Global groundwater drought recovery patterns

Can groundwater systems be resilient to droughts?

Utrecht University

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The average groundwater recovery rate [m/month] is shown, with darker regions indicating locations that recover quickly from droughts, compared with lighter-coloured regions, which show slower recovery. Areas in grey represent locations that were filtered out during the analysis.

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Credit: Utrecht University/Environmental Research Water

A few days of rain does not change the low groundwater levels after a long drought. To better determine how groundwater systems recover after a drought and which groundwater reserves are most vulnerable, hydrologist Sandra Hauswirth developed a method to classify groundwater systems based on their ability to recover from long drought. With a very high resolution global groundwater model (1 kilometer) it was possible to determine and analyse how a groundwater system responds during a drought and how quickly it can recover. This provides policymakers with the means to better respond to or prevent sever groundwater problems  in the future.

Hauswirth investigated the various factors that make the groundwater recover or not after a period of drought by looking at a large range of groundwater drought events around the globe. Climate plays a major role, but at the local level the geology and landscape are additional important factors  for drought recovery. Looking at these different drivers, she was able to make a classification in groundwater systems. It turned out that the majority of locations has resilient groundwater systems (57%), exhibiting rapid and robust recovery following droughts. Vulnerable (15%) and stable locations are shaped by geophysical constraints and heightened climate variability, whereas unstable regions (26%) are characterised by frequent, successive drought events leading to a reduced drought recovery capacity and strong impacts on the groundwater system.

Identification of regions at risk

This study provides the first global study of groundwater drought recovery based on high-resolution simulations of a global groundwater model that was developed at Utrecht University. Her research shows that regional climatic, geophysical and anthropogenic aspects play a key role in sustainable groundwater management practices. It can support the identification of regions at risk of crossing critical thresholds and support the development of targeted strategies to enhance global groundwater resilience. Regions and countries already known for their excessive groundwater use, for example for irrigation purposes, and declining groundwater trends (such as California, Spain, India or the Northern China Plain) more often show a complex mix of recovery regimes. These regions often are characterised by many vulnerable and unstable groundwater systems, as a result of groundwater abstraction, compared to more less affected regions.

Changes over time

The current analysis mainly focused on spatial patterns of groundwater recovery. Follow-up research by Hauswirth and her colleagues will also provide more insight into how these recovery processes change over time, looking not just at the past but also into the future under a changing climate.

The groundwater recovery regime classification helps categorise groundwater systems according to their recovery dynamics. Natural regions, with less human influence on groundwater abstraction, often show more resilient behaviour compared with regions known for declining groundwater trends (a, c, d, e), often due to groundwater pumping, where a more mixed recovery dynamic is found (vulnerable and unstable). Areas in grey represent locations that were filtered out during the analysis.

Credit

Utrecht University/Environmental Research Water

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Journal

Environmental Research Water

DOI

10.1088/3033-4942/aea63d

Method of Research

Computational simulation/modeling

Subject of Research

Not applicable

Article Title

Patterns and drivers of global groundwater drought recovery’

Where the waters meet: Connecting global limits and local water management

International Institute for Applied Systems Analysis

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Human activity and climate change are putting growing pressure on water resources, disrupting the predictability of the water cycle, and changing the availability and quality of freshwater. IIASA researchers and partners have developed a new framework for guiding water management and planning at the river-basin level, derived from the existing Global Water Planetary Boundary.

The Planetary Boundaries framework identifies limits for key Earth system components that keep our planet stable and safe for human life. These limits define a Safe Operating Space (SOS) within which the society can thrive without destabilizing the Earth system. Freshwater is one of these key system-components, with the Water Planetary Boundary defining the conditions needed to maintain a stable and resilient water cycle.

In their study, published in Environmental Research Letters, researchers propose a new approach to operationalize the Water Planetary Boundary to make it relevant for guiding water management and planning at the river-basin level.

“The Global Water Planetary Boundary framework has the great merit of bringing into focus the impacts human activity has on the global water cycle, yet it is not specifically designed to provide actionable strategies. We wanted to define a framework for its implementation at the basin scale, where actual water management occurs,” explains lead author Emilio Politti, a researcher in the Water Security Research Group of the IIASA Biodiversity and Natural Resources Program.  

According to the researchers, previous attempts to downscale the boundary relied heavily on single variables, such as total consumption of water that is available in groundwater, rivers, lakes, and aquifers (blue water) or individual water stores, which fail to capture the complex, multidimensional dynamics specific to river basins. No systematic transferable methodology was previously available to guide water authorities in designing holistic management plans grounded in the Planetary Boundaries framework.

The authors reviewed how the Water Planetary Boundary has evolved from a global measure based on water consumption to a more detailed approach that considers differences between places and their social and environmental needs. They then designed a framework that focuses on key water functions that are important for both people and the Earth system, helping to prevent local water overuse from developing into a bigger problem with cascading effects at regional and global scales.

The new framework can be applied to any river basin worldwide, regardless of its size, to determine whether the basin is being managed appropriately and remains within a safe limit for water use. It can also be used to evaluate how the basin’s situation may change under climate change or different management decisions, while considering the needs and values of local stakeholders. The framework aims to support economic efficiency, environmental sustainability, and social equity.

The authors say that the proposed reframing could benefit a range of groups. By involving local communities including disadvantaged groups in planning, it can help ensure that their needs and priorities are reflected in decisions about how water is shared and managed.

For river basin authorities and water managers, the framework provides a structured, integrated, adaptable decision-support tool to evaluate trade-offs and design resilient long-term adaptation plans, while policymakers and environmental agencies can obtain a transparent methodology to balance socioeconomic development with ecological limits and legislative requirements.

“Merely measuring water volume or consumption does not ensure a healthy river basin; maintaining water resilience requires protecting multi-dimensional functions, including water quality, connectivity, flow regimes, and ecosystem services,” says coauthor Silvia Artuso, a researcher in the IIASA Water Security Research Group. “Environmental protection and human societal wellbeing are deeply interdependent – ecological sustainability cannot be achieved at the expense of human needs, nor can human prosperity survive if ecological boundaries are breached.”

“This basin-scale SOS framework for water resources is the result of collaborative work carried out through the SOS-Water Horizon Europe project, coordinated by the IIASA Water Security Research Group and bringing together eleven partners from EU and non-EU countries. We have successfully tested the framework across several river basins, each facing different climatic and socio-economic conditions. Our goal is now to make this practical tool available to decision-makers, helping them strengthen water resilience and better prepare for changing conditions in the future” says coauthor Taher Kahil, Research Group Leader of IIASA Water Security Research Group and Coordinator of the SOS-Water project.

Reference:

Politti, E., Artuso, S., Calamita, E., Castelletti, A., Cetinic, K., Domisch, S., Giuliani, M., et al. (2026). Review and reframing of the operationalisation of the water planetary boundary for river basin planning. Environmental Research Letters. DOI: 10.1088/1748-9326/aea919

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Journal

Environmental Research Letters

DOI

10.1088/1748-9326/aea919

Subject of Research

Not applicable

Article Title

Review and reframing of the operationalisation of the water planetary boundary for river basin planning

 

East Asia's tropical cyclone risk is moving steadily north

Institute of Atmospheric Physics, Chinese Academy of Sciences

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Typhoon Khanun approaches the Korean Peninsula and Japan in August 2023. New research shows that tropical cyclone activity and coastal hazards in East Asia are shifting toward higher latitudes.

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Credit: NASA Worldview, Earth Observing System Data and Information System

Tropical cyclones form in the tropics. But they do not stay there—and increasingly, they are not staying south.

A new study published in Advances in Atmospheric Sciences finds that tropical cyclone activity and coastal hazard along East Asia have been shifting steadily northward. Using storm records from 1980 to 2025 across the western North Pacific, the world's most active tropical cyclone basin, researchers found fewer storms forming and making landfall at lower latitudes, and a growing share of activity farther north.

The shift is not a uniform increase in danger. It is a redistribution.

 “The key message is not that every coast is facing more tropical cyclones,” said lead and corresponding author Jia Sun of the First Institute of Oceanography, Ministry of Natural Resources, China. “The geography of the danger is changing. Higher latitude communities are becoming more exposed as tropical cyclone activity and landfall likelihood shift northward.”

Landfall likelihood decreased south of 20°N but increased north of 30°N—broadly covering parts of eastern China, the Korean Peninsula, and Japan. The storms also tended to form farther northwest, follow more landward and poleward tracks, and move modestly faster, cutting the average time landfalling cyclones spent over the ocean from about 5.6 days in 1980–2015 to about 4.7 days in 2016–2025.

 

That shorter journey can matter for preparedness. A tropical cyclone that forms closer to land and moves toward the coast more quickly may leave less time for forecasting, emergency planning, and public response.

“Preparedness plans often rely heavily on past experience,” said co-corresponding author Guihua Wang of Fudan University. “Our results show why coastal risk assessments and early warning systems must also account for changing tropical cyclone routes and travel times, especially in northern East Asia.”

Importantly, the study did not find a significant long-term increase in the maximum strength reached by the tropical cyclones. This suggests that the changing pattern of danger is being driven mainly by where tropical cyclones travel and make landfall, not by a steady strengthening of the tropical cyclones themselves.

Changes in large-scale winds over the Pacific appear to help steer more storms westward, poleward, and toward land. However, the authors caution that the observed pattern reflects a combination of long-term climate change and natural climate swings. Separating these influences will require longer records and targeted climate model experiments.

For coastal communities, the practical lesson is clear: yesterday’s tropical cyclone map may not describe tomorrow's risk. Planning must consider not only how strong a tropical cyclone may become, but also where it is increasingly likely to go — and how much warning time it may leave as that risk moves steadily north..

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Journal

Advances in Atmospheric Sciences

DOI

10.1007/s00376-026-5906-y

Article Title

Poleward Redistribution of Tropical Cyclone Hazards over East Asia

 

Can nanostructured surfaces help keep marine equipment clean?

Sultan Qaboos University

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The scanning electron microscope (SEM) images for different polymer micropattern (without ZnO coating) and their cross sections  D1 (a,d),  D2 (b,e), and D3(c,f) used in this study.

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Credit: Al-Busaidi A, Dobretsov S, Kyaw HH, Myint MTZ (2026) Antifouling properties of ZnO nanorods coating on micropatterned polymers. PLoS One 21(9): e0357826

MUSCAT, Oman — Researchers at Sultan Qaboos University have developed engineered surfaces that combine microscopic patterns with zinc oxide nanorods to reduce the attachment of bacteria and microalgae—a process that contributes to biofouling on submerged marine and industrial equipment.

Biofouling occurs when microorganisms and larger marine organisms accumulate on surfaces exposed to water. It can reduce vessel performance, increase fuel consumption, accelerate corrosion, block water intakes and heat exchangers, and affect aquaculture equipment. These challenges have driven efforts to develop durable antifouling materials with reduced environmental toxicity.

In the new study, researchers fabricated zinc oxide nanorod coatings on three differently patterned polymer surfaces, identified as D1, D2 and D3. The resulting materials combined microscale surface patterns with nanoscale zinc oxide structures.

The team tested the engineered surfaces under laboratory flow conditions using the bacterium Escherichia coli and the marine diatom Amphora sp. They also assessed possible acute toxicity using larvae of the whiteleg shrimp Litopenaeus vannamei.

The zinc oxide coatings made the patterned surfaces highly water-repellent, with water contact angles of approximately 150–165 degrees, compared with around 80–90 degrees for the uncoated surfaces.

The results showed that the coatings reduced bacterial attachment by 60.3%, 48.8% and 5.8% on the D1, D2 and D3 surfaces, respectively. Diatom coverage was reduced by 9.9%, 72.9% and 71.8% on the corresponding coated surfaces.

The researchers attributed the antifouling effects to a combination of factors, including the release of zinc ions, the generation of reactive oxygen species, surface wettability, and the interaction between the micro- and nanoscale structures.

Toxicity varied depending on the surface design. The zinc oxide-coated D1 surface showed the best overall balance between antifouling performance and low toxicity toward shrimp larvae. In contrast, the coated D3 surface demonstrated lower antibacterial performance and greater larval toxicity, highlighting the importance of carefully designing the underlying surface pattern rather than relying on the coating material alone.

Microscopic examination after the biological experiments showed that the zinc oxide nanorods remained structurally intact, indicating that the coatings were stable during the laboratory testing period.

The findings suggest that combining zinc oxide nanorods with specifically designed micropatterned surfaces could provide a promising approach for developing antifouling materials. Such materials could eventually support applications involving ship surfaces, aquaculture nets, water-intake systems and other equipment exposed to marine environments.

However, the researchers emphasized that the experiments were conducted under controlled laboratory conditions. Long-term field trials and further ecotoxicological assessments are required before the coatings can be considered for practical marine or industrial use.

The article, “Antifouling properties of ZnO nanorods coating on micropatterned polymers,” was published in PLOS ONE on 18 September 2026.

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Journal

PLOS One

DOI

10.1371/journal.pone.0357826

Method of Research

Experimental study

Subject of Research

Animals

Article Title

Antifouling properties of ZnO nanorods coating on micropatterned polymers

Dinos snacked on seafood washed up on ancient beaches, fossil study shows

Dinos and their prey likely ate seaweeds, which offers an explanation to mysteriously high carbon isotope signatures in their teeth

Frontiers

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Five specimens from the Cloverly Formation assemblage after destructive sampling for isotopic composition and laser ablation analysis. The specimens from left to right are three specimens of crocodilian teeth, the fourth tooth is a Deinonychus antirrhopus tooth, and, finally, on the far right is a Sauropelta edwardsi tooth. The specimens are mounted on adhesive putty attached to a glass slide with specimen labels below them.

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Credit: Sam Noble Oklahoma Museum of Natural History/Clayton Forster.

Storms routinely wash marine matter ashore, which land-living animals and other organisms exploit as food sources. This is known as marine subsidization (MS). Today, MS is particularly common in coastal ecosystems and is enhanced among animals when land ecosystems yield less food than usual, for example during droughts. A new Frontiers in Ecology and Evolution study has shown that dinos and their prey, too, may have indulged in seafood washed onto beaches.

“We show that coastal terrestrial organisms in the greenhouse climates of the Cretaceous relied on marine resources to supplement their diets in a similar way that modern organisms do,” said first author Dr Clayton Forster, a geologist at the University of Arkansas. “We can identify that marine resources are passed along the food chain and incorporated in the minerals of bones and teeth of dinosaurs, crocodiles, turtles, and fish.”

Mystery teeth

Plants contain ‘light’ (C-12) and ‘heavy’ (C-13) carbon isotopes. The ratio of these isotopes, expressed as δ13C, is a chemical ‘fingerprint’ that gets passed from food into the body of the consumer. When an animal eats, the δ13C value is incorporated into its tooth enamel with an upward shift in the δ13C value to a value higher than that of its food. This difference is between 11 and 13 parts per thousand in the tooth enamel of living animals.

In dino teeth, however, this difference has been found to be consistently higher, creating a mystery around carbon signatures of dino teeth. Their δ13C values were also higher than expected for animals that solely eat land-growing plants, which have lower δ13C values than most marine plants. If dinos or their prey snacked on marine matter, however, it could explain this discrepancy.

“By determining the carbon isotope composition of dinosaur, fish, and crocodile tooth enamel, we can determine what their primary dietary source was and if they were different between regions,” explained Forster.

To do so, the researchers used fossils from (once) coastal sites along the Western Interior Seaway – a vast inland sea that split North America into two landmasses around 100 million years ago – and the ancient Gulf of Mexico coastline. They also included fossils from land-locked sites. These sites formed during the early Albian (around 113-107 million years ago) or early Cenomanian (approximately 100-96 million years ago). The team used powder from these fossils to analyze isotopic composition during both ages and determined the latitudes on which the organisms lived.

The analyses showed that the δ13C value in fossils from coastal sites was not only higher than that from the land-locked formation, but also was consistent between coastal sites, regardless of latitude or age. The study is the first to identify MS in prehistoric ecosystems.

Suspect: seaweed

“Coastal-dwelling organisms must have eaten some kind of organic matter from the ocean, or prey that had done so. This pattern is shared from fish to megaherbivores and indicates that the extra carbon source must have been low in the food-chain to affect both aquatic and terrestrial animals,” Forster explained. The source also must have been an organism living in coastal, but not inland, habitats and remained available over many millions of years.

“Few organisms meet these criteria besides marine macroalgae or macrophytes – seaweeds,” said Forster. “Given the almost ubiquitous behavior of large coastal herbivores today to supplement their diet with seaweeds, it’s likely that most of the sampled herbivorous dinosaurs were no different.”

But not all dinos exploited marine resources. Tenontosaurus tilletti, a large herbivorous dinosaur found in many locations throughout the Cretaceous, for example, did not use marine sources for food. Its δ13C value was found to be similar to that of animals which are alive today and consume land-growing plants. Therefore, higher δ13C values likely reflect dietary preferences rather than geological processes that changed chemical traces in tooth enamel after animals died.

While the dataset clearly demonstrates MS in the coastal deposits the researchers examined, it lacks data from polar and equatorial latitudes during the early Albian and early Cenomanian. Future research needs to determine whether MS was common in different latitudes and time periods such as the preceding Jurassic Period or the subsequent early Cenozoic Era.

“Our study emphasizes the connections between terrestrial and marine ecosystems,” concluded Forster. “They are deeply intertwined and have been for hundreds of millions of years. It highlights the importance of environmental linkages across time and space and protecting them where they exist today.”

A large crocodilian tooth from the Wayan Formation. The specimen is shown next to a centimeter ruler in a specimen box on top of its specimen information card.

Credit

Idaho Museum of Natural History/Clayton Forster.

Theropod tooth from the Mussentuchit Member assemblage on a foam block next to a scale card.

Credit

North Carolina Museum of Natural Sciences/Clayton Forster.

A Tenontosaurus tilletti tooth from the Cloverly Formation assemblage in a glass sample vial.

Credit

Sam Noble Oklahoma Museum of Natural History/Clayton Forster.

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Journal

Frontiers in Ecology and Evolution

DOI

10.3389/fevo.2026.1895247

Method of Research

Experimental study

Article Title

Marine Subsidization of Dinosaurian Ecosystems

 

Scientists found a chimera mutant in the hybrid offspring of red swamp crayfish

KeAi Communications Co., Ltd.

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THE CRAYFISH CHIMERA (PROCAMBARUS CLARKII)

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Credit: ZIJIAN FENG & BO PENG

The chimera of different animals has been found in the past decades. Typically, chimeric individuals can be readily identified based on left-right asymmetries in body coloration. For example, cats with left-right differences in facial fur color and crayfish with left-right differences in body coloration are typical examples of chimeras. The common and general research questions in this field are: How do chimeras arise? What are the genetic and cellular mechanisms underlying their formation?

Recently, a study published in the KeAi journal Reproduction and Breeding, a group of researchers from China, reported a crayfish (Procambarus clarkii) chimera, derived from a F1 of hybridization between Black king crayfish and its wild type. This finding provides a valuable resource for scientists to dissect the molecular mechanisms underlying the formation and developmental maintenance of chimeras containing two or more genetic components.

“The cells with two distinct genetic components are irregularly distributed in the different organs of a crayfish chimera,” shares corresponding author Xufeng Bai, a professor at Huazhong Agricultural University. “To our surprise, however, two different colors and patterns are symmetrical on its body between left and right sides. It’s interesting to observe the sexual characteristic and important economic traits for the progenies of chimera.”

Genetic analysis, however, revealed a more complex picture. Multiple genotypes coexisted within the same individual and were distributed irregularly across different tissues and organs. This genetic distribution did not correspond completely with the striking bilateral symmetry observed in the carapace.

The researchers suggest that hybridisation between different varieties of red swamp crayfish may have contributed to the formation of the chimera.

The study provides a useful reference for further investigations into how tissues or organs with different genetic compositions can coexist and be maintained within a single organism. More broadly, the researchers suggest that such work could also contribute to understanding biological mechanisms associated with tissue compatibility and immune rejection in organ transplantation.

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Contact the author:

Xufeng Bai, College of Fisheries, Huazhong Agricultural University, xufengbai@mail.hzau.edu.cn

The publisher KeAi was established by Elsevier and China Science Publishing & Media Ltd to unfold quality research globally. In 2013, our focus shifted to open access publishing. We now proudly publish more than 300 world-class, open access, English language journals, spanning all scientific disciplines. Many of these are titles we publish in partnership with prestigious societies and academic institutions, such as the National Natural Science Foundation of China (NSFC).

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Journal

Reproduction and Breeding

DOI

10.1016/j.repbre.2026.07.001

Method of Research

Case study

Subject of Research

Animals

Article Title

Phenotypic and molecular characteristics of a chimera mutant of red swamp crayffsh (Procambarus clarkii)

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