The hydro-geomorphological setting explains much of the vulnerability. Chars are transient landforms, built from sediment deposited by one of the world’s most morphologically dynamic rivers, and they are periodically consumed by the same processes that create them. Riverbank erosion along the Padma proceeds through basal undercutting, slump failure and channel migration, so homesteads, farmland and infrastructure can vanish within a single monsoon season. Overlaying this chronic land loss is acute hydro-meteorological hazard: monsoon flooding that inundates fields, saturates soils, contaminates water sources and severs the thin threads of road connectivity that tie island communities to mainland markets. The study frames these as coupled hydro-geomorphic and socio-economic systems, in which a physical perturbation in one sector cascades into financial, health and educational losses downstream.

The economic findings are stark. Agriculture sustains 36 percent of local livelihoods on Char Janajat, yet the survey records catastrophic crop failures driven by flood submergence and the stripping of fertile topsoil by floodwater and erosion. Because topsoil loss is cumulative rather than episodic, households do not simply recover between flood years; their productive base erodes alongside the riverbank. This induces what the authors describe as long-term financial fragility, with landless and marginal households falling into debt, distress migration and asset liquidation. The multi-sectoral accounting matters: the researchers deliberately trace how a single hazard event propagates through crops, transport, health, housing and schooling simultaneously, rather than treating flood damage as a one-sector loss.

Transport infrastructure emerges as a seasonally critical failure point. Roads on the char suffer acute paralysis during flood peaks, cutting residents off from markets, health facilities and emergency services precisely when those links are most needed. The survey found that 35 percent of residents demand elevated road-cum-embankment structures as their priority intervention, a technocratic preference rooted in lived experience: raised roads that double as flood embankments maintain physical connectivity while providing refuge and erosion protection. This dual-function infrastructure concept, combining transport service with hydraulic defense, is increasingly central to deltaic adaptation engineering, and the Char Janajat data suggest strong local demand for it.

The public health dimension of the study is its most statistically rigorous component. Using a Pearson’s chi-square test of independence, the researchers modeled the relationship between sanitation conditions during disasters and post-disaster illness, and found a highly significant association between the two. With a 90 percent deficit in hygienic sanitation during disasters, the test yielded chi-squared of 14.92 on one degree of freedom, corresponding to p less than 0.001. In practical terms, floodwater mixing with latrine waste, and the destruction or submergence of sanitation infrastructure, translate directly into a measurable disease burden. The predominant illnesses reported were diarrhoea, affecting 34 percent of those who fell ill, followed by cold and fever at 26 percent and scabies at 19 percent, a profile typical of flood-borne water contamination and crowding in shelters.

What compounds this epidemiological crisis is an institutional void. The study documents a 95 percent deficit in formal disaster-preparedness training among residents, meaning almost no one on the char has received structured instruction in evacuation, hygiene management, water treatment or first aid during floods. In the absence of formal systems, households fall back on autonomous, improvised coping strategies. One striking example: 20 percent of households rely on local educated youth to manually excavate temporary drainage channels during waterlogging, an ad hoc, labor-intensive solution that moves floodwater off homesteads and fields but offers no protection against renewed inundation or bank collapse. The authors emphasize that these autonomous adjustments provide brief survival value but are routinely overwhelmed by macro-river dynamics beyond any community’s control.

The research also captures a surprising geographic nuance with implications well beyond Madaripur. The authors highlight what they call a paradigm shift in the area’s geomorphology: engineered embankments constructed around the Padma Bridge mega-project appear to exert a positive stabilizing influence on the peripheral char landscape, damping local erosion rates in the near field of the structures. This finding speaks to a long-running debate in river engineering and fluvial geomorphology, namely whether large hard infrastructure simply displaces erosion elsewhere or can genuinely anchor sediment in targeted zones. The Char Janajat evidence suggests that well-placed engineered works can stabilize chars, though the authors caution that such benefits are localized and cannot substitute for community-scale adaptation.

When residents were asked what should come next, their priorities were unambiguous. High-capacity flood shelters topped the list, demanded by 30 percent of respondents, followed by elevated road networks at 20 percent. These preferences reflect a clear-eyed assessment that autonomous coping is exhausted and that permanent institutional interventions are the only viable path. The study argues that residents’ demands align with an integrated approach to disaster management, combining river training works, raised and hardened infrastructure, protected water and sanitation systems, and pre-positioned shelter capacity. In deltaic Bangladesh, where roughly 130 million people live in the combined floodplains of the Ganges, Brahmaputra and Meghna systems, such integrated frameworks are moving from academic aspiration to policy necessity.

Methodologically, the study offers a template for vulnerability assessment in data-scarce, hazard-exposed settings. The randomized survey design with a quantified precision margin, triangulated with focus group evidence, allows the researchers to distinguish community-wide patterns from outlier experiences, while the chi-square analysis converts anecdote into statistical association. The authors note that raw survey data cannot be publicly archived: the Disaster Research Training and Management Center Ethics Committee at the University of Dhaka judged that even anonymized data could pose an identification risk to this displaced and highly vulnerable population, an ethical constraint worth noting as open-data mandates spread through the hazard-research community. The researchers conclude that their findings provide a critical empirical baseline for policymakers designing proactive, climate-resilient deltaic disaster management frameworks, and for targeting river training and protective investment toward the char communities where erosion and flooding currently outpace every form of local adaptation.

Subject of Research: Impacts of flood and riverbank erosion on livelihoods and health in a Padma River char community in Bangladesh

Article Title: Impact of flood and riverbank erosion on local livelihoods: a study on Char Janajat at Madaripur district

Article References: Islam, M. S., Akter, F., & Hossain, M. T. (2026). Impact of flood and riverbank erosion on local livelihoods: a study on Char Janajat at Madaripur district. Regional Environmental Change, 26(4), Article 186. https://doi.org/10.1007/s10113-026-02674-z

Image Credits: AI Generated

DOI: 10.1007/s10113-026-02674-z

Keywords: flood, riverbank erosion, livelihood vulnerability, Char Janajat, displacement, Padma River, Bangladesh, public health, sanitation, disaster adaptation, flood shelters, deltaic management

The study arrives at the intersection of two defining challenges of the twenty-first century: climate change and population ageing. Their convergence is particularly acute in China, which faces both a rapidly ageing population and an escalating frequency of devastating floods that cause annual economic losses exceeding ten billion US dollars. For older adults, floods carry risks well beyond immediate physical danger, including heightened rates of injuries, post-traumatic stress disorder, depression, and the exacerbation of diabetes and cardiovascular and respiratory conditions. These outcomes directly undermine healthy ageing, defined by the United Nations Decade of Healthy Ageing as the process of developing and maintaining the functional ability that enables well-being in older age.

To capture how nature-based solutions might counteract these harms, a research team led by Binhua Fu and Joseph Kimuli Balikuddembe of Sichuan University’s Institute for Disaster Management and Reconstruction conducted a scoping review following the Arksey and O’Malley framework and the PRISMA-ScR reporting guidelines. The team searched PubMed, Scopus, and Google Scholar for qualitative studies published between 2000 and early 2025, focusing on research that examined nature-based solutions for flood risk reduction—such as Sponge City infrastructure, green infrastructure, wetland restoration, and ecosystem-based adaptation—in settings across mainland China. Of 622 retrieved records, only 13 studies met the eligibility criteria, a finding that itself underscores how nascent and fragmented this evidence base remains.

The analytical machinery behind the review is worth noting for its technical sophistication. The researchers extracted data into six healthy ageing outcome domains aligned with the World Health Organization’s conceptual framework: physical activity and mobility, mental health, cognitive functioning, well-being and social support, environmental quality, and economic security. They then employed narrative synthesis alongside a Sankey diagram analysis, generated in R using the networkD3 package, to visualize weighted flows connecting geographical context, flood type, intervention type, and health co-benefit. This multi-level edge-list approach, in which each conceptual connection was weighted by its frequency across eligible studies, provided a quantitative representation of the dominant pathways within the qualitative literature.

Geographically, the evidence base spans at least nine provinces and provincial-level municipalities, with case studies concentrated in major urban centers such as Wuhan, Shanghai, and Guangzhou, and in designated pilot Sponge Cities including Guiyang and Ningbo. Temporally, the field is moving fast: ten of the thirteen included studies were published from 2020 onwards, coinciding with the scaling of China’s Sponge City Program amid mounting climate risks. Urban or pluvial flooding dominated the literature, addressed in ten of the thirteen studies, with fluvial, riverine, and general flooding covered by single investigations. Permeable pavements, rain gardens, bioswales, green roofs, and wetland restoration were consistently perceived as effective at reducing surface runoff and easing pressure on drainage networks.

The synthesis’s central revelation is the breadth of co-benefits these interventions deliver. The most prominently documented domain was psychosocial well-being and social support: aesthetically pleasing, accessible green spaces became hubs for conversation, leisure, and recreation, directly strengthening social and peer support networks and mitigating loneliness among older residents. Mental health benefits followed closely, with one study in Guangzhou linking the use of urban green infrastructure to measurable decreases in anxiety, dysphoria, and emotional exhaustion, and other studies reporting stress relief, relaxation, and high perceived aesthetic and health value. Physical activity and mobility improved as Sponge City features provided convenient, walkable spaces after rain, while urban parks encouraged walking and cycling.

Environmental improvements formed a cross-cutting co-benefit with direct implications for independent living. Studies reported enhanced air quality, noise mitigation, and cooling effects that reduce urban heat islands, creating safer and more comfortable outdoor environments for older adults. Cognitive functioning evidence was thinner but tantalizing: a single study associated urban green infrastructure use with memory enhancement, suggesting a possible pathway for NbS to support cognitive health in later life. Economic and community participation benefits emerged from multifunctional designs that integrated productive landscapes, including community engagement in risk-adaptive agriculture within flood detention zones and the use of green infrastructure spaces for vegetable and flower gardens—activities representing livelihood diversification, economic savings, and meaningful occupation for retired residents.

The review’s authors are equally candid about what the evidence lacks. Their analysis identified five principal gaps: an exclusively urban focus that neglects rural elderly populations; a methodological reliance on perceived rather than objectively or clinically measured benefits; a conceptual gap in which older adults appear only as incidental subsets of broader studies rather than central subjects of gerontological research; a thematic gap with cognitive function and nutrition severely underexplored; and an economic gap in the absence of quantified financial impacts on older persons. Sample sizes for older adult subgroups varied enormously, from as few as three retired persons to 95 participants aged 56 and above, and several key studies failed to report age-disaggregated data at all.

The policy implications are nonetheless substantial. The authors argue that the co-benefits provide a tangible pathway to operationalize China’s parallel national commitments to its “ecological civilization” vision and the Healthy China 2030 strategy, framing Sponge City rain gardens and urban wetlands not as drainage projects but as practical manifestations of a dual mandate: managing floodwater while creating the green, accessible environments that promote physical activity, mental restoration, and social connection. The economic case is compelling, the authors contend, because fostering environments that support activity, well-being, and cohesion can function as primary prevention, potentially reducing the incidence and severity of age-related chronic conditions and easing the mounting financial burden on China’s social and healthcare system—a perspective consistent with the One Health paradigm that treats investments in ecosystem health as direct investments in human health.

The rural blind spot carries particular equity weight. Rural communities in China are often on the front lines of riverine and pluvial flooding, yet they remain conspicuously absent from research on nature-based co-benefits, a disparity the authors warn risks exacerbating health inequalities among the elderly. They point to low-cost, replicable approaches such as flood-adaptive farming, grassland management, and riparian ecosystem restoration as candidates for scaling in rural settings, where older residents may be even more dependent on their immediate environment for both income and social connection.

The study’s limitations also shape its recommendations. The review was restricted to English-language publications, potentially excluding relevant Chinese-language studies, and, as is standard for scoping reviews, no formal critical appraisal of individual study quality was conducted. The predominance of qualitative and mixed-methods designs, while essential for understanding lived experiences and contextual factors, means the magnitude of health impacts remains unmeasured. The authors urge researchers to adopt longitudinal and mixed-methods designs employing validated health metrics, and call on policymakers and urban planners to intentionally design and evaluate nature-based solutions with geriatric outcomes as a primary objective, ensuring equitable distribution between urban and rural settings.

For a country that simultaneously confronts an “aging tsunami” and intensifying floods, the message of this review is that flood control and healthy ageing are not separate policy problems but two faces of the same infrastructure investment. If future research can move beyond perceived benefits to establish causal pathways and quantify costs, nature-based flood risk reduction may prove to be one of the most cost-effective preventive health strategies available to ageing societies in China and far beyond its borders.

Subject of Research: Beyond Flood Control: A Scoping Review Deciphering the Co-benefits of Nature-Based Flood Risk Reduction for Healthy Ageing in China

Article Title: Beyond Flood Control: A Scoping Review Deciphering the Co-benefits of Nature-Based Flood Risk Reduction for Healthy Ageing in China

Article References: Fu, B., Balikuddembe, J. K., Lu, Y., Yang, A., Di, B., Tian, B., & Reinhardt, J. D. (2026). Beyond Flood Control: A Scoping Review Deciphering the Co-benefits of Nature-Based Flood Risk Reduction for Healthy Ageing in China. International Journal of Disaster Risk Science. https://doi.org/10.1007/s13753-026-00741-x

Image Credits: AI Generated

DOI: 10.1007/s13753-026-00741-x

Keywords: Beyond, Flood, Control, Scoping, Review, Deciphering, Co-benefits, Nature-Based, Risk, Reduction, Healthy, Ageing

The Sinos River Basin drains 3,694 square kilometers along a gradient that descends from roughly 850 meters above sea level to nearly sea level, where the river discharges into the Jacuí River Delta near Porto Alegre. The basin is home to about 1.4 million people and hosts a dense mix of metallurgical industries, petrochemical plants, leather tanneries, agriculture, and urban development, making it one of the most heavily urbanized watersheds in the state. Decades of chronic contamination from industrial effluents, untreated domestic wastewater, and urban runoff have left a legacy of metals stored in the river’s bottom sediments. Geologically, the basin is underlain largely by volcanic basalts of the Serra Geral Formation, which naturally enrich local soils and sediments with elements such as aluminum, iron, chromium, nickel, and copper during weathering—a factor the researchers carefully separated from human pollution.

The study’s design exploited a rare natural experiment. A research team from the Federal University of Rio Grande do Sul, led by Ismael Krüger Pescke, Lívia de Oliveira Rozino, and Vera Maria Ferrão Vargas, had already collected sediment samples at five sites along the river’s longitudinal gradient before the floods struck. Gauging-station records showed that monthly mean discharge reached 296.2, 254.4, and 219.9 cubic meters per second in September, October, and November 2023—between 2.41 and 2.93 times the historical monthly averages. After the waters receded, the team returned to three representative sites that preserved the upstream-to-downstream gradient, including a relatively pristine reference site on the Rolante River tributary and the heavily impacted depositional zone at the river mouth.

In the laboratory, the researchers combined an unusually broad set of analytical tools. They measured grain-size distributions using sieving and pipette methods, extracted interstitial water—the water held between sediment grains—by centrifugation and filtration, and quantified fifteen elements including aluminum, arsenic, cadmium, chromium, cobalt, copper, iron, mercury, manganese, nickel, lead, antimony, selenium, vanadium, and zinc. Bulk sediments were analyzed by inductively coupled plasma optical emission spectroscopy, while the far more dilute interstitial waters required the greater sensitivity of inductively coupled plasma mass spectrometry. All analyses were performed in an ISO/IEC 17025-accredited laboratory with certified reference materials. On top of the raw chemistry, the team calculated contamination factors, ecological risk factors, the geoaccumulation index, and Hakanson’s Potential Ecological Risk Index, normalized metal concentrations by the fine-sediment fraction, and computed field-based sediment–interstitial water distribution coefficients.

The statistical results were strikingly clear. Redundancy analysis identified sediment granulometry as the primary driver of metal distribution, with a significance value of p = 0.003, and the first axis explained 56.2 percent of total variance. Spearman correlations revealed strong positive relationships between the fine fraction and lead (ρ = 0.88), zinc (ρ = 0.84), cobalt, aluminum, iron, and manganese (each ρ = 0.83), nickel (ρ = 0.81), and chromium (ρ = 0.76), all statistically significant. The tight correlation between aluminum and iron (ρ = 0.95) reflected their shared lithogenic origin and their role as constituents of reactive oxide and clay minerals that provide abundant sorption sites. Although a permutational multivariate analysis confirmed that overall metal composition shifted between sampling periods, that temporal signal lost its independent significance once the fine fraction was accounted for—meaning the flood’s apparent chemical effect was, in essence, a physical one.

The mechanism is straightforward but consequential. High-energy floodwaters erode and transport fine particles preferentially, and when flows slow in downstream reaches, those particles settle out. Because silt and clay particles carry high specific surface areas, cation exchange capacity, and reactive iron and aluminum oxide coatings, they act as the primary sinks for trace metals. After the event, sand content fell and the silt–clay fraction rose throughout the basin, and the downstream site at the river mouth accumulated the greatest metal load. Fine-fraction normalization sharpened the picture: the downstream site was not merely finer but genuinely enriched in metals per unit of reactive sediment, while an intermediate site showed dilution, likely from an influx of relatively uncontaminated material. The flood, in other words, created a patchwork of enrichment and dilution zones across the basin.

The ecological consequences were quantifiable. At the river mouth, contamination indices showed post-event enrichment of nickel, zinc, copper, and lead, with nickel, zinc, copper, and chromium exceeding Brazilian Level 1 sediment quality guidelines. The Potential Ecological Risk Index climbed from 100.02, in the low-risk category, to 172.06, crossing into the moderate-risk category. The geoaccumulation index shifted the mouth site from unpolluted to moderately polluted conditions. Crucially, the researchers demonstrated that these classifications depend heavily on the choice of background values: global averages such as typical shale compositions can misjudge basalt-rich regions, where natural weathering legitimately elevates chromium, nickel, copper, and zinc. Using the upstream reference site as a local geological background gave a more defensible picture, and the team argues that regional backgrounds, global references, and regulatory thresholds should be treated as complementary tools rather than substitutes.

Perhaps the most consequential discovery came from the interstitial water. Although dissolved metal concentrations were generally low, mercury exceeded Brazilian guideline values in every interstitial water sample—between 0.0003 and 0.0011 milligrams per liter—even though mercury remained below the limit of quantification in the bulk sediments. This means sediment chemistry alone can miss real exposure pathways, since interstitial water is the fraction immediately available for uptake across the biological membranes of bottom-dwelling organisms. Partitioning coefficients revealed metal-specific and site-specific behavior: nickel and zinc showed greater apparent retention in the solid phase after the event, while cadmium, manganese, and chromium responded heterogeneously across sites. At the river mouth, high accumulation coincided with detectable dissolved concentrations, combining contaminant storage with elevated exposure potential at the sediment–water interface—a scenario that could stress benthic organisms and early life stages of fish, consistent with biomarker and histopathological effects previously documented in native Sinos River fish.

The broader message is a warning about conventional monitoring. Routine sampling programs rarely capture the short-lived contamination pulses that follow extreme events, both because storms are unpredictable and because post-flood fieldwork is often logistically difficult and dangerous—indeed, unsafe conditions prevented the team from sampling at two of the five sites after the event, a limitation the authors acknowledge. Yet as climate change increases the frequency and intensity of extreme precipitation worldwide, similar patterns have now been documented after monsoon floods in South Korea, flash floods in former mining areas of Germany, and successive rainfall events in Algeria, suggesting that flood-driven sediment redistribution is a general mechanism rather than a local curiosity. The authors propose an integrated framework combining sediment texture, site-specific geological backgrounds, contamination indices, and sediment–interstitial water partitioning, deployed through adaptive monitoring that combines event-based campaigns with long-term programs. Such an approach, they argue, is essential for distinguishing genuine enrichment from simple sediment redistribution, detecting transient contamination pulses, and protecting the drinking water, fisheries, and recreation that millions of people depend on from rivers that climate change is increasingly turning inside out.

Beyond the immediate findings, the study carries methodological weight for the field of sediment geochemistry. The use of fine-fraction normalization proved decisive in separating two processes that would otherwise be indistinguishable in bulk chemistry: true metal enrichment, where reactive surfaces carry proportionally more contaminant, and simple hydrodynamic sorting, where metal loads rise merely because more reactive fine particles arrived. Without this correction, flood responses across different reaches of a river can appear contradictory, since deposition zones accumulate metals while scour zones shed them.

The partitioning results also underscore why bulk sediment analysis alone offers an incomplete picture of risk. Interstitial water occupies the pore spaces directly in contact with benthic invertebrates, fish eggs, and microbial communities, and its chemistry responds rapidly to shifts in redox conditions, organic matter degradation, and pH that floods can induce. A sediment that appears chemically stable in total concentrations may nevertheless release dissolved metals when flooded, or conversely re-adsorb them as fresh oxide surfaces settle out. Capturing these transient states requires sampling timed to hydrological events, which is precisely what most long-term monitoring programs are structurally unable to do.

The Sinos Basin’s vulnerability is amplified by its water use profile. Public abstraction points along the river supply drinking water to downstream communities, so sediment-derived contamination pulses have direct relevance to human exposure, an alignment with One Health framing that the authors emphasize. Vulnerable populations, including those relying on fisheries and informal water use, face disproportionate exposure. As extreme precipitation intensifies across subtropical regions, the combination of legacy industrial contamination, dense urbanization, and increasing flood frequency makes systems like the Sinos River likely candidates for repeated post-event contamination pulses, reinforcing the case for adaptive, event-triggered monitoring protocols alongside conventional scheduled sampling.

Subject of Research: How extreme hydrological events redistribute trace metal contamination and ecological risk through fine-sediment redistribution in subtropical river sediments

Article Title: Hydrological disturbance reshapes trace metal contamination and ecological risk through fine-sediment redistribution in subtropical river sediments

Article References: Pescke, I. K., de Oliveira Rozino, L., & Vargas, V. M. F. (2026). Hydrological disturbance reshapes trace metal contamination and ecological risk through fine-sediment redistribution in subtropical river sediments. Discover Geoscience, 4(1), Article 342. https://doi.org/10.1007/s44288-026-00692-2

Image Credits: AI Generated

DOI: 10.1007/s44288-026-00692-2

Keywords: trace metals, sediment redistribution, extreme hydrological events, Sinos River Basin, ecological risk assessment, fine sediments, granulometry, interstitial water, contamination indices, flood, Brazil, sediment-water partitioning