The seventh facet of uncertainty : wrong assumptions, unknowns and surprises in the dynamics of human–water systems

Di Baldassarre, Giuliano and Brandimarte, Luigi and Beven, Keith John (2016) The seventh facet of uncertainty : wrong assumptions, unknowns and surprises in the dynamics of human–water systems. Hydrological Sciences Journal, 61 (9). pp. 1748-1758. ISSN 0262-6667

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The scientific literature has focused on uncertainty as randomness, while limited credit has been given to what we call here the “seventh facet of uncertainty”, i.e. lack of knowledge. This paper identifies three types of lack of understanding: (i) known unknowns, which are things we know we don’t know; (ii) unknown unknowns, which are things we don’t know we don’t know; and (iii) wrong assumptions, things we think we know, but we actually don’t know. Here we discuss each of these with reference to the study of the dynamics of human–water systems, which is one of the main topics of Panta Rhei, the current scientific decade of the International Association of Hydrological Sciences (IAHS), focusing on changes in hydrology and society. In the paper, we argue that interdisciplinary studies of socio-hydrological dynamics leading to a better understanding of human–water interactions can help in coping with wrong assumptions and known unknowns. Also, being aware of the existence of unknown unknowns, and their potential capability to generate surprises or black swans, suggests the need to complement top-down approaches, based on quantitative predictions of water-related hazards, with bottom-up approaches, based on societal vulnerabilities and possibilities of failure.

Item Type:
Journal Article
Journal or Publication Title:
Hydrological Sciences Journal
Additional Information:
This is an Accepted Manuscript of an article published by Taylor & Francis in Hydrological Sciences Journal on 12/05/2016, available online:
Uncontrolled Keywords:
?? epistemic uncertaintysocio-hydrologyblack swansdisaster risk reductionresiliencewater science and technology ??
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Deposited On:
21 Jun 2016 15:30
Last Modified:
15 May 2024 02:38