Towards Floodable Cities: Floodability as An Alternative Flood Safety Standard (PAP014347)

Código

PAP014347

Autores

Kuei-Hsien Liao

Tema

Urban Floods

Resumo

In the face of increasing extreme storms in many regions of the world, flooding is becoming less predictable and less controllable. This has posed a greater challenge in flood hazard mitigation, especially in urban areas. Still prevailing as a mitigation measure, flood control-referring to using engineering structures such as levees, dams, channelization, and drainage pipe system to prevent flooding-has been recognized as an insufficient solution to long-term flood safety. In recent years resilience has emerged as an important subject in flood management. Originated in ecology in Holling (1973), resilience theory suggests that flood control, which is to artificially suppress the inherit system dynamics, could compromise the resilience of a city to floods. Flood resilience is nurtured through adaptation to, not resisting, flooding. In the era of climate change, a paradigm shift from flood control to flood adaptation in flood hazard mitigation is necessary. In this paper I propose a flood safety standard based on flood adaptation, alternative to the protection standard of flood control infrastructure (i.e., protection against X-year flood). The proposed standard is floodability, describing the degree to which a place can be flooded without incurring physical damage and socioeconomic disruption. Floodability is measured by the percentage of floodable lands in a given area, such as an urbanized floodplain. I demonstrate how floodability is estimated with case studies of several densely built-up areas in Singapore and Taiwan. Essentially, floodability is determined by the design of the built environment, i.e., buildings, open spaces, and infrastructure. As a safety standard, floodability addresses the adaptability of the built environment, which is fundamentally different from flood protection standard that addresses the controllability of the river and stormwater. Move towards floodable cities, increasing floodability requires retrofitting existing built environment. This implies that the spatial planning and design profession, including urban planning, landscape architecture, and architecture, needs to take greater responsibility in mitigating flood hazards. Instead of continuing to invest in building new and/or strengthening old flood control infrastructure, government should redirect the resources to flood adaptation measures. According to resilience theory, this is the best policy to ensure survival in an uncertain world of climate change.