Screening result from public data, not a construction recommendation. Sites, volumes and glacier areas come from the team's terrain analysis. Protected areas are checked against federal inventories. Natural hazards are read from federal index maps only; geology and access are not assessed, so no site is cleared.
A digital twin in three parts
781 km² holding about a third of Switzerland's glacier areaTerrain, 299 glaciers and the paths their meltwater takes, 15 basin sites with their volumes, federal protection inventories, hazard index maps, hydropower plants and dams.
Runoff period, emissions path, dam height, melt rate and glacier size. Change one in the row above and the ranking, the storage, the hydropower stress test and the business case follow.
Top of the shortlistwith the settings above
Score out of 100 and usable volume behind the chosen dam. Pick a site to open its evidence on the Sites sheet.
What is on each sheet
What mattersMove a weight and the sites re-rank.
Where basins could go
Click a site. Drag to pan, buttons or Ctrl + scroll to zoom.Base maps: team QGIS exports, © swisstopo. Satellite: Sentinel-2 mosaic of , swissEO S2-SR, © swisstopo, contains modified Copernicus Sentinel data. Glacier outlines: SGI 2016 (GLAMOS). Red line: study area (781 km²). Numbers on the map are the current rank. A dark dot marks a site under strict protection. Hazard layers: SilvaProtect-CH and the map of potential permafrost distribution (FOEN), index maps valid to 1:50,000, in the colours of map.geo.admin.ch. Plants and dams: SFOE. Meltwater flow paths are not in the evidence pack yet.
Ranked shortlist
Selected site
Right nowFederal measurements, pulled every 5 minutes and whenever the page is reloaded.
Rivers: Federal Office for the Environment, through the federal linked-data service (lindas.admin.ch). Air temperature and precipitation: MeteoSwiss automatic stations (data.geo.admin.ch). The gauges lie below reservoirs and diversions, so they show what each river carries now, not the inflow at a basin site.
The next five daysTrigger conditions over the glaciers, from the MeteoSwiss ICON-CH2 forecast.
A prototype of trigger conditions, not a warning service. A day is marked Watch when one condition is met and Elevated when thaw and heavy precipitation fall together. The two thresholds are the team's first setting. The card further down runs them over every day since March 2021 and four documented events; that is a test, not a calibration. Forecast: MeteoSwiss ICON-CH2 through Open-Meteo, at the 15 site locations, refreshed hourly. Official warnings: natural-hazards.ch.
Where a trigger would meet a mapped process
The same check for the hydropower on these rivers
Tested against the pastwhat the rule above would have said on every day since
What other thresholds would have said
A test, not a calibration. Every day is judged on the forecast for that day, kept in the forecast archive of Open-Meteo, and worked out as in the outlook above: the highest zero-degree level and the mean precipitation of the 15 site locations. The archive serves the best model it has for each date, so the model changes over the years; the live outlook uses MeteoSwiss ICON-CH2. A thunderstorm cell that misses the 15 points is not seen, and a multi-day event is judged on its strongest day. Four events cannot set a threshold: they show that the rule reacts on days that mattered, and the yearly counts show how often it reacts on days that did not.
Why this matters here
Blatten, 28 May 2025The Birch glacier above Blatten in the Lötschental collapsed on 28 May 2025. Ice and rock buried most of the evacuated village and dammed the Lonza. The federal gauge at Blatten has sent no reading since that day.
Three of the 15 ranked sites lie in that valley. Blatten is excluded as a settlement area, and the terrain analysis notes that the ground there has changed fundamentally. Fafleralp and the Jegigletscher forefield lie upstream of it.
- Shows where federal index maps place a process within 250 m of a site
- Shows when thaw or heavy precipitation is forecast there
- States every threshold and lets you move it
- Predict an event or its size
- Cover avalanches or glacier collapse
- Replace a hazard map or an on-site assessment
Avalanches are left out because the federal index map only models avalanches that start in forest, which says nothing above the tree line. The hazard index maps date from 2005 and 2006.
Why store: the water arrives earlier
Where the meltwater leaves
glacier area upstream of each exitThe six exits the terrain analysis lists, km² of glacier together. Its flow balance covers the whole terrain model, which reaches beyond the study area: 324.7 km² of glacier in the model, 324.4 km² arriving at its edge, so the routing closes. The report does not break down the remainder.
Where the ice sits, where basins fit
area by elevation bandTwo thirds of the area lies above 2,500 m and mean slope is 30° or more in every band, so flat ground is rare. All 15 ranked sites sit between 1,524 and 2,332 m, below most of the ice.
The ten largest glaciers
of 299 in the study area14 glaciers larger than 5 km² make up 75% of the glacier area. For the Grosser Aletschgletscher the analysis found no suitable site inside the area: its tongue ends in the steep Massa gorge. Thinning: how much the surface sank per year from 2000 to 2019, measured from space (Satellite sheet).
Ten years apart, seen from spaceDrag across the picture to compare.
Sentinel-2 true-colour scenes: swissEO S2-SR, © swisstopo, contains modified Copernicus Sentinel data .
Snow and ice left at the end of summer
what stays white, per year, from Sentinel-2How fast the ice is thinning
surface lowering per year, 2000–2019, measured from spaceThe latest passesAsked from the federal data catalogue when this sheet opens.
Sentinel-2 passes over the area every two to three days, and swisstopo publishes each mosaic 10 to 24 hours after the overpass. Your browser reads the picture and the cloud mask straight from the cloud-optimised files of the federal data catalogue (data.geo.admin.ch). Cloud share: cloud and cloud shadow inside the study area. Click a pass to see it.
Stress test: the hydropower on these rivers
A first-order stress test, not a plant model. The plants are matched to the nine catchments by name and location on the map; the match is this dashboard's and has not been checked with the operators. A run-of-river plant follows the monthly runoff up to its turbine capacity. A storage plant is shown by the energy of the water that reaches it, because its reservoir decides when that water is turbined. Every plant is scaled so that the reference runoff of 1981–2010 gives its expected production in the SFOE statistics. Runoff: Hydro-CH2018 at the gauge of each catchment, ensemble median; the range takes the lowest and the highest model month by month. Plants further down a river also take water from below the gauge, and pumping is left out.
What that does to the Swiss grid
The Swiss grid through the year
Wet and dry years on the grid
The storage lakes through the year
Energy held in the Swiss storage lakes as a share of what they can hold, week by week. The lakes are drawn down over the winter and refilled by snow and ice melt; how early and how fast they refill differs from year to year. Source: SFOE, filling of the storage lakes, read when this page was built.
The winter gap
net electricity import, October to MarchNet import is imports minus exports, summed over the winter half-year. Source: SFOE energy dashboard, cross-border exchange (Swissgrid figures). The winter energy of the basins is the illustrative Trift scaling of the Business case sheet, for the new sites still in play with the settings above. Nuclear outages and prices move the winter balance as much as the weather does; the grid itself, its lines and its market, is not modelled.
Business caseillustrative
Order-of-magnitude estimate, scaled in a straight line from the KWO Trift project (CHF 387 m, 85 Mio m³, 215 GWh of winter energy) and assuming a similar chain of power stations downstream. Investment follows the basin volume, energy follows the water the glaciers can supply. Head, the power chain and costs need a feasibility study.
If the glaciers shrink
usable storage against glacier sizeIn this scenario every glacier shrinks by the same share. Real retreat removes low-lying ice first, so a basin below a small, low glacier loses its supply sooner than shown. Move the Glacier size control at the top to apply a size to the whole dashboard.
Hydropower near the site
Plants of 300 kW or more from the SFOE hydropower statistics () and dams under federal supervision. Distances are straight lines; whether water from the site can reach a plant is not checked.
The winter store it would add to
energy held in Swiss reservoirs, weeklySwiss reservoirs fill with snow and ice melt from spring to early autumn and are drawn down over the winter, when the country imports electricity. Source: SFOE, filling level of the storage lakes, read when this page was built. The grid itself is not modelled.
Does the ranking hold up?
Evidence layers
A site cannot reach high confidence until the open layers are checked by a specialist.
Set against the federal report of 2024
- Finds sites from the terrain itself, so it also ranks places no operator has proposed
- Weighs storage, the late-summer gap, dam length, footprint and protection with weights anyone can move
- Asks the federal inventories for the protection status of each site, and re-asks on demand
- Responds to the runoff period, the emissions path and the glacier size, and shows the region's state today
- Cover Switzerland: the report lists projects in four cantons, this is one region
- Carry a design for each project: head, power chain and a dam sized by the operator
- Rank the Unterer Grindelwaldgletscher or the Oberaletsch, which the report lists
- Replace the weighing of interests that the report leaves to the authorities
From one region to Switzerland
reference architecture for a federal roll-out- swissALTI3D terrain, SGI glacier inventory
- Hydro-CH2018 runoff scenarios
- Protection inventories, hazard index maps
- Hydropower plants, dams, reservoir storage
- Live gauges, weather stations, ICON forecast
- Sentinel-2 satellite mosaics, every few days
- Flow routing and basin search in GRASS, on a study-area polygon
- Checks against the federal layers for each site found
- The study area is one polygon file: a new region is a new polygon
- A single JSON dataset per region
- Static JSON API with an OpenAPI description
- No server to run, any static host
- This dashboard, reading the region's dataset
- Live federal feeds asked from the browser
- GIS, utilities and offices reading the API
- Every source already covers the whole country, so no new data has to be bought or collected
- The dashboard and the API are static files: a federal or cantonal host can serve them as they are
- Data sovereignty: the live measurements, maps and satellite scenes come straight from Swiss federal services, and no account, key or tracker stands between a visitor and the data
- Jungfrau–Aletsch is the first region, with 303 of the about 961 km² of Swiss glacier area (SGI 2016)
- The terrain run has been done for this one region only and is not yet a repeatable job
- Site names and the match to Hydro-CH2018 catchments are not automated yet
- The forecast comes through Open-Meteo, free for non-commercial use: a federal service would read the MeteoSwiss open data itself
- This demonstration is hosted on GitHub Pages; the same files can move to a Swiss host unchanged
How this answers the Track 06 brief
Digital Twin Earth, SwitzerlandResponsible scope
triage upstream, professional validation downstream- Prioritises where experts investigate
- Explains why a site is shortlisted
- Exposes constraints and uncertainty
- Documents assumptions and evidence
- Recommends the next validation step
- Design dams or infrastructure
- Certify geology or hydrogeology
- Predict exact inflows
- Replace hydrological models
- Make legal or ecological approvals
Method limits. Surface runoff only (D8 routing on the 10 m swissALTI3D mean); subglacial flow and karst are missing. Meltwater is glacier area × the melt rate, with no rain or snowmelt from outside the glaciers. Glacier outlines (2013–2018) are older than the terrain model (2024/25), so forefields that have become ice-free since were not tested. Volumes tend to be slightly too small and dam length is indicative.
Sources and attribution.
- Team analysis: “Retention Basins for Glacier Meltwater, Jungfrau–Aletsch”, 2 Oct 2026 (GRASS r.watershed and r.lake; 43 candidates, 15 ranked).
- Terrain: swissALTI3D, © swisstopo. Glaciers: Swiss Glacier Inventory SGI 2016, GLAMOS.
- Runoff scenarios: Hydro-CH2018, FOEN, glacier catchment set L03, monthly total runoff, ensemble median and range.
- Protected areas: federal inventories of floodplains, mires, mire landscapes, BLN, game reserves and UNESCO World Heritage (FOEN) and hydropower-waiver areas (SFOE), queried through the geo.admin.ch API on 3 Oct 2026 for a square reaching 250 m from each point.
- Hazard process areas: SilvaProtect-CH (debris flow, rockfall, shallow landslide, 2006) and the map of potential permafrost distribution (2005), FOEN. For each site the share of the square reaching 250 m from it is measured: on the SilvaProtect-CH polygons of the federal data catalogue for debris flow, shallow landslide and rockfall, and on the federal map service for permafrost, on . Index maps, valid to 1:50,000.
- Hydropower plants (WASTA statistics), dams under federal supervision and the filling level of the storage lakes: SFOE. The plants and dams of the Risk outlook are read against the same index maps as the sites; their ground height comes from the swisstopo height service.
- Federal benchmark: Analyse des Wasserkraftpotenzials der Gletscherschmelze, report of the Federal Council of 6 December 2024 in fulfilment of postulate 21.3974. Project figures and assessments from its appendix.
- Energy sheet: electricity production by source, national consumption, cross-border exchange and the filling of the storage lakes from the SFOE energy dashboard (Swissgrid figures); precipitation at Grimsel Hospiz and air temperature at Jungfraujoch from MeteoSwiss open data. The match of plants to catchments is this dashboard's.
- Years of the Glacier size control: OGGM standard projections v1.6.1 (Open Global Glacier Model, Maussion et al. 2019), CMIP5 runs, glacier area of Randolph Glacier Inventory region 11, Central Europe.
- Test of the risk rule against the past: forecast archive of Open-Meteo (CC BY 4.0); the events are linked in the table on the Risk outlook sheet.
- Five-day forecast: MeteoSwiss ICON-CH2, served by Open-Meteo (CC BY 4.0). Satellite picture: swissEO S2-SR, swisstopo, from Copernicus Sentinel-2 data.
- Satellite sheet: Sentinel-2 scenes from swissEO S2-SR, © swisstopo, contains modified Copernicus Sentinel data 2015–2026; snow and ice extent is this dashboard's own count on those scenes. Glacier thinning: Hugonnet et al. 2021, Nature 592, from ASTER satellite stereo pictures, on Randolph Glacier Inventory 6.0 outlines.
- Round-table reference: SRF on the 15 hydropower projects; KWO on the Grimsel enlargement.