Flood and Evacuation Simulations for Urban Flooding

Crowd modeling is one of the key components of risk analysis and evacuation planning in emergency situations. This paper presents a simulation environment for experimenting with different city evacuation scenarios. The simulation couples a flood model with a crowd escape model. The developed agent-based crowd model mimics the behavior of pedestrians escaping from dangerous regions towards safe areas. The system is evaluated through a series of experiments, modeling the flooding of an area in St. Petersburg, Russia.

Evacuation models can be used to determine evacuation capacity, by estimating the time required for evacuating populations to leave areas exposed to a hazard. Disaster management practices and evacuation modeling are generally carried out to prepare for 'worst-case' conditions. However, hazard severity is highly variable. Performing evacuation modeling for multiple hazard scenarios may provide flexibility and a comprehensive understanding of evacuation capacity. A case study was undertaken to analyze the merit of scenario-based evacuation modeling. Results demonstrate a difference in clearance time between maximum and historic tsunami scenario modeling. During a smaller-scale event, allowing the maximum scenario population to evacuate can add congestion and inhibit evacuation of at-risk populations. Managing evacuation can improve evacuation efficiency by preventing unneeded congestion. Results show that traditional worst-case-scenario modeling may lead to overestimation of time needed to evacuate. Planning under such a scenario may increase risk to smallerscale hazards.

Flooding is viewed by many as a natural phenomenon, which is necessary for biodiversity. However, with the anthropogenic activities brought about by changes in land-use and climate, floods are observed to be more frequent and severe. In order to avert the negative impacts of flood, preparedness measure such as evacuation is increasingly necessary. This review is conducted to identify recent advances on evacuation research in the view of behavioral science, risk analysis and transportation modeling. The elements of the evacuation process such as decisions, warning, withdrawal, shelter and reentry with relevance to transportation planning constitutes the framework and emphasis of this review. Future uptakes for research include travel behavior that covers decision to evacuate and reentry, and in-depth consideration of the flood hazard, its associated risk and shelter information to evacuation transportation demand modeling.

Natural Hazards, 2018

In this study, an agent-based model is proposed in order to provide new insights into the policy analysis and strategy assessment of city-scale evacuation management. The proposed model is suitable for assessment of the influence of different departure times and communications among peer evacuees on the number of residents at risk who arrive at official shelters. A case study is applied to build a simulation model for the coastal city of Brisbane in Australia. The Brisbane River catchment experiences regular flooding almost every year; the second severest flood since the twentieth century occurred in 2011. During that event, over 15,000 properties were inundated and around 3600 households evacuated in metropolitan Brisbane alone. Making use of high-performance computing clusters, the evacuation simulation was coupled with results from a validated hydrodynamic model to test a variety of escaping scenarios based on the 2011 flood situation. This case study demonstrates the proposed model's capacity to represent the dynamic evacuation process and also shows that the model is able to help develop flood emergency plans and evaluate response measures through exploring key elements in a range of scenarios.

Procedia Engineering, 2016

This paper explores the uses of Agent Based Models (ABM) and its potential to test large scale evacuation strategies in coastal cities under threat of an imminent flooding due to extreme hydro-meteorological events. The first part of the paper is an introduction to the field of complex adaptive systems (CAS) and the principles and uses of ABM in this field. It is also presented the benefits and limitations of such models. The second part of the paper focuses on the theory used to build the ABM. For this study, theories and frameworks of human behaviour and disaster psychology were used. To feed the ABM model qualitative and quantitative attributes or characteristics of human beings are abstracted from literature review, fieldwork and expert's knowledge. The third part of the paper shows the methodology used to build and implement the ABM model using Repast Symphony, a Java based modelling system. The results of the initial experiments implemented in a region of the city of Marbella, southern Spain, are presented and discussed. The preliminary results are promising to further enhance the development of the model and its implementation and testing at full city scale.

Proceedings of the 5th …, 2008

This paper proposes an agent-based simulation system for Dam Break Emergency Plan validation.

Science and practice for an uncertain future

A number of evacuation models exist in literature, but investigations of their operational aspects and efficient implementation are rare. The purpose of this paper is to critically assess the operational aspect of pedestrian evacuation models for flash floods mitigation. Through a detailed real-life case study in Ras-Baalbek village-Lebanon, the efficiency of evacuation models when it comes to saving lives was examined. Potential evacuation times were established using an anisotropic least-cost-distance (LCD) approach combined with an exploratory geospatial analysis. The next step was a field verification of the obtained results and accordingly, a detailed evacuation plan that would allow evacuees for a quick departure before flash floods arrival was established. Based on the modeling results, evacuation signs were proposed to be installed on roads along with building vertical-evacuation structures to enhance the evacuation time. The obtained evacuation-modeling outcomes showcased to have multiple operational implications: flood risk outreach, educating and training (preparedness and response), reducing risk and casualties, long-term land use/land cover zoning and, ultimately, improving communities' resilience to floods.

Environmental Modeling & Assessment

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 agentbased model that simulates flood response preferences and actions taken within individual households to reduce flood losses. The model implements a human response framework in which agents assess different flood scenarios according to warning information and decide whether and how much they invest in response measures to reduce potential inundation 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.

2010

Whether to implement a mass evacuation of people from an area at risk of flooding can be a major issue for emergency managers. The modelling of the evacuation process generated by a forecast flood is important for those responsible for the efficient and safe movement of people during evacuations. Evacuation modelling can predict “bottlenecks” in the system before they are experienced, it can also be used to determine the impact of road closures due to flooding and the impact of phased evacuation on traffic loading. Being able to model alternative evacuation scenarios can lead to the establishment of appropriate evacuation policies and shelter strategies. With the increasing use of two dimensional hydraulic models that can provide accurate estimates of floodwater velocity and depth, and with the increased availability and accessibility of spatially-referenced population data and transport links, the modelling of mass evacuations for floods has increased. The model results can be used...