It is early June. Alpine resorts are getting ready for the summer season, and a group of researchers is heading up into the mountains—not in search of cooler air, but of answers. Alongside skis, they carry probes. They are not looking for downhill slopes, but for scattered patches of snow across ridgelines and high-altitude basins. They move through irregular landscapes, where snow no longer blankets the ground evenly but retreats into white islands—resilient remnants of a fading winter.
From these traces begins the effort to anticipate both droughts and floods. Because snow is water. And when that snow shrinks, changes form, and becomes unpredictable, what is at risk is far more than a landscape—it is a strategic, hidden water reserve on which rivers, lakes, crops, and life itself depend.
Talking about snow in June, then, is not the eccentricity of passionate scientists. It is a scientific, technical, and environmental necessity. Because managing water resources begins here too: with a snowpack that changes form but remains central. With a group of researchers climbing into the mountains not only to measure snow, but to provide us with a clearer, deeper, and truer understanding of our water future.
“Snow is the first building block of the Alpine water balance,” explains Francesco Avanzi, researcher at CIMA Research Foundation. “If we misjudge its quantity or properties, we miss the chance to anticipate droughts, manage floods, and more broadly, to design effective responses—from reservoir operations to river flow forecasting.”
The context of the SWE Intercomparison 2025
It is from this renewed awareness that the 6th Snow Water Equivalent (SWE) Intercomparison took place on June 3–4 in Châtillon and Breuil-Cervinia, Aosta Valley, organized by ARPA Valle d’Aosta, CIMA Research Foundation, and Eurac Research. Two days of fieldwork and research involving over 50 experts from 21 institutions, including regional environmental agencies, universities, Civil Protection, forest corps, energy producers, and applied research centers.
Over the years, the SWE Intercomparison has become a key technical and operational platform for studying the water resource stored in snow, with a strong focus on measurement techniques. However, the particularly dry years of 2022 and 2023 brought attention to an emerging issue: the discontinuity of the snowpack and its growing occurrence even during periods typically characterized by consistent snow cover.
The 2025 edition of the Intercomparison was conceived in this context. Its goal: to better understand the characteristics of patchy snow cover (snow patches)—snow that does not uniformly cover the ground but appears in irregular, fragmented patches, strongly influenced by topography, solar radiation, wind, and temperature.
From continuous snow to snow patches: a paradigm shift
“In typical winter conditions, snow is continuous, and our goal is to estimate the total water content at the watershed scale,” notes Simone Gabellani, Head of the Hydrology and Hydraulics Area at CIMA Research Foundation. “But when snow is patchy, as increasingly happens even during traditionally snowy periods, we need a paradigm shift. We must assess how much water is held in each patch, how their characteristics vary, and whether they can be monitored remotely—perhaps even via satellite.”
This change in perspective is urgent. As data show, patchy snow conditions are no longer the exception limited to the end of the melt season. In recent years, driven by rising temperatures and decreasing snowfall, snowpack discontinuity is occurring more frequently—even in mid-winter. A new approach is needed—one capable of addressing the complexity of a fragmented snowpack that behaves very differently from a continuous one.
A shared measurement protocol
During the Intercomparison, participants tested field protocols designed specifically for snow patches. After a preliminary satellite-based analysis to identify snow-covered areas, ten teams of five people each were equipped with dedicated instrumentation: snow depth probes (Hs), snow water equivalent (SWE) sampling kits, and GPS devices to geolocate measurement points. Each team traversed evenly spaced sampling lines, approximately 20 meters apart, measuring snow depth and identifying points of maximum accumulation, where snow pits were dug to perform more detailed SWE measurements.
The role of technology and the scientific community
“Working with patchy snow is not easy: we lack historical data, we lack models, we lack a shared vocabulary,” says Umberto Morra di Cella, UAV survey specialist and researcher at ARPA Valle d’Aosta and CIMA Research Foundation. “But what we’ve seen is that, despite their fragmentation, snow patches show certain recurring behaviors from year to year. This gives us hope: we can begin to build a robust scientific knowledge base—provided we invest in observations and collaborative comparisons like this one.”
In addition to the scientific and technical aspects, the Intercomparison also had strong collaborative value. The simultaneous presence of diverse institutions—with complementary methods, instruments, and expertise—enabled the comparison of measurement techniques, discussion of operational challenges, data validation, and the development of shared hypotheses. This growing community of practice is a fundamental pillar in addressing future water-related challenges.
From snow to drought: a transition we must predict
The challenge of patchy snow can no longer be postponed. Water resource management depends on our ability to predict how much and when snowmelt water will flow downstream. In a world increasingly affected by water crises, investing in the understanding of snow—even (and especially) when it appears as scattered patches—is an act of scientific and environmental foresight.
This is why, on the World Day to Combat Desertification and Drought, it makes perfect sense to talk about snow. Because the fight against drought also begins here: with a snowpack that changes form but remains essential. With a group of researchers climbing the mountains not only to measure snow, but to offer us a clearer, deeper, and truer understanding of our hydrological future.
