Between Vulnerability and Sustainability: Evaluating the Flood Impact on Urban Road Network

The intensity of urban flooding has significantly increased throughout the world over the last few decades. By focusing on the performance of road network, the aim of this paper is to apply the theory of Space Syntax and develop a new model for evaluating the impact of flood on cities. In specific, two interrelated topics are examined through a simulated flood scenario in Yonghe District in New Taipei City, which has the highest population density in Taiwan at 39,000 per km
²
: First, the occurrence of flood has a disruptive impact on road network and therefore may cause the total breakdown of urban system. Starting from an analytic mapping of road accessibility, this study quantifies the extent to which the flood will undermine the transport structure of the city and reveal signs of vulnerable condition in the area typically neglected in flood impact evaluation. Second, the adaptive management of disaster mitigation services is the key to a sustainable reduction of flood risk. By importing the GIS data of evacuation route and disaster shelters into the analysis of analytic mapping, we observe a strong correlation between the malfunction of road network and the potential magnitude of flood impact. In sum, this study demonstrates that the model based on Space Syntax theory can provide effective evaluation of flood impact on urban road network and be used by government authorities to ensure their flood mitigation plans.