Subsurface sources contribute substantially to fine‐grained suspended sediment transported in a tropical West African watershed in Burkina Faso

A - Papers appearing in refereed journals

Rode, M., Op de Hipt, F., Collins, A. L., Zhang, Y., Theuring, P., Schkade, U-K. and Diekkruger, B. 2018. Subsurface sources contribute substantially to fine‐grained suspended sediment transported in a tropical West African watershed in Burkina Faso. Land Degradation & Development. 29 (11), pp. 4092-4105.

AuthorsRode, M., Op de Hipt, F., Collins, A. L., Zhang, Y., Theuring, P., Schkade, U-K. and Diekkruger, B.
Abstract

Increasing watershed sediment yields is an important problem in Africa, but the sources of these sediment yields have only very rarely been investigated. This study therefore aims to discriminate subsurface and surface sources of fine‐grained sediments in a representative mesoscale (580 km2) West African savanna watershed. We used a sediment source fingerprinting approach for source apportionment including geochemical and radionuclide (137Cs, 210Pbex, and 7Be) composite signatures where 7Be was used as a tracer for the first time in the African environment. Two field campaigns were conducted collecting a total of 258 geochemical and 66 isotope samples. We found that subsurface source categories, dominantly river bank, contributed an unexpected high share of 43% (geochemistry) and 45% (radionuclides) to the sampled
fine‐grained sediments. Pairwise comparison of the averaged frequency distributions for predicted source proportions using five geochemical signatures with the frequency distribution generated using the single radionuclide signature suggested that the two distributions are not statistically different. Extrapolating our measured
contribution of subsurface erosion to areas with similar yields in comparable environmental settings, we can assume that subsurface sources are an important component of sediment loss across large areas of West Africa. Subsurface erosion, primarily associated with bank rather than gully erosion, is likely to increase in the future with projected rises in run‐off due to land use and climate change. Source tracing studies need to be undertaken more widely across Africa to help mitigation planning for sediment-related and land degradation problems.

Keywords137Cs; 210Pbex; 7Be; Fingerprinting; River bank erosion; Suspended sediment; West Africa
Year of Publication2018
JournalLand Degradation & Development
Journal citation29 (11), pp. 4092-4105
Digital Object Identifier (DOI)doi:10.1002/ldr.3165
Web address (URL)https://onlinelibrary.wiley.com/doi/full/10.1002/ldr.3165
Open accessPublished as non-open access
FunderBiotechnology and Biological Sciences Research Council
German Ministry of Education and Research
Funder project or codeS2N - Soil to Nutrition - Work package 3 (WP3) - Sustainable intensification - optimisation at multiple scales
Output statusPublished
Publication dates
Online09 Nov 2018
Publication process dates
Accepted11 Sep 2018
Copyright licensePublisher copyright
PublisherWiley
ISSN1085-3278

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