River Restoration. Группа авторов
landscape, the number of visitors). To alleviate this problem, authors often conduct a monetary evaluation of the benefits of restoration. The monetary amount resulting from this evaluation is more readily comparable to costs. Money is thus used as the “common denominator” in cost–benefit analyses (Brouwer and Sheremet 2017). Several meta‐analyses of the scientific literature dealing with nonmarket valuation of benefits have been undertaken within the field of river restoration (e.g. Bergstrom and Loomis 2017; Brouwer and Sheremet 2017).
It is possible to distinguish, within the literature, two main approaches to the monetary valuation of the benefits of restoration (Figure 1.12). The first is the benefit transfer approach, which is based on existing data on the value of certain ecosystem services. These data, measured, for example, on a previous restoration project, are used to deduce the value of the same services on another project at another site. This approach is generally used when study resources do not permit the production of primary data. For example, Alam (2008) used the work of Haque et al. (1997) to estimate the benefits produced by the restoration of the Buriganga River (Bangladesh) in terms of health and housing and land values. Several authors call for great caution in the use of this method because of the significant biases that exist when extrapolating data from one area to another, particularly because of the heterogeneity of their characteristics (e.g. Brouwer et al. 2016; Lewis and Landry 2017).
Figure 1.12 Economic methods used in international scientific publications to assess the benefits of river restoration.
The second approach to assessing benefits, utilized in the majority of publications, is through primary evaluation exercises. This includes all methods that produce data specific to one or a set of restoration projects. Among them, price‐based methods are currently seldom applied to restoration projects. These methods use the amounts of actual transactions for certain ecosystem services. For example, Vermaat et al. (2016) accounted for the benefits of several European restoration projects using, among other things, the real market prices of certain supplies (e.g. agricultural commodities, drinking water), regulations (e.g. fertilizers), and cultural services (e.g. fishing and hunting licenses, kayak rentals).
Cost‐based approaches are more represented in the scientific literature. These use the costs incurred in the absence of the ecosystem services as a proxy for ecosystem services values. For example, this method is used by Kenney et al. (2012, p. 608) to “estimate the cost‐effectiveness of restoration for infrastructure protection by comparing it to the avoided cost of riprap bank protection.”
Revealed preference approaches are used in about a quarter of primary assessments. These consist of the analysis of individual choices in marketable goods transactions. Individual preferences reveal the market value of these goods. For example, some studies conduct hedonic pricing approaches and examine changes in real estate prices in the context of river restoration (e.g. Chen 2017; Lewis and Landry 2017; Netusil et al. 2019). Others conduct travel cost approaches and measure the amount people pay to access a service (e.g. Loomis 2002; Becker and Friedler 2013; Akron et al. 2017).
Finally, stated preference methods are the most used in the field of river restoration. These methods simulate a market for ecosystem services through surveys of hypothetical changes in the provision of ecosystem services. People are asked to indicate explicitly or implicitly their willingness to pay for positive change (e.g. Loomis 1996; Chen et al. 2017; Vásquez and de Rezende 2019) or their willingness to accept negative change (e.g. Zhang et al. 2019). The extensive use of stated preference methods echoes the recommendations of some authors (e.g. Honey‐Rosés et al. 2013) who prefer, for operational reasons, to use approaches that rely on the demand for services to qualify their value. Generally speaking, these are more directly anchored in the reality and social expectations of the studied area.
Finally, it should be noted that these different approaches are not exclusive and that many studies use several of them to address the various benefits of restoration in a holistic manner. In this perspective, many authors refer to the conceptual framework of “total economic value” (TEV) (Randall 1987).
The perspectives adopted in the publications are, however, heterogeneous. Some authors focus their attention on a single type of service for which they wish to estimate the value. For example, Grossmann (2012) aimed to assess the economic benefits of retention of river‐carried nutrients by floodplain wetlands. This evaluation of a so‐called regulating ecosystem service (MEA 2005) had a demonstrative value, aiming to highlight the shadow price of the alluvial plains of the Elbe basin (Germany) according to evaluation of their capacity to retain pollutants. Following more pragmatic and operational approaches, other authors have attempted to estimate the value of ecosystem services based on the social demand for them, not only on their level of availability/supply (Honey‐Rosés et al. 2013). These approaches generally lead the authors to anchor their thinking to a specific restoration project. It is then a question of determining all the services that could be affected and measuring the overall benefit to society. These approaches based on the assessment of social demand for ecosystem services sometimes mobilize different scenarios corresponding to different restoration measures. By evaluating the fluctuation of assigned value according to different scenarios, these studies make it possible to prioritize the measures to be implemented within the project. For example, several cost–benefit analyses of restoration projects in the field of pollution treatment carried out on the Alexander‐Zeimar and Kishon rivers (Israel) show that, while the most ambitious restoration measures may present the best cost–benefit ratios (Becker and Friedler 2013), more‐targeted restoration measures may sometimes be more economically profitable (Becker et al. 2019).
Among the publications reviewed, few presented a negative economic balance of river restoration projects (e.g. Lee and Jung 2016). Most report excess cost–benefit analyses (e.g. Lee 2012; Polizzi et al. 2015; Kim et al. 2018; Logar et al. 2019). In other words, river restoration projects are presented as being economically profitable overall in relation to the benefits they produce. However, these publications show that not all services are equal when it comes to understanding the overall benefit of restoration projects. Some projects do not stand up to cost–benefit analyses if they do not take into account cultural services, particularly aesthetic or recreational services (e.g. Kenney et al. 2012; Garcia et al. 2016). The authors of these studies also underline the importance of these specific services for supporting river restoration policies, especially in urban areas. Cultural objectives, particularly landscape and recreational objectives, can also be added to traditional ecological objectives to strengthen the social amenities of rivers, and these are known to greatly increase the value of projects (e.g. Bae 2011).
A number of publications also discuss the fact that the assessment of restoration benefits is highly dependent on the spatial and temporal scale at which one places oneself (e.g. Turner and Boyer 1997; Becker et al. 2014). For example, there may be imbalances between the territories that pay for projects and those that benefit from them. Thus, Logar et al. (2019) highlight the tensions that exist in Switzerland between the scales at which projects are financed (national scale) and the scales at which projects are implemented (local scale), and they stress the interest in securing additional local funds to guarantee territorial equity. From a temporal point of view, Polizzi et al. (2015) showed that the benefits of a restoration project undertaken in Finland offset the costs in only 3–10 years, whereas Garcia et al. (2016) estimated the net benefit of an Israeli project at 30 years. Any evaluation of river restoration cannot be separated from consideration of the timescales of the project and its benefits.
Table 1.4 How are the notions of “preference” and “willingness” defined in the literature on the societal stakes of river restoration?
| Preference |
The notion of preference is used recurrently in |