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Regional variations in the sediment structure of trout streams in southern England: benchmark data for siltation assessment and restoration

Milan, D.J. and Petts, Geoffrey E. and Sambrook, H. (2000) Regional variations in the sediment structure of trout streams in southern England: benchmark data for siltation assessment and restoration. Aquatic Conservation: Marine and Freshwater Ecosystems, 10 (6). pp. 407-420. ISSN 1052-7613

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Official URL: http://dx.doi.org/10.1002/1099-0755(200011/12)10:6...

Abstract

1. Data are presented on the sedimentological characteristics of 51 river reaches which include trout (Salmo trutta) spawning grounds from three different hydrological regions of southern England: I, upland, hard-rock of the south west (20 sites); soft-rock of the east with, II, chalk (11 sites) and III, sandstone or limestone (20 sites). 2. Data were obtained using a standard sampling protocol: at each site, five randomly distributed freeze-cores to a depth of 30 cm were taken to yield a composite weight of at least 20 kg. 3. All sites had a well-developed armour layer and at more than 70% of the sites the armour layer had a median b-axis of more than 35 mm and included some cobbles (stones larger than 64 mm). 4. The substratum at 65% of the Type I sites had less than 10% finer than 1 mm contrasting with all sites of Type II having more than 25% sub-1 mm. The Type II sites contained high levels of sands (0.125-1 mm). Type III sites had a wide range of fine sediments (15-53% sub-1 mm) but were characterized by relatively high silt-clay contents (sub-0.063 mm) which exceeded 10% of the sample weights at six sites. At most sites, lower (15-30 cm) sections contained about twice the loading of fine sediments compared with the surface layer (0-15 cm). 5. A target loading for the substratum of a healthy stream of the important sub-1 mm size fraction is set at 14%. Benchmark particle-size distributions for trout streams in (a) upland and (b) lowland areas are presented for use in assessing levels of siltation and in channel restoration in southern England.

Item Type:Article
Research Community:University of Westminster > Life Sciences, School of
ID Code:5959
Deposited On:10 Feb 2009 15:26
Last Modified:22 Dec 2009 10:19

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