Appendix 3. Literature Review

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The benefit of river restoration (including floodplain connection) work needs to be assessed over both the short- and long-term to determine the degree of scheme success. As discussed by Roni (2005), Downes et al (2002) and Stewart- Oaten (1986) ideally monitoring should include Before and After assessment of what is referred to as the Impact reach together, with, where possible, a Control site for comparison. This approach is commonly referred to as the BACI method. In order to carry out such an assessment a combination of qualitative and or quantitative monitoring needs to be completed but determining the appropriate mix (i.e. where to concentrate effort) requires a clear set of objectives.

1. Evidence and knowledge base

The fact that river restoration and rehabilitation work generally lacks the evidence to demonstrate conservation benefit is widely asserted (Pullin and Knight, 2003; Sutherland et al., 2004; Pullin and Knight, 2009). As a result the proliferation of enhancement projects on the ground in the last few decades (Miller et al., 2010) has meant that the development of technology and techniques has rather outpaced the supporting science.

Of the most widely available literature, studies from the USA predominate. This is perhaps to be expected, however, owing to the fact that stream habitat enhancement was first popularized here, and also the sheer size of the country. Some early published attempts to evaluate the success of these endeavours relate to the durability of log structures in the north-eastern (Tarzwell, 1937) and Pacific states (Ehlers, 1956). The major increase in projects across the Atlantic since the 1990s has since been accompanied by a growing body of evaluation and monitoring literature (e.g., Lepori et al., 2005; Kail et al., 2007; Habersack et al., 2009).

Another bias which is important to note is that towards that discussion of monitoring of physical, rather than biological effects of restoration (Roni et al., 2002; Alexander and Allan, 2007), and within the latter, a strong bias towards the effects on fish (Pretty et al., 2003; McDonald et al., 2007; Baldigo and Warren, 2008). The particular interest in, more specifically, salmonid responses is likely due to the relative ease of collection and handling of the types of data involved and the fact that the motivation behind the majority of projects implemented globally has traditionally been enhancement of these fisheries. Indeed, Roni et al. (2008) cite Parish‟s suggestion (2004) that decline in important food fisheries may be a key driver of watershed and river restoration in developing countries into the future.

2. The big picture

In general, monitoring is not the norm for enhancement and rehabilitation projects, and so there is a very limited pool of information from which authors may draw. In conducting the US National River Restoration Science Synthesis (outputs available at, Bernhardt et al. (2007) found that only 10% of 37,099 projects included in the exercise had any form of assessment or monitoring. This, and the fact that the subject of monitoring is complex and multi-faceted, have led to most literature taking the form of opinion-style papers. The scarcity of controlled experiments has proven a significant obstacle in attempts at meta-analyses (Miller et al., 2010) and drawing conclusions from detailed reviews (Roni et al., 2002; Follstad Shah et al., 2007; Kondolf et al., 2007; Palmer et al., 2007; Roni et al., 2008). The necessary retrospective use of data collected for different purposes is fraught with problems, but usually the only way to proceed with these wider analyses.

3. Objective setting and monitoring design

Alexander and Allan (2007), like many others (e.g., Giller, 2005; Christian-Smith and Merenlender, 2008; Mant and Janes, 2008; O'Donnell and Galat, 2008), assert that, where monitoring is undertaken, appraisal is often hampered by the lack of a fully developed concept of the desired project outcomes. That there are no universal success criteria is widely acknowledged (Wohl et al., 2005) but Palmer et al. (2005) suggest five very generic properties which successful projects share:

  • There is a guiding image of the dynamic state to be restored;
  • There are measurable improvements in ecosystem properties;
  • Resilience is increased;
  • The works cause no lasting harm to the system; and
  • Some form of ecological assessment is completed.

When considering specific objectives which may be interrogated by monitoring, non- linear ecological responses and the high degree of variability in measurable ecosystem components are widely discussed issues (Heino et al., 2004; Nilsson et al., 2005; Wohl et al., 2005; Alexander and Allan, 2007; Schiemer et al., 2007). Being two of the most frequently monitored elements, the responses of fish (Pretty et al., 2003; Shields Jr. et al., 2003; Baldigo and Warren, 2008) and invertebrates (Harris et al., 1995; Miller et al., 2010) generate particular interest. Opinion on the best approach to objective setting in light of this is well established – to seek suitable control data from a similar, un-impacted (or less impacted) control site.

Wohl et al. (2005) go into detail as to how reference sites might be selected, and propose that projects should aim to restore the „normal‟ range of measured variables, rather than any fixed endpoint. Furthermore, this focus on processes rather than specific habitats or species represents an increasingly prevalent guiding principle (e.g., Roni et al., 2002; Clarke et al., 2003; Schiemer et al., 2007; Habersack et al., 2009). Indeed, results of studies have often shown little benefit to monitored target organisms unless very specific structural heterogeneity requirements are met (e.g., Pretty et al., 2003; Lepori et al., 2005).

4. A question of scale

The spatial extent and period of monitoring represent the bottom line of requirements for project managers, though the consensus among academics is that these must be determined on a case-by-case basis, and depend on what aspects are being monitored. Where geomorphological effects may be very quickly apparent (Habersack and Nachtnebel, 1995; Clarke et al., 2003; Shields Jr. et al., 2003; Caruso, 2006), ecological responses may take many years to occur (Roni et al., 2002; Shields Jr. et al., 2003; Heino et al., 2004) and, owing to natural variability, decades to detect (Downs and Kondolf, 2002; Klein et al., 2007; Baldigo and Warren, 2008). Florsheim et al. (2006) have looked at flow threshold models to identify when morphological monitoring may be necessary, and authors such as Bryant (1995) have been proponents of a pulsed approach to monitoring, with short periods of more intensive study spread over a longer period. With regard to the spatial extent of monitoring, again, highly naturally variable systems may require comprehensive monitoring, and details depend on the specific project context, particularly consideration of the reference, or control reach(es) (Wohl et al., 2005). Roni et al. (2002) highlight in their review our poor understanding of the links between wider physical processes and in-stream ecology, making particular reference to landslides, roads and grazing, while Miller et al. (2010) found the strength and consistency of invertebrate responses to be particularly related to watershed-scale conditions. Both of these points, together with the fact that it is usually the aim and effect of rehabilitation projects to increase spatial heterogeneity, suggest that one should perhaps pay more close attention to the wider context when planning monitoring.

5. How to proceed?

River restoration can be an expensive enterprise – Bernhardt et al. (2007) estimate an annual expenditure of over $1 billion in the US – and financial restrictions which lead to the neglect of monitoring, despite the fact that there is little doubt as to its value, are widely acknowledged (e.g., (Alexander and Allan, 2007; England et al., 2008)). Beyond practical requirements for adaptive management and feedback to the design of projects and techniques, funding mechanisms and policy drivers increasingly require demonstration of success. This will be welcomed by authors such as Bash and Ryan who, in 2002, found that only 18% of projects they studied explicitly required any monitoring (Bash and Ryan, 2002); Wohl et al. (2005); and Gillilan et al., who advocated that sponsors make project appraisal a requirement (Gillilan et al., 2005). Furthermore, Palmer et al. (2007) argue that, for the success of future projects, dissemination of such information should be obligatory. Despite there being a significant body of available academic literature (note especially Vol 15(3) of Restoration Ecology, and the forthcoming special issue of Hydrology and Earth System Sciences), guidance on the monitoring of river restoration is very rare (Woolsey et al., 2007). Phil Roni‟s book „Monitoring Stream and Watershed Restoration‟ (2005) is perhaps the only comprehensive document available, though „Monitoring ecological impacts: concepts and practice in flowing waters‟, edited by Barbara Downes et al. (2002) is also of note. „River Restoration: Managing the

Uncertainty in Restoring Physical Habitat‟, edited by Darby and Sear (2008) sets the context well and explores the concepts and manifestation of „success‟ in river restoration, but without detailing methods and procedures. The current document (PRAGMO) therefore, building on the frameworks developed in Mant and Janes (2008) and England et al. (2008), represents a significant step forwards, in addressing this need and keeping practitioners in close contact with the wide-ranging expertise related to this necessarily interdisciplinary business of river restoration.

6. River Restoration Design and Appraisal Process

Figure 3.2 (adapted from Bruce-Burgess 2004) outlines a 3 phased process which should be followed for any restoration project; others have also made excellent attempts to outline a pragmatic approach to the river restoration process with Holl and Cairns (1996) with adaptations by Woolsey et al (2007) and in particular stating 5 phases name: strategic planning, a preliminary phase where objectives are set, project planning, project execution and utilisation which includes project assessment. What is general missing from these approaches is a detailed explanation of how the appraisal process should be clearly shaped to ensure answer to specific questions can be answered.

7. Indirect Literature

There are a number of scientific papers which refer indirectly to river restoration monitoring. This indirect or „grey‟ literature is listed in the Reference Section under a separate heading.