Editorial: Special Issue From the Ninth International Conference on Flood Management

The Ninth International Conference on Flood Management (ICFM9 https://www.icfm.world/ICFM-Conferences/ICFM9) was held in Tsukuba, Japan, from February 18 to 22, 2023, under the theme “River Basin Disaster Resilience and Sustainability by All – Integrated Flood Management in the Post-COVID-19 Era.” The increasing frequency and severity of torrential rainfall due to global climate change have led to greater human losses and economic damage. The number of people vulnerable to devastating floods continues to rise due to large-scale urbanization, population migrations to and growth in flood-prone areas, deforestation, climate change, and rising sea levels. During the COVID-19 pandemic, immediate attention was often focused on preventing further virus transmission; however, the threat of floods remains as urgent as ever. The primary objective of ICFM9 was to draw lessons from past experiences and enhance the resilience of societies to flooding.

Since the adoption of The Sendai Framework for Disaster Risk Reduction (DRR) 2015–2030 at the Third United Nations World Conference on DRR in March 2015, the international community has also agreed on Transforming Our World: The 2030 Agenda for Sustainable Development in September 2015 and The Paris Agreement on Climate Change in December 2015. To support and implement these agreements, strong, coordinated, and strategic actions are necessary to enhance climate and disaster resilience and sustainability. ICFM9 was designed to contribute to a deeper understanding of the challenges posed by our changing world and to explore solutions that will strengthen resilience against flood-related disasters.

Flood disaster resilience and sustainable development are fundamentally and structurally interconnected. Addressing these challenges requires a comprehensive approach that transcends disciplinary boundaries, promotes holistic and integrated strategies, and ensures effective planning, implementation, and evaluation. With this in mind, ICFM9 facilitated in-depth discussions on a wide range of issues from scientific, technological, social, and economic perspectives.

The conference emphasized the necessity of adopting a comprehensive and forward-thinking approach to flood risk reduction, resilience building, and adaptive management. Its key messages reflected a growing recognition of the importance of integrated, inclusive, and science-driven strategies for managing flood risks in an era of increasing uncertainty. The ICFM9 highlighted the urgency of adopting holistic, data-driven, and socially inclusive approaches to flood management. Strengthening the link between science and decision-making, promoting open data sharing, enhancing flood modeling, integrating knowledge across disciplines, fostering skilled professionals, and prioritizing social equity will collectively shape a more resilient future in the face of escalating flood risks.

One of the central themes highlighted at the conference is the importance of utilizing an end-to-end approach that connects scientific advancements with practical decision-making and action on the ground. This approach fosters interdisciplinary collaboration among hydrologists, engineers, social scientists, policymakers, and emergency responders. It also relies on real-time data integration for predictive modeling, early warning systems, and dynamic flood response. Stakeholder engagement plays a crucial role in ensuring that local governments, communities, and industries have access to actionable knowledge. By directly linking cutting-edge research with real-world applications, flood management strategies become more effective and responsive to emerging challenges.

Another key message focuses on the promotion of data collection, archiving, and sharing. The availability of high-quality, openly accessible hydrological, meteorological, and socio-economic data is essential for improving flood risk assessment and management. Expanding open-access data platforms facilitates knowledge sharing between nations, agencies, and researchers. Standardizing data collection methods ensures comparability and interoperability across different regions. Encouraging community-based data collection, such as citizen science initiatives, can also help supplement official datasets. A global commitment to transparent and collaborative data management significantly enhances predictive capabilities and improves disaster preparedness.

Given the increasing intensity of floods due to global change, improving flood models and their economic impact assessments is crucial. Traditional flood models must be refined to account for the non-stationarity of climate variables, which requires dynamic and adaptive prediction methods. Additionally, models need to integrate complex urban hydrology, considering factors such as land-use changes, stormwater infrastructure, and impermeable surfaces. Economic impact assessments should go beyond direct damages, such as infrastructure loss, and include indirect consequences like supply chain disruptions and long-term socio-economic dislocation. Advancements in machine learning, remote sensing, and high-resolution simulations offer promising opportunities to develop more accurate risk assessments and cost-effective mitigation strategies.

Flood risk management is inherently multidisciplinary, making it essential to accelerate the integration of knowledge across different fields. Developing transdisciplinary research networks fosters dialogue between scientists, practitioners, and policymakers. Enhancing communication tools, such as visualization platforms and interactive dashboards, helps translate complex data into accessible information for decision-makers. Embedding flood resilience into broader policy frameworks, including urban planning, water governance, and sustainable development, further strengthens adaptation efforts. Faster knowledge integration reduces the gap between research and practice, promoting proactive rather than reactive flood management approaches.

The conference also underscored the importance of fostering facilitators who can bridge the gap between scientific research and policy implementation. This requires capacity-building initiatives for local governments, emergency response teams, and community leaders. Training programs in risk communication ensure that technical information is conveyed effectively to diverse audiences, while mentorship and knowledge transfer between experienced professionals and emerging leaders help sustain expertise in flood management. Strengthening human capital through education and training ensures that flood-prone communities can develop robust institutional frameworks to handle current and future challenges.

Flood management strategies must also be designed with an understanding of social inequalities and Indigenous peoples' rights. The impacts of flooding are not distributed equally across societies, with marginalized populations often bearing the greatest burden. A socially just approach to flood management requires recognizing and addressing vulnerabilities by integrating social justice principles into flood planning and response. Incorporating Indigenous knowledge into flood management strategies acknowledges traditional ecological practices that have proven resilient over centuries. Equitable disaster recovery must prioritize disadvantaged communities in relief efforts and long-term adaptation planning. Embedding social equity and Indigenous rights into flood management policies ensures that they are inclusive, sustainable, and culturally appropriate.

This special issue features 13 selected contributions from the conference, highlighting the broad scope of the research presented and the intensive discussions among ICFM9 participants. These contributions are categorized into four thematic groups based on their topics.

Arrighi et al. explore the impact of flooding on cultural heritage (CH), particularly in tourism-dependent cities, by developing a framework that evaluates resilience, indirect impacts, and flood risk. Their approach uses visitor numbers as a proxy for social appreciation and introduces a depth-idleness vulnerability function to estimate reopening times. They apply their model to Florence, Italy, showing that a medium recurrence flood requires 351 days for recovery and results in a loss of 10.5 million visitors annually.

Araujo et al. assess flood vulnerability through a disadvantage index (DI), incorporating socio-economic factors like age, gender, race, and housing conditions. By overlaying this index with flood exposure data, they identify priority areas for flood management in the Itapocu River Basin, Brazil, ensuring resources are directed toward the most vulnerable populations.

Bryant et al. investigate the impact of data aggregation on flood risk models, demonstrating that using a single statistic in non-linear damage functions leads to systematic overestimation, with biases varying across different regions of Germany. Their work underscores the need for refined modeling techniques to improve flood damage assessments.

Brandao et al. apply artificial neural networks (ANNs) to discharge simulation and flood forecasting, testing their efficiency for various lead times in an urban basin. Their findings indicate that ANN models are effective for short-term flood predictions but deteriorate in accuracy over longer lead times. They also explore the effects of climate change scenarios, predicting increased extreme weather events and short return-period floods.

Ghosh et al. highlight the limitations of traditional statistical forecasting techniques for urban flooding and propose integrating the Weather Research and Forecasting (WRF) model with a coupled hydrodynamic flood modeling framework. Their approach, which accounts for urban canopy scenarios, demonstrates the importance of incorporating urban characteristics into rainfall forecasting for more accurate flood predictions.

Ikeuchi et al. address the challenges of forecasting floods in fast-flowing watersheds using deep learning models. Their results show that feedback mechanisms and attention-based weighting improve model accuracy, particularly for large catchments, offering innovative solutions for early flood warning systems.

Takehiko et al. examine the impact of local topography on rainfall-runoff processes in Chiba Prefecture, Japan. They develop a coupled rainfall–runoff–inundation and river-flow model (RRI-RF) and demonstrate that coarse-resolution modeling underestimates discharge, emphasizing the importance of high-resolution elevation data in flood simulations.

Fan et al. discuss the increasing frequency of short-duration extreme rainfall events in small and medium-sized rivers (SMRs), where short lead times make accurate flood forecasting critical. They advocate for improved forecasting systems that allow local governments to issue timely evacuation orders, reducing casualties during flash floods.

Shrestha et al. quantify the long-term impact of climate change and land-use conversion on rice production and flood risk in Indonesia's Solo River basin. Using coupled hydrological models, they predict that future rice production may decrease by 24.6% by 2076, while flood-related crop damage could increase by 93.7%, highlighting the intersection of agriculture, hydrology, and climate change.

Zhang et al. conduct large-scale experimental modeling of dike-break-induced flooding, analyzing water level fluctuations, breach discharge, and surface velocity during dike failure. Their findings reveal that peak flood discharge is influenced by river water level and velocity, offering insights into flood dynamics and potential mitigation strategies.

Forbis and Ly examine the application of Forecast-Informed Reservoir Operations (FIRO) by the US Army Corps of Engineers (USACE) to improve water supply reliability without increasing flood risk. Their study, based on pilot projects in California, concludes that FIRO can enhance flood control operations and provides a framework for broader implementation across USACE reservoirs.

Rizaldi et al. explore the use of Paddy Field Dams (PFD) as an innovative flood mitigation strategy in Jakarta. Comparing PFD with other countermeasures such as embankments, dredging, and river widening, they find that PFD is a cost-effective and sustainable solution for managing urban flooding.

Takebayashi and Fujita analyze the collapse of the Koakagawa Bridge in Japan due to flood-induced scouring, using field surveys and numerical simulations. Their study identifies channel blockage from driftwood as a major contributing factor and recommends protecting downstream banks with non-erosive materials to prevent future failures.

These contributions collectively highlight the complex interplay between flood risk, climate change, infrastructure resilience, and predictive modeling. By leveraging advanced hydrological models, artificial intelligence, and innovative flood mitigation strategies, researchers aim to enhance flood preparedness and resilience in both urban and rural settings.

Building on the success of ICFM9, the momentum for advancing flood management strategies and resilience continues with the organization of the 10th International Conference on Flood Management (ICFM10 www.icfm10.com) in May 2026 under the title: “Adapting to Global Change: Innovative Approaches to Flood Management and Resilience.” This milestone event will serve as a global platform for sharing cutting-edge research, innovative solutions, and best practices in integrated flood management. As climate change intensifies flood risks worldwide, ICFM10 will foster collaboration among scientists, policymakers, and practitioners to develop forward-thinking strategies that enhance resilience, sustainability, and adaptive capacity. By bringing together diverse perspectives and expertise, the conference will continue to drive meaningful progress toward mitigating flood-related disasters and safeguarding communities.

We hope to see you in London, Canada in May 2026.

Editorial team:

Slobodan P. Simonovic

Nigel Wright

Cheng Zhang

Subhankar Karmakar

Lindsay Beevers