Attitudes of political-administrative decision makers towards the implementation of nature-based solutions in water management – a case study on a hypothetical constructed wetland in the Tárcoles River basin

ABSTRACT

Nature-based solutions (NBS) are actions that help communities address social-ecological challenges such as flooding and polluted groundwater. Nevertheless, research shows that in practice, NBS confront several barriers in planning and implementation, many of which are related to the different attitudes of political and administrative actors. There is knowledge missing on their viewpoints on NBS. We used Q-methodology to explore the attitudes towards the implementation of a constructed wetland as NBS, interviewing decision-makers from the Tárcoles River Basin Commission in Costa Rica, the administrative body in charge of the integrated management of the river. We determined three recognizable viewpoints: ‘the nature lover’, ‘the cost concerned’, and ‘the participation seeker’. Although all members of the commission shared a common vision, it was clear that their priorities differed. Regarding the ways of implementing NBS, interviewees agreed that the country urges a paradigm shift in policy design towards ecosystem-based approaches and emphasized the need for more cooperation among bodies of administration in river basin decision-making. We reflect on the lessons learned to improve planning and implementation of NBS, such as the importance of increasing knowledge and awareness of NBS, the support from all governance levels as well as the cooperation of researchers and policy-makers, and the consideration of NBS financing by private companies.

GRAPHICAL ABSTRACT

EDITED BY:

• Torsten Krause

KEYWORDS:

• Q-methodology
• river restoration
• constructed wetlands
• greywater treatment
• flood protection
• Costa Rica

1. Introduction

Rivers are one of the ecosystems which are most affected by the current climate and biodiversity crises in urban environments. Through human transformation, e.g. to produce energy or serve as drainage, the ecological status of urban rivers has been deteriorated. The consequences are erosion, polluted groundwater resources, increased flooding, a decline in biodiversity, and a loss of esthetics (Sabater et al. 2018). A concept that promises to address these challenges in a sustainable way is nature-based solutions (NBS). NBS are ‘actions which are inspired by, supported by or copied from nature’ (European Commission 2015), or more specifically, actions that (i) alleviate a well-defined societal challenge, (ii) utilize ecosystem processes, and (iii) are embedded within viable governance models (Albert et al. 2019). The term is used as an umbrella term for already existing concepts such as ecosystem-based adaptation or Green and Blue Infrastructure, amongst others (Albert et al. 2021). NBS for river restoration can be distinguished into measures implemented within the river corridor (in-stream) and measures implemented in the river basin (off-stream, basing wide) (Hack and Schröter 2021). An example for a NBS for decentralized water management is the constructed wetland. Their dual function as greywater treatment and flood protection make them particularly interesting in populated parts of riverine landscapes (Pérez Rubí and Stefanakis 2019; Hack 2021).

In recent years, the field of research has been broadened by publications, including on NBS in urban water management in European cities (Oral et al. 2020), the importance of NBS for climate change mitigation (Seddon et al. 2020b), and factors shaping public perceptions of NBS for hydro meteorological risk reduction (Han and Kuhlicke 2019). In addition, there are guidance documents for NBS planning (Albert et al. 2020), research on the governance of NBS in flood management (Zingraff-Hamed et al. 2020) and on the contribution of landscape planning and governance research to NBS development (Albert et al. 2019). Although NBS have the potential to address both environmental and social problems in many ways, various barriers hamper the planning and implementation of NBS in practice (Naumann and Kaphengst 2015; Dorst et al. 2022). These include a significant knowledge deficit regarding effectiveness (Albert et al. 2019), a lack of policy guidance, pilot projects to demonstrate the multiple benefits (Neumann and Hack 2019) and empirical knowledge on governance processes (Wamsler et al. 2020a). Further, the concept has remained highly academic and has not yet transcended the academic-practitioner divide (Seddon et al. 2020b; Neumann and Hack 2022). Although citizens participate in NBS, decision-making collaboration does not always improve the ecological impact (Wamsler et al. 2020b; Kiss et al. 2022). Intermediaries (Frantzeskaki and Bush 2021) and decision makers for river basin management (Albert et al. 2021; Tafel et al. 2022) play a key role for implementation but there is knowledge missing on the viewpoints of these intermediaries and decision makers on NBS. Following Tafel et al. (2022) we define decision-makers as individuals with responsibility for a team and topic within their authority.

To fill this research gap, in this study we aim to explore the different viewpoints of political and administrative actors on the implementation of NBS in the water sector. Particularly, we address the following research questions: What are viewpoints of decision makers towards the implementation of NBS in river basin management? What are the agreements and disagreements among the viewpoints? What can we learn from these viewpoints to improve NBS planning and implementation in general? We examine these questions using the example of the Tárcoles River basin in Costa Rica. In our study, we took a governance and policy process perspective to consider the specific role of river basin commissions and the perceived barriers arising in implementation processes from their viewpoint. Using Q-methodology, we investigate decision-makers´ subjective viewpoints and analyze whether certain patterns emerge and on which differences and prioritizations they are based. Q-methodology represents a research approach at the interface between qualitative and quantitative methods as it captures complex opinion patterns, attitudes and value orientations from a subjective perspective (Müller and Kals 2004). It enables an assessment of subjectivity using factor analysis to explore the viewpoints of participants (Zabala et al. 2018). To analyze the discourse, a sample of statements is used that is sufficiently representative of the full range of statements that could be made about a particular topic. These statements are then ranked by a group of people the researchers have pre-determined as being important (Zabala et al. 2018). Thereby, types of subjective views on a research topic can be defined and from them typical predominating opinions derived (Müller and Kals 2004). Therefore, the Q-methodology is a suitable method to capture the discourse on the NBS topic revealing the viewpoints of decision makers in a certain region.

One of the riverine landscapes with the highest contamination levels in Central America is the Tárcoles River basin (Espinoza and Villalta 2004). Especially in the urban areas, it is a hotspot for water conflicts caused by wastewater inflows, contamination from industry and agriculture, flooding, and deficits in infrastructure (Hernández et al. 2018). The situation of inadequate wastewater infrastructure and treatment, and consequently the large-scale use of septic tanks, is even classified as a national emergency (Quesada 2019). This serious situation not only threatens water supplies and ecosystems, but also damages aesthetics and thereby the attractiveness for tourism and recreation (Espinoza and Villalta 2004). Despite regional and national efforts, improving the situation is a slow and complex process (Quesada et al. 2020). In addition, the Tárcoles River basin is characterized by seasonally high rainfall, which in combination with high degrees of surface sealing results in recurrent flood events (Hernández et al. 2018; Chen et al. 2021).

The Tárcoles River basin qualifies for this study, as implementation barriers should be less strong. First, with the Tárcoles Commission (Commission for the Integral Management of the Grande de Tárcoles River basin – CGICRGT for its name in Spanish) there is a formal coordinating body with representatives of different national and local political entities as well as universities and local non-governmental organizations (Sistema Costarricense de Información Jurídica 2013). Institutional integration and collaborative governance therefore are already considered (see Figure 1).

Figure 1. The Tárcoles River basin and the responsibilities of the subcommissions.

Second, there are some NBS pilot projects in the basin running, amongst them three prototypes for household greywater treatment of different degrees of decentralization (household front in responsibility of the house owner, street block, and neighborhood level in responsibility of the municipality) and one prototype for stormwater storage (Chapa et al. 2020; Neumann and Hack 2022; Pérez Rubí and Hack, 2021; Chapa et al. 2023). Therefore, in this study, we choose the implementation of a constructed wetland inspired by the existing NBS pilot projects as an example of a NBS, to assess the familiarity and attitudes of the participants towards the measure.

The remainder of this paper is structured as follows. We introduce our case study and the Q-methodology and explain our data collection. After analyzing the data and presenting the results we discuss the differences in attitudes toward NBS regarding the implications for research. We conclude with recommendations on how the different attitudes can be handled in practice for fostering NBS planning and implementation.

2. Methods and data acquisition

2.1. A general overview of the Q-methodology

The study of subjectivity has intrigued academics for decades. Subjectivity, which deals with a person’s viewpoints, attitudes, and perspectives is known to be a crucial determinant of human behavior under widely recognized theoretical frameworks (Ajzen 1991; Ben-Akiva et al. 1999). In the 1930s, a group of psychologists developed a statistical method to elicit people’s subjectivity (Watts and Stenner 2005). This method, called Q-methodology, represents a qualitative-quantitative research approach that allows for the identification of distinct perspectives existing within a group, about a topic of interest (Zabala et al. 2018). The method is well suited for studying human subjectivity as it forces participants to critically engage with pre-defined opinion statements, thereby indirectly revealing participants’ subjective values. Q-methodology combines qualitative data retrieved from in-person interviews with quantitative factor analysis. Hence, findings from the numerical analysis are supported by expressions uttered during the interviews. The core elements of Q-methodology are pre-defined opinion statements, prepared by the researcher before conducting the interviews. Participants then rank these opinion statements based on their individual level of agreement or disagreement into a grid (see Figure 2). This sorting pattern, called Q-sort, represents a person’s individual viewpoint regarding that topic of interest. Using factor analysis, researchers reveal latent structures, the factors, by comparing Q-sorts of all study participants. Factor analysis helps to detect common as well as distinguishing elements among the study population. By complementing the quantitative factor analysis with the accompanying qualitative interview data, researchers then can construct social viewpoints from the underlying latent factors.

Figure 2. Grid used for sorting the 48 statements according to the participants’ individual highest agreement (+5) to highest disagreement (-5), whereby a predefined number of statements could be assigned to the single values.

Prominent applications of Q-methodology studied agri-environmental contract design (Schulze and Matzdorf 2023), cooperative peatland management (Norris et al. 2021), investigating acceptance of marine protected areas (Gall and Rodwell 2016) or eliciting researchers’ understanding of different sustainability concepts (D’Amato et al. 2019).

The research focuses on the hypothetical implementation of a constructed wetland as a measure for wastewater treatment and flood management. While there is extensive knowledge on the benefits and disbenefits, as well as guidelines on implementing NBS (Albert et al. 2019; Dorst et al. 2022), it remains unclear which obstacles are relevant for the implementation of NBS in the Tárcoles river basin. Whether or not NBS will be implemented in practice may hinge upon viewpoints of decision-makers (Tafel et al. 2022). Since decision-makers are familiar with local circumstances, they are in the position to subjectively evaluating potential obstacles when implementing NBS and hence contribute to inform policy. Therefore, relevant stakeholders have been interviewed. Using the Q-methodology, we identified certain patterns and their differences and prioritizations.

2.2. Procedure of the Q-study

The methodological procedure of a Q-study can be summarized with the following steps:

1. Determining research design, including the concourse and Q-set (section 2.2.1),

2. Selection of participants (P-set) (section 2.2.2),

3. Data collection through interviews (section 2.2.3),

4. Data analysis & Factor extraction (section 3), and

5. Interpretation of factors (section 4).

In the following, we will describe the design of this study within the first three steps, while then moving on with the analysis and interpretation of the data.

2.2.1. Concourse and Q-Set design

Statements for the Q-methodology have been developed based on interviews, peer-reviewed literature, and workshops. Statements on the comparison of NBS to technical alternatives were mostly derived from Albert et al. (2019), other technical aspects and the distribution of responsibilities in planning measures from Scott et al. (2018). A Q-study on another river-related case study in Latin America inspired the development of statements on environmental aspects, technical maintenance, and risks (Schulz and Adams 2020). Stefanakis (2019) as well as the Global Standard for Nature-based Solutions (International Union for Conservation of Nature 2020) state the relevance of NBS for ecosystem integrity and ecosystem services, in particular habitat creation and biodiversity protection, where several statements derived from. Input to statements around institutional responsibilities, the role of municipalities and the relevance of stakeholder participation and networking came from emails, interview excerpts, and workshop minutes with members of the Tárcoles Commission (see table Appendix A). Finally, experiences from the SEE-URBAN-WATER project (Neumann and Hack 2019; Chapa et al. 2020; Visión Urbana del Agua and Technische Universität Darmstadt 2020; Hack 2021), and an interview with the project lead proved to be particularly helpful for statements on aspects of the legal-regulatory situation, citizen acceptance, cooperation of the municipalities, and site-related challenges in implementation.

Initially from the sources mentioned above, around 150 statements were derived, which built the initial concourse of the study. From this initial set statements referring to the same or a very similar topic were merged and reformulated. Criteria for including statements were that statements covered the topics of ‘Engineering’, ‘Political-institutional’, ‘Environmental’, ‘Cost-effort’, and ‘Citizen’ aspects of NBS as we aimed to cover the focal topic of NBS implementation in river management. Apart from that, statements that occur more often in literature or are marked as more relevant topics in literature where prioritized. By merging and rephrasing according to contextual aspects, the number of statements could be reduced to 48. These formed the final Q-set, clustered into five categories which were named according to their content: 1) engineering perspective, 2) environmental perspective, 3) political-institutional perspective, 4) cost-effort-perspective, 5) citizens’ perspective (see Table 2). The final Q-set was tested in two pilot interviews which finally were included into the interview sample as no important aspects were missing and the statements were clear.

The aim hereby was to offer a diverse Q-set and to keep the number of statements regarding agreement and disagreement with NBS as balanced as possible.

2.2.2. Selection of participants (P-set)

Potential candidates for this research were identified based on a list of participant data from workshops with members of the Tárcoles Commission, carried out within the scope of the PlanSmart project. An initial selection was made, fulfilling criteria regarding the municipality (suburban and with river access) and the state of profession (pupils, students and retired persons were excluded) as they have to be experts in the subject matter. Potential interviewees from different disciplines and municipalities were requested for interviews and asked for other potentially interested persons suitable for this study.

The final group of 20 participants for this research comprised 12 men and 8 women, working in ministries (9 interviews), local governments (5 interviews), NGOs (3 interviews), universities (1 interview), and other public institutions (2 interviews) with different levels of influence on NBS decision-making.

For Q-studies, it is more relevant to have a good sampling strategy for the statements as for the study participants, as in Q-studies, ‘the subjects have the status of variables rather than of sample elements; the term “sample” refers to the set of items’ (p. 191; Brown 1980). The Q-set – the entire selection of statements – is supposed to include all relevant viewpoints of a debate the study population may hold. As mentioned, the set condition for this study was to include only decision makers in the study region. We followed the general rule of thumb hereby which is a participant-statement-ratio of 1:2 (Stenner and Watts 2012). Including participants from different relevant authorities in Costa Rica ensured that all potential viewpoints were identified.

2.2.3. Data collection

Initially, it was planned to conduct the interviews in person. However, due to the pandemic situation and COVID-19 travel restrictions, interviews were held online between March 24 and May 27, 2021 (see Sattler et al. (2022) for more discussion on online vs. in person Q-interviews).

The Q-sorting process, which is usually done with printed cards, was facilitated through an online tool (Aproxima HtmlQ¹). Prior to the interview, instructions were sent via email. The subsequent interviews were held in Spanish.

During interview sessions, the researchers read out the statements one by one and the participants sorted these into three initial piles depending on their agreement, disagreement or neutral opinion towards the respective statement. Additionally, researchers inquired about the participants’ reasoning by asking participants to think out loud when reading the statements. In the consecutive step, participants proceeded with sorting the statements into the grid according to their subjective agreement or disagreement (see Figure 2). The researchers recorded the transition of positively and negatively evaluated statements as well as participants’ thoughts regarding individual statements. On average, interviews lasted one hour and were recorded with permission and given consent.

3. Data analysis: factor extraction

A total of 20 interviews were conducted with stakeholders of the Tárcoles region. Hence, 20 Q-sorts were analyzed with the ‘qmethod’ package for R by Zabala (2014). The first part of the analysis examined correlations between the different Q-sorts, using Spearman correlation (Spearman 1904). This helped to illustrate similar sorting patterns, but not to determine the absolute number of existing viewpoints. In a consecutive step, we applied Principal Component Analysis (PCA) to reduce the dimensionality of the data.

The returned ‘factor loadings’ represent correlations of individual Q-sorts with specific factors. Like correlation coefficients, factor loadings range between −1 and 1, indicating how strong a person is associated to an underlying factor. Using this metric, we were able to see which individuals evaluated statements similarly and most likely share a common viewpoint. However, as some individuals loaded highly on multiple factors, we applied varimax rotation. This operation had the aim to maximize factor loadings on one factor only (Zabala 2014). A factor’s eigenvalue is the sum of squared factor loadings for that factor and is used to calculate the variance accounted for by that factor (Watts and Stenner 2005) (see Table 1). In other words, the eigenvalues measure of how much of the common variance of the observed variables a factor explains. For example, an eigenvalue of 4.86, as in the case of factor 1, states that factor 1 explains as much variance as 4.86 individual Q-sorts. Since factor analysis aims to reduce to dimensionality of data, one should only include factors that explain at least as much variance as an individual Q-sort. That means that factor should have at least an eigenvalue of 1 to be considered in the subsequent analysis (Kaiser-Guttman Criterion).

Table 1. Attributes of the extracted factors (viewpoints) F1, F2 and F3.

	Number of Q-sorts	Eigenvalues	Explained variance
F1	8	4.86	24.31
F2	6	4.18	20.91
F3	3	2.47	12.39

To determine the final number of factors to extract from the data, we used statistically objective criteria, such as percentage of variance explained per factor (Cattell 1966), number of flagged Q-sorts per factor, i.e. individual significantly loads on one factor only, verified by comparing the factor loadings of that particular Q-sort (Brown 1980), Kaiser-Guttman Criterion (1954), and Humphrey’s Rule (Fruchter 1954). Applying these criteria makes a balancing act of reducing the dimensionality of data while keeping a wide opinion spectrum in the analysis to account for individual viewpoints.

At the end of the process, three factors emerged from the data including 17 persons that significantly loaded on either of the identified factors. The remaining three Q-sorts could not be associated with either factor and therefore were not included in the development of the viewpoints. The reason for excluding the three Q-sorts from subsequent analysis is that ‘Only the most representative Q-sorts for each factor are used for subsequent calculations’ (Zabala and Pascual, 2016). The idea behind that is that only the most representative Q-sorts maximize the differences between factors and hence allow identification of distinct factors (see Appendix B for participants’ factor loadings for each factor).

4. Results

4.1. Three factors, three viewpoints

The results of the factor analysis, as shown in Table 2, depict the statement factor scores for each factor. The factor score ‘indicates how a statement has been evaluated by a representative agent of a factor’ (Zabala and Pascual, 2016). These factor scores along with the respective statements are shown in Table 2.

Table 2. Q-set formed by 48 statements (S1-S48), clustered by five categories. The values from −5 (highest disagreement) to 5 (highest agreement) indicate the respective factor scores of a statement.

		F1	F2	F3
Category 1: Engineering
S1	These measures [NBS] instead of technical solutions are of increasing importance in urban water management.	2	0	1
S2	There is a lack of knowledge in urban and landscape planning on how such a measure can be implemented in practice.	2	−2	5
S3	Creating green retention areas should be a main objective of urban planning.	5	2	0
S4	It should always be a case-specific decision whether such a measure [NBS] or a technical treatment is recommended at a site.	1	1	0
S5	Paved ground and roads are a status symbol for urban development of the region.	0	−2	−5
S6	The consequences of such ecosystem-based water treatment measures should be monitored and reviewed regularly.	0	−1	2
S7	No one knows whether the functioning of the constructed wetland will weaken over time.	−1	−3	−2
S8	A high share of sealed surfaces for rapid drainage of rainwater should be aimed for.	−3	−5	−4
S9	Water treatment should be planned & implemented mainly by technical/engineering departments.	−1	2	0
S10	Conventional grey water treatment plants cannot be replaced in their function by the measure shown.	−2	−4	−1
Category 2: Environmental
S11	Constructed wetlands contribute to the resilience of the region to climate change impacts.	4	0	2
S12	The creation of habitat and biodiversity protection are important side effects of such measures [NBS].	5	1	1
S13	An economic valuation of ecosystem services would show that their value exceeds the cost of the measure.	1	−1	4
S14	Environmental protection and restoration have direct positive health effects.	4	1	0
S15	Illegal discharge of sewage into the river is one of the biggest water-related problems.	2	4	1
S16	There are other much more important problems than contamination levels in the river.	−4	−3	−1
S17	We can address environmental protection after we have solved other social problems.	−5	−5	−3
S18	For flood protection, such measures will not help much.	−5	−3	−3
S19	Groundwater contamination through the measure [NBS] poses a risk, especially if residential areas or drinking water sources are nearby.	0	−4	−2
Category 3: Political-institutional
S20	It is problematic that the realization of such a project highly depends on individual views in the city administration.	−1	2	−2
S21	More projects need to be realized in order to improve the database for the evaluation and further development of the methods.	0	1	−1
S22	A paradigm shift in policy towards ecosystem-based approaches is necessary.	1	3	2
S23	It will be difficult to get the area provided by the municipality.	0	0	−4
S24	The implementation of the shown measure [NBS] should be decided at the municipality level.	−2	−1	0
S25	In general, the municipalities in the river basin should cooperate more in decisions that affect the river basin.	4	3	3
S26	Cooperations with educational institutions such as universities are relevant for the planning and implementation of such measures.	0	3	3
S27	Civil society, state institutions and the private sector should be equally involved in planning processes.	0	4	4
S28	Municipalities must not have any additional work resulting from the measure after implementation.	−2	−4	−5
S29	If the measure cannot comply with legal requirements e.g. on land use & road dimensions, it should not be implemented.	−1	0	−4
Category 4: Cost-effort
S30	Municipalities should have more funds available for this type of action.	1	5	−1
S31	Such measures [constructed wetlands] are more cost-effective than technical treatment plants.	−1	−2	1
S32	Private companies should contribute to the financing of the measures.	2	5	2
S33	The financing of such measures [NBS] should be provided by public funds.	−2	−2	−3
S34	The cost to connect the measure to the existing infrastructure could be the biggest economic barrier.	−4	1	−1
S35	A prior risk assessment must be a central part of the measure planning.	3	4	0
S36	Green spaces like these are prone to damage from vandalism.	−1	−1	1
S37	Costs and effort due to maintenance and repair are a disadvantage.	−4	−2	0
Category 5: Citizens
S38	Constructed green spaces have an important social function in cities.	3	2	2
S39	There should be more prototypes to demonstrate the effects to the public and to build trust.	1	−1	−1
S40	There is an appreciation amongst the population for urban green spaces.	3	0	−3
S41	The trust of the residents should not be underestimated.	0	0	−2
S42	Residents must have the opportunity to participate in building the constructed wetland. This also increases acceptance.	1	2	0
S43	All stakeholders must be involved in the planning and implementation phase.	2	3	5
S44	Upstream municipalities bear major responsibility for water quality in downstream municipalities.	3	0	3
S45	It can be difficult to convince the local population of the benefits from the measure.	−2	0	3
S46	Urban vegetation often causes problems (damage by roots, clogging by leaves, etc).	−3	−3	1
S47	Traffic space (pavements, streets, car parks) should not be restricted by these measures.	−3	−1	4
S48	Public places protected from view by, for example, high vegetation will encourage illegal activities such as drug use.	−3	1	−2

Each factor was interpreted as a specific viewpoint representing a shared perspective of study participants, which will be described in the consecutive section. These emerged factors appear quite distinct from each other when comparing which statements people strongly agreed with. By using a factors’ z-scores, so the weighted average² of statement evaluations per factor, and the factor scores, the statements evaluations of a representative agent of a factor, we were able to highlight commonalities and differences among the different factors. To visualize this, we illustrated the most opinionated categories per factor.

We summed up the absolute statement factor scores for each statement category per factor and plotted this in the form of a radar chart (see Figure 3). Thus, the further away from the center, the more people resonated with this particular category. This should help to illustrate that thematic aspects may stand out when comparing the different factors. Thereby it appears that factor 1 (Viewpoint 1: ‘The nature lover’) is more concerned about statements regarding the environment and engineering aspects, factor 2 (Viewpoint 2: ‘The cost concerned’) about the costs of institutional concerns, and factor 3 (Viewpoint 3: ‘The participation seeker’) mostly about engineering and public participation. The statements are disclosed in Table 2.

Figure 3. Illustration of prioritized categories per factor. Data based on the absolute sum of statement factor scores for each statement category per factor.

4.2. Interpretation of factors

Using the qualitative data from the interviews, we were able to derive points of consensus, particular narratives of the extracted factors, and distinguishing points.

4.2.1. Points of consensus

Although the objective of this paper is to describe the existing distinguishing viewpoints towards the implementation of NBS, it is worth noting to which statements the study participants had no deviating opinions. Highest consensus (lowest dispersion of z-scores, see Appendix B) lies in the need for a paradigm shift in policy design towards ecosystem-based approaches (S22) and for more cooperation among bodies of administration in river basin decision-making (S25). Further, all viewpoints reject the statement that the measure should be financed from public funds (S33). On the other hand, all three viewpoints recognize the important social function of urban green spaces (S38), agree that such measures are becoming increasingly relevant in urban water management (S1) and welcome the participation of the population in the construction of the measure, which in turn increases acceptance (S42). It shows that all viewpoints have a fundamentally positive attitude towards the expansion of nature-based measures in urban water management and emphasize the importance of a cooperative and participatory process.

4.2.2. Viewpoint 1: the nature lover

The first distinct viewpoint includes eight individuals and accounts for 24% of the study variance. Participants sharing this viewpoint are not directly involved in the financing of NBS, but rather deal with nature conservation issues and often have coordinating functions instead. Considering their statement evaluations, these people seem to have the greatest intrinsic motivation for promoting NBS.

This viewpoint is characterized by its clear priority to the ecological benefits of the measure including environmental conservation, biodiversity protection, and climate adaptation and only slightly less on engineering aspects (see Figure 3). ‘The nature lover’ prioritized six of the nine ‘environmental perspective’ statements with values of ± 5 or ± 4. In three of them it differs significantly from the other viewpoints (S11, +4; S12, +5; S14, +4). Further, ‘The nature lover’ promotes the implementation of prototypes to demonstrate the measure’s benefits and raise trust amongst the citizens.

We have already destroyed enough biodiversity. That’s why it is important to try to recover some systems that are no longer there. If we take advantage [of NBS], we could do wastewater treatment and increase biodiversity again. (P8 on S12)

Well, observing the consequences of the pandemic, I think that it is more than evident that the establishment and protection of the environment is vital in every sense, not only in terms of a contaminated basin such as the case of Tárcoles. (P2 on S14)

4.2.3. Viewpoint 2: the cost concerned

The second viewpoint is framed ‘the cost concerned’ and includes six participants, explaining 21% of the study variance. Individuals that loaded onto that factor are usually representatives of the municipalities. These municipalities usually must bear the costs for NBS in urban areas of river basins, thus driving the notion of this viewpoint into the cost domain. Two people of this viewpoint belong to urban planning ministries that also likely must deal with the financing of projects. Hence, this viewpoint is characterized by focusing on cost and institutional circumstances, giving less priority to social participation than the other viewpoints.

Particularly in their strong agreement that private companies should contribute to the financing of the measure distinguishes ‘the cost concerned’ from the other viewpoints. Compared to them, ‘the cost concerned’ sees an economic valuation of ecosystem services through the measure as critical or less reasonable (S13, −1).

I agree, but this is rarely done. People don’t know how to value a resource, for instance in a conservation area, like a watershed. There is no system in Costa Rica, nor are there people trained to make a valuation of how much the economic damage is, in other words, not to make such a decision. Generally, that is never valued or taken into account and even if it is valued, we move on to the same political problem. (P19 on S13)

It is because if private companies do not participate, these projects cannot be implemented. The limitation of financial resources is a dire problem for the municipalities. Especially now with the pandemic, there are many businesses that are closing […], there are people who are hungry and without work. So, when budget cuts have to be made, this [watershed protection] is the part we are going to cut the most. (P19 on S32)

In contrast to the first viewpoint, ‘the cost concerned’ keenly strives for an equal involvement of civil society, state institutions and private companies into planning processes (S27, +4). Also, it considers the costs to connect the measure to the existing infrastructure as the possibly highest economic barrier (S34, +1).

4.2.4. Viewpoint 3: the participation seeker

The last viewpoint is titled ‘the participant seeker’ and counts three participants. This perspective accounts for 12% of the study variance. As with ‘the nature lovers’, these are individuals who are not primarily concerned with financing. They count two representatives from the energy sector and an NGO representative who is heavily involved in community initiatives. Hence, this viewpoint stands out through its more pragmatic approach, partly marked by a skeptical attitude that the measure will find acceptance and recognition in society. For ‘the participation seeker’, nature cannot rule over all other criteria, but urban infrastructure also plays a major role. Thus, distinguishing from the previous viewpoints is that high importance is given to engineering aspects as well as stakeholder participation (see Figure 3).

I feel that having all parties involved in planning and implementation is very important for the success of the measure. I think that this is a good moment for the paradigm shift as all the planning and implementation time can be used to demonstrate to all the people, what an ecosystem-based model means and why it is so important to start implementing it. (P3 on S43)

Particularly differing from the first viewpoint, ‘the participant seeker’ considers the involvement of all stakeholders as crucially relevant. However, convincing the local community of the measure states a hurdle (S17, −3).

Compared to ‘the cost concerned’, ‘the participant seeker’ does not believe as much in the functional replacement of conventional treatment plants by the indicated NBS (S10, −1). Costs for constructed wetlands are perceived lower than for conventional treatment plants and lower than the economic value of provided ecosystem services (S31, +1; S13, +4).

4.2.5. Distinguishing points

Besides informing about consensus and factor-specific statements, the analysis also highlights statements to which there is no agreement whatsoever between the derived viewpoints. These concern the view that a lack of knowledge exists in urban and landscape planning regarding the practical implementation of the measure, which is strongest noted by ‘the participation seeker’. High divergence pertains to the society’s perception of the use of public space. ‘The nature lover’ clearly observes an appreciation for urban green spaces within the society and to a certain degree accepts a restriction of road traffic space for the implementation of the indicated measure. However, ‘the participation seeker’ holds the opposite opinion.

5. Discussion

5.1. Commonalities and disagreement among viewpoints

The quantitative analysis of interview data led to three emerging factors to which 18 interviewees significantly loaded on either of the identified factors. Each was translated to a viewpoint representing a shared perspective of study participants which was subsequently qualitatively analyzed. Differing viewpoints could be identified although all except one study participant were members of the Tárcoles Commission, supposedly sharing a common mission of pro-environmental attitudes. While one group of participants appears more concerned about statements regarding the environment and engineering aspects (Viewpoint 1: ‘The nature lover’), others more about the costs of institutional concerns (Viewpoint 2: ‘The cost concerned’) or mostly about engineering and public participation (Viewpoint 3: ‘The participation seeker’). However, all participants agreed that NBS are becoming increasingly relevant in urban water management, that a paradigm shift in policy design towards ecosystem-based approaches, and that more cooperation among bodies of administration in river basin decision-making is needed.

The recognition of the need for and preference of NBS and ecosystem-based approaches against traditional gray solutions could be explained by the fact that a large proportion of the participants has environmental and sustainability professions, which certainly influences the perception of these aspects. The agreement that more cooperation among bodies of administration in river basin decision-making is needed is probably rooted in the membership of most participants in a cross-administration and basin-oriented commission seeking this kind of cooperation (Meijerink and Huitema, 2017; Schröter et al. 2023).

Further agreement among all participants exists in the recognition of the important social function of urban green spaces and the participation of the population in the construction of the measure to increase its acceptance. The commitment of the participants as members of the Tárcoles commission to encourage public participation as a principal objective is possibly a reason for this shared attitude. It can be summarized that the participants of this study have a fundamentally positive attitude towards the expansion of nature-based measures in urban water management and emphasize the importance of a cooperative and participatory process. The former statement is contradicting findings of Neumann and Hack (2019) who studied the political-institutional readiness of Costa Rica to implement NBS and thereby revealed a generally pro-gray attitude among public authorities. However, both studies agree that a general lack of knowledge and a need for capacity building related to NBS, especially ‘the nature lover’ and ‘the participation seeker’ viewpoints recognized this. The Tárcoles River basin is shared by multiple municipalities, which is challenging (Naumann and Kaphengst 2015) as it can lead to conflicts of interest and requires collaborative planning. However, Neumann and Hack (2019) indicate insufficient networking, communication problems, and a lack of exchange precisely as hurdles in the promotion of NBS. Results of this study also point to a widespread desire among political-administrative actors for closer cooperation among municipalities. The creation of the Tárcoles Commission was a step toward greater cooperation among the administrations sharing the basin. Nevertheless, most political-administrative actors still seem to see room for improvement, regardless of their viewpoint.

Further consensus is revealed by this study in the need for a paradigm shift in policy, which is also made evident in the literature. Scott et al. (2018), for instance, recommend increased integration of NBS in the form of Green Infrastructure into planning processes through the establishment of long-term action plans, investment plans, and policies. Close collaboration with educational institutions, which is considered especially important by ‘the nature lover’ and ‘the participation seeker’, could also help to improve the situation. This would increase awareness of the problem and balance out the different levels of knowledge in the population, politics, and administration, which, according to Naumann and Kaphengst (2015), would help to successfully implement NBS.

As with most water infrastructure projects, the successful implementation of a NBS heavily depends on social acceptance which results from participation opportunities, the communication of technical information, and the public commitment to NBS (Neumann and Hack 2019). According to this study’s results, political-administrative actors also recognize that participation opportunities increase acceptance; however, this aspect is not particularly emphasized by any of the identified viewpoints. Involving stakeholders in the planning and implementation phase, on the other hand, is attributed greater relevance, especially by ‘the participation seeker’. This shows that, especially for this group, a transdisciplinary approach is recognized as the basis for successful implementation. Additionally, Scott et al. (2018) recommend highlighting the benefits of the measure in communication, demonstrating it through prototyping, and thereby improving the data base on NBS. results of this study only partially corroborated this point. ‘The nature lovers’ differ from the other viewpoints recognizing that prototypes are important to demonstrate benefits and build trust among the population. However, this does not appear to be a priority among all respondents.

Particularly striking in the opinions of the political-administrative actors is, on the one hand, the different perception of the appreciation for urban green spaces within the population and, on the other hand, the conflicting views as to whether traffic space may be restricted by the measure. According to ‘the nature lovers’, the implementation of a constructed wetland is allowed to take up existing traffic space, which means that they clearly prioritize green over gray infrastructure here. However, ‘the participation seeker’, who are more concerned about citizens’ interests, seem to see greater social value in the sidewalks, streets, and parking lots than in NBS, which is why they do not favor restrictions on traffic space for it. These two aspects were also addressed by Pérez Rubí and Hack (2021) as part of a residents’ survey in the Llorente district, canton Flores, in Costa Rica and produced partially contradictory results. Although almost all (93%) of the 60 respondents were in favor of more green spaces in their neighborhood, 70% rejected the necessary restriction of traffic space. The experience of the authors in the SEE-URBAN-WATER project supports the assessment of ‘the participation seeker’ that the social and cultural context, the degree of involvement of neighbors, and other institutional actors are crucial factors for the successful implementation of Green Infrastructure in already developed urban areas (see also Chapa et al. 2020).

A closer look into the functions and professions of the participants assigned to the different viewpoints bears additional insights. ‘The nature lover’ viewpoint includes participants who, due to their function, usually do not directly deal with the financing of NBS but are primarily concerned with nature conservation topics and often have coordinating functions. These participants seem to have the greatest intrinsic interest in the promotion of NBS. ‘The cost concerned’ viewpoint includes all representatives of municipalities among the participants possibly because the municipalities usually have to bear the costs of the considered NBS measure, especially in the urban areas of the river basin. Two participants related to this viewpoint are representatives of ministries involved in planning issues, and therefore it can be assumed that they are also involved in financing. ‘The participation seeker’ group has, in common with ‘The nature lover’, participants who are not primarily concerned with financing: two representatives from the energy sector (due to their function not primarily/less strongly connected with ecological solutions/NBS), one NGO representative who strongly focuses on community initiatives (participation).

5.2. Lessons learned for improvement of NBS implementation in general

NBS have been proposed as a holistic approach to help communities to adapt to and mitigate the effects of climate change. However, while NBS seem to be a promising approach for addressing social-ecological challenges, there are significant barriers for the implementation of these solutions in river basin management (Chapa et al. 2020; Seddon et al. 2020a; Dorst et al. 2022). Most of the barriers are related to the lack of knowledge, institutional silos and fragmentation, mainstreaming in regulatory plans and policies, and finally but not least, the allocation of economic resources for the implementation of these solutions (Wamsler et al. 2020a).

5.2.1. Lack of knowledge

Overall, there is great uncertainty regarding the cost and benefits of NBS among several stakeholders, including community members and decision makers (Neumann and Hack 2022). This lack of knowledge is frequently mentioned as a significant barrier for the implementation and uptake of NBS (Sarabi et al. 2019). Here, many decision makers are not only uncertain on the benefits of NBS, but also on the guidelines and management of these solutions. This can create conflict among actors as they all deal with complex social-ecological systems who are trying to maximize their economic and social welfare. Moreover, the lack of information can contribute to the resistance to change as many decision makers find it difficult to relate and materialize the benefits of NBS. Therefore, it is important to increase the awareness of NBS to contribute to solutions that are socially acceptable and sustainable.

5.2.2. Institutional silos and mainstreaming NBS in regulatory plans and policies

The other identified barrier for the implementation of NBS is the so-called ‘organizational silos’ (Frantzeskaki et al. 2020). This institutional fragmentation or silos is related to how different departments assume different responsibilities based on their own goals, frameworks, and procedures. Creating with this not only conflicts and confusion among institutions about who should manage, operate, and maintain the NBS in the long run, but also hampering the communication and collaboration between municipalities. That is, institutional silos increase the difficulties in communication and cross-department collaboration. Especially, when it comes about regulatory plans and policies that affect several municipalities and institutions at the same time. Contributing with this to missed opportunities and synergies between departments. Consequently, based on the experience in the San José Metropolitan Area of Costa Rica, it is important to break down organizational silos by promoting a shared vision of the benefits of constructing with nature rather than against it. This can create mutual understanding between departments to work together for the same goal and purposes. To reach a mainstreaming of NBS current constraints have to be overcome, support from all governance levels is needed (Wamsler et al. 2020a), as well as the cooperation of researcher and policymakers (Seddon et al. 2020b).

5.2.3. Financing

One aspect that was elaborated on in the interviews by many respondents is the available budget for NBS. Also in the literature, unsecured, insufficient or inflexible funding (Neumann and Hack 2019) and mobilization of investments (Seddon et al. 2021) as well as targeted financial and human resources (Wamsler et al. 2020a) are mentioned as implementation hurdles of NBS. Similarly, ‘the nature lover’ and ‘the cost concerned’ believe municipalities should obtain more budget for NBS. There is even stronger agreement that private companies should participate in funding. Industry and agriculture contribute significantly to the contamination problem of the Tárcoles River basin. According to the results, they are expected to fulfill this responsibility, for example, by investing in treatment by NBS. The results and existing literature indicate that financing cannot easily be provided by private households alone nor exclusively with public funds. Accordingly, the participation of private companies in financing NBS should be considered to achieve an effective and comprehensive wastewater treatment in the Tárcoles River basin.

5.3. Limitations of the study

The methodological limitations of this study are mainly that the results only reflect the attitudes of the selected target group, as a Q-study is representative in terms of statements, not in terms of participants. If applied in a different context, the viewpoints of decision makers would certainly be different as the attitudes reflect the experiences of the stakeholders in a certain case study. Further, due to the composition of the Tárcoles commission, the study participants belonged mainly to the environmental sector. While this could be interpreted as bias, it is even more interesting that we could identify the depicted differences between the three viewpoints. Regarding the term NBS, the ongoing discussion and different interpretations of the term did not allow us to ask decision makers specifically about NBS. Instead, constructed wetlands were selected and presented as an example to serve as a known model of NBS.

6. Conclusion

This study investigated the attitudes of political and administrative actors regarding the implementation of NBS in river basin management using the hypothetical example of a constructed wetland in the Tárcoles River basin in Costa Rica. Such NBS has a dual function as greywater treatment and flood protection, which makes it appropriate to implement in populated parts of riverine landscapes which, as in the case of Tárcoles River, are heavily polluted and with important flooding problems.

Applying Q-methodology, we identified three different viewpoints among the decision makers: ‘the nature lover’, ‘the cost concerned’ and ‘the participation seeker’. The different viewpoints disagreed on the lack of existing knowledge in urban and landscape planning regarding the practical implementation of the measure and the use of public space for NBS vs. traffic infrastructure. Agreement was reached in the need for a paradigm shift in policy design towards ecosystem-based approaches and for more cooperation among bodies of administration in river basin decision-making. Regarding finance options they don’t see that these measures may be financed by public funds. However, they should be implemented with public participation.

In our evaluation of the attitudes of political and administrative actors for a specific case study context, we confirmed that there are barriers for the implementation of NBS, which can provide lessons for an improved enforcement of these measures. Main barriers include the lack of knowledge, institutional silos and fragmentation, mainstreaming in regulatory plans and policies, and the allocation of economic resources for the implementation of these solutions. Other actors than those considered in this study potentially could highlight, or not, other barriers. This caveat should be considered when interpreting our results.

From these results, if the barriers stressed by the political and administrative actors considered in this study are representative and relevant, we deduce that policies should increase the awareness of NBS that are socially acceptable and sustainable to overcome the existing lack of common knowledge on NBS. Further, they should help develop mechanisms for more cooperation and communication between all decision makers to avoid confusion in management, operation and maintenance of NBS; and last but not least they may include the participation of private companies, along with communities, public institutions in financing NBS to achieve more effective and sustainable results.

To confirm our findings, future research could apply our study in a different case study context, with different NBS measures or a more diverse set of decision makers which are not only inclined to the environment sector.

Acknowledgements

The authors would like to express their special thanks to all decision-makers that agreed to participate in the Q-sort- Interviews.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Informed consent was obtained from all individual participants involved in the study.

Data availability statement

The data that support the findings of this study are available from the corresponding author, BS, upon reasonable request.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/26395916.2024.2339228.

Additional information

Funding

This work was supported by the German Federal Ministry for Education and Research Bundesministerium für Bildung und Forschung (BMBF) providing funding through a grant for the PlanSmart research group [grant no: 01UU1601B] and for the SEE-URBAN-WATER research group [grant no. 01UU1704], and by the University of Costa Rica [grant no: Pry01-532-2020], with direct funding from the participant academic units School of Architecture, Engineering Research Institute and Program for Sustainable Urban Development – ProDUS, in supporting PlantSER project.

Notes

1. https://github.com/aproxima/htmlq

2. The weights are based on the factor loadings and are calculated by w = f/(1-f^2) with w being the weight and f being the factor loading (see page 240 of Brown (1980) or visit https://github.com/aiorazabala/qmethod/blob/master/R/qzscores.R to see the implementation in R).