Testing the impact of direct and indirect flood warnings on population behaviour using an agent-based model

This paper uses a coupled hydrodynamic agent-based model (HABM) to investigate the effect of direct or indirect warnings in flood incident response. This model uses the LISFLOOD-FP hydrodynamic model and the NetLogo 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. Specifically, experiments are conducted using a novel “enhanced social modelling component” based on the Bass diffusion model. From the analysis of these 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, due to a lack of preparedness or a lack of phased evacuation measures. Furthermore, the methods outlined here 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

Novel framework for assessing long‐term flood risk management pathways focusing on river channel improvement and amenity policies

Many urban areas at higher flood risk owing to climate change, and mitigating these risks requires a combination of structural and nonstructural adaptation measures. Previous studies assessing adaptation measures are limited in quantifying the effects of climatic and social changes. As an interdisciplinary approach, this study developed an agent-based model of household locational choices and combined an advanced method for deriving on-site analytical flood risk curves (90 m resolution) to explicitly reflect the present/future flood risk on the flood insurance rate. To evaluate river channel improvements and amenity policies, the proposed framework was applied to a middle stream area of the Yodo River basin, Japan. The simulation results indicated that (1) both the design level and river pathway improvements influence the flood risk (2) developing wider areas over low- and no-risk areas rather than the intensive induction to limited no-risk areas lead to a more effective reduction in flood risk. In addition, (3) an appropriate amenity policy may contribute to the attenuation of the inequality of flood risk among regions owing to the pathway of improvement. The proposed interdisciplinary approach will help decision makers in long-term flood risk management

On Capturing Human Agency and Methodological Interdisciplinarity in socio-hydrology Research

Socio-hydrology has expanded and been effective in exposing the hydrological community to ideas and approaches from other scientific disciplines, and social sciences in particular. Yet it still has much to explore regarding how to capture human agency and how to combine different methods and disciplinary views from both the hydrological and the social sciences to develop knowledge. A useful starting ground is noting that the complexity of human–water relations is due to interactions not only across spatial and temporal scales but also across different organizational levels of social systems. This calls for consideration of another analytical scale, the human organizational scale, and interdisciplinarity in study methods. Based on the papers published in this journal’s Special Issue Advancing Socio-hydrology over 2019–2022, this paper illuminates how the understanding of coupled human–water systems can be strengthened by capturing the multi-level nature of human decision making and by applying an interdisciplinary multi-method approach

Social tipping points and adaptation limits in the context of systemic risk : Concepts, models and governance

Funding Information: SJ acknowledges the funding from the Finnish Academy, grant no 329239. TF is thankful to the support from the European Research Council (ERC) project #758014 under the European Union's Horizon 2020 Research and Innovation Program, and from the Netherlands Organization for Scientific Research (NWO) project #191.015. Publisher Copyright: Copyright © 2022 Juhola, Filatova, Hochrainer-Stigler, Mechler, Scheffran and Schweizer.Physical tipping points have gained a lot of attention in global and climate change research to understand the conditions for system transitions when it comes to the atmosphere and the biosphere. Social tipping points have been framed as mechanisms in socio-environmental systems, where a small change in the underlying elements or behavior of actors triggers a large non-linear response in the social system. With climate change becoming more acute, it is important to know whether and how societies can adapt. While social tipping points related to climate change have been associated with positive or negative outcomes, overstepping adaptation limits has been linked to adverse outcomes where actors' values and objectives are strongly compromised. Currently, the evidence base is limited, and most of the discussion on social tipping points in climate change adaptation and risk research is conceptual or anecdotal. This paper brings together three strands of literature - social tipping points, climate adaptation limits and systemic risks, which so far have been separate. Furthermore, we discuss methods and models used to illustrate the dynamics of social and adaptation tipping points in the context of cascading risks at different scales beyond adaptation limits. We end with suggesting that further evidence is needed to identify tipping points in social systems, which is crucial for developing appropriate governance approaches.Peer reviewe

Assessment of Urban Pluvial Flood Risk and Efficiency of Adaptation Options Through Simulations – A New Generation of Urban Planning Tools

We present a new framework for flexible testing of flood risk adaptation strategies in a variety of urban development and climate scenarios. This framework couples the 1D-2D hydrodynamic simulation package MIKE FLOOD with the agent-based urban development model DAnCE4Water and provides the possibility to systematically test various flood risk adaptation measures ranging from large infrastructure changes over decentralised water management to urban planning policies. We have tested the framework in a case study in Melbourne, Australia considering 9 scenarios for urban development and climate and 32 potential combinations of flood adaptation measures. We found that the performance of adaptation measures strongly depended on the considered climate and urban development scenario and the other implementation measures implemented, suggesting that adaptive strategies are preferable over one-off investments. Urban planning policies proved to be an efficient means for the reduction of flood risk, while implementing property buyback and pipe increases in a guideline-oriented manner was too costly. Random variations in location and time point of urban development could have significant impact on flood risk and would in some cases outweigh the benefits of less efficient adaptation strategies. The results of our setup can serve as an input for robust decision making frameworks and thus support the identification of flood risk adaptation measures that are economically efficient and robust to variations of climate and urban layout.</p

Agent-based simulator of dynamic flood-people interactions

This article presents a simulator for the modelling of the two‐way interactions between flooding and people. The simulator links a hydrodynamic model to a pedestrian model in a single agent‐based modelling platform, Flexible Large‐scale Agent Modelling Environment for the Graphical Processing Unit (FLAMEGPU). Dynamic coupling is achieved by the simultaneous update and exchange of information across multiple agent types. Behavioural rules and states for the pedestrian agents are proposed to account for the pedestrians' presence/actions in/to floodwater. These are based on a commonly used hazard rate (HR) metric to evaluate the risk states of people in floodwater, and by considering two roles for the pedestrians: evacuees or responders for action during or before the flood event, respectively. The potential of the simulator is demonstrated in a case study of a flooded and busy shopping centre for two scenarios: (a) during a flood evacuation and (b) pre‐flood intervention to deploy a sandbag barrier. The evacuation scenario points to changes in floodwater hydrodynamics around congested areas, which either worsen (by 5–8%) or lessen (by 25%) the HR. The intervention scenario demonstrates the utility of the simulator to select an optimal barrier height and number of responders for safe and effective deployment. Accompanying details for software accessibility are provided

A hazard-human coupled model (HazardCM) to assess city dynamic exposure to rainfall-triggered natural hazards

Human exposure to threats from natural hazards is generally estimated using a static approach with the fixed number of people located in hazard-prone zones; however, in reality this number varies due to population mobility. This study proposes a human–hazard coupled City Model (HazardCM) for accurately calculating city spatiotemporal dynamic exposure to different hazards. It includes four components: an urban environment module, agent-based model, city–hazard coupler, and dynamic exposure assessment. Rainfall-triggered natural hazards under extreme hydrometeorological events were modeled in Lishui, China. Scenarios covering different magnitudes, timings and locations, and return periods of hazards were investigated to derive the spatial distribution and evolution of human exposure. This model is the first that different natural hazards have been analyzed within a unified framework using a dynamic method and offers a new way to investigate exposure's space–time characteristics while considering the dynamic nature of both humans and hazards