Sustainable Flood Risk Management Research Articles

Participatory Framework for Urban Pluvial Flood Modeling in the Digital Twin Era

The recent advancement in digital twin technology, which creates virtual replicas of real-world processes, offers an interactive testbed for understanding and predicting environmental changes. As pluvial flood damage escalates globally in urban areas, there remains a gap in understanding the most effective collaboration between governments and local residents for sustainable flood risk management. To address this gap, we develop a participatory framework for urban pluvial flood modeling, incorporating open source software, virtual reality, minimum viable product, and gamification components. This framework engages citizens in every phase of the participatory modeling process, from input data preparation, through hydrological model construction, to model verification, and experiments. We present a case study on the recurring pluvial flood damages in South Korea's Gangnam region, demonstrating the practical implications of an interactive, web-based crowdsourcing platform to leverage community engagement and local knowledge. The results underscore the evidence of a proactive role for citizens, not merely as recipients of disaster information but as key contributors collaborating with a range of stakeholders in stormwater management and modeling. Combining digital twin technology with citizen participation can empower informed decision-making and collective actions in the evolving digital era, leading to a disaster-resilient community.

Urban flood risk management needs nature-based solutions: a coupled social-ecological system perspective

A growing number of Nature-based Solutions (NbS) has been advocated for urban flood risk management (FRM). However, whether NbS for FRM (NbS-FRM) achieves both social and ecological co-benefits remains largely unknown. We here propose and use a conceptual framework with a coupled social-ecological perspective to explore and identify such “win-win” potential in NbS-FRM. Through a scoping-review we find that ecological FRM measures are unevenly distributed around the world, and those solely targeting flood mitigation may have unintended negative consequences for society and ecosystems. In elaborating this framework with evidence from the reviewed studies, we find that NbS-FRM has the potential to provide both social and ecological co-benefits, with remaining gaps including a lack of resilience thinking, inadequate consideration of environmental changes, and limited collaborative efforts to manage trade-offs. The proposed framework shows how to move forward to leverage NbS for equitable and sustainable FRM with improved human well-being and ecosystem health.

Identifying the Contributing Sources of Uncertainties in Urban Flood Vulnerability in South Korea Considering Multiple GCMs, SSPs, Weight Determination Methods, and MCDM Techniques

This study quantified uncertainties involved in assessing the future flood vulnerability in 33 urban areas with population exceeding designated thresholds in South Korea. The driver-pressure-state-impact-response (DPSIR) framework was utilized as the study procedure, integrating social, economic, and environmental factors. In addition, a total of 220 cases of combinations were examined, encompassing twenty general circulation models combined with shared socioeconomic pathway scenarios, five weight determination methods, and three multi-criteria decision-making (MCDM) techniques, as sources of inherent uncertainties in the process. The rankings of urban flood vulnerability (UFV) for the selected cities were comprehensively assessed considering all combinations, followed by an analysis of variance test to investigate contributing sources of uncertainties. As a result, Incheon and Busan were found to be vulnerable to flooding, while Yeongcheon and Andong appeared to be safe cities. Some cities exhibited wide ranges in their rankings, such as Daegu, Yangpyeon, and Jeongeup. The identified contributing sources were weighting (58%), MCDM (27%), and the combination of weighting and MCDM methods together (15%). This study revealed that weight determination methods and MCDM techniques are the primary sources of uncertainties in the assessment of future UFV instead of multiple GCMs and SSPs. This finding underscores the importance for decision-makers and stakeholders to carefully consider these uncertainties for sustainable flood risk management and prevention.

A policy instruments palette for spatial quality: lessons from Dutch flood risk management

ABSTRACT Worldwide, more integrated and spatially embedded forms of flood risk management have been advocated. In the Netherlands, this ‘spatial turn’ can be associated with a quest for spatial quality, i.e. making use of existing landscape values to create more liveable, aesthetic and sustainable flood risk management solutions. Reflecting on Dutch flood risk management practice, this paper inventorizes which policy instruments are currently used to strengthen spatial quality, and how involved actors view these instruments. We present empirical insights on common concerns, standpoints and dilemmas from the Dutch Flood Protection Programme (DFPP), a large-scale reinforcement operation to climate-proof the Netherlands’ main flood defences by 2050. Spatial quality here remains a rather ambiguous policy objective, lacking a legally binding framework. Using the NATO-policy instruments’ typology as a starting point, and based on a co-learning process between science and practice, we present an instruments palette that can be used to strengthen spatial quality in flood risk management. Our findings reveal that the DFPP makes use of rather ‘soft’ policy instruments. The actual achievement of spatial quality goals seems to depend largely on the combined project team competencies, guidance and support provided by responsible water authorities, and commitment of other project partners.

Economic assessment of nature-based solutions to reduce flood risk and enhance co-benefits

Flooding is expected to increase due to climate change, urbanisation, and land use change. To address this issue, Nature-Based Solutions (NBSs) are often adopted as innovative and sustainable flood risk management methods. Besides the flood risk reduction benefits, NBSs offer co-benefits for the environment and society. However, these co-benefits are rarely considered in flood risk management due to the inherent complexities of incorporating them into economic assessments. This research addresses this gap by developing a comprehensive methodology that integrates the monetary analysis of co-benefits with flood risk reduction in economic assessments. In doing so, it aspires to provide a more holistic view of the impact of NBS in flood risk management. The assessment employs a framework based on life-cycle cost-benefit analysis, offering a systematic and transparent assessment of both costs and benefits over time supported by key indicators like net present value and benefit cost ratio. The methodology has been applied to the Tamnava basin in Serbia, where significant flooding occurred in 2014 and 2020. The methodology offers valuable insights for practitioners, researchers, and planners seeking to assess the co-benefits of NBS and integrate them into economic assessments. The results show that when considering flood risk reduction alone, all considered measures have higher costs than the benefits derived from avoiding flood damage. However, when incorporating co-benefits, several NBS have a net positive economic impact, including afforestation/reforestation and retention ponds with cost-benefit ratios of 3.5 and 5.6 respectively. This suggests that incorporating co-benefits into economic assessments can significantly increase the overall economic efficiency and viability of NBS.

IMPACT OF LAND USE ACTIVITIES ON THE HYDROLOGICAL REGIME IN THE JUNJUNG RIVER BASIN, PENANG ISLAND, MALAYSIA

Land use activities in the river basin have a very significant negative impact on the hydrological regime, especially surface runoff. The study of the impact of land use activities on the hydrological regime in the Junjung river basin aims to analyse changes in the rate of surface runoff due to current land use changes and land use planning in 2030. To achieve the goal of this study, curve number analysis was used as a determinant of hydrological parameters in the development of HEC HMS modelling in the study basin area. The results of the study found that the current land use in 2020 recorded an average curve number value of 85.77 and then increased to 86.36 in 2030 due to land use changes in 2030. The change in the value of the curve number has had an impact on the hydrological regime that is surface runoff because there is an increase in the percentage of impervious areas from 22.84 percent in 2020 to 31.14 percent by 2030. The rate of change in runoff is shown through the simulation of the peak flow rate that occurs according to the frequency of the event, which is between 0.7 to 4.9 percent. The results obtained from this study can be used as fundamental data for advanced studies of flood control and management for better sustainable flood risk management.

Flooding and Waste Disposal Practices of Urban Residents in Nigeria

The rising incidence of flooding is a cause for global concern. Flooding is caused by both natural and human factors. In Nigeria, flooding has been attributed chiefly to human factors, such as poor waste disposal practices and management. Despite this known link, no empirical study is known to have engaged with urban residents to understand their actual waste disposal practices and ascertain their knowledge of the connection of their waste disposal practices to the flooding they are increasingly experiencing. This work fills this gap via an in-depth engagement with residents and experts on their waste disposal practices in the flood-prone city of Port Harcourt via a mixed-methods case study. Questionnaire surveys and qualitative interviews served as the primary data collection tools. The study confirms the poor waste practices of residents and provides empirical data on the prevalence of various forms of waste disposal practices. This provides key information that can guide the needed change in waste practices to eliminate this known flood driver in the pursuit of sustainable flood risk management. This is pertinent as waste management is one of the areas where citizens have agency to act. A behavioural shift is needed in this regard and must be encouraged via targeted public sensitization. Having local vanguards champion waste management behavioural turn is also recommended. The relevant authorities are encouraged to adopt a more sustainable approach to waste management by ensuring there are waste services and putting in place adequate disincentives to deter offenders.

Natural flood management: Opportunities to implement nature‐based solutions on privately owned land

AbstractThe implementation of Natural Flood Management (NFM), as an example of a nature‐based solution (NbS), is promoted as a risk reduction strategy to support sustainable flood risk management and climate change adaptation more widely. Additionally, as an NbS, NFM aims to provide further multiple benefits, such as increased biodiversity and improved water quality as well as improved mental health. The implementation of NbS often needs private‐owned or managed land, yet can create conflicts between the different stakeholders which can undermine the social consensus required for successful implementation. Consequently, a main question is how the multiple benefits and requirements of NFM can be delivered to meet the different goals of the wide variety of stakeholders who must be involved. This article discusses the challenges and potential of implementing NFM as an alternative to the traditional technical mitigation measures in flood risk management. We outline four opportunities in the implementation of NFM: physical conditions of the catchment, social interaction, financial resources, and institutional setting. Their importance is then demonstrated and compared to different examples across the globe. Nevertheless, the core drivers reflect the social interaction and institutional setting and the role of stakeholders in the successful implementation of NFM.This article is categorized under:Engineering Water > Planning WaterHuman Water > Water GovernanceScience of Water > Water ExtremesWater and Life > Conservation, Management, and Awareness

Preliminary Study on Flood Simulation using the HEC-HMS Model for Muda River, Malaysia

Flooding poses a severe threat to human beings and causes significant damage to property, infrastructure, and agricultural production. The flood also has severe consequences for socio-economic activities and can lead to the loss of human life. One of the significant factors that cause the flood is rapid development, especially in the floodplain area. This study estimates the flood discharge along the Muda River, Malaysia using Hydrological Modelling System (HEC-HMS). The finding shows that the HEC-HMS model performed well during the validation period, in which the coefficient determination (R2) between observed and simulated discharge during the validation process ranges from 0.51-0.84. In terms of design flood, the model simulated the peak flow with 1247-1448.8 m3/s and 1798.5-3662.5 m3/s for 50 and 100-year ARIs, respectively. The results obtained from this study can be used as fundamental data for advanced studies of flood control and management for better sustainable flood risk management.

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.

Understanding Flood Vulnerability in Local Communities of Kogi State, Nigeria, Using an Index-Based Approach

In West Africa, the impacts of flooding are becoming more severe with climate warming. Flood-prone communities in Kogi State in north-central Nigeria are affected by annual flooding and some extreme flood events. The negative impacts remain a major obstacle to development, environmental sustainability, and human security, exacerbating poverty in the region. Reducing and managing the impacts of flooding are increasingly becoming a challenge for individual households. Analysing vulnerability to flooding (a function of exposure, susceptibility, and lack of resilience) and identifying its causes using an index-based approach to achieve sustainable flood risk management were the focus of this study. A semi-structured questionnaire was used to collect relevant data from 400 households in 20 purposively selected communities. Based on expert opinions and an extensive literature review, 16 sets of relevant indicators were developed. These indicators were normalised and aggregated to compute the flood vulnerability index (FVI) for each community. This was then used to compare, classify, and rank communities in terms of their vulnerability to flooding. The results of the study showed that the selected communities were at varying levels of the risk of flooding. Four of the communities including the Onyedega, Ogba Ojubo, Odogwu, and Ichala Edeke communities were found to have very high vulnerability to flooding compared to others. Several factors such as poor building structures, lack of evacuation and flood management measures, over-dependence of households on agriculture, lack of diversification of economic activities, and weak household economic capacity were identified as causes. These findings are useful for developing flood risk reduction and adaptation strategies, such as ecosystem-based approaches, to reduce current and future vulnerability to flooding in Nigeria and other developing countries with similar conditions.

Comparison of sustainable flood risk management by four countries – the United Kingdom, the Netherlands, the United States, and Japan – and the implications for Asian coastal megacities

Abstract. Sustainable flood risk management (SFRM) has become popular since the 1980s. Many governmental and non-governmental organisations have been keen on implementing the SFRM strategies by integrating social, ecological, and economic themes into their flood risk management (FRM) practices. However, the justifications for SFRM are still somewhat embryonic, and it is not yet clear whether this concept is influencing current policies in different countries. This paper reviews the past and current flood management experiences from flood defence to SFRM in four developed countries to highlight lessons for coastal megacities in development. The paper explores recent strategies such as “Making Space for Water”, Planning Policy Statement 25 (PPS25), and the National Planning Policy Framework (NPPF) in the UK and “Room for the River” in the Netherlands, which were implemented to mitigate flooding, integrate FRM with sustainability concepts, and deliver sound FRM practice for future generations. In this context, the United States has also established a National Flood Insurance Program (NFIP), and in a different approach, Japan has developed an advanced flood warning and evacuation contingency system to prepare for climatic extremes. These case studies give good lessons in achieving long-term SFRM to deliver sound flood management practices considering socio-economic and environmental concerns. Most developing coastal megacities especially in Asia are still heavily reliant on a traditional hard-engineering approach, which may not be enough to mitigate substantial risks due to human factors (e.g. large population, rapid socio-economic growth, subsidence from excessive groundwater extraction) and natural factors (e.g. climate change including sea-level rise and land subsidence). It is clear that different countries and cities have their interpretation of SFRM, but this paper explores how policymakers can adopt “mixed options” to move towards long-term thinking about sustainability with social, economic, and environmental considerations.

Performance of an environmentally‐aligned, low maintenance flood alleviation scheme on the Burn of Mosset, Forres, Scotland

AbstractFlooding of the town of Forres, Scotland prompted the implementation of a flood alleviation scheme (FAS) featuring a low earth‐fill dam constructed upstream of the town to create a flood retention area, limiting peak discharges entering the urban area. Flow through the dam is controlled by a weir, and it was recognised that if coarse sediment, large wood, and/or debris collected at the weir this could adversely affect its performance. To ensure reliable operation of the weir, the “Burn Management Works” (BMW) were designed to reconnect the embanked, elevated river channel to its floodplain, naturally retaining coarse sediment, large wood, and debris upstream of the dam. The FAS became operational on August 28, 2009 and impounded floodwater for the first time just 1 week later. Here, we report the results of monitoring of the BMW performed between 2011 and 2018. We find that the BMW have fulfilled their primary, flood alleviation functions by retaining large amounts of sediment and large wood without the need for maintenance. In so doing, the BMW has evolved from the single‐thread, trapezoidal, pilot channel constructed through the initially dry pasture, to the shifting mosaic of anastomosed channels, ponds, wetlands, and scrublands that now comprise the fully‐connected floodplain. In parallel, local interest groups have transformed this flood defence asset into a bird and wildlife area that is enjoyed by the community. Lessons learned from the BMW can inform other projects seeking to use nature‐based solutions to deliver sustainable flood risk management while simultaneously achieving goals for river restoration and community engagement.

A comparative flood damage and risk impact assessment of land use changes

Abstract. Sustainable flood risk management encompasses the implementation of nature-based solutions to mitigate flood risk. These measures include the establishment of land use types with a high (e.g., forest patches) or low (e.g., sealed surfaces) water retention and infiltration capacity at strategic locations in the catchment. This paper presents an approach for assessing the relative impact of such land use changes on economic flood damages and associated risk. This spatially explicit approach integrates a reference situation, a flood damage model, and a rainfall-runoff model considering runoff re-infiltration and propagation to determine relative flood risk mitigation or increment related to the implementation of land use change scenarios. The applicability of the framework is illustrated for a 4800 ha undulating catchment in the region of Flanders, Belgium, by assessing the afforestation of 187.5 ha (3.9 %), located mainly in the valleys, and sealing of 187.5 ha, situated mainly at higher elevations. These scenarios result in a risk reduction of 57 % (EUR 100 000) for the afforestation scenario and a risk increment of <1 % (EUR ∼ 500) for the sealing scenario.

RegioFEM — Applying a floodplain evaluation method to support a future‐oriented flood risk management (Part II)

AbstractFlood risk managers face increasing challenges in anticipating future developments and coordinating flood risk management on a regional level. The regional floodplain evaluation matrix (RegioFEM), a method to support a future‐oriented flood risk management at a regional scale, was applied in a section of the Raab River in Austria. The developed method uses several parameters assessing the consequences of changes in the study area, which lead to changes in flood risk. Settlement development, planned flood protection measures and the likely increase of flood runoff due to climatic changes are considered. Parameters include hydrological (e.g., peak reduction), hydraulic (inundation area), spatial (affected buildings) and monetary (damage potential) ones. The results of the application of the RegioFEM were presented at a regional expert workshop, conducted to gain feedback about the possibilities and limitations of implementing the method into practice. Considering future changes and evaluating their impacts on flood risk can provide stakeholders and decision makers valuable information for sustainable flood risk management.

Modelling differential geomorphic effectiveness in neighbouring upland catchments: implications for sediment and flood risk management in a wetter world

In July 2007 an intense summer storm resulted in significant activation of the sediment system in the Thinhope Burn, UK. Catchment- and reach-scale morphodynamic modelling is used to investigate the geomorphic work undertaken by Thinhope Burn; comparing this with the more subdued responses shown by its neighbours. Total sediment efflux for Thinhope Burn over the 10 yr period 1998-2007 was 18, 801 m3 four times that of the larger Knar Burn catchment and fifty-four times that of the smaller Glendue Burn catchment. For a discharge of 60 m3s-1, equivalent to the July 2007 Thinhope flood, sediment efflux was 575 m3, 76 m3, and 67 m3 for Thinhope, Glendue and Knar Burns respectively. It is clear that Thinhope Burn undertook significantly more geomorphic work compared to its neighbours. Analysis of the population of shear stress for reach-scale simulations on Thinhope Burn highlighted that the final three simulations (flood peaks of 60, 90, 236 m3s-1) all produced very similar distributions, with no marked increase in the modal shear stress (∼250 Nm-2). This possibly suggests that flows >60 m3s-1 are not able to exert significantly greater energy on the channel boundary, indicating that flows in the region of 60 m3s-1 attain ‘peak’ geomorphic work. It is argued that factors such as strength resistance of the key sediment sources (e.g. paleoberms perched on terraces), structural resistance to flood waves imposed by valley form resistance, location sensitivity and transmission resistance, may all offer explanations for increased geomorphic effectiveness compared with its neighbours. With the expectation of greater rainfall totals in the winter and more extreme summer events in upland areas of the UK, it is clear that attention needs to focus upon the implications of this upon the morphological stability of these areas not least to aid future sustainable flood risk management.

High-Resolution Hydrological-Hydraulic Modeling of Urban Floods Using InfoWorks ICM

Malaysia, being a tropical country located near the equatorial doldrums, experiences the annual occurrence of flood hazards due to monsoon rainfalls and urban development. In recent years, environmental policies in the country have shifted towards sustainable flood risk management. As part of the development of flood forecasting and warning systems, this study presented the urban flood simulation using InfoWorks ICM hydrological−hydraulic modeling of the Damansara catchment as a case study. The response of catchments to the rainfall was modeled using the Probability Distributed Moisture (PDM) model due to its capability for large catchments with long-term runoff prediction. The interferometric synthetic aperture radar (IFSAR) technique was used to obtain high-resolution digital terrain model (DTM) data. The calibrated and validated model was first applied to investigate the effectiveness of the existing regional ponds on flood mitigation. For a 100-year flood, the extent of flooded areas decreased from 12.41 km2 to 3.61 km2 as a result of 64-ha ponds in the catchment, which is equivalent to a 71% reduction. The flood hazard maps were then generated based on several average recurrence intervals (ARIs) and uniform rainfall depths, and the results showed that both parameters had significant influences on the magnitude of flooding in terms of flood depth and extent. These findings are important for understanding urban flood vulnerability and resilience, which could help in sustainable management planning to deal with urban flooding issues.

Community action on natural flood management and the governance of a catchment‐based approach in the UK

AbstractThere is increasing interest in natural flood management (NFM) and the delivery of public environmental goods. Yet the implementation of NFM can be ad‐hoc and is regionally diverse. Communities often play a role in NFM and thus we assess NFM governance in the UK and communities' position within it. We develop a theoretical framework using the concepts of public goods, social capital, collective action and polycentrism and use it to examine the governance of the design and implementation of NFM in Pickering and Calderdale in Yorkshire, to contribute to a debate on how NFM should be managed, by whom, and under what governance arrangements. Drawing on stakeholder interviews, we find that the participation of community flood groups (CFGs) in NFM improved community access to strategic conversations on flood risk management (FRM). In turn CFGs raised the public profile of NFM, enabled the deployment of NFM measures, and helped to generate the evidence base on them. We conclude that there is a need for a polycentric community and catchment‐based approach to better coordinate NFM governance across and between scales, to support community access and contribution to flood risk strategy, and to foster sustainable flood risk management.

Toward sustainable policy instruments: assessing instrument selection among policy actors

To address complex environmental problems we need sustainable policy solutions, which are often disregarded by policy actors in charge of addressing these problems. In this article, we study factors that promote or hinder policy actors’ selection for sustainable policy instruments using the case of flood risk management in Switzerland. We evaluate flood risk management instruments based on three key sustainability dimensions and forgo conventional approaches to categorizing policy instruments. In a survey, we ask policy actors which policy instruments they prefer and thus evaluate which policy actors select sustainable policy instruments. Results indicate that problem perception is the key determinant influencing policy actors’ selection of sustainable flood risk management instruments. Results also suggest that the tendency to select sustainable flood risk management instruments differs depending on actor type and actor level. These findings help us understand which settings promote the selection of sustainable policy solutions to tackle complex environmental problems.

Regional flood frequency analysis and uncertainties: Maximum streamflow estimates in ungauged basins in the region of Lavras, MG, Brazil

Regionalization techniques are an important alternative to overcome the scarcity of streamflow data and to provide adequate estimates for flood management. This work aims to generate a maximum streamflow regional function and evaluate the uncertainties in estimates for a basin in the South of Minas Gerais, Brazil. Six streamflow gauging stations, that presented stationarity and no trends according to the Mann-Kendal test, were used to develop the regional function by the dimensionless curve method. The annual maximum streamflow series were adjusted to the probability density functions (PDFs) 2-parameter Log-Normal, 3-paramenter Log-Normal, Gumbel, and Gamma. Then, the goodness-of-fit of the PDFs was verified by the Anderson-Darling test. For the regional analysis, heterogeneity and discordancy measures verified the homogeneity of the region, and the jack-knifing technique evaluated the predictive performance of the regional function by the coefficient c of Camargo and Sentelhas. The uncertainty analysis for at-site and regional function estimates was assessed by Monte Carlo simulations and bootstrapping. The performance of the regional function was classified as optimum for most of the watersheds, but as good when considering the prediction in certain return periods. The uncertainties were larger in ungauged basins, especially for greater return periods and drainage areas. The regional function developed can be employed in ungauged sites, but also to improve data in poorly monitored watersheds. Thus, this study demonstrates the adequate applicability of regionalization in ungauged watersheds and provides a simple alternative for maximum streamflow estimates in order to promote sustainable flood risk management.