Controls on spatial and temporal variations in sand delivery to salmonid spawning riffles

Milan, David

Abstract

Fine sediment infiltration into gravel interstices is known to be detrimental to incubating salmonid embryos. Infiltration into spawning riffles can show large spatial variations at the scale of a morphological unit and over time, with significant implications for embryo survival. Furthermore, some process-based infiltration studies, and incubation-to-emergence models assume that fines are delivered to redds via suspension rather than bedload. This process-based 12-month study examined spatial patterns of predominantly sand infiltration into gravels in an upland trout stream, using infiltration baskets. An assessment of Rouse numbers for infiltrated sand indicated that it was transported predominantly as bedload at flow peaks. Clear temporal and spatial patterns existed, with highest rates of infiltration strongly associated with higher discharges (r2 = 0.7, p < .05). Seasonal variations in the delivery of different grain sizes were also a feature, with enhanced contributions of 0.5–2 mm sediment during elevated winter flows and 0.125–0.5 mm sediment during spring and summer; the latter is potentially harmful to the later stages of embryo incubation. Clear spatial patterns were also evident across riffles, with highest rates of infiltration tending to occur in areas of lower relative roughness—the areas competent to transport sand for longer periods. Incubation-to-emergence models should take into consideration spatial patterns of fine sediment dynamics at the pool–riffle scale, to improve prediction.

Citation

Milan, D. (2017). Controls on spatial and temporal variations in sand delivery to salmonid spawning riffles. Hydrological Processes, 31(12), 2179-2195. https://doi.org/10.1002/hyp.11172

• Journal Article Type: Article
• Acceptance Date: Mar 13, 2017
• Online Publication Date: May 5, 2017
• Publication Date: Jun 15, 2017
• Deposit Date: May 15, 2017
• Publicly Available Date: Mar 20, 2018
• Journal: Hydrological processes
• Print ISSN: 0885-6087
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 31
• Issue: 12
• Pages: 2179-2195
• DOI: https://doi.org/10.1002/hyp.11172
• Keywords: Bedload; Brown trout embryos; Fine‐grained sediment; Hydraulics; Relative roughness; Siltation
• Public URL: https://hull-repository.worktribe.com/output/451362
• Publisher URL: http://onlinelibrary.wiley.com/doi/10.1002/hyp.11172/abstract
• Additional Information: This is the accepted manuscript of an article published in Hydrological processes, 2017. The version of record is available at the DOI link in this record.
• Contract Date: Mar 20, 2018