Saturday, May 17, 2025

GRIT remaps the world’s rivers, branching into the unknown to aid global flood modelling

University of Oxford

GRIT drainage area map — image:
Global map of the GRIT network. The network is shown for all reaches wider than 30 m as well as their downstream segments. The width is scaled by partitioned drainage area here for visualization purposes. The inset maps show the multi-threaded river network at regional scale in seven selected regions of the globe (Fraser, Amazon, Rhine-Meuse, Congo, Padma-Brahmaputra, Mekong and Pearl Rivers). Line widths in inset panels have their own scale also reflective of drainage area rather than river width.
Credit: Wortmann et al., 2025/Water Resources Research/American Geophysical Union
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Credit: Wortmann et al., 2025/Water Resources Research/American Geophysical Union

Key research findings

GRIT is the first global river network to include river splits, canals, and multi-threaded channels—features that were missing from previous reference datasets.
The network includes 19.6 million km of mapped rivers and 67 thousand bifurcations, with accurate flow directions and channel data.
It is already outperforming previous river models in terms of accuracy, especially in flat, flood-prone, or heavily populated areas.

A team led by researchers at the University of Oxford has created the most complete map of the world’s rivers ever made offering a major leap forward for flood prediction, climate risk planning, and water resource management in a warming world. The new study, published in Water Resources Research, introduces GRIT—a mapping system that finally shows how rivers really flow, branch, and connect landscapes.

Rivers support life—but they also pose growing risks. As rainfall becomes more erratic and sea levels rise, floods are expected to become more frequent and severe in many parts of the world. Yet existing global river maps are outdated and overly simplified, assuming that rivers flow in a single direction and never split. They often overlook complex features, such as when a single river channel splits into multiple channels. These branching river systems are important because they are often found in densely populated, flood‐prone regions, and they are crucial for understanding water movement across the Earth's surface.

To address this limitation of existing river maps used for water management and flood prediction, the team have developed a new global river network called Global RIver Topology (GRIT), which includes these branching rivers and large canals, capturing the complexity.

GRIT was created by combining high‐resolution satellite imagery of rivers with advanced elevation data of the earth's surface. GRIT not only includes the main river channels but also provides information on river flow directions, widths, and points where rivers split. The GRIT river network has a total length of 19.6 million km and includes 67 thousand bifurcations. GRIT stands to significantly enhance applications in hydrology, ecology, geomorphology, and flood management.

“We needed a global map that reflects the way rivers actually behave,” said Dr Michel Wortmann, who developed GRIT at Oxford as a Research Associate on the EvoFLOOD project. “It’s not enough to assume rivers just go downhill in a straight line—especially not when we’re trying to predict floods, understand ecosystems, or plan for climate impacts. This map shows the world’s rivers in their full complexity.”

A major step forward for flood prediction and climate resilience

Rivers are vital for ecosystems and human life, but as climate change drives more extreme weather, they are becoming increasingly dangerous—especially during floods. To prepare, scientists and governments need to understand where water is likely to go at large scales. GRIT allows for a far more complete view of water movement, helping to improve flood models, water management systems and disaster planning.

The new river network also supports the development of global data-driven (AI) models for flooding, drought, water quality, habitat conservation, and environmental risk.

While GRIT already marks a big leap forward, the Oxford team notes that it’s just the beginning.

“GRIT has been built to evolve,” said Louise Slater, Professor of Hydroclimatology at the University of Oxford. “Because it’s fully automated, in contrast with previous global networks, we can keep updating it with the latest satellite images and topographic data, to understand shifts in the rivers and landscape.”

This work was funded by the EvoFLOOD Large Grant (NE/S015728/1), a £3.7m NERC-funded research programme on the Evolution of Global Flood Hazard and Risk.

Notes for editors:

The paper ‘Global River Topology (GRIT): A Bifurcating River Hydrography’ will be published Open Access in Water Resources Research on 15 May 2025 at 14:00 BST / 09:00 EDT. DOI: 10.1029/2024WR038308

Journal

Water Resources Research

DOI

10.1029/2024WR038308

Article Title

Global River Topology (GRIT): A Bifurcating River Hydrography

Article Publication Date

15-May-2025

New study reveals how to reclaim space for civil society in times of democratic decline

The Hebrew University of Jerusalem

A new study shows that highlighting shared values and common goals can significantly increase the acceptance of civic organizations that are often seen as controversial and delegitimized for challenging the status quo. The research tested different messaging strategies on more than 1,600 Jewish Israeli participants, using real-world examples from a delegitimized prominent NGO. Messages that focused on widely supported activities—like providing services to marginalized communities—or that framed the organization as part of a shared value-based identity led to greater perceived legitimacy. The findings offer a practical and research-backed approach for protecting democratic discourse in polarized societies.

[Hebrew University of Jerusalem]– In a time when civil society voices are increasingly dismissed as radical or disloyal, new research led by PhD student Lee Aldar and Professor Eran Halperin at The Hebrew University of Jerusalem, found that a discourse emphasizing shared values and common goals – like fairness, solidarity, and support for vulnerable communities – can significantly boost the legitimacy of controversial civil groups, even among skeptical or even hostile public.

Published in Communications Psychology, the study tested the effects of different psychological interventions on over 1,600 Jewish Israeli participants, representing the political right, center, and left. The researchers focused on attitudes toward a widely delegitimized Israeli civil society organization known for its work on democratic values, minority rights, and government accountability. Over time, this NGO has been the target of smear campaigns that frame its actions as disloyal, extreme, or threatening. The team tested how carefully framed messages could shift perceptions without watering down the group’s mission. Two strategies stood out: highlighting widely supported public service efforts and redefining what it means to be “one of us.”

Using a method known as an “intervention tournament,” the researchers presented participants with simulated social media posts styled as if written by the NGO itself. Some emphasized shared values such as human dignity and fairness; others highlighted common interests, such as improving healthcare access or supporting vulnerable communities. The goal was to test which types of messages might shift public attitudes.

One intervention emphasized mainstream activities—like providing services to marginalized communities and advocating for public housing—while another used value-based recategorization, presenting a new definition of what it means to be part of one group or another based on values rather than labels. Both approaches led to a significant increase in perceived legitimacy of the NGO.

"Even in deeply polarized societies, highlighting what people have in common can change how they view others—especially those they may disagree with," said Prof. Eran Halperin, an expert on intergroup relations and political psychology. "This isn't just about changing minds; it’s about making space for internal criticism and protecting the democratic principle of free expression."

Importantly, the effective interventions didn’t attempt to address the NGO’s more controversial positions or confront misinformation head-on. Instead, they offered a reframing: showing that organizations labelled as being “illegitimate” or “anti-Israel” in fact often promote activities based on values that many would agree with, given the chance to reconsider them.

The study’s results carry global relevance. In countries as diverse as Brazil, Poland, Russia, and the United States, human rights groups and civil society watchdogs have faced rising hostility for opposing government actions. The researchers argue that re-legitimizing these actors is essential to safeguarding democratic institutions—and that the path forward lies in reclaiming narratives based on identity, values, and interests that are shared with different groups in their societies.

“This is not about asking civil society actors to dilute their missions; politicians, journalists and ordinary citizens still bear the primary responsibility for making space for debate – even when its uncomfortable – about policies.” said Lee Aldar, the study’s lead author. “It’s about finding enough common language and shared truths that remind the public these voices belong to the society they’re trying to improve.”

The study adds a powerful tool to the psychological and political toolkit of organizations fighting for democracy—and suggests that even amid division, common ground remains a force for change.

Journal

Communications Psychology

DOI

10.1038/s44271-025-00238-1

Method of Research

Experimental study

Subject of Research

People

Article Title

Intergroup psychological interventions highlighting commonalities can increase the perceived legitimacy of critical voices

Older adults are getting infected with HIV, but prevention focuses on young people

Prevention and treatment campaigns are not adequately targeting the particular needs of the 50+ years age group.

University of the Witwatersrand

Prevention and treatment campaigns are not adequately targeting the particular needs of the 50+ years age group.

Indeed, between 2000 and 2016, the number of adults aged 50 years and older living with HIV in sub-Saharan Africa doubled. At present, their HIV prevalence is exceeding that of younger adults.

By 2040, one-quarter of people living with HIV in Africa will be aged 50 years and older; tailored awareness and treatment campaigns are pressing.

Dr Luicer Olubayo, a researcher at the Sydney Brenner Institute for Molecular Bioscience (SBIMB) at Wits University and the first author of a study published in The Lancet Healthy Longevity journal, which investigated HIV in older people in Kenya and South Africa, noted that perceptions on who acquires HIV are limited. “We often think of HIV as a disease of younger people. It doesn’t help that intervention campaigns are mainly targeted at the youth.”

Moreover, older adults are less likely to believe that they can get HIV. This misconception is pervasive and has consequences for reaching global targets to achieve UNAIDS’ 95-95-95 targets by 2030 (95% of people living with HIV know their status, 95% of people who know their status are on treatment, and 95% have a suppressed viral load).

“While HIV prevalence among individuals over 50 years of age is similar to or even exceeds that of younger adults, HIV surveys focus on younger individuals, leaving considerable gaps in understanding HIV prevalence, incidence and treatment outcomes in older populations,” says Associate Professor F. Xavier Gómez-Olivé, at the MRC/Wits-Agincourt Research Unit.

Stigma remains a barrier to treatment

The uptake of HIV testing among older adults is poor, which delays diagnosis and limits access to care. This is, indeed, one of the signifiers of the pervasiveness of stigma surrounding the disease.

“We know that there is significant social stigma related to HIV infection. This is why understanding HIV-related stigma in older adults remains crucial as a way to inform interventions to support older people’s mental health and overall well-being,” says Olubayo.

Interventions could focus on repeated testing, the use of pre-exposure prophylaxis (PrEP), and campaigns to increase awareness and reduce infections among the elderly.

“HIV can be managed alongside other chronic conditions, too, since HIV is managed as a long-term illness,” says Gómez-Olivé.

Non-communicable diseases, such as hypertension, diabetes, and obesity, have dramatically increased in sub-Saharan Africa, particularly among older people. HIV treatment and intervention can be included in the healthcare ecosystem of long-term illnesses.

Apart from stigma, a complex interplay of factors shapes HIV risk

The study shows that age, education, gender, and where people live all affect their risk of HIV. Even though more people now have access to HIV treatment, older adults—especially in rural areas—still face significant challenges in preventing HIV, such as low education levels and gender inequality.

Widowed women had the highest HIV rate (30.8%). This may be due to losing a partner to HIV, stigma, and a greater risk of unsafe behaviours like transactional sex and limited power to negotiate condom use. People without formal education and those with low income also had higher rates of HIV infection.

The benefit of longitudinal data to make decisions

An important added value of this study is the provision of longitudinal insights into the HIV epidemic among older adults in sub-Saharan Africa. “Our study is beneficial in that older populations are under-represented, and not much is known about them over time. What changes are occurring? We have to answer these kinds of questions. With longitudinal data, we can look at the effectiveness of antiretroviral therapy coverage in older people,” says Gómez-Olivé.

The study used data collected in urban Kenya and in urban and rural sites across South Africa during two data collection waves: 2013-2016 and 2019-2022.

Throughout a decade of research, the team has been gaining a deeper understanding of this ageing HIV epidemic. Numerous important insights about HIV in older populations have been achieved, and research gaps are being covered.

Data for the study were drawn from the Africa Wits-INDEPTH Partnership for Genomic Research (AWI-Gen) from adults aged 40 years and older. AWI-Gen is a multicentre, longitudinal cohort study conducted at six research centres in four sub-Saharan African countries (South Africa, Kenya, Burkina Faso, and Ghana) to investigate various health determinants.

Journal

The Lancet Healthy Longevity

DOI

10.1016/j.lanhl.2025.100701

Article Title

The prevalence, incidence, and sociodemographic risk factors of HIV among older adults in sub-Saharan Africa (AWI-Gen): a multicentre, longitudinal cohort study

The most extreme solar storm hit Earth in 12,350 BC, scientists identify

University of Oulu, Finland

New research uncovers the strongest solar event ever detected — rewriting our understanding of space weather and radiocarbon dating.

An international team of scientists has discovered an extreme spike in radiocarbon corresponding to the year 12350 BC during the dusk of the last Ice Age. However, the strength of the event could not be assessed earlier because of the lack of an appropriate model. Presently, it has been identified as the most powerful solar particle storm known to date – a colossal space weather storm that struck Earth 14300 years ago. This recent finding expands the timeline and intensity of known solar activity and sets a new upper boundary for such solar phenomena.

In the study, Postdoctoral Researcher Kseniia Golubenko and Professor Ilya Usoskin at the University of Oulu, Finland utilised their newly developed chemistry–climate model called SOCOL:14C-Ex, specifically designed to reconstruct solar particle storms under ancient glacial climate conditions. The model confirmed that the detected solar event was approximately 18% stronger than the notorious AD 775 event — until now the strongest solar storm ever recorded in tree-ring archives.

“Compared to the largest event of the modern satellite era — the 2005 particle storm — the ancient 12350 BC event was over 500 times more intense, according to our estimates”, says Dr. Golubenko.

Other large known solar particle storms have occurred around 994 AD, 663 BC, 5259 BC and 7176 BC, and a few other candidates are under investigation. The new model was also verified using wood samples recently found in the French Alps, dating back some 14300 years.

Solar particle storms are rare, but when they occur, they bombard Earth with an enormous amount of high-energy particles. In comparison, the famous Carrington event in 1859 was a different kind of event and not accompanied by a solar particle storm.

“The ancient event in 12350 BC is the only known extreme solar particle event outside of the Holocene epoch, the past ~12000 years of stable warm climate”, says Golubenko. “Our new model lifts the existing limitation to the Holocene and extends our ability to analyse radiocarbon data even for glacial climate conditions.”

In the study, Golubenko and Usoskin, designed the SOCOL:14C-Ex model to assess the solar particle storm intensity under glacial conditions. The model was successfully validated using data in tree rings from the AD 775 event and applied to the late Ice Age conditions to study the 12350 BC event.

With the model, the researchers assessed the strength, timing, and terrestrial effects of the most extreme solar particle event presently known. The model — now validated under both Holocene and glacial conditions — marks a major step forward in analysing radiocarbon variations across different climatic and geomagnetic epochs.

The international research team included scientists from France and Switzerland, and was led by Professor Edouard Bard from CEREGE, France.

A new era for radiocarbon dating – and worst-case scenario for solar storms

Solar particle storms can greatly enhance the normal production of cosmogenic isotopes like radiocarbon (14C) in the atmosphere by galactic cosmic rays. Such enhanced production, preserved in annual tree rings, serves as a clear cosmic timestamp making possible absolute dating of tree samples. Such dramatic spikes — known as Miyake events, named after the Japanese researcher who first discovered them — offer invaluable data for scientists studying both solar activity, ancient Earth systems and space climate.

“Miyake events allow us to pin down exact calendar years in floating archaeological chronologies”, describes Usoskin. Radiocarbon signals from such events have already enabled researchers to precisely date Viking settlements in Newfoundland and Neolithic communities in Greece.

The findings revise our understanding of solar physics and space weather extremes. “This event establishes a new worst-case scenario,” Golubenko notes. “Understanding its scale is critical for evaluating the risks posed by future solar storms to modern infrastructure like satellites, power grids, and communication systems.”

The new research article New SOCOL:14C-Ex model reveals that the Late-Glacial radiocarbon spike in 12350 BC was caused by the record-strong extreme solar storm was published 28 April 2025 in the esteemed scientific journal Earth and Planetary Science Letters.

Through the winter with a balanced diet

University of Würzburg

Honeybees at beehive — image:
Honeybees at a beehive.
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Credit: Pedro Alonso Alonso

Especially in temperate climates, winter poses a major challenge for honeybee colonies. To ensure their survival, the animals must maintain the right temperature in the hive and raise the next generation of workers. The availability of pollen from flowers plays a vital role as well.

However, it is not just the quantity of food that matters. As researchers at Julius-Maximilians-Universität Würzburg (JMU) have now discovered, the diversity of plants providing pollen also plays an important role.

The study was led by Professor Ingolf Steffan-Dewenter, Chair of Animal Ecology and Tropical Biology at JMU, and is part of the European project BeeConnected. The team has now published the results of the study in the Journal of Applied Ecology.

Balanced diet ensures resilient bees

Just like humans, bees also need various nutrients: amino acids, fatty acids, vitamins, proteins and minerals.

“A rich and balanced diet not only ensures successful brood development, but it also promotes the overall health of the bee colony – and healthy bees are more resistant to stressors,” explains biologist Giulia Mainardi, PhD student in the project.

The development of the winter bees, which sustain the colony during the cold months, also depends on access to high-quality food resources..

The researchers wanted to know how different landscapes and weather conditions influenced the survival rate of honeybee colonies. To this end, they investigated pollen diversity – i.e. the variety of flowers that the bees collected – in Germany, France and Greece as well as the number of days on which the bees were able to forage due to the weather.

Pollen diversity as the seasons change

“We found that areas with high agricultural use provide bees with a higher diversity of pollen in autumn. This is probably also due to agro-environmental measures such as organic farming, flower strips and intercropping,” says Mainardi.

In summer, on the other hand, pollen diversity was greater in near-natural areas. “Presumably because these also have a wider range of plants when agricultural areas have a lack of flowers after the flowering period of the dominant crop,” Mainardi continues.

The study shows that the survival of honeybee colonies was much higher at locations with high pollen diversity, whereas the results regarding the weather conditions were less conclusive. “Our results underpin that the survival of colonies during winter depends not only on parasites like the Varroa mite and bad weather conditions but also on the quality of food resources,” explains Steffan-Dewenter.

How animals and humans can benefit

The researchers clearly recommend preserving and enhancing floral diversity, with cooperation among beekeepers, farmers, urban planners and conservationists. In addition to honeybees, other important pollinators such as bumblebees, solitary wild bees, syrphid flies and butterflies would also benefit.

This would not only benefit honeybee health, but also ensure pollination services, high crop yields and contribute to food security for humans.

Journal

Journal of Applied Ecology

DOI

10.1111/1365-2664.70054

Method of Research

Observational study

Subject of Research

Animals

Article Title

Floral diversity enhances winter survival of honeybee colonies across climatic regions

Article Publication Date

16-Apr-2025

Helping families financially could reduce child maltreatment

COVID-19 eviction moratoria reduced report rates of child abuse by up to 21%

States that halted evictions had fewer cases of abuse, neglect

University of Georgia

Federal or statewide policies that help families in economic crises could dramatically reduce the rate of child abuse and neglect, according to a new study from the University of Georgia.

The study suggests that the eviction moratoria put into place during the COVID-19 pandemic had a significant impact on lowering report rates of child maltreatment.

“Almost every parent loves their child. No one would like to or intend to abuse or neglect their child,” said Liwei Zhang, lead author of the study and an assistant professor in the UGA School of Social Work.

“Sometimes these situations are just the pressure of living in poverty. Since poverty is a risk factor, then if we can support families with better financial assistance, we could probably help prevent maltreatment.”

States that halted evictions had fewer cases of abuse, neglect

Researchers analyzed hundreds of counties across 10 states that had implemented statewide pauses on evictions during the pandemic.

At the same time, they compared these with seven states, including Georgia, that did not put a hold in place.

When looking at Child Protective Services data and biweekly reports from child protective services, the researchers found a decrease in child abuse or neglect rates in the states with eviction bans.

Report rates of physical abuse dropped by 16%, sexual abuse fell 21% and neglect dropped by 12%.

Secure housing may have positively influenced how parents treated their children

Many of the families were low income. The safety net of not being evicted over missed payments possibly made a difference in child maltreatment, the researchers said.

“Parents may not be able to support their children with sufficient food or housing, and that really places them in a challenging situation. There may also be mental health issues or substance abuse issues, so parents should know to not feel ashamed to ask for help,” Zhang said.

While the eviction moratorium was a huge help for these households, it disproportionately affected small, independent landlords and their livelihoods.

“The families who couldn’t afford to pay their rent were able to have their rent delayed, but the small landlords were experiencing financial challenges too,” Zhang said. “Even though the results show that the eviction moratorium seems to have worked in reducing child maltreatment, I would say we need something sustainable that could support both sides when another wave of crisis happens.”

Policies should be prioritized in future disasters

The study draws a connection between decreased economic hardships and increased child well-being, emphasizing the benefits of federal and state assistance programs in times of crisis, Zhang said.

“We had so many policy changes during that time. Now is the time for us to learn from those lessons during that period rather than moving forward without looking back. We need to always learn from history to then improve our services,” she said.

Co-authors on this study include Yi Wang and Lawrence Berger. The research was funded by the National Institutes of Health, the Russell Sage Foundation and the Bill and Melinda Gates Foundation.

Journal

PEDIATRICS

DOI

10.1542/peds.2024-068174

Article Title

State-Based Eviction Moratoria and Child Maltreatment During the COVID-19 Pandemic

Article Publication Date

18-Apr-2025

Saturday, May 17, 2025

Journal

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Article Title

Article Publication Date

Journal

DOI

Method of Research

Subject of Research

Article Title

Stigma remains a barrier to treatment

Apart from stigma, a complex interplay of factors shapes HIV risk

The benefit of longitudinal data to make decisions

Journal

DOI

Article Title

A new era for radiocarbon dating – and worst-case scenario for solar storms

Further reading:

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Journal

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Method of Research

Subject of Research

Article Title

Article Publication Date

States that halted evictions had fewer cases of abuse, neglect

Secure housing may have positively influenced how parents treated their children

Policies should be prioritized in future disasters

Journal

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Article Title

Article Publication Date