Author: Kevin Werbylo

Post Date: 7/8/2016

Contributed by Kevin Werbylo, Headwaters Corporation

Oftentimes, articles posted in academic journals (i.e., Water Resources Research, Journal of Hydrology, etc.) are exceptionally informative and relevant to the work performed by water resources professionals, but the articles themselves are not read by many non-academic practitioners. Here, I attempt to address this issue by providing an extended summary of a journal article that is very relevant to all professionals who practice river restoration. The paper, “The science and practice of river restoration,” was authored by Ellen Wohl, Stuart N. Lane, and Andrew C. Wilcox, and has five main sections, each of which is summarized below. Many direct quotes are taken from the article (link to the online version of the article: Citations within the article’s direct quotes were included and are provided at the end of this post.

Full citation: Wohl, E., S.N. Lane, and A.C. Wilcox (2015). The science and practice of river restoration, Water Resources Research, 51, 5974 – 5997, doi: 10.1002/2014WR016874.

What is River Restoration?

The authors state that the term “river restoration” is applied to a broad range of activities that “share the goal of improving hydrologic, geomorphic, and/or ecologic processes within a degraded watershed and replacing lost, damaged or compromised elements of a natural system [Wohl et al., 2005],” which can range from “isolated structural modifications such as bank stabilization… to manipulation of ecosystem processes and biota across large river basins over a period of decades [e.g., Warne et al., 2000; Bloesch and Sieber, 2003].” In the end, the authors suggest that river restoration can be used to describe any type of river management activity that “attempts to create or maintain some aspect of river form and function that is desirable apart from hazard reduction [Palmer et al., 2005]” and can include projects aimed at improved “fish habitat, water quality or river recreation, for example.”

Historical Development of River Restoration

The authors point out that although activities aimed at improving river aesthetics and recreation have been conducted for more than 100 years, a large majority of the river engineering activities prior to the late 20th century were focused on “enhancing navigation and reducing the risks of loss of life and property.” These river engineering activities altered rivers so severely that river restoration accelerated in the 1980s, with fish habitat improvement being the main objective. The authors state that although these early efforts were mostly “form-based,” in that they were focused on the “physical manipulation of channel form [Gowan and Fausch, 1996],” a more recent movement has gained traction that promotes “channel-floodplain connectivity and other process-based restoration” efforts aimed at improved water quality.

Current Scope of River Restoration

The authors outline the present-day scope of river restoration by highlighting the activities performed at two different scales: small to medium-sized rivers, and medium-sized to large rivers. In small to medium-sized rivers, restoration efforts are focused on creating step-pools for grade control, naturalization of urban streams, improved water quality in reaches affected by mining operations, offsetting the effects of agriculture and grazing on low-gradient streams, and an overall improvement in water quality. Each of these are accompanied with stories of successes and shortcomings. In medium-sized to large rivers, restoration efforts generally involve removal or setbacks of large structures (levees, dams, etc.), flow releases from dams, sediment augmentation, and the placement of in-channel structures. Again, the authors highlight examples, successes, and shortcomings.

Critical Perspectives on River Restoration

The fact the many river restoration projects fail in one form or another is becoming a commonly acknowledged shortcoming in the restoration community. Here, the authors outline three key research themes that must be addressed in order to advance the practice of restoration: “(1) the problem of conceptualization and how we approach restoration; (2) developing restoration projects at the interface of science and society; and (3) in relation to the science of restoration itself.”

The authors state that the problem of conceptualization and how restoration is approached can be addressed by recognizing that river systems are spatially and temporally variable and that restoration efforts should be focused on the creation of a “dynamic state,” as opposed to a single desired form. The authors state that once this is recognized and restoration goals have been set, three types of restoration can be implemented: (1) form/structure (e.g., meanders); (2) process (e.g., flow regime); and (3) a combination of form and process. Ecologists typically prefer to restore process or a combination of form and process, as these two types of restoration generally tend to promote more sustainable and resilient rivers. The challenge then becomes implementing process-based restoration activities in actual river systems (e.g., changing a flow regime on a highly regulated river, reconnecting the floodplain in an area where people live, etc.).

The authors suggest that the idea of developing restoration projects that consider both science and society is necessary because scientific and societal restoration goals might differ significantly, but both must be considered when setting restoration goals and objectives. This is especially true when considering the role of society in restoration, as projects are often supported “financially, culturally, and politically [Mann et al., 2013; Seidl and Stauffacher, 2013]” by non-scientific communities. Engaging these communities in the planning and goal-setting stage of a restoration project is important and can lead to a more “democratic” restoration process, but it could lead to a potential downfall if these communities do not accept or recognize the benefits of restoration.

The science of river restoration is still under development. The authors urge the use of “response curves,” where responding variables can be monitored in relation to a range of control variables. The curves can be used to measure successes/failures of a project, and in the modeling and planning of future restoration projects. Developing these curves is difficult due to the need to isolate and quantify responding variables when considering potentially numerous controlled (and uncontrolled) variables. Applying these curves, as well as physical and numerical models, at different scales and locations becomes an entirely new problem.

Finally, the authors address changes that are or have been critical in shaping the science of restoration. Stream mitigation banking has provided a means for stream restoration, but allows developers the ability to forgo an actual restoration project by simply buying restoration ‘credits’ at an entirely different location. Technology has facilitated a more widespread collection of data (topographic, biological, etc.), and improved communication between academics, scientists and practitioners, and has led to a greater development and application of the practice of restoration. Monitoring is a challenge because of willingness and funding, and the use of adaptive management is becoming more widespread. The authors list a few “key gaps” in the restoration community, which include: the understanding of sediment balance and the use of bankfull discharge as a design guide, among others.

Concluding Remarks on Article

This article is an outstanding resource not only because of its abundance of information ranging from the history and development of river restoration to key ideas for practitioners to consider going forward, but because of its real-life applicability. Many of the article’s main points, particularly in the Critical Perspectives section (e.g., restoring channel processes as opposed to simply considering channel form, considering political and social approaches to restoration planning and design, etc.), are high-level concepts that we as practitioners should consider every day, but sometimes overlook as we are focused on the nitty-gritty details of analysis and design. Additionally, the article contains hundreds of citations that readers can use as references for additional information on all of its topics.

Additional References

Bloesch, J., and U. Sieber (2003), The morphological destruction and subsequent restoration programmes of large rivers in Europe, Arch. Hydrobiol., 14(3), 14, 363–385.

Gowan, C., and K. D. Fausch (1996), Long-term demographic responses of trout populations to habitat manipulation in six Colorado streams, Ecol. Appl., 6, 931–946.

Mann, K. B., K. A. Berry, S. Bassett, and S. M. Chandra (2013), Voting on floodplain conservation: The role of public values and interactions along the Carson River, Nevada, Soc. Nat. Resour., 26, 568–585.

Palmer, M. A., et al. (2005), Standards for ecologically successful river restoration, J. Appl. Ecol., 42, 208–217.

Seidl, R., and M. Stauffacher (2013), Evaluation of river restoration by local residents, Water Resour. Res., 49, 7077–7087.

Warne, A. G., L. A. Toth, and W. A. White (2000), Drainage-basin-scale geomorphic analysis to determine reference conditions for ecologic restoration – the Kissimmee River, Florida, Geol. Soc. Am. Bull., 112, 884–899.

Wohl, E., P. L. Angermeier, B. Bledsoe, G. M. Kondolf, L. MacDonnell, D. M. Merritt, M. A. Palmer, N. L. Poff, and D. Tarboton (2005), River restoration, Water Resour. Res., 41, W10301, doi:10.1029/2005WR003985.