Understanding Slush Flows: The Arctic Hazard Threatening Lives and Infrastructure

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Slush flows endanger Arctic roads and communities. Discover how new tools are improving slush flow forecasting to mitigate risks in Norway and beyond.

Slush flows – masses of water-saturated snow that can travel long distances at high speed – are a significant yet under-researched natural hazard. Unlike avalanches, which require steep slopes of 30 to 45 degrees to initiate, slush flows often start on gentler slopes of less than 30 degrees. This is because they rely on oversaturation of snow by water, creating an unstable mass that can suddenly surge downhill.

The Impact in Norway

In Norway, slush flows are a recurring danger. These events can be deadly and cause widespread disruption. Finnmark, with its vast expanse of nearly 48,000 square kilometers and over 4,200 kilometers of roads, is particularly vulnerable. Roads are a lifeline in this remote region, essential for commuters, access to hospitals, and the fishing industry. Yet, closures caused by slush flows can force detours of four to nine hours, with significant consequences for residents and businesses.

Trond Jøran Nilsen, an avalanche planning expert in Finnmark County, highlights the challenge: “The roads in this county are like the lifeline for people because it’s almost the only way to get around. So it is really important the work the road authorities are doing to keep the roads open.” However, while tools and models for avalanche forecasting are well-developed, slush flow prediction remains in its infancy due to limited knowledge of the processes behind these events.

A New Tool for Slush Flow Forecasting

To address this gap, researchers at the University of Tromsø are developing a digital tool to map slush flow hazards as part of our project. This innovative hazard map integrates data on extreme weather conditions—such as heavy rain, high temperatures, and strong winds—to predict areas at risk.

Christopher D’Ambiose, who leads the research at the university, is adapting an avalanche simulation model he previously developed for Austria to account for slush flows. “I’m currently in validation mode. I have the simulation working. I’ve come up with a method for automatically identifying potential release areas. Now I need to make sure that the simulations actually match reality,” he explains.

These simulations are vital for understanding the cascading effects of slush flows. For example, when a slush flow hits a lake, it can overflow, gathering debris and mud, potentially endangering roads and communities downstream. By providing timely warnings, this tool could save lives and prevent costly damage.

Unique Arctic Challenges

Slush flows are more common in Norway and Scandinavia than in southern regions like the Alps. This is due to unique environmental factors in the Arctic, such as the midnight sun, which prevents freezing at night, allowing water to accumulate in the snow. Additionally, Norway’s thin soil layers—a remnant of the last Ice Age—limit water drainage, exacerbating the risk.

In contrast, the Alps experience nighttime freezing, which helps reduce snow’s water content. Any residual water there can also seep into the thick soil layer, further stabilizing the snowpack. In Norway, however, the lack of these mitigating factors makes slush flows more likely during warm periods or winter rains, especially when weather systems bring moisture from the ocean.

Field Tests to Enhance Slush Flow Forecasting

Field assessments are a critical part of slush flow research. In Finnmark, road authorities collaborate with researchers from the Arctic University of Norway to observe and document slush flow paths. This data is uploaded to a national database to improve hazard maps and identify potential release areas.

Christopher D’Ambiose emphasizes the importance of these efforts: “It’s an important part of the research because we expect warmer and wetter winters up here in the Arctic. So we expect more of this kind of wet snow hazard to come in. Wet snow hazards could be wet snow avalanches or slush flows.”

Field tests involve measuring the water content of snowpacks, a key indicator of stability. Researchers use simple but effective methods, such as checking if snow can form a snowball, squeeze out water, or visibly show water between snow grains. These classifications help validate simulation models and improve hazard predictions.

A Safer Future for Norway and Beyond

By combining field data with advanced simulations, the research team aims to create a comprehensive national hazard map for slush flows. This tool could help road authorities in Norway and other regions with seasonal snowpacks to mitigate risks, protect infrastructure, and save lives.

As warmer and wetter winters become more common in the Arctic, understanding and preparing for slush flows will be crucial.

Watch our latest video to see how these innovative efforts aim to save lives, protect roads, and enhance climate resilience in Scandinavia.

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High temperatures

Record-breaking summertime temperatures have been recorded in the Netherlands in recent years. With global temperatures rising, such extreme weather events will occur more often, and for longer periods. Prolonged high temperatures, with warm nights as well as hot days, can cause heat stress* and related health issues, particularly among city populations.

*Heat stress occurs when the human body cannot get rid of excess heat and can impact wellbeing through conditions such as heat stroke, exhaustion, cramps and rashes.

"We want to enable municipality decision makers who are working on spatial developments to identify heat stress 'hot spots' and cool areas, analyse the future effects of climate change, and model the effect of different heat stress-reducing measures. The tool must provide them with an easy starting point to integrate heat stress risks in their projects."

Issue

Despite the cooling effect of the sea in the region of Zeeland, the growing risk of heat stress has become a concern.

Elderly and other vulnerable people are more impacted by the effects of prolonged heat, which can cause headaches, dizziness, insomnia and other health issues – even death. Excess temperatures also affect general comfort and liveability of cities. Water quality can be reduced, both for drinking and swimming, and infrastructure can be affected. Buildings and concrete surfaces trap heat, potentially leading to damage, and release it during the night, keeping temperatures warm.

During heat waves, it is important that everyone has access to a cool and comfortable place. Appropriate spatial planning can help to decrease and deal with heat stress. Environmental factors like water bodies, trees, and shade have a major impact on stress caused by high temperatures. Therefore, planting trees, removing concrete surfaces, creating green roofs and cool spaces can improve our comfort and health. The IMPETUS Atlantic team is developing a digital tool to support regional decision making for city planning to address these needs.

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Flood risk

By 2050, sea-level within this region is predicted to rise by 15-40 cm, with more frequent extreme weather and more (severe) storms triggered by climate change. These changes will exacerbate the natural risk of flooding in the IMPETUS ‘Atlantic’ region, because it is surrounded by rivers and the sea, and is below sea level.

*Risk takes into account two aspects; the chance that an event will occur and the negative impact of such an event once it occurs. When there is a low chance that an event will occur, but its impacts are huge, the risk is still significant.

“In the Netherlands, an extensive system of dikes protects us against sea and river flooding. We have always put our faith in this defence and focused almost solely on flood prevention. However, pressure on our system will increase with climate change and rising sea levels. To adapt and maintain a safe living environment, we should develop other safety measures, like more robust spatial planning and contingency plans."

Issue

Rotterdam city, is located in Rijnmond – ‘mouth of the Rhine’. The Rhine river flows through this densely populated area and characterises the region. Protections such as sea dikes and storm surge barriers have been constructed to protect the region, but flooding still occurs.

People living in the city are accustomed to seeing smaller floods. The changing climate affects the interplay between rainfall, river levels and sea storms, increasing the flooding risk. Water levels could rise by a few metres, even in populated areas, with potentially massive impacts. 

Mitigation measures such as storm surge barriers reduce the chance that high water reaches the city, but to minimise the impact of floods when they do occur, adaptation strategies are also needed. A city that can adapt to be safe from floods must be carefully designed. How best to design such an adaptive city?

Critical infrastructure, such as hospitals and evacuation routes, must be accessible at all times. Planning how to best protect them, homes and lives is complex. Flood water behaves in a complex way and flood risks show strong spatial variations. The IMPETUS Atlantic team is developing a digital tool to support regional decision making for adaptive city planning. 

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Energy and waste water

To become climate-neutral by 2050, climate mitigation* efforts are crucial in our strategy for how to deal with climate change. Reducing our energy consumption is a significant mitigation step. In the Netherlands, 15% of energy is consumed in the Rijnmond area around the port of Rotterdam, in large part by a major petrochemical industry cluster.

*Climate mitigation encompasses measures such as technologies, processes, or practices that reduce carbon emissions or enhance the sinks of greenhouse gases.

Issue

The Rotterdam port petrochemical industry cluster is Europe’s largest. It consumes 70% of the Rijnmond region’s energy. A large part of this energy is wasted (64%, 203 petajoules). More than half of that energy is lost with wastewater. In addition, most energy processes within these industries rely on fossil fuels, which has a significant impact on the climate.

Energy use must be minimised and fossil fuels should be replaced by renewable sources if climate change is to be mitigated. Electrification of processes opens up the possibility to use more renewable energy and can greatly impact decarbonisation. Recovering wasted heat would significantly reduce energy consumption and is a first step towards a more circular industry. 

Supporting industries in a transition towards climate-neutrality depends on identifying how best to reduce their carbon footprint without sacrificing production or performance. The IMPETUS Atlantic team is creating a digital tool that supports decision making about pathways towards an effective energy transition for EU industry.