No abstract

Fine sediment storage within gravel beds is a key component of catchment sediment budgets and affects the health of benthic and hyporheic habitats. Here, we assess the performance of two substrate infiltration traps for the characterization of fine sediment (<2 mm) accumulation. One design, the vertically extending sediment trap, permits both lateral and vertical exchange in the sediment column, whereas the second type, a more traditional fixed-area sediment trap with impermeable side walls, permits only vertical exchange. Traps were deployed at three sites on the River Tame, Birmingham (UK), over varying installation periods (14-401 days). Results indicate that the facilitation of multiple pathways of exchange within the vertically extending sediment traps (vertical and lateral) resulted in a significantly greater amount of fine sediment being accumulated than in adjacent fixed-area sediment traps. This suggests that lateral transport is an important component contributing to fine sediment accumulation. However, there are notable and inherent problems associated with the use of different types of sediment trap and in the way the data should be presented and interpreted. This paper discusses the practical implications of the study findings and reflects on the complexities of undertaking accurate sediment deposition measurements in the field. Excessive quantities of fine sediment stored within river networks is an important driver of aquatic habitat degradation (Descloux, Datry, & Marmonier, 2013;Packman & MacKay, 2003;Phillips & Walling, 1999), which poses a serious long-term threat to in-stream ecosystems (Négrel et al., 2014;Prosser et al., 2001). Fine-grained sediment affects the entire aquatic ecosystem from reducing primary production (Jones, Duerdoth, Collins, Naden, & Sear, 2014;Wagenhoff, Lange, Townsend, & Matthaei, 2013) and altering macroinvertebrate diversity via enhanced drift and direct burial (Larsen & Ormerod, 2010;Wood, Toone, Greenwood, & Armitage, 2005), through to reducing habitat heterogeneity and limiting oxygen exchange within interstitial pore spaces (Huston & Fox, 2015;Owens et al., 2005). Understanding fine --------------------------------------------------------------------------------------------------------------------------------This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

This paper reports on the progress to date of a long-term investigation of the effects of drainage and afforestation on the hydrology of a peat bog near Edinburgh based on the use of runoff plots and other related equipment. The hydrology of the area immediately after ploughing is described and recently collected data are presented to show how this has changed over a six-year period. The main changes appear to be a substantial reduction in water yield and a move towards a less flashy runoff regime. Data are presented to show that these are most probably due to an increase in the amount of rainfall intercepted by the vegetation now covering the area and to a deterioration in the hydraulic efficiency of the drainage network.