Turbidity and suspended solids variations downstream of a regulating reservoir

Gilvear, D.J. and Petts, Geoffrey E. (1985) Turbidity and suspended solids variations downstream of a regulating reservoir. Earth Surface Processes and Landforms, 10 (4). pp. 363-373. ISSN 0197-9337

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Official URL: http://dx.doi.org/10.1002/esp.3290100408


A controlled reservoir release from Llyn Celyn to the Afon Tryweryn, Wales, U.K., has been used to study suspended load and turbidity variations. Turbidity was monitored continuously at two sites and 235 suspended solids samples were obtained at these and three additional sites during the passage of the release wave. The results are compared with data for a natural tributary flood event. The reservoir release data relate to sediment source depletion and reflects changing sources along the channel. Close to the dam, fine organic matter dominates the seston which scanning electron microscopy revealed to be predominantly allochthonous organic matter, with algal fragments and inorganic diatom frustules, derived from the periphyton of the channel bed. Coulter Counter analysis showed the seston to be relatively coarse with a median particle-size of 20 m. Within 3 km of the dam, however, minerogenic particles dominate the sediment load of which more than 90 per cent is finer than 10 m. This represents the flushing of channel-bed accumulations derived from tributary sources. The relationships between suspended sediment concentration and turbidity during the release are characterized by a marked, anticlockwise hysteresis. This contrasts with the clockwise hysteresis for the tributary flood event, but the different relationships cannot be explained by particle-size variations alone; seston composition also appears to be an important control.

Item Type: Article
Subjects: University of Westminster > Science and Technology > Life Sciences, School of (No longer in use)
Depositing User: Miss Nina Watts
Date Deposited: 10 Feb 2009 11:56
Last Modified: 22 Dec 2009 10:28
URI: http://westminsterresearch.wmin.ac.uk/id/eprint/5927

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