Biomic river restoration: A new focus for river management

Abstract

River management based solely on physical science has proven to be unsustainable and unsuccessful, evidenced by the fact that the problems this approach intended to solve (e.g., flood hazards, water scarcity, and channel instability) have not been solved and long-term deterioration in river environments has reduced the capacity of rivers to continue meeting the needs of society. In response, there has been a paradigm shift in management over the past few decades, towards river restoration. But the ecological, morphological, and societal benefits of river restoration have, on the whole, been disappointing. We believe that this stems from the fact that restoration overrelies on the same physical analyses and approaches, with flowing water still regarded as the universally predominant driver of channel form and structural intervention seen as essential to influencing fluvial processes. We argue that if river restoration is to reverse long-standing declines in river functions, it is necessary to recognize the influence of biology on river forms and processes and re-envisage what it means to restore a river. This entails shifting the focus of river restoration from designing and constructing stable channels that mimic natural forms to reconnecting streams within balanced and healthy biomes, and so levering the power of biology to influence river processes. We define this new approach as biomic river restoration.

Using diatoms to assess river restoration: A pilot study in Whychus Creek, Oregon, USA

“…River restoration seeks to reinstate impaired stream functions, forms and habitats (Geist & Hawkins, 2016;Johnson et al, 2019) often with the aim of aiding the recovery of a particular riverine species that has been driven close to extinction by alteration of the river environment.…”

Invasive Japanese knotweed (Reynoutria japonica Houtt.) and related knotweeds as catalysts for streambank erosion

“…Mindful actions taken against R. japonica and its relatives should provide social, environmental, and financial benefits, and be a promising first step towards biomic river restoration (Johnson et al, 2020). By mindful, we mean acknowledging the constant labour and dogged persistence needed for non‐chemical control methods, as well as the negative risks and externalities associated with chemical control; while similarly acknowledging that taking no action can be worse than not accepting such challenges.…”

Biogeomorphology, quo vadis? On processes, time, and space in biogeomorphology

“…When searching for adequate NbS, it is essential to define the scale(s) of interest and assess the strength of cross‐scale dynamics (e.g. Allen and Holling, 2010; Naylor et al ., 2017; Gurnell et al ., 2019; Johnson et al ., 2020; Polvi et al ., 2020). This may allow weighting how changes at one level may propagate across scales, or how legacies at the higher scale may hinder/reinforce desired management goals. Allow for the cyclicity of natural processes.…”

“…For managers of coastal, fluvial and hillslope environments, a stable system may be preferable. However, for long‐term cost‐effective and sustainable application of NbS (Johnson et al ., 2020), it is important to recognize the importance of naturally occurring unstable phases in biogeomorphic systems (e.g. succession after disturbance; Toone et al ., 2014) and therefore account for the associated uncertainties during planning (Darby and Sear, 2008).…”

“…Monitoring of NbS can greatly improve our understanding of biogeomorphic feedback systems across a variety of scales and for a range of environments, adding to the scientific knowledge base. Many monitoring campaigns focus on a limited number of parameters but to better understand and evaluate biogeomorphic feedback systems, programmatic, richer, and smarter (matched in space and time) monitoring design is required (Weber et al ., 2018; Firth et al ., 2020; Johnson et al ., 2020; Seddon et al ., 2020; Viles, 2020). By including these requirements in the NbS project proposal, evaluation of the effectiveness of the NbS will be better informed and, importantly, in doing so lessons may be learned on biogeomorphic feedback systems facilitating the NbS.…”