Flood Risk Management Approaches Research Articles

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.

Assessment of flood risk in a coastal city considering multiple socio-economic vulnerability scenarios

Abstract. The Intergovernmental Panel on Climate Change stresses the importance of vulnerability and exposure along with hazard in defining flood risk. Therefore, a novel approach for flood risk quantification is proposed that evaluates the impact of various realistic socio-economic scenarios on risk reduction. The flood hazard is derived from a hydrodynamic flood modelling framework over Mumbai, India's highly flood-prone coastal megacity. The socio-economic vulnerability is assessed by a multivariate approach based on principal component analysis and data envelopment analysis. Finally, the flood risk is quantified and mapped by aggregating hazard and vulnerability for different socio-economic scenarios, also key indicators contributing to a significant reduction in vulnerability and risk are identified. This non-structural long-term flood risk management approach will benefit densely populated urban areas, especially in developing, and underdeveloped countries.

Housing amenity and affordability shape floodplain development

Flood damage has severe and long-term repercussions for households and communities, and continued housing development in floodplains escalates damages over time. Policies and interventions to reduce damage depend on assumptions about housing stock and residents, but assessments of flood exposure to date largely focus on community-scale characteristics at a single point in time, masking potential within-community differences and their evolution through time. We measure residential development in the floodplain nationwide over time to characterize the type and value of U.S. floodplain housing stock and to assess how new development contributes to flood exposure. Over 4M U.S. residences built from 1700 to 2019 (4.8% of all residences built during that time) are located within current regulatory floodplains. These residences are concentrated at the affordable and expensive extremes of the housing value spectrum, reflecting deep differences in the social vulnerability of floodplain residents. Floodplain housing stock often differs substantially from the local market, with coastal floodplains containing relatively expensive housing and inland floodplains containing relatively affordable housing. New housing development has not occurred equally across these contexts. In the past two decades, more floodplain development has occurred in communities with relatively expensive floodplain housing, and mobile home construction in floodplains has slowed. The bifurcated patterns in floodplain housing, across values and geographies, demonstrate the importance of considering the specific population at risk and how it may differ from the broader community when tailoring flood risk management approaches.

Advocating integration of human responses in the flood resilience framework for inland cities of northern China

ABSTRACT Frequent urban flooding poses a predominant challenge to resilience managers and the public in inland cities. Nevertheless, various facets of the formation, development, and response to inland flooding in developing countries are still less understood. Using the statistics data of typical flood events in China, this paper examines the causes of devastation in inland areas of the north combined with a comprehensive risk assessment methodology and explores a nuanced understanding of resilience. The conclusions reveal that the inland cities of northern China are facing an imminent threat from escalating flood hazards. 11% of the flood-influenced population and 17% of the disaster-caused economic losses are concentrated in the region. Increased extreme precipitation, heightened exposure and vulnerability, and a sluggish human response to crises are main factors contributing to these complex disasters. The study also proposes a transformative flood resilience framework for inland flooding from three dimensions, emphasizing the integration of human responses. The three aspects of the framework are summarized based on the driving factors mentioned earlier and a simplified multidimensional perspective of resilient cities, reflecting the adaptive and evolutionary features of resilience. Hence, incorporating the resilience strategies to urban flood risk management is a relatively practical approach to urban flood risk management in inland regions.

A novel flood risk management approach based on future climate and land use change scenarios

Climate change and increasing urbanization are two primary factors responsible for the increased risk of serious flooding around the world. The prediction and monitoring of the effects of land use/land cover (LULC) and climate change on flood risk are critical steps in the development of appropriate strategies to reduce potential damage. This study aimed to develop a new approach by combining machine learning (namely the XGBoost, CatBoost, LightGBM, and ExtraTree models) and hydraulic modeling to predict the effects of climate change and LULC change on land that is at risk of flooding. For the years 2005, 2020, 2035, and 2050, machine learning was used to model and predict flood susceptibility under different scenarios of LULC, while hydraulic modeling was used to model and predict flood depth and flood velocity, based on the RCP 8.5 climate change scenario. The two elements were used to build a flood risk assessment, integrating socioeconomic data such as LULC, population density, poverty rate, number of women, number of schools, and cultivated area. Flood risk was then computed, using the analytical hierarchy process, by combining flood hazard, exposure, and vulnerability. The results showed that the area at high and very high flood risk increased rapidly, as did the areas of high/very high exposure, and high/very high vulnerability. They also showed how flood risk had increased rapidly from 2005 to 2020 and would continue to do so in 2035 and 2050, due to the dynamics of climate change and LULC change, population growth, the number of women, and the number of schools – particularly in the flood zone. The results highlight the relationships between flood risk and environmental and socio-economic changes and suggest that flood risk management strategies should also be integrated in future analyses. The map built in this study shows past and future flood risk, providing insights into the spatial distribution of urban area in flood zones and can be used to facilitate the development of priority measures, flood mitigation being most important.

Plugging the holes: Identifying potential avenues and limitations for furtheringDutchcivil society contributions towards flood resilience

AbstractClimatic changes can cause unpredictability in flood regimes that traditional flood risk management (FRM) approaches may struggle with. Therefore, flood resilience is seen as a supplementation to these approaches, putting a larger emphasis on flood acceptance and minimising consequences. An (emergent) group contributing towards flood resilience is civil society. This paper examines how civil society contributions can be furthered and guided in the Netherlands as well as exploring potential limitations in doing so. To achieve this, England is used as a good practice example due to a more developed and defined role for civil society being present here. Data were collected on both actual (England and the Netherlands) and potential (The Netherlands) civil society contributions. These were compared to identify potential avenues for Dutch civil society contributions to flood resilience that can be further investigated. The research shows that the most promising avenues are improving advocacy from citizens, improving local flood awareness and developing relationships between FRM authorities and existing citizen groups that can be harnessed and mobilised to support flood resilience. Additionally, the research also provides insights into potential limitations for transferring resilience approaches from one context to another beyond the cases discussed in this publication.

Bottom-up approach for flood-risk management in developing countries: a case study in the Gianh River watershed of Vietnam

Bottom-up approach for flood-risk management in developing countries: a case study in the Gianh River watershed of Vietnam

A GIS-Based Index of Physical Susceptibility to Flooding as a Tool for Flood Risk Management

The identification and classification of flood-prone areas comprise a fundamental step in the Flood Risk Management approach, providing subsidies for land use planning, floodproofing policies, the design of mitigation measures and early warning systems. To address this issue, a frequently used preliminary tool is the flood susceptibility mapping of a region using a range of widely available data. Therefore, the present study introduces an index-based approach able to qualitatively assess flood-prone areas, named Physical Susceptibility to Floods Index (PhySFI), based on a multi-criteria decision-making method and developed in a GIS environment. The methodology presupposes a critical discussion of variables commonly used in other flood indexes, intending to simplify the proposed representation, and emphasizes the role of the user/modeler. PhySFI is composed of just four indicators, based on physical parameters of the assessed environment. This index was developed and first applied in the city of Rio de Janeiro, as part of the Rio de Janeiro Climate Change Adaptation Plan. The validation process was based on a comparative analysis with flood extent and height simulated by the hydrodynamic modeling of four watersheds within the study area, with different urbanization processes for each one. The results indicate that the index is a powerful preliminary tool to assess flood-prone areas in coastal cities.

Resilient Infrastructure as a Tool for Flood Risk Management in Nigeria: A Review

Flooding is a disaster which may occur naturally or as an effect of human activities. Flooding which is a global hazard has resulted in devastating effects on humans and the environment. Thousands of lives are lost and properties worth several millions of dollars are destroyed annually due to flooding in Nigeria. Various Flood Risk Management (FRM) approaches have been employed to manage this menace in Nigeria resulting in little success. This paper highlights the types, causes and impact of flooding in Nigeria as well as evaluate the efforts at local and national levels in FRM. After due considerations of performance and lapses of past efforts, the article advances the resilient infrastructure approach as a formidable and sustainable FRM option for Nigeria.

Integrated Flood Risk Management Approach Using Mesh Grid Stability and Hydrodynamic Model

Today, inhabitants residing in floodplains face a serious and perpetual threat of flooding. Flooding causes fatalities and considerable property damage in metropolitan areas. Therefore, robust structural measures need to be adopted to eliminate flood catastrophe. Structural measures in the floodplain are the most promising solutions. However, there are cost-associated factors for proposing a flood retention plan. Navsari city (98.36 km2, area extent) of Gujarat was used as a case study to investigate the impact of mesh grid structures (100 m, 90 m, and 50 m) along with structural measures for the preparation of a flood retention plan. The HEC-RAS 2D hydrodynamic model was performed for the Purna River. The output of the model was characterized by four different scenarios: (i) Without weir and levees (WOWL), (ii) With weir (WW), (iii) With levees (WL), and (iv) With weir and levees (WWL). The statistical parameters (R2, RMSE, NSE, inundation time, and inundation area) were determined to evaluate model accuracy. The outcome of the model revealed that a 50 m size mesh grid exhibited more accurate results, yielding high NSE and R2 values (0.982 and 0.9855), a low RMSE value (0.450 m), and a smaller inundation area (114.61 km2). The results further revealed that the WW scenario was the most effective flood retention measure as it delayed the flood water for up to 16 h, and managed the flood with the WOWL case. Moreover, the mean error (WW scenario) estimated from profiles 1 and 2 ranged from (−0.7 to 0.62) and from (−0.1 to 0.02 m), respectively, which were evaluated as very low when compared with other scenarios. The novel scenario-based flood retention plan emphasizing the stability of mesh grid structures using the hydrodynamic model can be applied to any other region around the globe to recommend efficacious structural flood measures for flood decision making systems.

An Assessment of the Ecosystem-Based Adaptation Approach for Flood Risk Management in the Upper Suswa-Magadi Catchment

Flood is a natural disaster that occurs due to the sudden onset of rainfall that causes runoff waters from high altitude areas to low altitude areas. The purpose of the study was to assess ecosystem-based adaptation in flood risk management in the upper Suswa- Magadi catchment. The study used a descriptive research design. Purposive sampling and stratified random sampling methods were used to select three locations of the Upper Suswa-Magadi catchment. These included Suswa, Keekonyokie and Mosiro. The locations had a population of 8,094 households, from which a sample size of 370 was obtained. The study relied on both primary and secondary data. The questionnaires, key informant interviews, and observations were used to collect data. The study concluded that; Community participation in EbA could increase the soil texture, and increased afforestation could help in the absorption of runoff water increasing the infiltration rates of water and causing flash floods. The study recommended the creation of awareness on the EbA measures to curb flash floods which could help the community members to avert the effect of flash floods and encourage the community to participate in the application of EbA measures in order to increase the soil texture, increase afforestation could help in the absorption of runoff water increasing the infiltration rates of water causing a flash flood. This can be done through community-based organizations that easily understands their problems and supports project that will assist them.

Site assessment and evaluation of the structural damages after the flood disaster in the Western Black Sea Basin on August 11, 2021

On August 11, 2021, one of the most destructive flood disasters occurred in the Western Black Sea Basin of Turkey. The flood resulted in the death of 76 individuals, 30,000 people being affected by the disaster. A maximum precipitation depth of 400 mm/day was recorded at one station, indicating a return period exceeding 500 years for the rainfall event. During a two-day site visit immediately following the flooding event, damages to infrastructures, water structures, bridges, retaining walls, roads, and private houses were observed in the Bozkurt and Ayancık regions. Based on the observations, the flood wave propagated through the initial meandering river bed and floodplain, exceeding the channelized river bed capacity. Due to the massive sediment transport and drifting of trees, several bridges have been blocked and overflown where the basements of the structures in these regions were flooded. The enormous flood flow triggered extensive scouring on bridge piers, building foundations, and retaining walls, eventually causing the walls and bridges to collapse. The collapse of structures blocked the waterway and amplified the backwater effect when combined with the sediment transport. The total collapse of the retaining walls in some sections of the stream caused accelerated scouring in the foundations of the nearby buildings. Damages were also observed on the side roads along the river beds. This paper evaluated the driving mechanism of damages caused by flood flow from hydrological, structural, and geotechnical perspectives. Based on these observations and assessments, recommendations on engineering design guidelines for structures close to the floodplain, such as bridges, retaining walls, and side roads, were elaborated. Emphasis was placed on the flood-resistant design of these structures to develop a comprehensive approach for flood risk management.

Community Based Flood Risk Management Approach in Northeastern Uganda

This study was conducted in the Amuria district of Northeastern Uganda. The aim of the study was to assessthe performance of Community Based Disaster Risk Reduction (CMDRR) approach in mitigating disastereffects in the area. The objectives were to assess the effectiveness of community preparedness, response, andrecovery efforts in mitigating disasters in the study area. Aberilela and Wera sub-counties were purposivelyselected, and two parishes were chosen from each of the two sub counties based on their vulnerability to flooddisasters. A sample of 300 household heads were randomly selected. Methods of data collection includedquestionnaires, in-depth interviews with key informants, focus group discussions, observation, and documentsreview. The collected data were analysed using descriptive statistics and triangulated with thematic analysisof the data from interviews and field observations. Results from the study indicate that the CMDRR approachhad performed well despite some shortcomings. The approach had been able to prepare the community bytraining them in disaster management activities, developing hazard prone maps, disaster plans, establishedeffective rescue measures and other response measures for the affected communities. However, it had failedin building capacity among the communities to stock essential services including food, early warning systemsand in detecting and predicting disaster as well as building gender and age balanced capacity in thecommunities. Overall, the performance of CMDRR committees in Amurai and particularly Abarilela andWera sub-counties was above average. The study recommends that government should adopt this approachand replicate it in other disaster-prone areas for effective disaster management.

Sustainable Urban Drainage System (SUDS) as Nature Based Solutions Approach for Flood Risk Management in High-Density Urban Settlement

Nature-based Solution (NBS) is an umbrella for ecosystem-based approaches to prevent or mitigate the impacts of hydro-meteorological hazards. The increasing hydro-meteorological disaster occurrence such as floods in Bandung City because of both climate change phenomenon and rapid growth of Bandung City has caused a big impact on people live in slums and high-density settlement. Realizing this risk, Bandung City has implemented strategies to reduce flood risk, including the Sustainable Urban Drainage System (SUDS) as stated on the Bandung City Spatial Plan (RTRW) 2011-2031. However, this measure had not effectively reduced flood risk in Bandung City. Therefore, this research focuses to analyse the implementation of SUDS and how it can capture the concept of NBS, with the study case Cibadak Administrative Village, one of the poor and high-density urban settlements in Bandung City. The result was developed using a mixed method consisting of a descriptive quantitative approach, spatial analysis for satellite imagery, and content analysis technique to analyse each challenge of SUDS implementation. The result indicates the lack of capacity in scale, budget, natural characteristic, and social demographic for SUDS implementation in poor and high-density urban settlement in Bandung, which aligns with the challenge of NBS implementation in the global south.

Game theoretic approach for flood risk management considering a financial model

In process of flood risk management, there is usually a conflict between the governments, insurance companies and people as players in sharing financial responsibilities, because of how calculate insurance premium, compensation and governmental assistances. In order to this conflict resolution, in this paper a new methodology is proposed based on game theoretic approach by using Nash equilibrium method, that for the first time, the payoff functions of insurance companies and government have been associated to each other. In this method, according to maximization of player's payoffs, the best response has been found and for the first time, comprehensive financial model has been developed for sharing players' financial responsibilities in flood risk management plans. In order to increase the accuracy of flood insurance calculations, the parameters of deductible and franchise have been applied. The key findings indicate, success of flood risk management plans depend on purchasing flood insurance with full coverage and government financial assistances simultaneously. The developed flood insurance plan has most sensitivity to parameters of deductible and insurance rate. This model could be utilized as practical and academic model in flood risk management. The applicability and efficiency of the methodology are examined in Northeast of Tehran as capital of Iran.

Interactions between pluvial and fluvial floods in floodplains in Lower Wortley, Leeds, UK

ABSTRACT Heavy precipitation with unplanned land use can alter the catchment response time; thus, natural processes of floods can be affected. As a result, floods from multiple sources can be observed concurrently or consecutively at the same location. However, the location-dependent interactions between floods and the consequences of flood combinations have not been studied sufficiently. This research examined the interactions and the consequences of combined floods occurring on the settlements on floodplains along urban streams in an ungauged and urbanized catchment. The flood extents, merging from the river overflow and the rainfall-induced runoff, were simulated directly for Lower Wortley, Leeds, UK. The study demonstrates that an assessment of the floods occurring from multiple sources at the same location is necessary to improve flood risk management approaches, because the merger floods could significantly increase the impact of any single flood, and so the flood defences become deficient.

A Comparative Study of the Effects of the 1872 Storm and Coastal Flood Risk Management in Denmark, Germany, and Sweden

From November 12th to 13th in 1872, an extreme coastal flood event occurred in the south Baltic Sea. An unusual combination of winds created a storm surge reaching up to 3.5 m above mean sea level, which is more than a meter higher than all other observations over the past 200 years. On the Danish, German, and Swedish coasts, about 300 people lost their lives. The consequences of the storm in Denmark and Germany were more severe than in Sweden, with significantly larger destruction and higher numbers of casualties. In Denmark and Germany, the 1872 storm has been more extensively documented and remembered and still influences local and regional risk awareness. A comparative study indicates that the collective memory of the 1872 storm is related to the background knowledge about floods, the damage extent, and the response to the storm. Flood marks and dikes help to remember the events. In general, coastal flood defence is to the largest degree implemented in the affected areas in Germany, followed by Denmark, and is almost absent in Sweden, corresponding to the extent of the collective memory of the 1872 storm. Within the affected countries, there is local variability of flood risk awareness associated with the collective memory of the storm. Also, the economic dependency on flood-prone areas and conflicting interests with the tourism industry have influence on flood protection decisions. The processes of climate change adaptation and implementation of the EU Floods Directive are slowly removing these differences in flood risk management approaches.

Politics of flood risk management in Switzerland: Political feasibility of instrument mixes

AbstractComplex environmental problems affect multiple policy sectors, decision‐making levels and territories simultaneously and, as such, call for encompassing policy solutions. However, no consensus exists on how encompassing policy solutions are designed. A trade‐off persists between single instruments, leading to sectoral “silo” thinking and complex instrument mixes, constituting the risk of not being implemented due to actors' objections. Policy designs, including balanced policy mixes, can fulfil various goals, interests and priorities; address numerous challenges; and involve multiple actors. Such balanced policy mixes, however, can only manage complex environmental problems successfully when supported by actors belonging to different sectors, levels and territories. This study therefore analyses the political feasibility of balanced instrument mixes via actors' policy preferences in the case of Swiss flood risk management. Public and private actors involved in flood risk management are surveyed on their preferred instrument mixes. Based on these preference data, the political feasibility of instrument mixes is evaluated by combining the number (density) and coerciveness (intensity) of instruments with the balance of different instrument types (balance) in an index. Results indicate that actors' preferences for a balanced instrument mix are weak. In particular, actors' roles and sectoral interests in the policy design process influence their preferences. These findings suggest that policy mixes, including simple, minimally intervening and sector‐specific flood risk management instruments, are more likely to be politically feasible than balanced instrument mixes. Therefore, traditional “silo” thinking continues to outweigh encompassing policy solutions and impedes possible steps towards an integrated flood risk management approach in Switzerland.

Community Based Flood Risk Management: Local Knowledge and Actor’s Involvement Approach from Lower Karnali River Basin of Nepal

Connecting to the disaster risk reduction (DRR) studies, community-based initiatives are found to be more effective in both developed and developing countries, with a specific focus on the empowerment of local communities to build resilience. Building on social capital theory, the paper investigates on local knowledge (LK) practices experienced by the actors in an emerging economy using the community-based flood risk management (CB-FRM) approach. The qualitative research method was used by collecting data from focused group discussions, and interviews with the key informants including actors from local governments and non-government organizations. Additionally, informal discussions, field visits, and desk studies were undertaken to support the findings. The findings reveal that the local communities carry out various local knowledge experiences to respond during disaster management phases. They own a creative set of approaches based on the LK and that empowers them to live in the flood-prone areas, accepting the paradigm shift from fighting with floods to living with that. The local actor’s involvement is recognized as an essential component for CB-FRM activities. Yet, their program’s implementation is more oriented towards humanitarian assistance in emergency responses. Even, they often overlook the role of LK. Additionally, the results show a high level of presence of local communities during the preparedness and recovery phases, while NGOs and local governments have a medium role in preparedness and low in recovery phase. The lack of local ownership has also emerged as the major challenge. The research provides valuable insights for integrated CB-FRM policies by adopting to LK practices.

Managing coastal flood risk to residential properties in England: integrating spatial planning, engineering and insurance

Flooding is the most damaging natural hazard in England today. Coastal flood risk management aims to reduce the impacts of coastal flooding through adaptation measures including spatial planning, engineered hard and soft interventions, and insurance. Yet there are few reviews which collectively assess these measures. This paper aims to characterise and evaluate coastal flood risk management policy in England across planning, engineering and insurance approaches, focusing on their ability to manage risk to residential properties. An analysis of the literature and government reports reveals that together these management approaches address the different dimensions of flood risk. Nonetheless, the three approaches are legislated and regulated in relative isolation, and in their current formation have contrary implications for existing and future residential developments. There is also further scope to increase the resilience of planning, defence and insurance to social and environmental uncertainties in financing, governance and climate change. We recommend that future research and strategies in coastal flood risk management give greater consideration to multiple flood risk management approaches in conjunction, continuing to expand the integration between planning, engineering and insurance approaches.