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Can channel banks be the dominant source of fine sediment in a UK river?: an example using 137Cs to interpret sediment yield and sediment source

Pulley, S. and Foster, I. D. L. (2017) Can channel banks be the dominant source of fine sediment in a UK river?: an example using 137Cs to interpret sediment yield and sediment source. Earth Surface Processes and Landforms. 42(4), pp. 624-634. 0197-9337.

Item Type: Article
Abstract: Cultivated fields have been shown to be the dominant sources of sediment in almost all investigated UK catchments, typically contributing 85 to 95% of sediment inputs. As a result, most catchment management strategies are directed towards mitigating these sediment inputs. However, in many regions of the UK such as the Nene basin there is a paucity of sediment provenance data. This study used the 137Cs inventories of lake and floodplain cores as well as the 137Cs activities of present day sediment to determine sediment provenance. Sediment yields were also reconstructed in a small lake catchment. Low 137Cs inventories were present in the lake and floodplain cores in comparison to the reference inventory and inventories in cores from other UK catchments. 137Cs activities in the present day sediments were low; falling close to those found in the channel bank catchment samples. It was estimated that 60 to 100% of the sediment in the Nene originated from channel banks. Pre 1963 sediment yields were approximately 11.2 t km-2 yr-1 and post 1963 was approximately 11.9 t km-2 yr-1. The lack of increased sediment yield post 1963 and low sediment yield is unusual for a UK catchment (where a yield of 28 to 51 t km-2 yr-1 is typical for a lowland agricultural catchment), but is explained by the low predicted contribution of sediment from agricultural topsoils. The high channel bank contribution is likely caused by the river being starved of sediment from topsoils, increasing its capacity to entrain bank material. The good agreement between the results derived using cores and recently transported sediments, highlight the reliability of 137Cs when tracing sediment sources. However, care should be taken to assess the potential impacts of sediment particle size, sediment focusing in lakes and the possible remobilisation of 137Cs from sedimentary deposits.
Subjects: G Geography. Anthropology. Recreation > GB Physical geography > GB651 Hydrology. Water > GB980 Ground and surface waters > GB1201 Rivers. Stream measurements
Q Science > QE Geology > QE500 Dynamic and structural geology > QE571 Sedimentation and deposition
Creators: Pulley, Simon and Foster, Ian D L
Publisher: John Wiley & Sons
Faculties, Divisions and Institutes: Faculties > Faculty of Arts, Science & Technology > Environmental Science
Date: 20 March 2017
Date Type: Publication
Page Range: pp. 624-634
Journal or Publication Title: Earth Surface Processes and Landforms
Volume: 42
Number: 4
Language: English
ISSN: 0197-9337
Status: Published / Disseminated
Refereed: Yes

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