Development of a Coupled Human And Natural Systems (CHANS) Modelling Approach for flood risk assessment and management

Keywords: CHANS modelling, inundation model, agent-based model, risk assessment, flood risk management

Flooding is the most wide-spreading natural hazard threatening people’s lives and properties worldwide. In recent years, rapid urbanisation and more frequent weather extremes have led to increased risk of flooding, evidenced by the costly summer floods occurred in Europe and China in July 2021 and, most recently, the deadly event affecting most areas across Pakistan. Effective flood risk management is essentially needed to protect people’s lives and properties.

Human activities may significantly influence flooding processes and the subsequent risk. However, few flood risk assessment and management practices directly consider human activities and social dynamics. This study aims to develop a Coupled Human And Natural System (CHANS) model to simulate the human-nature interacting processes during a flood event, which is subsequently applied to assess flood impact and evaluate the effectiveness of different disaster management options. The CHANS modelling framework is implemented by coupling the in-house High-Performance Integrated hydrodynamic Modelling System (HiPIMS) and an agent-based model built on the Flexible Large-scale Agent Modelling Environment of the Graphics Processing Unit (FLAMEGPU). The agent-based model simulates the complex behaviours of individuals and households reacting to the dynamic flooding process predicted by HiPIMS. The new CHANS modelling framework is tested by simulating the household damage caused by the 2015 Desmond flood in the 2500 km² Eden Catchment in England, and the simulation results are consistent with the data released in government reports. The model is further applied to explore the role of early warning and sandbagging in mitigating flood impacts. The validated CHANS flood risk modelling and assessment framework is further applied to the City of Can Tho in the Vietnamese Mekong Delta to assess compound flood risk taking into account dynamic household vulnerability and explore different risk mitigation measures.