A three-dimensional fuzzy methodology for flood risk analysis

This paper presents a methodology for assessing spatial and temporal uncertainty associated with flood risk management. Traditional modelling approaches focus on either temporal or spatial variability, but not both. There is a need to understand the dynamic characteristics of flood risk and its spatial variability. The traditional two-dimensional (2D) fuzzy set, with one dimension for the universe of discourse and the other dimension for its membership degree, is not sufficient to handle both, spatial and temporal variation of flood risk. The theoretical foundation of this study is based on the development of a three-dimensional (3D) fuzzy set that includes flood risk variability in space and time. The proposed methodology extends the acceptance level of partial flood damage concept to a 3D representation and allows capturing change of decision makers' preferences in time and space. The main objective of the paper is to present an original methodology for flood risk management that is capable of (a) addressing uncertainty caused by spatial and temporal variability and ambiguity; (b) integrating objective and subjective risks; and (c) assisting flood management decision making based on a more detailed understanding of temporal and spatial variability of risk. Presented methodology is illustrated using the Red River flood of 1997 (Manitoba, Canada) as a case study.