Leaky Dams
In the UK, small leaky woody dams have become a common flood control practice (focusing on attenuation benefits). In fact, Natural England offers stewardship grants (see RP32: Small Leaky Woody Dams) of £401 to £500 per dam per year. 'Leaky Dams' are another example of inexpensive, low-tech, instream structures designed to emulate specific natural processes.
With these types of structures, some practitioners and designers tend to focus a bit heavily on the stability of the structure itself. This is presumably because it is assumed that failure would be a bad thing, but in natural systems, woody debris jam "failures" and beaver dam "blowouts" are often associated with some of the most diverse habitats and most desirable features. That said, in systems that have ample sediment supplies, such leaky dams can be good at promoting structurally forced riffle features (Wheaton et al. 2015).
A fact sheet from Yorkshire Dales River Trust on Leaky Dams.
Additional reference from Wild Trout Trust
References
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DeVries, P., Fetherston, K.L., Vitale, A., and Madsen, S. (2012). Emulating Riverine Landscape Controls of Beaver in Stream Restoration. Fisheries 37(6): 246-255. DOI: 10.1080/03632415.2012.687263
These "low walls" are very similar to the "leaky dams".
Figure 5 from DeVries et al. (2012) showing log wall and engineered flow-choke structures similar to leaky dams, intended to emulate beaver dam effects. -
Stratford, C., Miller, J., House, A., Old, G., Acreman, M., Dueñas-Lopez, M.A., Nisbet, T., Newman, J., Burgess-Gamble, L., Chappell, N., Clarke, S., Leeson, L., Monbiot, G., Paterson, J., Robinson, M., Rogers, M., and Tickner, D. (2017). Do trees in UK-relevant river catchments influence fluvial flood peaks? CEH Project no. NEC06063, NERC/Centre for Ecology & Hydrology, Wallingford, UK, 46 pp.
Related News -
Wheaton, J., Fryirs, K., Brierley, G.J., Bangen, S.G., Bouwes, N., and O'Brien, G. (2015). Geomorphic Mapping and Taxonomy of Fluvial Landforms. Geomorphology 248: 273–295. DOI: 10.1016/j.geomorph.2015.07.010