Uncertainty of late has become an increasingly important and controversial topic in water resource management, and natural resources management in general. Diverse managing goals, changing environmental conditions, conflicting interests, and lack of predictability are some of the characteristics that decision makers have to face. This has resulted in the application and development of strategies such as adaptive management, which proposes flexibility and capability to adapt to unknown conditions as a way of dealing with uncertainties. However, this shift in ideas about managing has not always been accompanied by a general shift in the way uncertainties are understood and handled. To improve this situation, we believe it is necessary to recontextualize uncertainty in a broader way-relative to its role, meaning, and relationship with participants in decision making-because it is from this understanding that problems and solutions emerge. Under this view, solutions do not exclusively consist of eliminating or reducing uncertainty, but of reframing the problems as such so that they convey a different meaning. To this end, we propose a relational approach to uncertainty analysis. Here, we elaborate on this new conceptualization of uncertainty, and indicate some implications of this view for strategies for dealing with uncertainty in water management. We present an example as an illustration of these concepts.

Over the past decade a series of major revisions to the generation and use of knowledge in the context of natural resources management has started to undermine basic assumptions on which traditional approaches to water management were based. Limits to our ability to predict and control water systems have become evident and both complexity and human dimensions are receiving more prominent consideration. Many voices in science and policy have advocated a paradigm shift in water management-both from a normative (it should happen) and a descriptive (it happens, and how) perspective. This paper summarizes the major arguments that have been put forward to support the need for a paradigm shift and the direction it might take. Evidence from the fields of science, policy, and management is used to demonstrate a lacuna in the translation of political rhetoric into change at the operational level. We subsequently argue that learning processes and critical reflection on innovative management approaches is a central feature of paradigm change and that contributions from psychology which emphasise the roles of frames and mental models can be usefully applied to paradigm change processes. The paper concludes with recommendations to facilitate debate and test alternative approaches to scientific inquiry and water management practice leading to critical reflection and analysis.C. Pahl-Wostl (B) · N. Isendahl · M. Brugnach

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[1] Multiplicative random cascades (MRCs) can parsimoniously generate highly intermittent patterns similar to those in rainfall. The elemental MRC model parameter is the cascade weight, which determines how rainfall at one scale is partitioned at the next smallest scale in the cascade. While it is known that the probability density of these weights may vary with both time scale and rainfall intensity, nearly all previous studies have considered either time scale or intensity separately. We examined the simultaneous dependency of the weights on both factors and assessed the impacts of explicitly including these dependencies in the MRC model. On the basis of the observed relationships between cascade weights and time scale and intensity, four progressively more ''dependent'' models were constructed to disaggregate a long time series of daily rainfall to hourly intervals. We found that inclusion of the intensity dependency on the model parameters that generate dry intervals greatly improved performance. For the relatively small range of time scales over which the rainfall was disaggregated, varying model parameters with time scale resulted in minor improvement.