Back to Blog

Large differences in Alpine hydro balances

Eylert Ellefsen
Archived blog post. This blog post has been transferred from our previous blogging platform. Links and images may not work as intended.

EQ's new hydrology models indicate that we enter August with large differences in hydrological balance across the Alpine area. Switzerland and Austria now have reservoir fillings of, respectively, 12% and 8% above their seasonal normal, whereas France and Italy are on their seasonal normal. High snow reservoirs and delayed melting during the spring, was followed by a heatwave end of June and start of July. This sparked melting, led to high inflow levels and ultimately rapidly increasing hydro reservoir levels in Switzerland and Austria. The graph illustrates the status in Alpine hydrological balances at the beginning of August.

Follow EQ's hydro project

Montel's analysis service, Energy Quantified, is currently developing brand new hydrology models across Europe. This blog post is based on some preliminary results.

How did we end up here?

The difference in reservoir status may be explained by diverse development in many of the factors that contribute to the reservoir levels. The table shows net precipitation, inflow and net production, for the Central Western European (CWE) area and Italy in July.

Italy, as a whole, showed higher precipitation than normal, while the central part was rather dry. The temperatures averaged 2 °C higher than normal. However, notice that by mid-July temperatures were close to normal.

Italy and Switzerland came out with relatively high production, while the other countries produced slightly less than their seasonal normal. The total net hydro production (pumping plants not included) of about 19 TWh, represents about 20% of total consumption in the region.If we exclude Germany, which has low hydropower generation, the coverage is about 25%.

These numbers indicate the importance of hydropower in the spot markets during the summer period.

Delayed melting and a heatwave

The hydropower situation in the Alpine region (CWE+IT markets) was influenced by the heatwave we saw at the end of June and during July. The seasonal snow levels melted very quickly during the last weeks in June/start of July, and hydro reservoir levels increased rapidly in Switzerland and Austria in particular due to the high inflows.


During July the inflows levels declined towards normal levels despite a rather dry period. This indicates that melting from glaciers contributed to higher reservoir levels in the central parts of the Alps.

Development in snowpack

The energy content in the snowpack varied across the Alps this year. For France, the snowpack was lower than normal, while for the Central Alps – Switzerland and Austria – the levels were far higher than normal. Due to precipitation and delayed melting during May, the Swiss snowpack was at an all-time high by end of May. The main melting process started as late as week 23, and we see from the charts the declining snowpack during weeks 24–30.

Temperatures by end of June increased towards 6 °C above normal (week 26), which means about 15 °C at 2000 meters above sea level.

We saw more or less the same development for Austria.

For France, the inflows did not exceed the normal due to moderate snow levels, while we for Italy saw inflows somewhat above normal in June/July as an average.

All-time high seasonal reservoir levels

The Swiss reservoir level end of July reached an all-time high and hydro production has increased due to continued high inflows. For Austria, the production has softened the last weeks as Austria is not so exposed to the high mountain areas as Switzerland. French hydropower production has been moderate during July and reservoir filling now close to normal.


We invite you to follow Montel's EQ and the development of our hydro system.

More from the Blog

Austrian hydropower: Extreme precipitation and flooding in week 32

Eylert Ellefsen

The hydropower situation in Austria is now at a nearly maximum resource level. Production from the reservoirs has to be increased in the coming weeks to avoid further flooding and uncontrolled production levels. So far, we haven't seen any effect on the spot market as the German renewables are the main price drivers. However, the strong Austrian hydropower will contribute to slightly lower domestic spot prices.

Read Story

Yr-2021 power contracts: Massive market movements, uncertainty and COVID-19 recovery

Eylert Ellefsen

The market outlooks for 2021 are very exciting with uncertainty about French nuclear capacity, effects of German coal-fired and nuclear phase-outs, and consumption and financial recovery from COVID-19. In addition, there is an upward potential for both CO2 and gas prices.

Read Story

Romanian hydropower situation back to normal?

Eylert Ellefsen

The hydropower situation in Romania and most of Southeastern Europe improved in July after a wet June. Price differences between Austra (CWE region) and Hungary/Romania (SEE region) are significantly reduced from the start of Q2. Outlooks for August indicate that the price difference most likely will come out lower than 7 €/MWh which has been traded in the end of July.

Read Story

Ready to try Energy Quantified?

No payment or credit card required.
Would you rather like a personal demo? Book one here with Hugo