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| Titel |
Sediment record in a small reservoir in W Scotland: implications of the deposition rate |
| VerfasserIn |
E. Munoz-Salinas, P. Bishop |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250019794
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| Zusammenfassung |
| Widespread landscape responses to the deglaciation of N Britain were glacio-isostatic
rebound and the development of knickpoints (KPs) in many trunk streams and their
tributaries. Since KPs are abrupt steps in the long profile, they were ideal locations for mill
dam construction between the 16th and 19th centuries in Scotland. Data from the sediment
infilling a small mill dam near Loch Lomond are reported here with the goal of understanding
the sedimentation history of the reservoir and its implications. Data were derived from
analyses of a sediment core through the mill dam sediments and an exposed sedimentary
section adjacent to the coring site. Stratigraphic description and analyses on the core, along
with dating using analyses of 137Cs, and 210Pb isotopes, show that the dam was probably
built up around 150 years ago and probably functioned for about 50 years before the dam
wall was breached, leading to fluvial incision through the sediments impounded
in the reservoir. The sedimentary record indicates that coarser material has been
deposited following dam breaching. This observation may indicate an increase in the
river’s erosive capacity but since the channel perimeter up- and down-stream of the
dam is mainly composed of very cohesive sediment and bedrock, dam breaching
seems to have had little impact on channel morphology. This finding highlights the
need to take into account the total landscape setting of a dam when considering the
impacts of dam failure. Settings such as northern Britain, which is dominated by
Holocene surface uplift and bedrock substrates, are probably generally associated
with minimal downstream impact when sediment is released from breached dams. |
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