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Copyright of Canadian Water Resources Journal / Revue Canadienne des Ressources Hydriques is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The flood control operation of river barrages represents a multi-objective optimization problem with conflicting decision objectives, introducing risks into the decision-making process. Most existing optimization methods for operational rule sets encounter challenges related to the insufficient representation of flood accuracy and prolonged computational duration. Considering these two issues, this study aimed to propose a novel multi-objective barrage optimization operation approach based on a hydrodynamic model and a data-driven evolutionary algorithm. This approach employs a hydrodynamic model to precisely simulate the flood propagation process and provide the required hydraulic characteristics. Utilizing the results provided by the hydrodynamic model as foundational data, a multi-objective particle swarm algorithm was employed to drive the search for Pareto-optimal operational rules. Subsequently, the Kriging model is integrated into the optimization process, wherein only potential nondominated solutions in the offspring population were selected for exact objective function evaluations. This significantly reduced the frequency of calls to the hydrodynamic model, thereby enhancing the efficiency of optimization computations. The proposed approach was applied to a real multi-barrage flood control system for the rivers in the urban city of Chengdu, China. The results indicate that this method can optimize and solve the multi-objective operational rules for barrage flood control with limited computational resources. The obtained Pareto-optimal operational rules also illustrate the trade-off relationships among multiple objectives, suggesting that it is possible to mitigate downstream flood risks at the cost of increasing upstream flood risks, and vice versa. The new method can provide precise guidance for flood control scheduling of barrages during the flood season, enabling decision makers to choose the operation rules according to their own risk preferences. [ABSTRACT FROM AUTHOR]

Natural hazards and disasters threaten human life, damage properties and affect human-populated environments. Flood hazard assessment procedure was carried out using hazard criteria concepts through GIS, hydrological and hydraulic modeling coupling techniques utilizing HEC-HMS for the hydrological modeling and HEC-RAS for the hydraulic modeling. The objective of this study is to use geo-based hydrologic and hydraulic models to develop flood hazard maps of wadi Yutum floodplain areas in southern Jordan, focusing on the Amman-Aqaba Desert Highway along wadi Yutum for different design storm return periods. A GIS-based model to estimate the flood flow at the gauging stations of Wadi Yutum basin, which is the basin that drains into the city of Aqaba, was developed. Most of the developments in Aqaba are located on alluvial wadi fans, which are, unavoidably, subject to the risk of flooding. Initially, Intensity Duration Frequency (IDF) curves were generated to assess the rainfall-runoff situation in the basin. Based on the analysis and modeling, flood hazard maps for 25, 50, and 100-years return periods were generated with peak flows of 1523 m³/s, 1813 m³/s, and 2111 m³/s, respectively. These flood hazard maps aim to identify hazard locations within the flood plains of the target area. A risk map that categorizes three risk classes (high, medium and low) was generated by coupling the flood hazard map with a socio-economic map. High and medium risk zones identify hazard risk to the current facilities, road and trail users. The most affected element is the Amman-Aqaba Desert highway; the main entrance to Aqaba city, with an average daily traffic volume of 20,182 vehicles. Given that the vehicle occupancy rate on the highway is 1.6 person per vehicle, more than 32,000 persons could be affected on a given day depending on the time and the severity of the storm. Flood hazard, vulnerability, and risk mapping are essential tools for informed decision-making, helping to minimize the impacts of flooding and enhance the resilience of communities in the face of this natural hazard. [ABSTRACT FROM AUTHOR]

Predicting streamflow for an ungauged river is essential for effective water resource management, flood risk mitigation, ecological protection, and infrastructure planning, providing critical insights despite the absence of direct measurement data. Therefore, the objective of this paper is to assess the use of a rainfall-runoff model for predicting streamflow in the ungauged Awun River Watershed, Kwara State, Nigeria. Due to the absence of measured data, regional calibration techniques were employed, utilizing data from nearby gauged river with similar hydrological characteristics. The hydrologic model predicted a peak discharge of 2164 m³/s and a total runoff volume of 19967.78 m³ during the modeling period, providing valuable insights for flood forecasting and water resource planning. Performance evaluation metrics indicated a Nash-Sutcliffe Efficiency (NSE) of 0.54 and a Mean Error (ME) of 0.33, reflecting moderate agreement between observed and simulated runoff data. The Percent Bias (PBIAS) of 49.25% highlighted a tendency towards overestimation. Furthermore, a high R-squared (R²) value of 0.89 demonstrated that the model successfully explained 89% of the variance in observed runoff, effectively capturing the key hydrological characteristics of the Awun River watershed. This modeling framework is valuable for land-use planning, water resource management, decision-making, and flood risk assessments in the Awun River region.

Urbanization and climate change increasingly challenge urban water management. In this context, the design of stormwater drainage systems, which traditionally relies on historical rainfall records, is being questioned. Although significant efforts have been dedicated to optimizing drainage networks, the upgrading of existing systems remains understudied. This research devised a set of viable stormwater drainage networks, referencing the road network of the Sino-Singapore Tianjin Eco-City (data from Google Maps). On this basis, utilizing design rainfall data (sourced from the local meteorological center), an extensive array of scenario analyses was conducted. The investigation assessed the performance of implementing two redundancy-based interventions—introducing loops and enlarging pipe diameters—as well as the patterns of flood risk response, and by integrating a multi-objective optimization algorithm, this study proposes a framework for the optimization of grey infrastructure upgrades based on component replacement. The findings suggest that a precise deployment strategy for grey infrastructure is essential. The former improves the effective flow distribution of the drainage system, while the latter enhances its flow capacity, making each intervention suitable for drainage systems with a different degree of centralization. Further research shows that an integrated hybrid scheme brings significant flood risk improvement with strong applicability for most urban drainage systems. The upgrade model proposed in this study could be a valuable initiative, offering theoretical insights for the construction and development of resilient cities. [ABSTRACT FROM AUTHOR]

Flood mapping is a crucial tool for assisting urban planning and emergency response plans and, consequently, preventing or reducing the risks associated with flood disasters. However, in developing countries that often lack or have limited data, to produce such maps is a challenging task. When topographic data are lacking, digital elevation models (DEMs) derived from the Shuttle Radar Topography Mission (SRTM) are frequently used as a freely available surrogate, albeit with additional uncertainty. This work presents an integrated framework to investigate flood inundation areas using a Bayesian approach, while including steps for calibrating SRTM data and determining the river bathymetry below the WSE. A flood event in the Itaqui municipality, in the state of Rio Grande do Sul, southern Brazil is used to demonstrate the proposed framework. Findings suggest benefits in using calibrated SRTM DEMs for flood mapping regardless of whether flood inundation areas were derived directly from projections of WSEs on the terrain or based on hydraulic simulations. Results further highlight the potential of using a Bayesian approach to improve quality and reliability of flood hazards maps, especially in regions that lack topographic data. [ABSTRACT FROM AUTHOR]

Although risk perception and flood preparedness were crucial in flood management, perceived flood risk was not always translated into flood preparedness. It was essential to investigate the potential association between risk perception and flood preparedness. This study focused on Nanjing as the research region, designed questionnaire survey and explored the influence relationship between risk perception and flood preparedness. Participants showed the medium perception of food risk and higher flood preparedness. Higher risk perception was observed in individuals with regular exercising, the elderly, low education level and long living time. Higher flood preparedness occurred among groups of females, the elderly and high education level. Individuals relied more on threat appraisal to perceive risk, which failed to trigger high enough coping appraisal. Inadequate risk perception led to a strenuous transform into flood preparedness with unbalanced relationship. Groups with distinct socio-economic characteristics exhibited varying preferences to achieve risk perception and flood preparedness. Females relied more on flood knowledge to perceive flood risk. Path analysis suggested that threat appraisal transformed into flood preparedness under the effect of response intention and social-economic features. Groups with high education level or bad health were more likely to perceive risk and engage in preventive behavior. These findings could provide critical insights into intervention strategies for enhancing public flood preparedness in flood management. [ABSTRACT FROM AUTHOR]

While greening vacant houses is encouraged as a sustainable strategy, there is a paucity of quantitative research on its effects. The purpose of this study is to evaluate the flood risk and CO2 mitigation effects of greening neglected vacant houses and barren sites in densely built old downtown areas. To achieve this goal, an investigation was conducted of the actual conditions of vacant houses and barren sites in Ami-dong and Chojang-dong in Busan Metropolitan City. Subsequently, four scenarios for greening vacant houses and barren sites were developed, and rainfall runoff simulations were performed using the K-LIDM model. Furthermore, the annual CO2 fixation for greening with trees was calculated using established research formulas. This study found that 73% of vacant houses in the study area remain unoccupied for an extended period, and when demolished, 56% become concrete-paved barren sites. The runoff simulations indicated that greening with trees led to a 1.71% decrease in annual runoff volume in the long-term model, with peak runoff volume reductions of 3.06% and 2.38% during 2-year and 30-year rainfall events in the short-term model, respectively. Planting trees could accommodate 3058 trees, fixing 62,124 kg of CO2 annually. This study demonstrates the climate change response effects of greening vacant houses. [ABSTRACT FROM AUTHOR]

In the context of global climate change, the frequency of watershed flooding events resulting from extreme rainfall has significantly increased. Especially at river or lake confluences, the presence of backwater effects greatly amplifies the flood risk. To investigate the influence of backwater effects on the hydraulic characteristics of rivers and lakes, this study focuses on the Dongping Lake in China. An enhanced two-dimensional hydrodynamic model was employed to simulate and analyze three different degrees of backwater effects. The results indicate that, compared to the working conditions without the backwater effect, the highest lake water level increased by 1.0 m and 0.1 m under severe and moderate backwater effect conditions, respectively. The total outflow flood volume decreased by 30.1% and 2.3%, respectively. The demolition time for the Jinshan Dam needs to be advanced by 12.5 h and 10.0 h, respectively, and the inundation area in the western region expanded by 2.73% and 0.32%. Additionally, the average inundation depth increased by 0.93 m and 0.08 m, respectively. These results provide valuable data support for the safe operation of Dongping Lake, the formulation of flood defense strategies, and, likewise, offer valuable insights into the risk management of flood events in other rivers and lakes with backwater effects. [ABSTRACT FROM AUTHOR]

With the inexorable march of climate change, increased flooding is inevitable. Understanding the feedback between federal flood mitigation policies and the ways in which local governments build flood resilience is a significant gap in the literature. In particular, the effect that federal flood mitigation grants have on the intensity of local flood mitigation is nonexistent. This work measures flood risk mitigation by using the level of participation in FEMA's Community Rating System (CRS). Communities that participate in the CRS and undertake mitigation are awarded points; more points imply a higher level of participation. Since its inception in 1990, CRS communities have received considerably more federal pre‐disaster flood mitigation grants compared to non‐CRS communities. This study assesses the effect of federal pre‐disaster flood mitigation grants on the level of participation in the CRS program. We use data on Hazard Mitigation Assistance programs and CRS participation data between 2010 and 2015. We link these data to flood risk and socioeconomic information. Our results indicate (i) federal pre‐disaster flood mitigation grants do not appear to significantly influence the level of CRS participation, (ii) the effect of flood risk and socioeconomic factors on the level of CRS participation are mixed, and (iii) the current level of CRS participation is influenced by the previous level of CRS participation, which is not tied to federal pre‐disaster flood mitigation grant. These findings add to the growing discussions on the drivers and barriers of local flood risk mitigation. [ABSTRACT FROM AUTHOR]

Sustainable Urban Drainage Systems (SUDS) include strategies and solutions for distributed stormwater management and control. They are strongly encouraged, especially in highly urbanized areas that suffer the combined effect of impervious surfaces and the increase in extreme rainfall events due to urbanization growth and climate change. Their integration into traditional urban drainage systems can mitigate flood risk and pollution of receiving water bodies. The main goal of SUDS is to restore the natural water balance by increasing infiltration and evapotranspiration processes and promoting rainwater harvesting and reuse. This paper proposes an analytical-probabilistic approach for SUDS modeling applicable to different systems. Developed equations allow estimating the runoff and residual storage probability for evaluating the efficiency of the storage volume both in terms of flood control and, depending on SUDS type, in terms of emptying time or water needs supply. The modeling considers the possibility of consecutive chained rainfalls; this feature is relevant for SUDS, often characterized by low outflow rates. Relating characteristic parameters to a probabilistic level (the Average Return Interval, ARI) makes the formulas interesting to be used in the design practice. An application to two case studies confirmed the goodness of the proposed method. [ABSTRACT FROM AUTHOR]

Freeboard—elevation of a structure above the base flood elevation (BFE)—is a critical component in mitigating or avoiding flood losses. However, the unrevealed benefits and savings of freeboard installation have prevented communities from adopting this approach. To improve decision-making for residents, prospective residents, and other stakeholders in flood-vulnerable communities and enhance flood risk mitigation strategies, this study presents the methodology underlying a new webtool, FloodSafeHome, that estimates comprehensively the economic benefits and savings of freeboard installation for new construction of residential buildings. Specifically, the proposed evaluation framework has been designed to calculate monthly savings for individual buildings by assessing freeboard cost, insurance savings per year, and expected annual flood loss. This new evaluation method is built into a web-based, decision-making tool for use by the public and community leaders in three southeastern Louisiana parishes (i.e., counties), to identify expected future benefits of building residences with freeboard and enhance their decision-making processes with interactive risk/benefit analysis features. For example, results indicate the levels of freeboard that optimize the cost-benefit ratio for flood-insured homes in the study area. This approach is expected to improve long-term flood resilience and provide cost-efficient flood mitigation strategies, particularly in disaster vulnerable regions.

Floods are among the most destructive natural hazards in the world, posing numerous risks to societies and economies globally. Accurately understanding and modeling floods driven by extreme rainfall events has long been a challenging task in the domains of hydrologic science and engineering. Unusual catchment responses to flooding cause great difficulty in predicting the variability and magnitude of floods, as well as proposing solutions to manage large volumes of overland flow. The usage of Nature-Based Solutions (NBS) has proved to be effective in the mitigation of flood peak rate and volume in urban or coastal areas, yet it is still not widely implemented due to limited knowledge and testing compared to traditional engineering solutions. This research examined an integrated hydrological and hydraulic modeling system to understand the response of an at-risk watershed system to flooding and evaluate the efficacy of NBS measures. Using the Hydrologic Engineering Center Hydrologic Modeling System and River Analysis System (HEC-HMS and HEC-RAS) software, an integrated hydrologic-hydraulic model was developed for Hurricanes Matthew (2016) and Florence (2018) driven floods across the Little Pee Dee-Lumber Rivers watershed, North and South Carolina (the Carolinas), USA. The focus was on Nichols town, a small town that has been disproportionately impacted by flooding during these two hurricane events. Different NBS measures including flood storage ponds, riparian reforestation, and afforestation in croplands were designed, modeled, and evaluated. Hurricane Matthew's flooding event was used for evaluating the NBS scenarios given its high simulation accuracy in flood inundation compared to the less accurate results obtained for Hurricane Florence. The scenario comparison evidenced that large-scale natural interventions, such as afforestation in croplands, can reduce the inundated area in Nichols town by 8% to 18%. On the contrary, the smaller-scale interventions such as riparian reforestation and flood storage ponds showed a negligible effect of only 1% on flood mitigation. [ABSTRACT FROM AUTHOR]

There are different perspectives of what constitutes disaster risk. Among the "hazards"‐tradition research, more focus is given to modelling hazards, and less effort is made to understand the vulnerabilities. Considering vulnerabilities as the inherent characteristics of the place that create the potential to harm, this paper highlights the importance of understanding the vulnerabilities of the place before defining actions for flood risk mitigation (FRM). In this sense, a participatory approach, the Project PLANEJEEE, was developed to understand the social and institutional vulnerabilities of FRM in Campina Grande, Brazil. Data was collected with the collaboration with 199 stakeholders through surveys, workshop and focus groups. The results reflect the analysis of risk perception and coping capacity of communities at risk (n = 172), and the institutional context with the involvement with policymakers and local specialists (n = 27). Although results confirm that individuals faced severe flood risk cases previously, they still need resources for increasing their coping capacity and their own risk protection. Institutional vulnerabilities are shown with the contrast between challenges and actions for FRM. Findings show that multiple challenges in social and institutional contexts should be systematically addressed to propose actions to reduce flood risk vulnerability, and increase resilience. [ABSTRACT FROM AUTHOR]

Abstract There are different perspectives of what constitutes disaster risk. Among the “hazards”‐tradition research, more focus is given to modelling hazards, and less effort is made to understand the vulnerabilities. Considering vulnerabilities as the inherent characteristics of the place that create the potential to harm, this paper highlights the importance of understanding the vulnerabilities of the place before defining actions for flood risk mitigation (FRM). In this sense, a participatory approach, the Project PLANEJEEE, was developed to understand the social and institutional vulnerabilities of FRM in Campina Grande, Brazil. Data was collected with the collaboration with 199 stakeholders through surveys, workshop and focus groups. The results reflect the analysis of risk perception and coping capacity of communities at risk (n = 172), and the institutional context with the involvement with policymakers and local specialists (n = 27). Although results confirm that individuals faced severe flood risk cases previously, they still need resources for increasing their coping capacity and their own risk protection. Institutional vulnerabilities are shown with the contrast between challenges and actions for FRM. Findings show that multiple challenges in social and institutional contexts should be systematically addressed to propose actions to reduce flood risk vulnerability, and increase resilience.

This article deals with household‐level flood risk mitigation. We present an agent‐based modeling framework to simulate the mechanism of natural hazard and human interactions, to allow evaluation of community flood risk, and to predict various adaptation outcomes. The framework considers each household as an autonomous, yet socially connected, agent. A Beta–Bernoulli Bayesian learning model is first applied to measure changes of agents' risk perceptions in response to stochastic storm surges. Then the risk appraisal behaviors of agents, as a function of willingness‐to‐pay for flood insurance, are measured. Using Miami‐Dade County, Florida as a case study, we simulated four scenarios to evaluate the outcomes of alternative adaptation strategies. Results show that community damage decreases significantly after a few years when agents become cognizant of flood risks. Compared to insurance policies with pre‐Flood Insurance Rate Maps subsidies, risk‐based insurance policies are more effective in promoting community resilience, but it will decrease motivations to purchase flood insurance, especially for households outside of high‐risk areas. We evaluated vital model parameters using a local sensitivity analysis. Simulation results demonstrate the importance of an integrated adaptation strategy in community flood risk management. [ABSTRACT FROM AUTHOR]

Nature-based solutions (NBS) for mitigating climate change are gaining popularity. The number of NBS is increasing, but research gaps still exist at the governance level. The objectives of this paper are (i) to give an overview of the implemented NBS for flood risk management and mitigation in Germany, (ii) to identify governance models that are applied, and (iii) to explore the differences between these models. The results of a hierarchical clustering procedure and a qualitative analysis show that while no one-size-fits-all governance model exists, polycentricism is an important commonality between the projects. The study concludes by highlighting the need for further research on traditional governance model reconversion and paradigm changes. We expect the findings to identify what has worked in the past, as well as what is important for the implementation of NBS for flood risk management in future projects. [ABSTRACT FROM AUTHOR]

This article examines the role of policy entrepreneurs in promoting change in flood risk mitigation at the local level in Sweden through a comparative study of two Swedish municipalities with different approaches to flood risk governance; as a technical issue or a social issue. The municipality in which flood risk mitigation is addressed as a social issue exhibits a larger size of the network mitigating flood risk, more diverse actors involved, and a more central location of the politicians and senior management. Moreover, the analysis points to the salience of a bureaucratic policy entrepreneur in promoting this shift toward addressing it as a social issue, and shows how they use relational strategies to frame the issue as relating to climate change action. The article operationalizes sociability and credibility, two of the attributes of policy entrepreneurs, and thus, contributes to the theoretical and methodological discussion of policy entrepreneurs in general, and as they pertain to environmental policy in particular. Related Articles: David, Charles‐Philippe. 2015. "Policy Entrepreneurs and the Reorientation of National Security Policy under the G. W. Bush Administration (2001‐04)." Politics & Policy 43 (1): 163‐195. https://doi.org/10.1111/polp.12106 Shock, David R. 2013. "The Significance of Opposition Entrepreneurs on Local Sales Tax Referendum Outcomes." Politics & Policy 41 (4): 588‐614. https://doi.org/10.1111/polp.12028 Sidha, Zedekia, Patrick Asingo, and Justine Magutu. 2021. "Street‐Level Bureaucrats as Policy Entrepreneurs: The Nexus between Timing of Traffic Enforcement Activities and Road Safety Policy Outcomes." Politics & Policy Early View. https://doi.org/10.1111/polp.12386 [ABSTRACT FROM AUTHOR]

Local actors appear as inseparable components of the integrated flood risk mitigation strategy in Vietnam. Recognizing this fact, this study examined the long-term improvement in precautions taken by commune authorities and households between two major floods in 1999 and 2017 by applying both quantitative and qualitative methods. Two flood-prone villages were selected for a survey; one in a rural area and the other in a suburban area of Thua Thien Hue Province, central Vietnam. The findings indicate that most villagers doubted the structural works' efficacy and were dissatisfied with the current efforts of local authorities. Households' self-preparation thus became the decisive factor in mitigating risk. While most households have paid greater attention to flood precautions in 2017, others seem to be lagging. Poverty-related barriers were the root causes restraining households in both rural and suburban villages. The suburban riverine residents were further identified as vulnerable by their limitations in upgrading structural measures, which was ascribed to the inconsistency in the ancient town's preservation policy. This multidimensional comparison, in terms of vulnerability, emphasized the importance of space-function links in the suburb and the contradictions of different policy initiatives, such as landscape rehabilitation, disaster prevention, and livelihood maintenance. [ABSTRACT FROM AUTHOR]

Abstract The generation of hydrological data for accurate flood predictions requires robust and, ideally, dense monitoring systems. This requirement is challenging in locations such as the Himalayas, which are characterised by unpredictable hydroclimatic behaviour with dramatic small‐scale spatial and temporal variability. River level monitoring sensors that are affordable and easy‐to‐operate could support flood risk management activities in the region. We therefore identify potential for a local participatory monitoring network that also serve to overcome existing data gaps, which represent the main bottleneck for establishing an effective community‐based flood early‐warning system. We have applied a citizen science‐based hydrological monitoring approach in which we tested low‐cost river level sensors. Initial results, collected over summer 2017 from two stations on the River Karnali, suggest that our system can successfully be operated by non‐scientists, producing river level data that match those obtained from an adjacent government‐operated high‐tech radar sensor. We discuss potential opportunities to integrate these low‐cost sensors into existing hydrological monitoring practice. Combined with an adaptive, community‐led approach to resilience building, we argue that our low‐cost sensing technology has the potential not only to increase spatial network coverage in data‐scarce regions, but also to empower and educate local stakeholders to build flood resilience.

The generation of hydrological data for accurate flood predictions requires robust and, ideally, dense monitoring systems. This requirement is challenging in locations such as the Himalayas, which are characterised by unpredictable hydroclimatic behaviour with dramatic small‐scale spatial and temporal variability. River level monitoring sensors that are affordable and easy‐to‐operate could support flood risk management activities in the region. We therefore identify potential for a local participatory monitoring network that also serve to overcome existing data gaps, which represent the main bottleneck for establishing an effective community‐based flood early‐warning system. We have applied a citizen science‐based hydrological monitoring approach in which we tested low‐cost river level sensors. Initial results, collected over summer 2017 from two stations on the River Karnali, suggest that our system can successfully be operated by non‐scientists, producing river level data that match those obtained from an adjacent government‐operated high‐tech radar sensor. We discuss potential opportunities to integrate these low‐cost sensors into existing hydrological monitoring practice. Combined with an adaptive, community‐led approach to resilience building, we argue that our low‐cost sensing technology has the potential not only to increase spatial network coverage in data‐scarce regions, but also to empower and educate local stakeholders to build flood resilience. [ABSTRACT FROM AUTHOR]

Abstract Voluntary household decisions about whether or not to structurally mitigate or insure can directly and indirectly influence the flood vulnerability of a community. We look to understand the factors that influence flood risk mitigation decisions using a serious game experiment. Serious games can augment existing data collection methods used to understand flood risk mitigation by tracking decisions over multiple turns within an experimental research framework. In this game, participants choose where to live and how to distribute income given information about flood risks. We analysed data using a generalised linear mixed model that accounted for repeated‐measures effects. Experiencing an in‐game flood had a strong positive association with mitigation decisions, compared to a much weaker effect of a participant having experienced a flood in real‐life. We find that real‐life low‐income individuals were no less likely to implement in‐game mitigation measures than their higher‐income counterparts, suggesting that low income and/or cost is a practical barrier to risk mitigation. Our findings also suggest that incentivising flood risk mitigation should be done quickly following a flood.

Voluntary household decisions about whether or not to structurally mitigate or insure can directly and indirectly influence the flood vulnerability of a community. We look to understand the factors that influence flood risk mitigation decisions using a serious game experiment. Serious games can augment existing data collection methods used to understand flood risk mitigation by tracking decisions over multiple turns within an experimental research framework. In this game, participants choose where to live and how to distribute income given information about flood risks. We analysed data using a generalised linear mixed model that accounted for repeated‐measures effects. Experiencing an in‐game flood had a strong positive association with mitigation decisions, compared to a much weaker effect of a participant having experienced a flood in real‐life. We find that real‐life low‐income individuals were no less likely to implement in‐game mitigation measures than their higher‐income counterparts, suggesting that low income and/or cost is a practical barrier to risk mitigation. Our findings also suggest that incentivising flood risk mitigation should be done quickly following a flood. [ABSTRACT FROM AUTHOR]

• A flood risk function is provided to describe flood hazard probability of Beijing. • Drivers on spatial heterogeneity in flood risks varies with research scales. • Green infrastructure is more effective to mitigate urban flood risks. • Grey infrastructure aggravates flood risks, especially in exurbs of Beijing. • This study serves for infrastructure management to improve urban resilience. Improving infrastructure construction with nature-based solutions is a feasible strategy to mitigate flood risks and enhance urban resilience. This study fitted the flood risk function of Beijing based on extreme precipitation indices to analyze the probability of flood hazards and its economic losses. Then primary drivers on flood risks and its spatial relationship were identified, especially the effects of blue, green, and grey infrastructure. Results showed that flood risks of Beijing decrease from the northwest to southeast, while economic losses decrease from the southeast to the surrounding areas. Natural topography especially slope is the major driver of spatial heterogeneity in flood risks at the grid scale (q statistic=0.101), while socio-economic development especially economic intensity are the major drivers at the community scale (q statistic=0.194). Additionally, the attributing effects of classified infrastructure on flood risks are ranked as: green infrastructure (βmin=-0.28) > grey infrastructure (βmax=0.13) > blue infrastructure (βmin=-0.2). It indicates that green infrastructure plays a more effective role in mitigating flood risks in most urban areas of Beijing rather than blue infrastructure, while grey infrastructure aggravates flood risks, especially in the northeastern suburbs. This study provides a reference for decision making on infrastructure construction and flood management in rapid-urbanization cities. [ABSTRACT FROM AUTHOR]

Copyright of World Water Policy is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study offers insights into factors of influence on the implementation of flood damage mitigation measures by more than 1,000 homeowners who live in flood‐prone areas in New York City. Our theoretical basis for explaining flood preparedness decisions is protection motivation theory, which we extend using a variety of other variables that can have an important influence on individual decision making under risk, such as risk attitudes, time preferences, social norms, trust, and local flood risk management policies. Our results in relation to our main hypothesis are as follows. Individuals who live in high flood risk zones take more flood‐proofing measures in their home than individuals in low‐risk zones, which suggests the former group has a high threat appraisal. With regard to coping appraisal variables, we find that a high response efficacy and a high self‐efficacy play an important role in taking flood damage mitigation measures, while perceived response cost does not. In addition, a variety of behavioral characteristics influence individual decisions to flood‐proof homes, such as risk attitudes, time preferences, and private values of being well prepared for flooding. Investments in elevating one's home are mainly influenced by building code regulations and are negatively related with expectations of receiving federal disaster relief. We discuss a variety of policy recommendations to improve individual flood preparedness decisions, including incentives for risk reduction through flood insurance, and communication campaigns focused on coping appraisals and informing people about flood risk they face over long time horizons. [ABSTRACT FROM AUTHOR]

• Intelligent pump operation optimizes the effectiveness of flood control systems. • NSGA-II constructs the optimal operation rules with FSP water level and water head. • Objectives: minimize variations and peaks of water level & the number of duty pumps. • The configured optimal operation rules effectively improve current operation rules. • The improvement rates of three objectives achieve 43%, 3% and 71% respectively. Rapid urbanization in metropolitan areas easily triggers flashy floods. Urban drainage systems conveying stormwater out of cities are key infrastructure elements for flood mitigation. This study develops an intelligent urban flood drainage system accounting for carryover storage through optimizing the multi-objective operation rules of pumping stations for effectual flood management in Taipei City. The Yu-Cheng pumping station constitutes the study case, and a large number of datasets collected from 17 typhoon/storm events are adopted for model construction and validation. Three objective functions are designed to minimize: (1) the sum of water level fluctuations in the flood storage pond (FSP); (2) the sum of peak FSP water levels; and (3) the mean absolute difference of pump switches between two consecutive times along operation sequence. The non-dominated sorting genetic algorithm II (NSGA-II) is applied to searching the Pareto-optimal solutions that optimize the trade-off between the objectives. We next formulate the optimal operation rules through a two-tier sorting process based on a compromised Pareto-optimal solution. The comparison of the simulated results obtained from both the optimal operation rules and current operation rules indicate that the optimal operation rules outperform current operation rules for all three objectives, with improvement rates reaching 43% (OBJ1), 3% (OBJ2) and 71% (OBJ3), respectively. We demonstrate that the derived intelligent urban flood drainage system can serve as reliable and efficient operational strategies for urban flood management and flood risk mitigation. [ABSTRACT FROM AUTHOR]

The potential of woodland and floodplain woodland plantations in a wide area, of high flood risk, along the Spey River (Scotland) is investigated, to mitigate the floods’ catastrophic impact. The spatial analysis required various datasets to be overlaid, to define the suitable sites for woodland and floodplain woodland establishment. These datasets that concern the topography, the physical and technical characteristics (existing woodland, road system, urban and rural areas, river system and open water areas, railway) and the protected sites of the study area were obtained and merged using Geographical Information System (GIS) techniques. The most suitable and unsuitable areas within the region were identified, using multi-criteria evaluation methods (Boolean approach). In total, 13 constraints were created by expressing true/false statements for each factor, and were combined together using spatial analysis tools. The results revealed the high potential of woodland and floodplain woodland plantations to prevent floods, with 59.2% of the total study area (177.5 km2) determined to be appropriate for such practices’ application. The River Dulnain tributary demonstrated the highest potential for floodplain woodland planting, followed by Rivers Avon and Fiddich, and the southwestern and northeastern Spey River parts. The methodology proposed is simple and provides rapid and accurate results at low cost, while the datasets can be easily accessed and are available in convenient type/format. This useful methodology for researchers and authorities could be applied successfully to similar watersheds, contributing significantly to flood risk mitigation and the enhancement of the flood-preventative measures’ planning efficiency.

In the last half century, Tecuci City was hit several times by damaging floods, as it happened in 1972, 1973, 2003, 2004 and especially in 2007. These events led to the implementation of measures for flood risk mitigation. This paper highlights the flood potential in Tecuci City and reveals the measures that were or should be taken in order to mitigate the flood risk in this city. It is based on statistical analysis of hydrological data recorded on Bârlad, Rateş and Tecucel rivers and of data obtained by field investigations. While in the 1970s – 1980s the flood risk mitigation measures were mainly of structural type (Bârlad River’s embankment and channelization, Rateş channel achievement), after 2007, a greater attention was payed to managing Tecucel River and to non-structural measures.

Highlights • Evaluation of green roofs for stormwater management at urban basin scale. • Green roofs cause peak flow and volume reduction in the urban drainage network. • Green roofs are more effective during frequent storms of smaller magnitude. • Non-linear reduction of outlet peak flow if network mainly at maximum convey capacity. • Effectiveness may increase with spatially heterogeneous implementation. Abstract Urbanization modifies the hydrologic cycle, resulting in increased runoff rates, volumes, and peak flows in the drainage network. In this paper, the implementation of green roofs as source control solutions for mitigating the impacts of urbanization is analysed at the urban catchment scale. The hydrologic-hydraulic response of a 2 km2 urban basin is investigated under various implementation scenarios and rainfall characteristics. In particular, a distributed hydrologic model is employed to assess the impact of 4 spatially homogeneous installations of green roofs (25%, 50%, 75%, 100% of roofs area converted) when forced by 6 storms differing in both duration and return period. In addition, a spatially heterogeneous configuration is tested, with green roofs concentrated where the drainage network is more prone to high degrees of filling. Results show that implementing green roofs at the urban watershed scale can be considered a valuable strategy to reduce both flow peak and volume in urban drainage networks, although the approach is more effective for frequent storms of smaller magnitude. In addition, it is found that the urban system may respond non-linearly to the extent of green roofs implementation in terms of peak flow reduction at the network outlet, and that non-linearity is mainly related to the network being close to its flow convey capability. Finally, planning redevelopment efforts on the basis of local insufficiencies in network convey capacity has the potential of increasing the effectiveness of Low Impact Development solutions. [ABSTRACT FROM AUTHOR]

Herein we investigate Life Cycle Cost (LCC) and Return on Investment (ROI) as potential decision variables for evaluating the economic performance (ROI) and financial feasibility (LCC) of a set of flood mitigation strategies over time. The main novelty of this work is the application of LCC and ROI analyses at the urban level to an asset portfolio of flood-prone buildings. Reduced flood damage is treated probabilistically as avoided costs (LCC analysis) and returns (ROI analysis), respectively. The proposed methodology is applied to the case of Dar es Salaam, Tanzania, which suffers severe riverine flooding on a sub-annual basis. Specifically, LCC and ROI of five mitigation scenarios that include large-scale catchment rehabilitation, settlement set-backs and waste management are compared with the current situation. The main result is that the highest-performing flood mitigation option includes both conventional interventions and ecosystem rehabilitation. [ABSTRACT FROM AUTHOR]

What is the decision-making mechanism people rely upon to mitigate flood risk? Applying Bayesian Network modeling to a comprehensive survey dataset for the US Gulf Coast, we find that the overall support for flood mitigation can be inferred from flood insurance purchase behavior (i.e. without insurance versus with insurance purchased mandatorily, voluntarily, or both). Therefore, we propose a theoretical decision-making mechanism composed of two dimensions including informed flood risk and sense of insecurity. The informed flood risk is the primary determinant on one’s overall support for flood mitigation. Risk mitigation decisions are largely contingent on the level of risk that is effectively conveyed to individuals. Additionally, sense of insecurity plays a moderate role in determining individuals’ overall support for flood mitigation. The sense of insecurity can move people toward overall support for mitigation, but the effect is not as large as the informed risk. Results of this study have fundamental policy implications. The flood risk informed by Federal Emergency Management Agency’s flood maps not only provides the compulsory basis for flood insurance purchase but also determines individuals’ overall support for flood mitigation. Flood map inaccuracy can immensely mislead individuals’ overall risk mitigation decision. Meanwhile, this flood risk mitigation decision-making mechanism inferred from a survey data in the US Gulf Coast needs to be tested and validated elsewhere.