Risk of Mobility Disruption Index to Evaluate Flood Resilience in Urban Basins

The concept of infrastructure resilience consists of the ability of a system to absorb impacts and recover from unexpected natural disasters events. Increased flood resilience can be achieved through urban interventions which respond to flood risks, minimizing them. More resilient cities to flooding can be built with techniques that harmonize the relation between stormwater and urban space. The transport networks appear as an important urban system to support human safety during flooding events, enabling people mobility and aid access to the impacted location. In this context, it is proposed an index that is able to measure the vulnerability of the urban mobility system to floods, as a support tool to evaluate potential interventions that increase resilience in cities. The Risk of Mobility Disruption Index (RMDI) represents the system`s ability to continue providing part of its services during the occurrence of a flood event. This index is composed of the Indicator of Mobility Risk (IMR), which indicates the degree of impact of the flood in the traffic of cars and people, and the Indicator of Difficulty of Aid Access (IDA), which indicates potential difficulties in the organization of emergency actions. The IMR consists of an Indicator of Road Hierarchy (IRH), which specifies how regions are important to transit, and an Indicator of Non-coverture by Rail Transport (INRT), which shows which areas have lower availability of transportation alternatives. The IRH and the INRT are related to a hazard indicator, represented by the Indicator of Permanence Factor (IPF), which counts the total time that an area remains flooded in certain depth ranges, covering situations of greater difficulty for the traffic of cars and pedestrians up to the complete disruption of the transport system. IDA represents, indirectly, the difficulty of a certain region in receiving help from a specialized team. In this paper, due to the ease of data access, the Fire Department facilities that exist inside the basin under analysis are considered. Each facility receives an area of influence, according to its geographic distribution. Areas of influence are penalized for access to aid according to the flooding depth in the area where the Fire Department is installed and its surroundings. The RMDI is applied to the Canal do Mangue basin, localized at the central region of Rio de Janeiro city, Brazil, to observe most vulnerable points in relation to mobility.