Flood Risk Reduction Research Articles

Flood management in the built environment: the micro-scale contribution to a distributed strategy

Abstract The built environment offers an opportunity to implement Flood Risk Management measures by spatially distributing them as a complementary alternative to large-scale protection schemes. Specifically, micro-scale solutions focus on buildings, open spaces, users, and small infrastructure, addressing various flood management strategies with different performance indicators. These measures encompass, for instance, private precautionary measures like floodproofing or elevation, and nature-based solutions. However, their adoption faces technology, economics, and social challenges. To effectively reduce flood risk and increase the built environment’s resilience to floods, a systemic approach is necessary, evaluating and jointly implementing diverse measures across the built environment. Drawing from a systematic literature review and expert interviews, this study explores micro-scale Flood Risk Management measures within the built environment, examining their barriers and drivers. Additionally, it introduces an atlas of multi-strategy measures, qualitatively comparing their performance. The paper concludes by emphasizing the need for a holistic perspective on flood adaptation and highlights opportunities to enhance building-level adaptation actions through collaboration with various stakeholders.

Snow runoff modelling in the upper Indus River Basin and its implication to energy water food nexus

Pakistan's hydropower sector depends heavily on glacier and snowmelt water that originates from the Upper Indus Basin (UIB). It is expected that climate change may adversely affect future hydropower generation capacity as a result of fluctuations in the magnitude, seasonality and hydrological extremes of the Indus River flow. This study employed the Degree-Day Snowmelt Runoff Model alongside the Moderate Resolution Imaging Spectroradiometer MODIS and daily ground-based hydro-meteorological data to model the snowmelt runoff response in the UIB. The results indicated a significant increase in the annual and seasonal runoff under both RCP4.5 and RCP8.5 scenarios, suggesting more water availability for hydropower and irrigation. By the end of the century, annual river flow is projected to increase by 28 % to 69 % under the RCP4.5 and RCP8.5 climate scenarios. Consequently, rise in annual river flow is expected to increase the electricity generation capacity of future hydropower projects by 93 % to 167 % under the RCP4.5 and RCP8.5 scenarios, respectively. The construction of robust multipurpose dams may potentially reduce flood risks in downstream areas during peak flows, while also supplying water for hydropower generation and irrigation during low flows. This, in turn, may enhance the resilience of both the hydropower and agriculture sectors in the face of climate change.

Integration of seasonal frequency domain electromagnetic surveys and geological data for assessing the integrity of earthen levee systems. The case study of the Panaro River (Northern Italy)

Floods rank among the most widespread and destructive natural hazards worldwide. The progressive degradation, impairment, and breach of earthen riverine levees can occur in both natural and anthropogenic environments, stemming from various scenarios or sequences of events. These may include hydraulic failure due to overtopping because of inadequate height, and structural failure occurring even prior to overtopping, due to insufficient geotechnical and hydraulic characteristics combined with external and internal erosion.Following the catastrophic flood of December 2020, caused by the collapse of a section of the levee system of the Panaro River (a tributary of the Po River, Northern Italy), local Authorities initiated a comprehensive investigation into the causes of the breach. Numerous factors, including geological, geomorphological, and ecological features, were found to have contributed to the progressive decrease of the levee integrity prior to and during the flood. This prompted a broader multidisciplinary study of the Panaro River levee system.The study expanded its focus to include the collapsed section (rebuilt in 2020), as well as an additional 30 km stretch of both the right and left levees north of Modena, totaling 60 km. Detailed geological and geophysical data were integrated into the analysis, with particular emphasis on evaluating the characteristics and integrity features of the levee system.This analysis was carried out using Frequency Domain Electromagnetic Methods (FDEM) on the top of the levees, previously calibrated using Electrical Resistivity Tomography (ERT), geological mapping, core logs, and Cone Penetration Tests (CPTs). The FDEM surveys were repeated in different environmental conditions, specifically in the dry 2021 summer season and in the wet 2023 spring season, during heavy rainfalls that caused disastrous floods in several areas of the Emilia-Romagna Region. Out of the 60 km surveyed in the study area, the comparison of the two datasets highlights an interval of about 4 km where the internal portion of the levees is characterized by relatively coarse-grained materials and higher permeability making it more prone to internal erosion phenomena. This paper describes and integrates the results of these investigations, drawing attention to the strengths and limitations of the FDEM method when applied to extensive surveys on earthen riverine levee systems. The proposed methodology contributes as well to maintenance and retrofitting efforts to reduce flood risk in the context of the present climate change scenarios.

Assessing the drivers of flood risk reduction actions of businesses

Assessing the drivers of flood risk reduction actions of businesses

Integrated assessment for groundwater quality and flood vulnerability in coal mining regions.

Coal mining activities greatly damage water resources, explicitly concerning water quality. The adverse effects of coal mining and potential routes for contaminants to migrate, either through surface water or infiltration, into the groundwater table. Dealing with pollution from coal mining operations is a significant surface water contamination concern. Consequently, surface water resources get contaminated, harming nearby agricultural areas, drinking water sources, and aquatic habitats. Moreover, the percolation process connected with coal mining could alter groundwater quality. Subsurface water sources can get contaminated by toxins generated during mining activities that infiltrate the soil and reach the groundwater table. The aims of this study are the creation of models and the provision of proposals for corrective measures. Twenty-five scenarios were simulated using MODFLOW; according to the percolation percentage and contamination, 35% of the study area, i.e., the middle of the research area, was the most affected. About 38.08% of the area around the mining zones surrounding Margherita is prone to floods. Agricultural areas, known for applying chemical fertilizers, are particularly vulnerable, generating a risk of pollution to surrounding water bodies during flooding. The outputs of this research contribute to identifying and assessing flood-vulnerable regions, enabling focused measures for flood risk reduction, and strengthening water resource management.

Social learning and collective action in flood-hazard management in Manitoba, Canada

ABSTRACT Knowledge of social learning about flood hazards in the literature, especially regarding its transformation into collective action for risk reduction, is very limited. This study addresses these gaps by developing an integrated framework that describes how social learning is transformed into collective action – particularly the underlying components and processes – and then applying it to empirical case studies of two communities, (namely, St. Adolphe and St. Agathe) of the Rural Municipality of Ritchot, Manitoba, Canada. Primary data were collected during the summer months of 2022 using participatory research appraisal (PRA) tools (i.e. key informant interviews and oral histories), while secondary data were collected primarily via government and NGO sources. The findings revealed that a) the flood experience and related interactions among community members and local institutions produced unique and distinct types of social learning, and b) that local and multilevel institutions had helped to create learning platforms that facilitated the formation of strategies for collective action related to flood risk reduction. These processes resulted in single – and double-loop learning at the community level. Based on the findings of this work, we recommend that learning and reflection relating to community members’ flood experiences be integrated into disaster risk reduction and management policies.

A Coupled Human and Natural Systems (CHANS) framework integrated with reinforcement learning for urban flood mitigation

To address the challenge of escalating urban flood risk and the deficiency in effective flood emergency management, this study introduces a novel Coupled Human and Natural Systems (CHANS) modelling framework that employs hierarchical reinforcement learning to optimise mobile pump scheduling and placement for urban flood risk mitigation. The CHANS framework integrates hydrodynamic and agent-based models within a multi-GPU computing environment for high-resolution, real-time flood inundation modelling and risk assessment to enrich Reinforcement Learning (RL) training. In the application to Ninh Kieu District in Can Tho City, Vietnam, the new RL-enabled modelling framework is used to evaluate optimal mobile pumping strategies for concurrent pluvial flooding and post-flooding events against the traditional deployment approaches. Results demonstrate that RL-based strategies can significantly enhance flood risk reduction, outperforming traditional methods by achieving 2× and 4× improvements in the concurrent and post-flooding periods/events, respectively. Incorporating human factors and adapting to local conditions, the RL agent provides valuable insights into mobile pump scheduling and deployment strategies. Sensitivity analysis confirms the robustness of the CHANS modelling framework and underscores the role of RL in optimising mobile pump scheduling and placement where traditional rule-based strategies are challenging.

Merging modelled and reported flood impacts in Europe in a combined flood event catalogue for 1950–2020

Abstract. Long-term trends in flood losses are regulated by multiple factors including climate variation, demographic dynamics, economic growth, land-use transitions, reservoir construction and flood risk reduction measures. The attribution of those drivers through the use of counterfactual scenarios of hazard, exposure or vulnerability first requires a good representation of historical events, including their location, their intensity and the factual circumstances in which they occurred. Here, we develop a chain of models that is capable of recreating riverine, coastal and compound floods in Europe between 1950 and 2020 that had a potential to cause significant socioeconomic impacts. This factual catalogue of almost 15 000 such events was scrutinized with historical records of flood impacts. We found that at least 10 % of them led to significant socioeconomic impacts (including fatalities) according to available sources. The model chain was able to capture events responsible for 96 % of known impacts contained in the Historical Analysis of Natural Hazards in Europe (HANZE) flood impact database in terms of persons affected and economic losses and for 81 % of fatalities. The dataset enables the study of the drivers of vulnerability and flood adaptation due to a large sample of events with historical impact data. The model chain can be further used to generate counterfactual events, especially those related to climate change and human influence on catchments.

“We live here because of nature”: transformation towards better flood resilience on small Danish islands

Climate change is increasing the threat of flooding on small Danish islands. This article presents the results of a qualitative case study of flood risk perceptions and adaptive actions on three small Danish islands. The study explores how an empirical study of the islanders’ sense of place can contribute to a transformation towards better flood resilience. It finds that sense of place is closely connected to living close to nature, but also it highlights that the meaning given to ‘nature’ varies among the islanders. For some, nature is an uncultivated, wild landscape; for others, it is the present, cultural landscape. Another difference concerns whether the islands are described as a place to make a living or as a place to get away from everyday life. For some, farming and grazing are central to how they make a living on the islands; for others, these activities belong to the past. This insight into differences in the islanders’ sense of place contributes to understanding different perspectives regarding what is worth protecting, and what it is possible to protect from flooding, as well as why it is difficult for the islanders to reach agreement on the subject. This understanding has transformative potential, as it can give the islanders themselves, as well as authorities responsible for flood protection, a valuable insight into what drives and hinders actions to manage or reduce flood risk on small islands.

Global insights on flood risk mitigation in arid regions using geomorphological and geophysical modeling from a local case study

This research provides a comprehensive examination of flood risk mitigation in Saudi Arabia, with a focus on Wadi Al-Laith. It highlights the critical importance of addressing flood risks in arid regions, given their profound impact on communities, infrastructure, and the economy. Analysis of morphometric parameters ((drainage density (Dd), stream frequency (Fs), drainage intensity (Di), and infiltration number (If)) reveals a complex hydrological landscape, indicating elevated flood risk. due to low drainage density, low stream frequency, high bifurcation ratio, and low infiltration number. Effective mitigation strategies are imperative to protect both communities and infrastructure in Wadi Al-Laith. Geophysical investigations, using specialized software, improve the quality of the dataset by addressing irregularities in field data. A multi-layer geoelectric model, derived from vertical electrical sounding (VES) and time domain electromagnetic (TDEM) surveys, provides precise information about the geoelectric strata parameters such as electrical resistivity, layer thicknesses, and depths in the study area. This identifies a well-saturated sedimentary layer and a cracked rocky layer containing water content. The second region, proposed for a new dam, scores significantly higher at 56% in suitability compared to the first region’s 44%. The study advocates for the construction of a supporting dam in the second region with a height between 230 and 280 m and 800 m in length. This new dam can play a crucial role in mitigating flash flood risks, considering various design parameters. This research contributes to flood risk management in Saudi Arabia by offering innovative dam site selection approaches. It provides insights for policymakers, researchers, and practitioners involved in flood risk reduction, water resource management, and sustainable development in arid regions globally.

Resilience to future floods through flood memory approach: An example from West Bengal, India

Managing flood situations is a combination of structural, non-structural, and socio-ecological approaches, where the latest includes an operative involvement from the local community, based on their experiences in past flood episodes. The instances of considering this indigenous knowledge and perception while planning for the flood mitigational framework in India are neither very popular a practice nor they are frequently exemplified - but while looking at the case studies from all over the world, this could be a powerful tool for gauging flood scenarios and the living with it. This paper aims to inspect the ways and approaches through which a local community memorizes the fury of floods, how this information can be put in a quantitative way, and can be realistically functioning for coping with future flood consequences. Focusing on the flood memory approach for community resilience, we present the findings of archival research, site-specific folklores and mythological stories (cultural), social methods, verbal methods, exploration of flood markers (structural), and campaigns and exhibitions (educational). A digital questionnaire-based survey was conducted in the most flood-suffering wards of the Kolkata Municipal Corporation area in West Bengal, and upon receiving the reactions, a Flood History Volatility Scale (FHVS) has been devised to test how the strength of an individual's flood memory varies due to some controlling factors. Based on the results obtained from memory work and perceiving the importance of community knowledge during the survey, a comprehensive flood risk management approach has been proposed for flood risk reduction and developing community resilience.

Developing a flood risk assessment model with genetic algorithm-based weights

To reduce flood risk efficiently within constrained disaster prevention budgets, governments employ economic analyses and qualitative flood risk assessments. However, conventional methods, such as entropy weight and the Analytic Hierarchy Process method, have limitations in terms of the accuracy of the flood risk index. Here, we overcome these limitations by applying a genetic algorithm (GA) – an optimization method mimicking a natural selection process and biological genetic evolution. We developed a new flood risk index by using GA to calculate weights to indicators associated with four items (Hazard, Exposure, Vulnerability, and Capacity) for 161 Korean cities and counties from 2016 to 2021. The indicators (number of buildings, farmland area, dependent population, etc.) for the Exposure and Vulnerability items were reflected in the evaluation only for damaged targets directly exposed to flood risk, using grid cells of indicators overlaid on the flood risk map. Our GA-based method aimed to optimize each indicator’s weights to minimize errors between damage rankings and flood risk index rankings. Results show that our method reduced errors by 21.42 % during 2016–2021, outperforming traditional methods. Therefore, it is easy to identify municipalities that lack disaster prevention capabilities and are vulnerable to flood risk by comparing flood risk indices under the same conditions, such as maximum rainfall index. Our proposed method could better aid local government in decision-making for flood risk mitigation by allocating constrained budgets efficiently.

Unlocking urban blue-green infrastructure: an interdisciplinary literature review analysing co-benefits and synergies between bio-physical and socio-cultural outcomes

ABSTRACT Conventional methods of urbanization and risk management have exposed communities to multiple climatic, ecological, and social vulnerabilities. Urban blue-green infrastructure (BGI) refers to a range of nature-based approaches to mitigating the impacts of hazards and enhancing the connections between natural and social capitals, with a particular focus on the presence and management of water elements. However, the bio-physical benefits of BGI are often prioritized over a wider range of potential social-ecological co-benefits. This article draws on a narrative literature review to present the bio-physical and socio-cultural co-benefits of urban BGI, and to examine the relationships, synergies, and trade-offs between these. This review identifies a wide range of socio-cultural and bio-physical benefits of blue-green stormwater infrastructure, including improved mental and physical wellbeing, enhanced cultural connections and values, strengthened social cohesion and sense of place, amelioration of urban heat island effects, reduction of flood risks, improved water quality, and enhanced biodiversity. A number of environmental and socio-cultural trade-offs were identified between these co-benefits, however, including the presence of negatively viewed insects and plant-produced allergens. Aimed at expanding knowledge on the effective implementation of urban BGI to achieve such outcomes, this review highlights wider co-benefits and relationships between them.

Grasslands and flood mitigation – Contrasting forages improve surface water infiltration rates

Grasslands globally deliver many ecosystem services, including water management to alleviate flood risk reduction. Two replicated field experiments were conducted to study how agricultural forage species with diverse rooting systems, sown as single species, affected rooting, soil structure and earthworm populations, and consequently water infiltration to understand how they each might influence flood risk from grasslands. Experiment One showed soils under red clover (Trifolium pratense), white clover (Trifolium repens) and chicory (Cichorium intybus) had higher infiltration rates three years after establishment, compared to perennial ryegrass (Lolium perenne). Higher red clover and chicory root biomass or increased earthworm abundance under white clover may have caused these effects. Experiment Two monitored infiltration at intervals over several years post establishment to understand the timeframe for changes in rates; plantain (Plantago lanceolata) was sown as an additional forage. Infiltration declined post establishment, the timing and extent of decline varying with forages; forage effects were significant after 27 months (P < 0.05). Infiltration rates were higher under red and white clover compared to ryegrass, with chicory and plantain intermediate (P < 0.05). Forages again differed in likely mechanisms delivering higher water infiltration, notably between the two clover species. White clover had higher earthworm biomass (P < 0.05), whereas red clover had a higher average root diameter compared to the other forages (P < 0.05). Drivers of intermediate benefits of chicory and plantain also differed: chicory had higher earthworm abundance (month 38) compared to plantain, which had higher average root diameter compared to ryegrass (month 41); 30 months post-establishment soil bulk density was lower under both forages compared to ryegrass and red clover, with white clover intermediate (P < 0.05); bulk density and penetration resistance did not relate to infiltration. Findings demonstrate that a shift from perennial ryegrass-dominated pastures to swards with more contrasting forages provides an ecohydrological approach to mitigating flood risk and climate adaptation.

Flood threat to livable communities: Understanding the impact of emotional conflicts and information availability on disaster preparedness through mitigation capacity in Nigeria's coastal region

Climate change poses significant risks to coastal regions, compromising habitats, economies, and well-being through flooding. This research assesses the indirect effects of information availability and emotional factors, such as property emotional attachment and emotional burdens on flood disaster preparedness through mitigation capacity. Data from 360 individuals across three Nigerian coastal communities were analyzed using a partial least squares structural equation model (PLS-SEM). Evidence demonstrated that information availability directly enhances disaster preparedness. Conversely, information availability is not significantly associated with mitigation capacity. Strong emotional attachment to property negatively impact mitigation capacity, but no direct effect on disaster preparedness. Mitigation capacity exhibits a significant positive direct effect on disaster preparedness. Notably, heightened emotional burden bolsters flood disaster preparedness by first increasing mitigation capacity. In contrast, intensified emotional attachment to property dampens mitigation capacity, thereby diminishing disaster preparedness. These insights highlight the necessity of integrating frameworks for addressing issues of information dissemination, property emotional attachment, and emotional burden when devising flood risk reduction strategies for coastal communities.

A MAP-based approach to identify the social vulnerability to flood hazard in states adjacent to Mexican Gulf

The impact of floods can significantly differ based on the local circumstances. The severity of the impact caused by a natural flood in one area compared to another depends on the distinct vulnerability factors present within the affected community, encompassing cultural, social, and economic aspects. Understanding a society's capacity to anticipate, adapt to, endure, and recover from the effects of natural floods relies on evaluating its social vulnerability, which is closely connected with potential risks and community resilience. This study adopts a framework that can analyze the interaction between natural hazards and social factors and is flexible to be applied to different geographic locations. This framework encompasses flood hazards and social vulnerability within the scope of flood risk reduction. This paper explores how social vulnerability can be integrated into the analysis of flood risks within the states adjacent to the Mexican Gulf. Initially, social components are selected and applied to measure and map the Social Vulnerability Index (SVI). Next, a MAP-based methodology is adopted to identify the spatial variability of social vulnerability concerning flood hazards. Then, a risk matrix is developed and the classifications on SVI map are aligned with those on a flood hazard map; provided by the Federal Emergency Management Agency (FEMA). This led to the development of a qualitative social vulnerability exposure map to flood hazards, emphasizing regions marked by high levels of both flood risk and social vulnerability. The findings of this study highlight the importance of integrating social vulnerability into flood risk mitigation policies and emergency management, and planning.

The Importance of Law Enforcement and Spatial Planning Regulations Regarding Flood Management

Spatial planning in Indonesia, both national and regional spatial planning, has become a crucial problem that has developed dynamically in recent years. The urgency of spatial management in human life encourages the existence of statutory regulations to address spatial planning. Spatial planning is an important component in determining the success of a region's development, especially in the context of sustainable development. Rapid regional growth, both in urban and rural areas, has had a positive economic impact, but has also given rise to environmental problems, manifested in increasingly critical environmental conditions and the increasing intensity of natural disasters, partly caused by spatial planning violations. One of the significant impacts of spatial planning violations is flooding in Indonesia, which is often caused by land misuse. Therefore, enforcement of spatial planning laws and regulations closely related to flood management is critical. This study uses a qualitative research approach focusing on literature analysis, government policies, and empirical data related to flood management in Indonesia. Empirical data was obtained through interviews with legal experts, spatial planning experts, and related stakeholders. Deductive methods are used in data analysis to identify patterns and relationships between law enforcement, spatial planning regulations, and flood management. The results of this study show that strict law enforcement, clear spatial regulations, and increasing institutional capacity are the keys to reducing flood risk. With synergy between law enforcement and capacity building, potential flood risks can be minimized while building better community involvement and awareness.

Socio-Economic Vulnerability to Potential Flood in Tamakoshi River in Nepal

Tamakoshi, a transboundary river flowing from Tibet, China to Nepal has experienced several disastrous flash floods resulting in the loss of lives, infrastructures, settlements, lands, and other assets. Many households, populations, and public and private properties such as houses, land, roads, bridges, etc. are likely to be affected by the potential flash floods. This study discusses the occurrence of flash floods, losses and damages from such floods in the past, and socio-economic vulnerability to potential flash floods. It further discusses the preparedness and response activities and identifies the measures for flood risk reduction. The methods adopted for data collection included observation, household surveys, and focus group discussions. The villages selected for detailed study are Gongarkhola, Jagat, Jamune, Bhorle, and Sigati bazaar, identified as the most vulnerable settlements along the Tama Koshi River. It is found that flash floods and high-intensity precipitation occur frequently in the study area resulting in loss of life and properties, and people and properties are exposed to the potential flash floods. Local people are still feeling vulnerable to such flash floods. The government authorities alone are not able to achieve greater success in carrying out preparedness and response activities for flood risk reduction without the active involvement and participation of the vulnerable communities. Development and effective implementation of land-use guidelines and building codes, watershed management, early warning systems, and networking among the people residing across the river are some of the activities identified to reduce flood risk. Although people have a good understanding and knowledge about floods and their occurrences, they pay less attention to preparedness and mitigation. It is also concluded that structural measures alone are not sufficient and effective enough for flood risk reduction

Advancements in enhancing flood evolution and urban inundation predictions: A study of local time stepping algorithm and GPU-accelerated hydrodynamic model

In recent years, floods occur frequently affected by extreme rainstorms. Timely flood prediction and rapid simulation are crucial in mitigating their impact. However, the current models often utilize the global time step method for updates and solving, resulting in high computational costs. To further improve the efficiency while ensuring calculational accuracy, this study proposes the local time stepping and GPU-accelerated hydrodynamic model based on non-uniform grid. The proposed model utilizes the HLLC approximate Riemannian solution to estimate interface flux and employs the local time step algorithm, enabling each unit to update variables using the locally permitted maximum time step. It relies on non-uniform grid technology, the local time step algorithm, and GPU acceleration to optimize computational efficiency, facilitating swift simulation of flood evolution processes across large-scale terrains. The results show that the hydrodynamic model has good stability. The results show that the model has good accuracy and stability. It can accurately predict the flood evolution process, flood arrival time, flood inundation range, and urban inundation process in complex terrains. Researchers can identify effective measures for reducing flood risks and improving the area’s resilience against flooding events. Due to its significantly improved efficiency in flood prediction, it is more suitable for actual large-scale flood processes.

Land Cover and Socioeconomic Analysis for Recommended Flood Risk Reduction Strategies in Java Island, Indonesia

Land Cover and Socioeconomic Analysis for Recommended Flood Risk Reduction Strategies in Java Island, Indonesia