Abteilung Umweltsozialwissenschaften

Many public environmental decisions are wicked problems due to high complexity and uncertainty. We test a participatory value-based framework based on multi-criteria decision analysis (MCDA) to tackle such problems. Our framework addresses two important gaps identified in reviews of MCDA applications to environmental problems: including stakeholders and treating uncertainty. We applied our framework in two complex real-world cases concerning a paradigm shift in the wastewater sector; the transition from centralized wastewater systems to decentralized non-grid systems. Non-grid systems may solve some problems of centralized systems by reducing costs, increasing flexibility, and addressing growing demands on environmental issues, especially in rural areas. But non-grid systems have rarely been implemented in OECD countries, because it is unclear whether a transition is recommendable, and whether stakeholders would accept this shift. This problem allows addressing several fundamental research questions. As theoretical contribution, we found that stakeholder participation in MCDA is necessary, because different preferences of stakeholders can lead to different best-performing options in the assessments. Compared to the typical integrated assessment (IA) approach that excludes stakeholders' preferences, the MCDA process led to clearer outcomes. Results indicate that including the uncertainty of predicted consequences of options with Monte Carlo simulation helped discriminate between options and identify best-performing options. Challenging the uncertainty of elicited stakeholder preferences with sensitivity analyses, we found that best-performing options were especially sensitive to the MCDA aggregation model. Despite the high uncertainty, it was possible to suggest robust consensus options that would perform reasonably well for all stakeholders. As practical contribution, results indicated that a transition from the centralized to decentralized non-grid systems seems feasible. Most stakeholders assigned highest weights to environmental protection objectives in decision-making workshops. These stakeholder preferences implemented in MCDA led to a generally better assessment of innovative non-grid systems, especially when including urine source separation. Stakeholders perceived the MCDA process as beneficial and found results plausible. We conclude that the proposed participatory value-based framework is rigorous, but still feasible in practice. The framework is certainly transferable to any context and is open to testing and refinement in various applications to wicked decision problems.

Investigating wastewater management matters: in many OECD countries, the conventional centralized system is reaching its limits. Alternative decentralized options exist. Some directly affect citizens with in-house wastewater treatment. Involving citizens in decision processes would legitimate the outcome and facilitate implementation. However, citizen participation is challenging because they are numerous, and need to learn about the topic and construct their opinion. To include citizens, we propose an innovative online survey based on Multi-Attribute Value Theory (MAVT). Citizens receive value-focused information, and can communicate their preferences, captured as weights assigned to objectives. We collected quantitative and qualitative data, and elicited preferences from 184 young Swiss citizens, who will have to live with the decision outcome. In addition to reporting on insights for wastewater management, we assessed our survey, i.e. whether respondents learnt about the topic, constructed preferences, and understood the requirement to think in terms of objectives. Water quality and health protection mattered the most. The objectives directly concerning the respondents (time demand, attractiveness) were the least important. The best-ranked option in the subsequent Multi-Criteria Decision Analysis was a decentralized source separating system with dry toilets. Respondents were unaware that such decentralized options exist, indicating that learning about the topic occurred. Preferences were mostly newly constructed from no opinion, or pre-existing ones were reinforced. Our value-focused online survey helped citizens to understand the complex decision and construct their preferences. Swiss decision-makers, and beyond, should not be scared of a paradigm shift in wastewater management: the young generation seems ready to decentralize.

Public decisions are typically related to large investments leaving long legacies. We should therefore strive for wide societal agreement regarding such decisions, which meet the diversity of preferences between stakeholders and over time. But if, how and why do stakeholder preferences change over time? In decision analysis, these questions received little attention. We explored them using three real-world public decision processes, based on Multi-Criteria Decision Analysis (MCDA). We used repeatedly elicited ranking of objectives over time. These were obtained during three to five moderated workshops we organised several months apart (total N = 200 questionnaires, and 100 stakeholders). We analysed individual and aggregated (group) preferences, their changes and potential drivers including demographic and experience variables. We also analysed the effect of preference evolution on the performance of decision-alternatives with MCDA over time. We found that stakeholder preferences often changed over time, both on an individual and group level. These changes did not systematically diminish over time, but some convergence of preferences was observed for stakeholders who repeatedly participated in workshops. High-ranking objectives were relatively stable and similar between stakeholders. While preference changes could not be explained by demographics and personal experiences, repeated interaction with the decision problem might play a role. Neither the observed disagreement between stakeholders, nor the preference changes over time affected the best and worst performing alternatives in our decision problems. Thus, despite changing stakeholder preferences over time, public decision-makers can contrive robust solutions to complex public decision problems in the present.

Werterhalt und Bewirtschaftung von Kanalisation und ARA können kleine Gemeinden vor Herausforderungen stellen. Es gibt Alternativen, aber lohnen sich diese? Zwei Gemeinden wurden bei der strategischen Planung für ihr neues Abwassersystem unterstützt. Viele Ziele wurden als entscheidungsrelevant identifiziert, insbesondere Umweltschutzziele. Es zeigte sich, dass dezentrale Technologien mit Stoffstromseparierung die Anforderungen häufig besser erfüllen können als konventionelle Abwassersysteme.

Wie kann die Abwasserentsorgung in einer ländlichen Gemeinde in der Schweiz in Zukunft gewährleistet werden? Welche Bedürfnisse der lokalen Nutzer/-innen muss ein modernes Abwassersystem erfüllen? Das Wasserforschungsinstitut Eawag und das Amt für Umwelt Solothurn (AfU) sind diesen Fragen gemeinsam nachgegangen und zeigen die Ergebnisse in der vorliegenden Studie auf.
In der Schweiz ist die überwiegende Mehrheit aller Einwohner/-innen an ein zentrales, netzgebundenes Abwassersystem angeschlossen. Auch im Kanton Solothurn besitzen alle ländlichen Gemeinden ein solches System aus Kanalisation und Abwasserreinigungsanlage (ARA). Diese Systeme wurden ursprünglich mit Subventionen vom Kanton und vom Bund realisiert. Langfristig müssen diese nach dem Verursacherprinzip durch Gebühren finanziert werden.

How to ensure future wastewater disposal in rural communities in Switzerland? What needs of local stakeholders should a modern wastewater system meet? Eawag, the Swiss Federal Institute of Aquatic Science and Technology, and the Office for the Environment Solothurn (AfU) have jointly investigated these questions and present the results in this study.
In Switzerland, the vast majority of inhabitants are connected to a centralized, grid-based sewer system. In the canton of Solothurn, all rural municipalities make use of such a system consisting of a sewer network and a wastewater treatment plant (WWTP). From the 1960s to the early 1990s, communities initially implemented these systems with subsidies from the cantonal and the federal government. To finance these systems in the long term, legal regulations prescribe fees to be charged according to the polluter-pays-principle.