River restoration success: a question of perception

Abstract

What defines success and failure of river restoration measures is a strongly debated topic in restoration science, but standardized approaches to evaluate either are still not available. The debate is usually centered on measurable parameters, which adhere to scientific objectivity. More subjective aspects, such as landscape aesthetics or recreational value, are usually left out, although they play an important role in the perception and communication of restoration success. In this paper, we show that different perceptions of restoration success exist by analyzing data from 26 river restoration measures in Germany. We addressed both objective parameters, such as hydromorphological changes and changes in fish and benthic invertebrate assemblages, from field investigations, and subjective parameters, such as opinions and perceptions, from water managers via an online survey. With regard to the objective hydromorphological and biotic parameters, our results agree with many studies that have reported improvements in the hydromorphology following restoration; however, there is no similar agreement between results concerning changes in the benthic invertebrate and fish assemblages. The objective results do not correspond to the subjective parameters because self-evaluation of the restoration projects by water managers was overly positive. Indeed, 40% of the respondents admitted that their evaluation was based on gut feeling, and only 45% of the restoration measures were monitored or occasionally checked. This lack of objectively recorded data meant that the water managers were not able to reasonably evaluate restoration success. In contrast, some self-evaluation responses reflected a different perception of the restoration success that was based on landscape aesthetic values or on benefit for the public; others adopted a general "condemned to success" attitude. Based on our data, we argue (1) that goals should be thoughtfully formulated prior to restoration implementation and (2) that it is necessary to monitor river restoration success from different perspectives.

Demonstration Restoration Measures in Tributaries of the Vindel River Catchment

“…However, even when restoration methods are developed by testing and evaluating innovative components, it is difficult to know when the most appropriate methods have been achieved. Unfortunately, the potential for learning from, and then improving on, restoration efforts is poorly utilized, because few projects are monitored to demonstrate the longer term results of restoration, and even fewer projects will report on failures (Bernhardt et al 2005, Jähnig et al 2011, Kondolf et al 2011). …”

Status of and Perspectives on River Restoration in Europe: 310,000 Euros per Hectare of Restored River

“…Based on the collected answers from the participants, we could not estimate the desirable persistence of the projects' ecological results over a certain duration. Although the goal of a restoration project should be to enhance the existence of resilient river systems, regardless of the duration [3,9,14,15,32], most restoration-related actions are technical interventions (fish-ladder construction, floodplain-lake reconnection, etc.). Hence, these projects could be considered permanent assets that undergo amortization (depreciation over time).…”

Achieving Successful River Restoration in Dense Urban Areas: Lessons from Taiwan

“…Moreover, while Taiwan's local authorities usually allocate relatively small budgets for the maintenance of river projects, local NGOs and communities are widely regarded as a solid, bottom-up force supporting urban river space as a multi-functional natural resource by regular cleaning-up, disposing of rubbish and environmental monitoring [42]. This shows the lack of a sound official post-restoration monitoring measure to assess and report the effectiveness of restoration efforts, reinforcing previous studies indicating that river restoration has largely been done but with no process to evaluate its actual performance [16,25,26,31].…”