Analysis of Cascading Effects on Key Urban Networks During Flooding in Brazzaville, Congo

Abstract

This manuscript analyses the cascading effects between urban technical networks in Brazzaville, Congo. To this end, we have identified the urban networks that are essential to the functioning of the city, namely the road network, the drinking water network, the sanitation network and the electricity network. The working methodology is based on a spatial analysis of flooding and an analysis of vulnerability using indicators of exposure (direct contact with water), sensitivity (malfunctions caused when in contact with water) and adaptability (continuity of operation once in contact with water) of the urban technical networks. The analyses show that all the technical urban networks appear to be dependent or interdependent on each other. The road network is the most exposed, but causes very little disruption to the others, while the electricity network is the one that causes the most disruption once it malfunctions. The cascading effects between urban technical networks stem from functional, physical or cybernetic dependency and can cause partial or total failure of the affected network. A power failure could extend functional vulnerability to the drinking water supply network via pumps, which depend on electricity. This research is being carried out in the context of urban risk management, with the aim of ensuring urban resilience to flooding.