使用物理化学和统计分析对最终的综合示踪剂进行定义。使用逐步判别函数分析选择每个支流的最佳示踪剂参数。这些参数被引入一个包含蒙特卡罗模拟的质量平衡混合模型，以表示不确定性。在不同的时间尺度上量化了每个支流的总平均贡献。支流的年泥沙通量贡献范围在坎什河出口处从 3%到 22%，年泥沙通量范围从 0.87 到 40.7kt/yr。普兰奎特和克里夸兹支流似乎是产生最大泥沙通量的支流。相比之下，在其流域面积上实施了大量侵蚀控制措施的支流，其泥沙通量值最低。我们的结果表明，坎什河流域最近的土地管理政策产生了积极影响。
