An integrated framework to assess compound flood risks for interdependent critical infrastructure in a coastal environment
Abstract
Compound flooding refers to flood events caused by multiple factors, including marine processes (e.g. storm tides and waves), hydrometeorological signals (e.g. rainfall and river flows) among others. Saint Lucia is a tropical island in eastern Caribbean Sea, which is frequently affected by weather-related extreme events such as tropical storms and the associated risks are exacerbated due to its mountainous topography and high concentrations of infrastructure and human communities close to the coast. At the southern coast of Saint Lucia, significant infrastructures such as Hewanorra International Airport and Vieux Fort Seaport, and human settlements such as towns of Vieux Fort and La Tourney are located at low-lying areas and are at risk of compound flooding. A hydrologic model (i.e. HYdrological MODel) and a two-dimensional hydrodynamic model (i.e. LISFLOOD-FP) are set up and calibrated to investigate the combined effects of storm tides, wave run-up, rainfall, and river flows on flood risks in Saint Lucia. Results indicate the necessity to consider multiple contributing factors as well as to characterize the effects of uncertain boundary conditions. In flood-prone areas, there are infrastructures supporting major services in the study area, and by extension, the economy of the Island. A network-based model, which considers direct and indirect connections between infrastructures, is set up to explore risks of assets in conditions of non-flooding and flooding. Modelling results reveal the fundamental importance of various components including electricity distribution, flood control, information and communication services, transportation, housing and human settlements, tourism, and particularly the normal operations of Hewanorra International Airport. Prioritization of risks is critical for developing effective mitigation methods for infrastructure networks.