Abstract
Densely populated coastal urban areas are often exposed to multiple hazards, in particular floods and storms. Flood
defenses and other engineering measures contribute to the mitigation of flood hazards, but a holistic approach to flood
risk management should consider other interventions from the human side, including warning information, adaptive
behavior, people/property evacuation, and the multilateral relief in local communities. There are few simulation approaches to consider these factors, and these typically focus on collective human actions. This paper presents an agent-based model that simulates flood response preferences and actions taken within individual households to reduce flood losses. The model implements a human response framework in w
hich agents assess different flood scenarios according to warning information and decide whether and how much they invest in response measures to reduce potential inun-
dation damages. A case study has been carried out in the Ng Tung River basin, an urbanized watershed in northern Hong
Kong. Adopting a digital elevation model (DEM) as the modeling environment and a building map of household
locations in the case area, the model considers the characteristics of households and the flood response behavior of
their occupants. We found that property value, warning information, and storm conditions all influence household losses,
with downstream and high density areas being particularly vulnerable. Results further indicate (i) that a flood warning
system, which provides timely, accurate, and broad coverage rainstorm warning, can reduce flood losses by 30–40%;
and (ii) to reduce losses, it is more effective and cheaper to invest early in response measures than late actions. This dynamic agent-based modeling approach is an innovative attempt to quantify and model the role of human responses in
flood loss assessments. The model is demonstrated being useful for analyzing household scale flood losses and responses and it has the potential to contribute to flood emergency planning resource allocation in pluvial flood incidents.
