The Science of the total environment

1879-10266682019Jun10The Science of the total environmentSci Total EnvironQuantification of tributaries contributions using a confluence-based sediment fingerprinting approach in the Canche river watershed (France).457469457-46910.1016/j.scitotenv.2019.02.458S0048-9697(19)30970-2Since 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 km²; 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^-1. 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.Copyright © 2019 Elsevier B.V. All rights reserved.PataultEdouardEIMT 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. Electronic address: edouard.patault@imt-lille-douai.fr.AlaryClaireCIMT Lille Douai, Univ. Lille, EA 4515, LGCgE, Civil Engineering and Environmental Department, F-59000 Lille, France.FrankeChristineCMINES ParisTech, PSL Research University, Center of Geosciences, 35 rue Saint-Honoré, 77305 Fontainebleau Cedex, France.AbriakNor-EdineNEIMT Lille Douai, Univ. Lille, EA 4515, LGCgE, Civil Engineering and Environmental Department, F-59000 Lille, France.engJournal Article20190301