Modular River Survey

Trees, wood and beavers were once widespread natural features of British rivers and they have been a focus of our research since the 1970s.

Wood and trees interact with river flows and transported sediments to create complex and biodiverse river systems. Beavers add to this complexity by felling trees, constructing beaver dams and canals, and inducing side channels and wetlands to develop.

In the UK, widespread tree and wood clearance over centuries and the extirpation of beavers has degraded our river systems. However, over the last 50 years the importance of trees and wood for our river systems has begun to be recognized.

Wood is now being reintroduced into rivers through less severe riparian tree and wood management, the introduction of wood structures in river restoration designs, and most recently in the form of leaky barriers within Natural Flood Management (NFM) schemes.

Most recently, beavers have started to be reintroduced. Our Riverwood and MoRPh surveys provide robust monitoring tools to quantify wood and tree impacts on rivers.

Sponsors and Collaborators #

In alphabetical order:

Environment Agency, Kings College London, Natural Environment Research Council, Queen Mary University of London, Scottish Natural Heritage (now NatureScot), University of Birmingham, University of Southampton.

Webinar #

Webinar hosted by the Royal Geographical Society and British Society for Geomorphology: ‘Learning from nature – Supporting NFM design while enhancing river form and function’. https://www.rgs.org/events/talks-on-demand/learning-from-nature-nfm

Selected Publications #

Research Reviews #

Gurnell, A.M., Gregory, K.J. and Petts, G.P., 1995. The role of coarse woody debris in forest aquatic habitats: implications for management. Aquatic Conservation 5, 143-166. https://doi.org/10.1002/aqc.3270050206

Gurnell, A.M., 1998 The hydrogeomorphological effects of beaver dam building activity. Progress in Physical Geography, 22, 167-189. https://doi.org/10.1177/030913339802200202

Gurnell, A.M., Piégay, H., Swanson, F. and Gregory, S., 2002. Large wood and fluvial processes. Freshwater Biology, 47, 601-619. https://doi.org/10.1046/j.1365-2427.2002.00916.x

Gurnell, A.M., Tockner, K., Petts, G.E., Edwards, P.J., 2005. Effects of deposited wood on biocomplexity of river corridors.. Frontiers in Ecology and Environment, 3, 377-382. https://doi.org/10.1890/1540-9295(2005)003[0377:EODWOB]2.0.CO;2

Ruiz-Villanueva, V., Piégay, H., Gurnell, A., Marston, R., Stoffel, M. 2016. Recent advances quantifying the large wood cycle and dynamics in river basins: new methods, remaining challenges. Reviews of Geophysics. 54, 611–652. https://doi.org/10.1002/2015RG000514

Gurnell, A.M., Burgess-Gamble, L., England, J. 2018. Trees and wood: working with natural river processes. Water and Environment Journal, 33, 342-352. https://doi.org/10.1111/wej.12426

Grabowski, R.C., Gurnell, A.M., Burgess-Gamble, L., England, J., Holland, D., Klaar, M.J., Morrissey, I., Uttley, C., Wharton, G. 2018. The current state of the use of large wood in river restoration and management. Water and Environment Journal 33, 366-377. https://doi.org/10.1111/wej.12465

Wohl, E., Comiti, F., Fausch, K., Gurnell, A.M., Jaeger, K., Kramer, N., Lininger, K., Piégay, H., Ruiz-Villanueva, V., Scott, D., Stout, J., Walters, D. 2019. The natural wood regime in rivers. BioScience, 69, 259-273. https://doi.org/10.1093/biosci/biz013

Gurnell, A.M., Bertoldi, W. 2020. Wood in fluvial systems. In: Shroder, J.J.F. Editor in Chief), Wohl, E. Ed.), Treatise on Geomorphology. Academic Press, San Diego, CA, https://doi.org/10.1016/B978-0-12-409548-9.12415-7

Research Projects #

Gregory, K.J., Gurnell, A.M. and Hill, C.T., 1985. The permanence of debris dams related to river channel processes. Hydrological Sciences Journal 30, 371-381.

Gurnell, A.M. and Sweet, R., 1998. The distribution and magnitude of large woody debris accumulations and pools in relation to woodland stream management. Earth Surface Processes and Landforms, 23, 1101-1121. https://doi.org/10.1002/(SICI)1096-9837(199812)23:12%3C1101::AID-ESP935%3E3.0.CO;2-O

Gurnell, A.M., Petts, G.P., Hannah, D.M., Smith, B.P.G., Edwards, P.J., Kollmann, J., Ward, J.V., Tockner, K., 2000. Wood storage within the active zone of a large European gravel-bed river. Geomorphology, 34, 55-72. https://doi.org/10.1016/S0169-555X(99)00131-2

Bertoldi, W., Gurnell, A.M., Welber, M. 2013. Wood recruitment and retention: The fate of eroded trees on a braided river explored using a combination of ﬁeld and remotely-sensed data sources, Geomorphology, 180-181, 146-155. https://doi.org/10.1016/j.geomorph.2012.10.003

Bertoldi, W., Welber, M., Gurnell, A.M., Mao, L., Comiti, F., Tal, M. 2015. Physical modelling of the combined effect of vegetation and wood on river morphology, Geomorphology, 246: 178-187. https://doi.org/10.1016/j.geomorph.2015.05.038

England, J., Dobbek, L., Finn Leeming, B., Gurnell, A.M., Wharton, G. 2019. Restoration of a chalk stream using wood: evidence of habitat improvements. Water and Environment Journal, 33, 378-389. https://doi.org/10.1111/wej.12466

Gurnell, A.M., Hill, C.T., Davis, R.J., Tooth, S. 2022. Trees, large wood and streams: using archive survey data to inform changing interactions in a human-impacted landscape. Earth Surface Processes and Landforms. https://doi.org/10.1002/esp.5453

Gurnell, A.M., Hill, C.T., Tooth, S., 2025. Surveys conducted a third of a century apart reveal changes to in-stream large wood, riparian vegetation and stream planform in response to management within a UK national park.Earth Surface Processes and Landforms, 50: e70025. https://doi.org/10.1002/esp.5267

Gurnell, A.M. and Gurnell, J. 2026. A preliminary assessment of the effects of beaver engineering on river condition and its relevance for Biodiversity Net Gain, Journal of Environmantal Management, 401. https://doi.org/10.1016/j.jenvman.2026.128818

Reports #

Gurnell, A.M., 1997. Analysis of the effects of beaver dam building activities on local hydrology, Scottish Natural Heritage Review Series, Volume 85. https://www.nature.scot/doc/naturescot-review-85-analysis-effects-beaver-dam-building-activities-local-hydrology