Department Systems Analysis, Integrated Assessment and Modelling

Surface water quality management requires foresighted decision making regarding long-term investments. It should consider multiple objectives (e.g. related to different pollutants and costs), integrate multiple sources of pollution (point and diffuse sources), and external conditions that change over time (climate, population and land-use changes). Multi-attribute value theory can support such decisions, especially the development of an assessment method. Integrated surface water quality assessment methods including micropollutants are currently lacking or in development in many countries. Important steps for the development of such an immission oriented and integrated surface water quality assessment method are discussed in this paper and exemplified for organic micropollutants. The proposed assessment method goes beyond simple pass-fail criteria for single substances. It provides a continuous assessment on a scale from zero to one based on five color-coded water quality classes and suggestions for the visualization of assessment results. It takes into account the toxicity of the micropollutants and their mixture to aquatic organisms by comparing measured concentrations to environmental quality standards (EQS). The focus of this paper is on aggregation over multiple substances and time. Advantages and disadvantages of different aggregation methods are discussed as well as their implications for practice. The consequences of different aggregation methods are illustrated with didactical examples and by an application of the proposed water quality assessment method to pesticide monitoring data from Switzerland. Recommendations are provided that account for the purpose of the assessment. Furthermore, the paper illustrates how the proposed method can facilitate dealing with uncertainty and a transparent communication of monitoring results to support water quality management decisions.

Der Schweizer Makrozoobenthos-Index IBCH geniesst für die Zustandsbewertung von Fliessgewässern bei den Kantonen eine hohe Akzeptanz. In den letzten zehn Jahren zeigte sich aber, dass nicht nur anthropogene Faktoren die Bewertung beeinflussen, sondern auch natürliche wie die Höhenlage oder die biogeografische Region. Basierend auf einer Analyse der bisherigen Ergebnisse wurde der IBCH_2019 entwickelt, der diese Mängel korrigiert und eine plausiblere Bewertung der Gewässer erlaubt.

Mit einem statistischen Modell wurden schweizweite Monitoringdaten über die Zusammensetzung von Makrozoobenthosgemeinschaften in Schweizer Fliessgewässern ausgewertet. Temperatur, Landwirtschaft und Hydromorphologie wurden dabei als wichtige Einflussfaktoren im Modell identifiziert. Arten aus der gleichen Familie reagieren in vielen Fällen unterschiedlich auf natürliche und menschliche Umwelteinflüsse. Neben der taxonomischen Auflösung wirkt sich auch die Stellenauswahl auf die Aussagekraft der Resultate aus.

Freshwater ecosystems are increasingly under threat as they are confronted with multiple anthropogenic impairments. This calls for comprehensive management strategies to counteract, or even prevent, long-term impacts on habitats and their biodiversity, as well as on their ecological functions and services. The basis for the efficient management and effective conservation of any ecosystem is sufficient knowledge on the state of the system and its response to external influence factors. In freshwater ecosystems, state information is currently drawn from ecological assessments at the reach or site scale. While these assessments are essential, they are not sufficient to assess the expected outcome of different river restoration strategies, because they do not account for important characteristics of the whole river network, such as habitat connectivity or headwater reachability. This is of particular importance for the spatial prioritization of restoration measures. River restoration could be supported best by integrative catchment-scale ecological assessments that are sensitive to the spatial arrangement of river reaches and barriers. Assessments at this scale are of increasing interest to environmental managers and conservation practitioners to prioritize restoration measures or to locate areas worth protecting. We present an approach based on decision support methods that integrates abiotic and biotic ecological assessments at the reach-scale and aggregates them spatially to describe the ecological state of entire catchments. This aggregation is based on spatial criteria that represent important ecological catchment properties, such as fish migration potential, resilience, fragmentation and habitat diversity in a spatially explicit way.We identify the most promising assessment criteria from different alternatives based on theoretical considerations and a comparison with biological indicators. Potential applications are discussed, particularly for supporting the strategic, long-term planning and spatial prioritization of restoration measures.

Despite the large literature about non-additive value aggregation techniques, in the large majority of applied decision support processes, additive value aggregation functions are used. The main reasons for this may be the simplicity of the approach, minimum elicitation requirements, software availability, and the appeal of the underlying preference independence concepts that may be strengthened by an adequate choice of sub-objectives and attributes. However, in an applied decision support process, the decision maker(s) or the stakeholders decide on the sub-objectives and attributes to characterize the state of a system and they have to provide information that allows the decision analyst to express their preferences as a value function of these attributes. It is the task of the decision analyst to find the parameterization and parameter values of a value function that fits best the expressed preferences. We describe a value function elicitation process for the ideal morphological state of a lake shore, performed with stakeholders from federal and cantonal authorities and from environmental consulting companies in Switzerland. This process led to the elicitation of strongly non-additive and partly even non-concave value aggregation functions. The objective of this paper is to raise the awareness about the importance of carefully testing the assumptions underlying parameterized (often additive) value aggregation techniques during the preferences elicitation process and to be flexible regarding evaluating value functions that deviate from the often used additive aggregation scheme. This can lead to a higher confidence that additive aggregation is suitable for the specific decision problem or to the selection of alternative aggregation techniques that better represent the decision maker’s preferences in case additivity is violated.

Die Makrozoobenthos-Erhebungsmethode des Modul-Stufen-Konzepts (MSK) wird breit angewandt. Wie eine Umfrage zeigt, entspricht sie überwiegend den Erwartungen der Anwender und Anwenderinnen. Um die Verlässlichkeit zu steigern, bedarf es jedoch einer Weiterentwicklung der Methode. So soll die Methode künftig den natürlichen Hintergrund miteinbeziehen, weitergehende Indices sollen auf Schweizer Daten getestet und die Ergebnisse publiziert werden.

Environmental decision support intends to use the best available scientific knowledge to help decision makers find and evaluate management alternatives. The goal of this process is to achieve the best fulfillment of societal objectives. This requires a careful analysis of (i) how scientific knowledge can be represented and quantified, (ii) how societal preferences can be described and elicited, and (iii) how these concepts can best be used to support communication with authorities, politicians, and the public in environmental management. The goal of this paper is to discuss key requirements for a conceptual framework to address these issues and to suggest how these can best be met. We argue that a combination of probability theory and scenario planning with multi-attribute utility theory fulfills these requirements, and discuss adaptations and extensions of these theories to improve their application for supporting environmental decision making. With respect to (i) we suggest the use of intersubjective probabilities, if required extended to imprecise probabilities, to describe the current state of scientific knowledge. To address (ii), we emphasize the importance of value functions, in addition to utilities, to support decisions under risk. We discuss the need for testing "non-standard" value aggregation techniques, the usefulness of flexibility of value functions regarding attribute data availability, the elicitation of value functions for sub-objectives from experts, and the consideration of uncertainty in value and utility elicitation. With respect to (iii), we outline a well-structured procedure for transparent environmental decision support that is based on a clear separation of scientific prediction and societal valuation. We illustrate aspects of the suggested methodology by its application to river management in general and with a small, didactical case study on spatial river rehabilitation prioritization.

Ecological assessment requires the integration of many physical, chemical, and/or biological quality elements. The choice of the aggregation method of such partial assessments into an overall assessment can considerably affect the assessment outcome – an issue that has been controversially discussed within the scientific community for the last decade. Current practice often considers only two different aggregation methods, the weighted arithmetic mean (additive aggregation) and the one-out, all-out method (minimum aggregation). However, both have important drawbacks. Additive aggregation compensates a bad status of one quality element by a number of elements featuring good status. Minimum aggregation can lead to overly pessimistic assessment results, since only the quality element in the worst status is considered. Here, we introduce a toolbox containing current and new aggregation methods, demonstrate and discuss their properties with simple, didactical examples, and suggest in which situations best to use them. Then, we illustrate the consequences of selected aggregation schemes for ecological river assessment with the case study of the Swiss Modular Concept of stream assessment (SMC), which we apply to ten river reaches in the Mönchaltdorfer Aa catchment in Switzerland. To be able to do so, we used multi-criteria decision analysis, i.e., multi-attribute value theory, to arrange the SMC quality elements into an objectives hierarchy, and to translate their individual assessments into value functions. Our case study revealed that choosing the most appropriate aggregation method particularly matters, if objectives with significantly different qualities are aggregated. We argue that redundant objectives (i.e., quality elements), often found at the lower levels of the objectives hierarchy, should best be aggregated additively allowing for compensation to increase the statistical significance of the results. Further, we suggest that complementary sub-objectives that often occur at higher levels may be optimally aggregated with a mixture of additive and minimum aggregation. Such a mixed method will allow some compensation, but nevertheless penalize for very bad states. Since here we compare commonly used aggregation methods with some which we believe have never been discussed in an assessment context before, our study concurrently informs ecological assessment in theory and in practice.

River monitoring and assessment programs are important tools to quantify the condition of river ecosystems, identify deficits, and provide preliminary indication of how to improve them. But, they are limited in delivering comparable assessment results across national or transnational borders, aggregating site-specific assessments into broader scale assessments, and supporting river management decisions. We present a multi-criteria decision analysis approach for improving the comparability of ecological assessment methods of different origin and for combining these assessments into a joint procedure. The approach consists of seven consecutive steps. The most central ones concern the hierarchical allocation of ecological assessment endpoints, and the harmonization of the scoring procedure of attributes (ecological indicators or assets) to a common scale from 0 to 1. We demonstrate the approach integrating three programs developed to assess the hydromorphological river condition in Switzerland, Germany, and the USA. In our example, the integrated assessment produces comparable results for the whole range from natural to impacted rivers, while data continuity with original assessments was maintained. Our approach provides a common assessment standard due to the definition of the minimum amount of information required, is flexible regarding measurement and assessment endpoints, and bridges the gap between river quality assessment and management.

Formal methods of decision analysis can help to structure a decision making process and to communicate reasons for decisions transparently. Objectives hierarchies and associated value and utility functions are useful instruments for supporting such decision making processes by structuring and quantifying the preferences of decision makers or stakeholders. Common multi-attribute decision analysis software products support such decision making processes but they can often not represent complex preference structures and visualize uncertainty induced by uncertain predictions of the consequences of decision alternatives. To stimulate strengthening these aspects in decision support processes, we propose a set of visualization tools and provide a software package for constructing, evaluating and visualizing value and utility functions. In these tools we emphasize flexibility in value aggregation schemes and consideration and communication of prediction uncertainty. The use of these tools is demonstrated with an illustrative example of river management decision support.

This publication describes the concept for the ecological assessment of the condition of Switzerland's lakes. It is published as part of the FOEN «Environmental studies» series. The concept is an integral part of the modular stepwise procedure for studying and assessing surface bodies of water. It describes the use of instruments supporting the decision-making process in the development and application of modules for assessing the condition of lakes, and provides an overview of the priorities in the area of module development.

Das per 1.1.2011 in Kraft getretene revidierte Gewässerschutzgesetz bringt den Kantonen in der Schweiz zusätzliche Verpflichtungen bezüglich der Revitalisierung morphologisch beeinträchtigter Gewässer und der Verminderung negativer Auswirkungen von Wasserkraftanlagen auf Gewässerökosysteme. Da auch neue Finanzierungsquellen erschlossen werden, sind diese neuen oder verstärkten Verpflichtungen eine grosse Chance für die ökologische Aufwertung der schweizerischen Gewässersysteme. Ähnliche Anforderungen an das Gewässermanagement wurden auch im Ausland etabliert, etwa in der Europäischen Union durch die Wasserrahmenrichtlinie (WFD, 2000). Das Ziel des Gewässermanagements muss es sein, mit den verfügbaren Mitteln einen möglichst grossen ökologischen und gesellschaftlichen Nutzen zu erzielen.