SpongeBoost is a Horizon Europe project focused on restoring the natural sponge function of landscapes, an approach intended to help ecosystems retain and manage water more effectively. Its award highlights practical restoration as well as collaboration, environmental education, public engagement and the capacity to inspire comparable work elsewhere in Europe. The announcement describes these qualities as evidence of approaches worth sharing, rather than treating the award as a measure of scientific performance alone. The 2027 award will recognise one project after the consortium first selects three nominees for further information and a final assessment.

Eligible initiatives must contribute to restoring or improving natural water retention, have been implemented or substantially developed within the previous five years, and be located in an eligible European country. The geographic scope includes European Union Member States as well as Switzerland, the United Kingdom, Norway and the Balkan countries. Projects should primarily involve restoration, rewetting or other nature-based measures carried out in outdoor landscapes. SpongeBoost says it is particularly interested in projects that combine on-the-ground restoration with strong local cooperation, innovative methods, environmental education or activities designed to help others learn from and reproduce their results.

After reviewing all nominations, the SpongeBoost consortium will contact three selected projects and invite them to provide further details about their work. The winner will then be chosen from that group. Members of the consortium will visit the winning project for a field visit, where they will present the award and exchange experiences with the people behind the initiative. The visit is also intended to showcase the project’s approaches and lessons for other restoration initiatives across Europe. The announcement does not provide a judging rubric, a prize amount or a claim that the nominated projects have been independently evaluated for a defined outcome such as a measured reduction in flooding or drought impacts.

The final award builds on previous editions that highlighted examples of sponge-landscape restoration and drew attention to projects addressing land and water challenges. Because the call is open to anyone, nominees are not limited to formal research partnerships, although the project must meet the stated eligibility criteria. The announcement positions public participation and recognition as central parts of the 2027 process: a project may be nominated by its participants or by others who regard it as inspiring or deserving of wider recognition. SpongeBoost is funded by the European Union’s Horizon Europe research and innovation programme under grant agreement No. 101112906, and the announcement states that the views expressed are those of the author or authors and do not necessarily represent those of the European Union or the European Climate, Infrastructure and Environment Executive Agency.

Subject of Research: SpongeBoost award nominations for European landscape restoration

Article Title: SpongeBoost invites nominations for inspiring restoration projects across Europe

Article References: SpongeBoost invites nominations for inspiring restoration projects across Europe. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: SpongeBoost, landscape restoration, natural water retention, flood resilience, drought resilience, nature-based solutions, rewetting, European Union, environmental awards, invites, nominations, inspiring

The technical core of the collection begins with the integration of advanced technologies into climate-responsive planning and inclusive governance frameworks. As urban areas across the continent expand at unprecedented rates, the editorial argues that long-term sustainability in infrastructure development depends on coupling smart systems with people-centered design. The goal, according to research highlighted from the symposium, is to create intelligent and adaptable urban environments in which digital innovation serves residents rather than displacing them. This framing rejects the notion that technology alone can fix urban dysfunction; instead, it positions technological tools as one layer within a broader architecture of governance, planning, and community participation that must evolve together.

Energy poverty emerges as one of the most urgent and tractable problems. Many informal settlements and marginalized communities across African cities still experience unreliable electricity access and remain dependent on polluting fuels such as paraffin and firewood, with direct consequences for health, safety, and household economics. One study presented at the symposium examines the decentralization of solar energy systems as a mechanism for addressing energy poverty and advancing energy justice in these marginalized communities. Distributed solar generation, the research suggests, can bypass the slow and often inequitable expansion of centralized grids, delivering clean power directly to households that have historically been excluded from formal energy infrastructure. The editorial frames such decentralized systems as fundamentally important to any serious agenda of urban equity.

Closely related is the problem of municipal solid waste, which remains a critical environmental and social challenge for many African cities. Rather than treating waste purely as a disposal burden, research presented at the symposium explores renewable energy from solid waste as an innovative dual-purpose solution. By converting waste streams into energy, cities could simultaneously address the solid waste management crisis and alleviate energy poverty in marginalized communities. This kind of circular approach, in which one urban system’s output becomes another’s input, exemplifies the resourcefulness the symposium sought to champion, and it illustrates how technical interventions can generate social benefits when they are designed with equity in mind from the outset.

The collection also turns its attention to the countryside, noting that rural communities in Global South countries are undergoing a radical transformation. Scholars cited in the editorial identify the major drivers of rural-urban interaction and trace their implications for land use, governance, and socio-economic organization in urbanizing rural regions. Their contribution goes beyond diagnosis: they conceptualize a novel framework for the governance and planning of rural-urban interfaces, recognizing that the boundary between city and countryside is increasingly porous. As settlements sprawl and economic activity straddles both realms, planning regimes designed for a neat urban-rural divide are failing, and new governance models are needed to manage the flows of people, resources, and land-use pressures that connect them.

In South Africa specifically, the editorial confronts a stubborn legacy. The expansion of dormitory settlements on city peripheries remains a dominant feature of the country’s post-apartheid urbanization, and this phenomenon persistently reproduces the spatial and infrastructural inequalities of the apartheid era, producing marginalized informal communities within cities. These communities face a housing crisis characterized by a growing backlog, unaffordability, and spatial inequality. Research presented at the symposium identifies divergent pathways to formalizing informal settlements, which often generate tensions between state-led urban modernization and community-driven adaptation strategies. The friction between top-down upgrading programs and the organic, incremental strategies residents themselves pursue is a recurring theme, and one that any workable policy must navigate rather than override.

Against this backdrop, the collection advances concrete institutional remedies. One contribution calls for the professionalization of the human settlements development sector, arguing that the scale and complexity of the housing backlog demand a skilled, accountable, and properly credentialed workforce. Another study operationalizes the Sustainable Development Goals principle of “leaving no one behind” by identifying and characterizing marginalized and vulnerable groups, including persons with disabilities, child-headed households, older persons, and refugees. By making these populations visible in data and policy, the research argues, inclusion can move from aspiration to measurable practice, ensuring that vulnerable groups are accounted for in all spheres of settlement planning and service delivery.

Climate change adds a further layer of hazard to already fragile urban systems. In Lagos, Nigeria, the interaction between urban expansion and flood occurrence was the focus of research presenting innovative strategies to enhance urban resilience. These strategies include integrating climate-tailored early warning systems and fostering active community participation in flood management. The Lagos case demonstrates that resilience is not merely an engineering problem of drainage and barriers; it is also a social problem of communication, trust, and local knowledge. Early warning systems only save lives when communities are organized and empowered to act on them, which reinforces the symposium’s broader emphasis on participatory governance.

Human-made hazards feature prominently as well. Artisanal cobalt miners in the Democratic Republic of the Congo confront exploitative working conditions, hazardous labor, and societal degradation, and the research presented calls for transformative policies and legal frameworks that prioritize equitable resource governance, social justice, and human rights. As global demand for cobalt, a critical mineral for batteries and the energy transition, continues to rise, the conditions under which it is extracted become a matter of international as well as local consequence. The editorial positions equitable resource governance as inseparable from the agenda of sustainable settlements: a city cannot be just if the resource economies feeding it are not.

The unifying conclusion is that the realization of innovative technologies, sustainability, equity, social justice, and resilient infrastructure for sustainable cities and communities cuts across jurisdictional boundaries and requires a multidisciplinary approach to solving these grand challenges. Broader stakeholder collaboration across inter- and intra-organizational systems, including researchers, policymakers, public and private practitioners, non-governmental organizations, and communities, is described as a fundamental requirement for co-creating innovative solutions. As one contribution notes, intentional resource coordination and sustained collaborative commitment can generate meaningful long-term effects on social and upward mobility within underserved urban communities. The message from the Pan African City Symposium is ultimately one of cautious optimism: the problems are interconnected, but so are the solutions, and the expertise to pursue them now spans the entire African diaspora and beyond.

Subject of Research: Sustainable, inclusive, and equitable human settlements in Africa and the Global South

Article Title: Editorial: The dynamics of sustainable, inclusive and equitable human settlements (volume 2): Pan African City symposium 2025

Article References: Khumalo, P., Lukhele, T., & Ntakana, K. (2026). Editorial: The dynamics of sustainable, inclusive and equitable human settlements (volume 2): Pan African City symposium 2025. Frontiers in Sustainable Resource Management, 5, Article 1969053. https://doi.org/10.3389/fsrma.2026.1969053

Image Credits: AI Generated

DOI: 10.3389/fsrma.2026.1969053

Keywords: human settlements, urbanization, energy poverty, informal settlements, solar energy, solid waste management, flood resilience, housing inequality, rural-urban interface, sustainable development, energy justice, Pan African City Symposium

The core idea behind the study is resilience, a concept that has moved to the center of disaster risk management worldwide. Rather than asking only how likely a flood is, resilience assessment asks how well a system, whether a city, a village, or an entire river basin, can absorb a disturbance, continue functioning, and recover afterward. While urban flood resilience has been studied extensively in recent years, with detailed indices developed for cities in China, Norway, Brazil, and elsewhere, the authors point out that resilience assessments at the watershed scale, where floods are actually generated and routed across the landscape, have remained largely unexplored. This gap matters because watershed-scale analysis captures interactions between upstream and downstream areas that city-level studies simply cannot see: how runoff generated on bare slopes travels toward settlements, how road networks and health infrastructure shape recovery capacity, and how social and economic conditions vary across an entire basin.

To structure their analysis, the researchers turned to the pressure-state-response framework, a conceptual model originally developed for environmental statistics by the OECD and Canadian statistician David Rapport in the late 1970s and early 1990s. The framework organizes information about an environmental system into three linked categories. Pressure describes the forces stressing the system, such as steep topography, intense rainfall, and hydrological conditions that promote runoff. State captures the current condition of the system, including social and economic characteristics of the population living with flood exposure. Response describes the capacity to act, encompassing flood-related infrastructure, health facilities, and other resources that determine how effectively a community can prepare for and recover from a disaster. By mapping dozens of variables from six domains, topography, meteorology, hydrology, social conditions, economic conditions, and flood-related infrastructure, onto these three categories, the team built a multidimensional portrait of resilience across the Gavkhoni Watershed.

One of the study’s key methodological innovations lies in how the variables were weighted. In many multi-criteria assessments, weights are assigned by expert judgment, which introduces subjectivity. Here, the researchers used the entropy method, a technique rooted in Claude Shannon’s 1948 mathematical theory of communication. Entropy weighting assigns importance to each variable based on how much informational variation it carries across the study area: variables that discriminate strongly between different locations receive higher weights, while those that are nearly uniform receive lower ones. This data-driven approach means the resilience map reflects the actual spatial structure of the watershed rather than the intuitions of a panel. The authors have made their Python code for entropy calculation freely available on GitHub, a transparency measure that allows other researchers to reproduce and adapt the method for their own regions.

The mathematical heart of the study is the catastrophe progression method, an approach derived from René Thom’s catastrophe theory, a branch of mathematics developed in the 1960s and 1970s to describe systems that change abruptly rather than smoothly. Catastrophe theory shows that certain continuous systems can undergo sudden jumps in behavior, and it classifies these jumps into a small number of canonical forms with names like the cusp, the swallowtail, and the butterfly, each defined by the number of control variables governing the system. In the catastrophe progression method, these forms become aggregation tools: instead of simply averaging indicators, the method combines them using the nonlinear formulas associated with each catastrophe model, allowing the composite score to reflect abrupt transitions and threshold effects that a linear average would smooth away. The technique has previously been applied to problems ranging from groundwater potential assessment to predicting coal and gas outbursts in mines.

Choubin and Dastranj applied these catastrophe models at three nested levels. First, within each subsystem, variables were aggregated using the cusp, swallowtail, or butterfly model depending on how many indicators belonged to that group. Second, the pressure, state, and response scores for each subsystem were combined. Finally, the comprehensive combination of pressure, state, and response across the entire framework produced a single resilience value for every location in the watershed, which was then translated into a flood resilience map. This hierarchical structure preserves the conceptual logic of the pressure-state-response model while exploiting the nonlinear mathematics of catastrophe theory, creating a hybrid conceptual-mathematical framework that the authors argue is well suited to the complexity of watershed systems.

To test whether their results were robust, the researchers performed a sensitivity analysis, systematically removing individual input variables and measuring how much the resulting resilience map changed. The findings are striking. The single most sensitive variable in the entire model turned out to be the number of outpatient health centers: removing it changed the resilience map by an average of about 16 percent. Road density ranked second in importance, with its removal producing a 5.5 percent change. These results carry a powerful practical message: in this watershed, the capacity of communities to respond to floods, embodied in healthcare access and transport connectivity, matters as much as or more than the physical drivers of flooding itself. A family’s ability to reach medical care after a disaster, and the ability of emergency services to reach affected areas, are quantifiably central to resilience.

The map itself delivers an urgent warning. About 12 percent of the Gavkhoni Watershed shows very low resilience to floods, and a further 28 percent shows low resilience. Taken together, roughly 40 percent of the basin, a very large area, requires serious measures to improve its resilience status. The authors emphasize that this finding should guide prioritization: with limited resources, watershed managers can target interventions, from infrastructure investment to social and economic support programs, at the areas where the map shows resilience is weakest. Because the framework separates pressure, state, and response, it also indicates what kind of intervention is most appropriate in each location, whether reducing the physical drivers of runoff, strengthening the socioeconomic fabric of exposed communities, or expanding response infrastructure such as roads and health facilities.

Beyond its immediate findings for central Iran, the study represents a significant methodological contribution to the growing field of resilience science. Most flood resilience research to date has concentrated on urban areas, where data are abundant and impacts are concentrated, but floods originate and propagate at the watershed scale, and resilience built in one part of a basin can be undermined by vulnerability in another. By demonstrating that the pressure-state-response framework and catastrophe progression models can be combined and operationalized across an entire basin, the researchers offer a template that can be adapted to other data-scarce regions around the world, many of which face intensifying flood hazards under climate change. The free availability of the underlying code lowers the barrier for other teams to replicate the approach.

The work, funded by the Iran National Science Foundation under project number 4026136, also underscores a broader shift in how societies think about disaster risk. For decades, the dominant paradigm was hazard prediction: build better models of where and when floods will strike. The resilience paradigm complements this by asking what makes a system able to bend without breaking. As the Gavkhoni study shows, answering that question requires looking far beyond rainfall and topography to the clinics, roads, livelihoods, and institutions that determine whether a flood becomes a catastrophe or a recoverable event. With roughly two-fifths of a major Iranian watershed flagged as having low or very low flood resilience, the study provides both a scientific framework and a practical roadmap for turning resilience from an abstract ideal into a mapped, measurable, and manageable target.

Subject of Research: Watershed-scale flood resilience assessment using the pressure-state-response framework and catastrophe progression models

Article Title: Watershed-scale flood resilience mapping using a pressure-state-response framework and catastrophe progression models

Article References: Choubin, B., & Dastranj, A. (2026). Watershed-scale flood resilience mapping using a pressure-state-response framework and catastrophe progression models. Natural Hazards, 122(21), Article 669. https://doi.org/10.1007/s11069-026-08445-7

Image Credits: AI Generated

DOI: 10.1007/s11069-026-08445-7

Keywords: flood resilience, watershed, pressure-state-response framework, catastrophe theory, catastrophe progression method, entropy weighting, Gavkhoni Watershed, Natural Hazards, sensitivity analysis, disaster risk management, Iran, flood mapping

The service at the center of the study is EkoLakay, a container-based sanitation system operated in northern Haiti that provides households with a toilet that collects waste in sealed containers, which are swapped out weekly and transported to a treatment facility. In a country where sewer connections are rare and pit latrines often discharge untreated waste into the environment, container-based sanitation is one of the only household-level options that qualifies as safely managed sanitation under international definitions. The service currently costs 350 Haitian gourdes per month, a fee equivalent to less than three US dollars, yet even this modest amount proves prohibitive for some households. That gap between the cost of running the service and what the poorest families can afford is precisely where the question of targeted subsidies enters, and where the study makes its most consequential contribution.

To measure willingness to pay, the researchers used contingent valuation, a survey-based method in which respondents state whether they would pay a specified price for a good or service. It is a technique long used in environmental and development economics to attach values to things that lack market prices, and it requires careful design to avoid inflating or deflating responses. In this study, households were asked about their willingness to pay for EkoLakay service at different price points, and the resulting distribution tells a clear story. Sixty percent of surveyed households said they would pay the current fee of 350 gourdes per month. When the hypothetical price dropped to 250 gourdes, willingness to pay rose to 77 percent, and at 150 gourdes it reached 85 percent. In other words, demand for the service is high but highly price-sensitive, and each reduction in the monthly fee unlocks a substantial additional share of the population.

Those percentages translate directly into policy arithmetic. The authors calculate that a subsidy reducing the effective price to between 150 and 200 gourdes per month could push container-based sanitation coverage in the study area to as much as 80 percent of households. That is a striking figure for a city where safely managed sanitation coverage is otherwise minimal, and it suggests that relatively modest per-household transfers could produce large gains in public health protection. The economics hinge on the fact that the service already functions at scale; the constraint is not the technology or the collection logistics but the affordability of a recurring fee for households living close to the margin. Subsidy design, in this framing, becomes the central lever for expanding coverage rather than an afterthought.

Perhaps the most analytically interesting part of the study is its multivariate regression analysis, which examined which household characteristics were associated with willingness to pay. Three factors stood out: household wealth, the degree of privacy afforded by the household’s current sanitation arrangement, and satisfaction with that current facility. Wealthier households were more willing to pay, which is unsurprising but important, because it means that a uniform price will systematically exclude the poorest, reinforcing the case for targeted rather than universal subsidies. Households whose current toilets offered more privacy, and those who were dissatisfied with what they had, were also more willing to pay for the container-based service, indicating that the perceived quality and dignity of existing arrangements shape demand in measurable ways.

Just as revealing was what did not predict willingness to pay. Whether a household currently owned a private toilet showed no significant association with its willingness to pay for EkoLakay service. At first glance this seems paradoxical: why would families who already have a toilet pay for another one? The focus group discussions, conducted with household members and community leaders, supplied the answer. Participants described the hidden and recurring burdens of pit latrines, including the high cost of emptying a full pit, the persistent smell, and problems with pests. In dense urban neighborhoods where pits are difficult or impossible to empty safely, these costs can be substantial and unpredictable, making a flat monthly fee for a service that removes waste weekly genuinely attractive even to toilet owners.

The focus groups also surfaced contextual factors that a survey alone would have missed. Some participants expressed a desire for multiple toilets within the home, reflecting household sizes and living arrangements that a single facility cannot comfortably serve. Others pointed to the particular value of container-based sanitation in flood-prone areas, where pit latrines can overflow during heavy rains and contaminate yards, wells, and streets. Cap Haitien, like much of coastal Haiti, faces recurrent flooding that turns inadequate sanitation from a chronic nuisance into an acute hazard. In such settings, a sealed container that is removed before it fills offers a form of resilience that conventional on-site systems cannot match, and households appear to recognize and value that difference.

These findings matter well beyond northern Haiti. Container-based sanitation has attracted growing attention in the global sanitation sector as a service model for dense, low-income urban areas where sewers are infeasible and on-site systems fail to protect public health. Operators in Kenya, Ghana, Peru, and elsewhere face the same core dilemma as EkoLakay: the full cost of weekly collection and treatment cannot be recovered from the poorest customers at a price they can afford. The Cap Haitien study provides a template for how operators and governments can estimate the demand curve for such a service and identify the price point at which coverage expands most efficiently. It also demonstrates that willingness to pay is shaped by service attributes, such as privacy and flood resilience, that conventional subsidy formulas based purely on income may overlook.

The study’s implications for targeting are subtle. Because wealth predicts willingness to pay, subsidies aimed at the poorest households would reach those least able to pay the current fee, which is the standard logic of targeted transfers. But because satisfaction with existing sanitation and privacy also predict willingness to pay, a subsidy design that considers the quality of a household’s current facility, not just its income, could allocate resources more effectively. A family with a recently built, well-maintained private toilet may have less to gain from switching than a family using an unimproved shared latrine, even at similar income levels. Incorporating such indicators into eligibility criteria could stretch limited public budgets further, a consideration of acute importance in Haiti, where fiscal capacity is severely constrained and donor funding for water and sanitation is volatile.

The authors are careful to note the limits of what contingent valuation can establish. Stated willingness to pay is not the same as actual payment behavior, and hypothetical responses can diverge from what households do when a real bill arrives. Yet the consistency of the pattern across price points, the plausible direction of the regression results, and the corroborating qualitative evidence give the findings credibility, and the practical payoff is concrete: a quantified estimate that reducing the monthly fee to 150 to 200 gourdes could lift coverage to roughly 80 percent of households in the study area. For basic service providers and government partners in the region, that number converts an abstract debate about equity into a specific, costable policy choice. For the residents of Cap Haitien, it raises the prospect that a safe, dignified, and reliably collected toilet, one of the most fundamental determinants of urban health, could move within reach of the majority of families rather than a fortunate few.

Subject of Research: Willingness to pay for container-based sanitation services and targeted subsidy design in urban Haiti

Article Title: Willingness-to-pay for container-based sanitation and implications for targeted subsidy design in urban Haiti

Article References: Lubeck-Schricker, M., Bauza, V., Felix-Jean, W., Goddard, F. G., Pierre, M. F., Ozeris, B., Schelling, M., & Kramer, S. (2026). Willingness-to-pay for container-based sanitation and implications for targeted subsidy design in urban Haiti. PLOS Water, 5(9), e0000618. https://doi.org/10.1371/journal.pwat.0000618

Image Credits: AI Generated

DOI: 10.1371/journal.pwat.0000618

Keywords: container-based sanitation, willingness to pay, Haiti, Cap Haitien, sanitation subsidies, contingent valuation, EkoLakay, urban sanitation, PLOS Water, public health, pit latrines, flood resilience

The core insight of the study is that flood resilience cannot be assessed by hydrology alone. A city’s vulnerability to flooding depends not only on where water will go during an extreme event, but also on which facilities matter most when disaster strikes. Hospitals, emergency service centers, utilities and administrative hubs form the backbone of a city’s response capacity, and when these facilities are disrupted, the consequences ripple far beyond the flooded footprint. Operational efficiency drops, public dissatisfaction rises, and the continuity of essential services is impaired precisely when citizens depend on them most. The researchers therefore framed their investigation around a two-part question: where will the water go, and what will it hit that the city cannot afford to lose?

To answer the first half of that question, the team turned to HEC-RAS, the Hydrologic Engineering Center’s River Analysis System, a widely used one-dimensional hydraulic modeling platform developed by the US Army Corps of Engineers. The researchers investigated the hydrological conditions of Hamedan City and its surrounding areas, then simulated river behavior under multiple flood scenarios defined by different return periods. Return periods, expressed in years, describe the average interval between flood events of a given magnitude; a 100-year flood, for example, has roughly a one percent chance of occurring in any single year. By running the model across this spectrum of scenarios, the team captured how inundation extents and water depths change as floods grow rarer and more severe.

The hydraulic output from HEC-RAS was then integrated with a Geographic Information System, or GIS, to delineate flood-prone areas across the city. This integration is where the technical power of the approach emerges. Hydraulic models produce spatially distributed estimates of water surface elevations along river reaches, and when those elevations are draped over high-resolution terrain data within a GIS environment, they generate precise floodplain boundaries. Planners can overlay any layer of urban information, from land parcels to road networks to building footprints, onto these boundaries to see exactly what lies within the inundation zone. The resulting maps translate abstract hydraulic computations into actionable spatial intelligence for zoning and emergency planning.

In parallel, the team built a vulnerability classification system for urban assets. They established a set of criteria and sub-criteria designed to capture the multiple dimensions along which urban facilities can be evaluated, ranging from operational characteristics to economic significance. To determine the relative importance of these factors, the researchers designed a structured questionnaire and distributed it to selected experts, whose judgments were then aggregated. The arithmetic mean of the expert responses fed into the Analytic Hierarchy Process, a well-established multi-criteria decision-making method, implemented in the Expert Choice software. AHP works by decomposing a complex decision into a hierarchy of criteria and alternatives, deriving weights through pairwise comparisons, and producing a ranked prioritization that is transparent and reproducible.

The AHP results revealed a clear hierarchy of concerns. The quantitative level of operation, a measure of how intensively and measurably a facility functions, received the greatest weight among all evaluated indicators, signaling that experts view operational capacity as the dominant factor in urban vulnerability. At the other end of the scale, economic value was assigned the lowest weight, suggesting that the sheer monetary worth of a facility matters less to resilience than its functional role during a crisis. This finding carries practical weight for municipal decision-makers: protecting a modest but operationally critical service center may deliver more resilience per unit of investment than safeguarding a high-value property with limited emergency significance.

With critical urban centers identified and prioritized through the AHP framework, and flood-prone zones delineated through the HEC-RAS and GIS pipeline, the final analytical step was a spatial overlay. By intersecting the layer of prioritized urban facilities with the mapped flood extents in the GIS environment, the researchers identified and enumerated the vulnerable centers, those critical assets that fall within areas likely to be inundated under the modeled scenarios. This intersection transforms two separate analyses into a single, decision-ready product: a ranked list of the facilities whose flooding would inflict the greatest damage on the city’s capacity to function and respond.

The framework’s architecture is deliberately transferable. The authors note that the approach can potentially be applied to other urban areas, provided that appropriate local data are available and that the hydraulic component undergoes site-specific calibration and validation. That caveat is important. Hydraulic models are only as reliable as the terrain data, flow measurements and roughness coefficients that feed them, and a model calibrated for Hamedan’s river channels and topography cannot simply be transplanted elsewhere without adjustment. The vulnerability weighting, too, depends on expert panels whose composition and judgments will vary between cities, meaning that the specific rankings are context-dependent even if the methodology is universal.

The study is also candid about its boundaries. The assessment rests on current hydrological conditions and conventional flood return periods; explicit future climate projections are not incorporated into the modeling. This is a meaningful limitation in an era when climate change is altering precipitation patterns and intensifying extreme rainfall events in many regions, including arid and semi-arid landscapes like western Iran. The authors recommend that future studies integrate climate projections and scenario-based precipitation changes to evaluate how urban flood risk evolves under future climate conditions. Such an extension would allow planners to stress-test their resilience strategies against the wetter extremes that a changing climate may deliver, rather than against the historical record alone.

For Hamedan, the practical implications are immediate. The identification of vulnerable critical centers gives municipal authorities a concrete starting point for protective investment, whether through physical flood defenses, facility hardening, relocation of the most exposed assets, or revised zoning that restricts new critical infrastructure from flood-prone land. For the broader field of urban flood management, the study demonstrates how hydraulic simulation, geospatial analysis and structured expert judgment can be woven into a single coherent workflow. As cities worldwide grapple with the compounding pressures of growth and climate volatility, frameworks of this kind, which ask not just where the water will flow but what the city can least afford to lose, are likely to become an increasingly standard part of the flood resilience toolkit.

Subject of Research: GIS-integrated HEC-RAS flood simulation and AHP-based vulnerability assessment of critical urban centers in Hamedan City

Article Title: Enhancing Flood Resilience: a GIS-Integrated Approach to River Flow Modelling and Urban Zoning using HEC-RAS Simulation

Article References: Naseri, A., Estelaji, F., Yari, M. H., Asl, B. R., Zahedi, R., & Abedi, B. (2026). Enhancing Flood Resilience: a GIS-Integrated Approach to River Flow Modelling and Urban Zoning using HEC-RAS Simulation. Water Resources Management, 40(12), Article 528. https://doi.org/10.1007/s11269-026-04893-9

Image Credits: AI Generated

DOI: 10.1007/s11269-026-04893-9

Keywords: flood resilience, HEC-RAS, GIS, AHP, urban zoning, Hamedan, hydraulic modeling, flood vulnerability, river flow simulation, urban planning, Water Resources Management, multi-criteria decision making

The core problem the researchers identify is structural. For decades, flood risk identification and resilience assessment have been treated as separate exercises, typically published in parallel literatures, using different indicator sets, and feeding into different branches of policy. Risk mapping tells planners where hazard, exposure, and vulnerability converge; resilience assessment tells them how quickly a community or infrastructure network can bounce back after an event. But because the two are rarely analyzed together, management strategies can develop internal contradictions: a city may invest heavily in defenses for high-risk zones while neglecting the recovery capacity of those same zones, or bolster resilience in areas where the hazard itself is comparatively modest. Climate change and rapid urbanization have intensified both the frequency and the severity of flood disasters, and the study argues that this segmented approach now generates structural inconsistencies that undermine regional resilience.

To close that gap, the team developed a full-cycle framework in which flood resilience is embedded directly into flood risk management rather than appended to it. The quantitative engine of the framework is the extension catastrophe progression method, or ECPM, a multi-criteria evaluation technique derived from catastrophe theory. Catastrophe progression methods are well suited to problems where several indicator systems must be combined without arbitrary weighting, because they use the mathematical structure of catastrophe models to aggregate indicators in a standardized way. The extension component widens the set of relationships the method can handle, allowing the researchers to score flood risk and flood resilience across the study region on comparable scales. Validation drew on receiver operating characteristic analysis, with the area under the curve used to test how well the modeled risk surfaces discriminated between locations with and without recorded flood problems.

The indicator architecture is deliberately comprehensive. Flood risk was evaluated across hazard, exposure, and vulnerability dimensions, incorporating variables such as the concentration index of daily precipitation, which captures how violently rainfall is packed into short episodes, along with the concentration index of monthly precipitation, typhoon frequency, distance to rivers, digital elevation model data, land-use type, population density, and gross domestic product density. Resilience was organized around a pressure-state-response logic and drew on concepts from the sustainable livelihoods framework, adding indicators such as road density, railway density, and distance to hospitals to represent the infrastructure and service capacity that determines how quickly a flooded area can be served, evacuated, and rebuilt. All layers were assembled in a geographic information system so that every indicator could be mapped, overlaid, and compared cell by cell across the delta.

The study region is the Yangtze River Delta, an urban agglomeration in eastern China where megacities such as Shanghai, Nanjing, Hangzhou, and Suzhou sit on low-lying ground threaded by rivers and canals and exposed to typhoons arriving from the western Pacific. The region’s eastward slope toward the coast, its extraordinary concentration of population and economic assets, and its history of compound flooding driven by both rainfall and storm surge make it an ideal laboratory for a risk-resilience coupling analysis. It is also a region where urbanization has reshaped the hydrological cycle itself, sealing surfaces, channelizing rivers, and amplifying the intensity of extreme precipitation events, trends documented extensively in prior research on Chinese deltas.

The headline findings are striking. Flood risk in the delta rises from west to east, with high-risk and highest-risk zones together covering 58.0 percent of the region. Resilience displays a broadly similar eastward gradient, with high and highest resilience areas accounting for 73.9 percent of the territory. At first glance that symmetry might look reassuring, but the joint analysis reveals that the match is far from uniform. When the two surfaces are crossed, the largest zoning category is high risk paired with high resilience, covering 35.60 percent of the delta, meaning that more than a third of the region faces serious flood danger but possesses substantial capacity to cope and recover. The most alarming category is the inverse: high-risk, low-resilience areas account for 12.35 percent of the region and are concentrated mainly in highly urbanized districts, where dense built environments, high exposure, and constrained drainage combine to produce danger without adequate defensive depth.

These zoning categories are not merely cartographic curiosities; they translate directly into differentiated prescriptions. In high-risk, high-resilience zones, the priority is to protect and maintain existing coping capacity while monitoring whether intensifying hazards gradually erode it. In high-risk, low-resilience zones, the framework calls for simultaneous risk reduction and resilience enhancement, combining engineered defenses with investments in emergency services, transport redundancy, and social preparedness. Areas of low risk but high resilience can absorb redirected resources with lower urgency, while low-risk, low-resilience zones represent latent vulnerabilities where relatively modest, early investments could prevent future mismatches from forming. The authors frame this as precision flood management, an analogy to precision medicine in which treatment is tailored to the specific profile of each zone rather than applied uniformly across the region.

The study’s methodological contribution lies in showing that the coupling itself carries information that neither risk maps nor resilience maps provide alone. A resilience score of 73.9 percent for the delta sounds impressive until it is laid over a risk surface showing that 58.0 percent of the same territory faces high or highest danger; the residual mismatch, concentrated in exactly the fast-growing urban cores where people and assets pile up, is where the next generation of flood losses is most likely to accumulate. By quantifying the overlap and the divergence, the framework gives governments a diagnostic tool for identifying which districts need protection, which need recovery capacity, and which need both at once, moving flood governance away from one-size-fits-all defense spending toward targeted, evidence-based regulation.

The implications extend well beyond the Yangtze River Delta. Rapidly urbanizing deltas across Asia, Africa, and the Americas face the same collision of intensifying hydro-climatic hazards and constrained adaptive capacity, and many lack any systematic way to see where their risk and resilience profiles have slipped out of alignment. The integrated framework, validated with ROC analysis and grounded in openly available indicator data, offers a replicable template for regional and city-level assessments elsewhere. As extreme precipitation becomes more concentrated and tropical cyclones reach further inland under a warming climate, the study suggests that the most dangerous places will not necessarily be those with the highest flood risk on paper, but those where high risk and low resilience coincide, hidden in plain sight until a coupled analysis makes the divide visible.

Subject of Research: An integrated flood risk and resilience coupling framework applied to the Yangtze River Delta to identify spatial mismatches for precision flood management

Article Title: Bridging the divide: an integrated risk-resilience coupling framework to decode spatial mismatches for precision flood management

Article References: Yu, W., Jiang, M., Wang, X., Yin, L., & Zhang, B. (2026). Bridging the divide: an integrated risk-resilience coupling framework to decode spatial mismatches for precision flood management. Natural Hazards, 122(19), Article 639. https://doi.org/10.1007/s11069-026-08401-5

Image Credits: AI Generated

DOI: 10.1007/s11069-026-08401-5

Keywords: flood risk, flood resilience, Yangtze River Delta, extension catastrophe progression method, spatial mismatch, precision flood management, urbanization, climate change, natural hazards, GIS, disaster risk reduction, resilience assessment

What unfolded across China in the summer of 2026 was not a string of isolated bad luck. It was, according to the scientists and commentary accompanying the events, a demonstration of a new normal: extreme events once labeled “once-in-a-century” are increasingly compound, concurrent, and geographically dispersed, arriving faster than the institutions and infrastructure built to manage them. A warming trend that outpaces the global average, as officially acknowledged by Chinese meteorological authorities, is raising both the frequency and the intensity of extremes. When a single season delivers typhoon remnants to a northeastern inland province, catastrophic urban flooding to central China, and near-record heat to the northwest simultaneously, the premise that hazards arrive one at a time, separated by decades of recovery and planning, collapses entirely.

The term “once-in-a-century” is shorthand for an event with a 1 percent chance of occurring in any given year, a statistical construct known to hydrologists as the hundred-year return period. Specialists have long recognized that this language is easily misinterpreted: it describes a probability, not a promise that such an event will occur only once every hundred years. In any given century, a 1-percent-annual-chance flood may strike twice, three times, or not at all, and independent river basins can each experience their own hundred-year event in the same year. Yet the intuitive public reading — that a community has earned a century of safety after surviving one such flood — persists, and it shapes how residents, officials, and even engineers respond when the waters return far sooner than the label implies.

Climate change has rendered the historical baseline on which those return periods rest effectively obsolete. The statistics embedded in flood maps and design standards assume stationarity, the idea that the range of natural variability observed in the past will continue into the future. That assumption no longer holds. On 20 July 2021, Zhengzhou recorded 201.9 millimeters of rainfall in a single hour, a new national record, with three-day cumulative rainfall of 617.1 millimeters, approaching the city’s entire annual mean. The deluge overwhelmed a city that had, in part, been built under China’s “sponge city” programme, an ambitious urban design initiative intended to absorb and reuse stormwater rather than shunt it into overburdened drainage networks. Four years later, in August 2025, Zhengzhou’s flood-control emergency response was again raised to Level III, with work, business, classes, and public transport suspended citywide. The hundred-year flood had taken four years to make its second appearance.

These events carry direct and severe health consequences, from drowning and traumatic injury to the disruption of routine and emergency medical care. Globally, public health systems have developed genuine capacity to respond to the acute aftermath of a single flood. China’s Centers for Disease Control and Prevention, for example, issues detailed post-flood guidance on indoor mold identification and remediation, with explicit precautions for vulnerable groups including pregnant women, children under 12, adults over 65, and people with asthma. This is well-designed, evidence-based guidance. But it is guidance calibrated to a single, bounded event: dry the building, remove saturated porous materials within 48 hours, ventilate, and protect vulnerable residents during cleanup. It says nothing about a household, or a health system, absorbing a second or third such event within years rather than decades, nor about heat and flood advisories issued in the same week to the same population. Adaptation guidance built for isolated disasters, however rigorous, is necessary but insufficient for compound, recurring ones.

The problem is not merely communicative but structural. Reservoirs, drainage systems, evacuation routes, and emergency stockpiles are sized against historical exceedance probabilities, and insurance and recovery budgets are paced to the expectation of long intervals between catastrophic losses. When extremes cluster, recovery is truncated. Communities still repairing one flood face the next before foundations have dried, and the cumulative physical and psychological burden of repeated displacement and rebuilding accumulates in ways that single-event frameworks never anticipated. Meanwhile, simultaneous hazards compete for the same response capacity: the personnel, shelters, and supply chains needed for flood evacuation in one province are the same resources a heat emergency in another might demand, and heat itself compounds flood risk by pre-conditioning drought, hardening soils, and altering atmospheric moisture available for subsequent downpours.

Three shifts follow from this pattern, argued in commentary published in The Lancet Regional Health – Western Pacific by John S. Ji and Qihong Deng. First, risk communication should retire probabilistic century-scale language in public-facing materials in favor of terms that convey trend and recurrence, such as “increasingly frequent severe rainfall” rather than “once-in-a-century flood,” so that recurrence within a decade is not received as a statistical anomaly requiring no institutional response. The words officials choose shape whether a second hundred-year flood in four years is read as a freak coincidence or as evidence of a trend demanding action. Second, infrastructure and early-warning design standards, including within the sponge city and reservoir safety programmes, should incorporate non-stationary risk models that use recent-period distributions rather than full-record historical baselines, which mathematically dilute the recent shift toward higher-intensity rainfall. A century of rain-gauge data in which the wettest years cluster in the last decade tells a very different story than the same record averaged across its full length.

Third, public health guidance should evolve from single-event response protocols toward compound-event and cumulative-exposure frameworks, addressing populations facing sequential or simultaneous heat and flood risks within the same season, as well as the mental and physical health burdens of repeated displacement and recovery. That means modeling the health effects of mold exposure after repeated inundation, planning clinically for populations that experience flooding and extreme heat within weeks of one another, and treating the psychological toll of chronic disaster exposure as a first-order public health concern rather than an afterthought. The tools exist — epidemiological surveillance, seasonal forecasting, and increasingly sophisticated artificial intelligence-based forecasting and digital simulation systems that Chinese cities are already deploying — but they must be aimed at the compound problem, not the singular one.

Experts and meteorological authorities have officially acknowledged the warming trend and the rising frequency of extremes, and there are encouraging signs of technical adaptation in forecasting and alerting. Public health guidance and infrastructure standards, however, continue to speak as if these events remain rare. This summer made the mismatch impossible to ignore. Flood warnings in the northeast and heat alerts in the northwest arrived in the same week, and a city rebuilt to absorb the once-unthinkable watched the once-unthinkable return within a political term. The climate has changed. The language, and the standards built upon it, need to change with it.

Subject of Research: Compound climate extremes and the obsolescence of once-in-a-century risk communication

Article Title: Compound climate extremes and “once-in-a-century” risk communication

Article References: Ji, J. S., & Deng, Q. (2026). Compound climate extremes and “once-in-a-century” risk communication. The Lancet Regional Health – Western Pacific, 74, Article 101973. https://doi.org/10.1016/j.lanwpc.2026.101973

Image Credits: AI Generated

DOI: 10.1016/j.lanwpc.2026.101973

Keywords: compound climate extremes, once-in-a-century flood, risk communication, non-stationary risk, sponge city, Zhengzhou rainfall, Typhoon Bavi, Tropical Storm Maysak, public health preparedness, extreme heat, climate change, flood resilience