An agent-based model for flood risk warning

Abstract

Abstract. This paper presents a new flood risk behaviour model developed using a coupled Hydrodynamic Agent-Based Model (HABM). This model uses the LISFLOOD-FP Hydrodynamic Model and the NetLogo (NL) agent-based framework and is applied to the 2005 flood event in Carlisle, UK. The hydrodynamic model provides a realistic simulation of detailed flood dynamics through the event whilst the agent-based model component enables simulation and analysis of the complex, in-event social response. NetLogo enables alternative probabilistic daily routine and agent choice scenarios for the individuals of Carlisle to be simulated in a coupled fashion with the flood inundation. Experiments are also conducted using a novel, enhanced social modelling component, comprised of the Bass Diffusion Model, to investigate the effect of direct or indirect warnings in flood incident response. From the analysis of these coupled simulations, management stress points, predictable or otherwise, can be presented to those responsible for hazard management and post-event recovery. The results within this paper suggest that these stress points can be present, or amplified, by a lack of preparedness or a lack of phased evacuation measures. Furthermore, the methods here outlined have the potential for application elsewhere to reduce the complexity and improve the effectiveness of flood incident management. The paper demonstrates the influence that emergent properties have on systematic vulnerability and risk from natural hazards in coupled socio-environmental systems.

Flood Evacuation Routes Based on Spatiotemporal Inundation Risk Assessment

“…However, in large-scale evacuation situations, time delays occur due to congestion (e.g., bottleneck effect). Phased evacuation was suggested in a simulation-based previous study [42][43][44] as a method to reduce the time delay due to congestion in an evacuation situation. Since this study focuses on the prediction of the changing pattern of urban flooding according to the progress of flooding, it can be used to establish a phased evacuation strategy.…”

Response to RC#3

“…However, to further reassure the referee, the authors are confident that the hydraulics modelled are well validated for the Carlisle 2005 case study, as is supported by the large body of cited works in section 2.1 of the submission and that the human dynamical routine is eminently sensible and realistic (sufficiently so to answer the questions posed in the paper). Additionally, and as the referee will be aware, ABMs are historically difficult to validate (Ormerod and Rosewell, 2006 source added to revised submission) and whilst techniques have been introduced to improve this, the authors feel that the model offers a sufficient balance between " clear explanation and description of the phenomena" and the "simplest possible realistic agent-rules of behaviour" for the model to be considered a valid base for comparison to other models (such as those suggested by the referee i.e. Lumbroso et al & Dawson et al) The authors would also argue that the level of cognition afforded to the agents operating within the model is not so high as to require significant justification beyond that provided as the process represented is of sufficient alignment to produce useful results for an intended purpose, namely to test hypothesis which would be difficult to evaluate in any other way.…”