Spatial and temporal analysis of urban flood risk assessment

Urban flood risk assessment requires quantification of uncertainty that is spatially and temporally variable. This paper presents a new approach to urban flood risk assessment by: (a) integrating objective and subjective uncertainties and (b) providing full insight into spatial and temporal change of flood risk. A 1-D storm sewer model and a 2-D surface flow model are integrated to describe the dynamic interactions between overland flow on the streets and flow through the storm sewer network. The fuzzy set theory approach is used to assess spatial and temporal variability of urban flood damage, and the acceptable level of partial flood damage. The spatial and temporal variability of fuzzy performance indices: (i) combined reliability-vulnerability; (ii) robustness and (iii) resiliency, are generated as the outcome of the urban flood risk analysis. The methodology is illustrated using the residential community of Cedar Hollow (London, Ontario, Canada) as a case study.