Norwegian reservoir levels likely to peak by mid August

We expect Norwegian reservoirs will reach 93%-95% of max capacity in the first half of August, but developments will be bumpy and uneven across the country.

Some key observations:

• In April and May, inflow levels to Norwegian reservoirs were only 50% of normal.
• In June, inflow levels were at an all-time high of 170% of normal as temperatures mostly averaged 4–6 degrees higher than the historical average throughout the country.        
• From the start of July (midweek 27), inflows are declining strongly.

Based on these latest develoments, we have reviewed the Norwegian hydro-balance and updated our forecasts for snow, groundwater and hydro-reservoir levels.

We've also made a special case study of NO2 which we’ll publish later this week.

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The key numbers

Inflows dropped sharply from 29 June (start of wk 27) as the weather turned colder. Currently (wk 28) inflows are at 90% of normal, while only a few weeks ago they were close to 200 % of normal, as illustrated with the following snapshot from EQ’s online hydrology tracking and forecasting service:

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• For the April-mid-July period (wk 14-end of wk 29), the net accumulated inflows were about 8 TWh (111%) higher than normal.
• By week 14 the snow/groundwater level was about 61 TWh, or 20 TWh higher than normal.
• Since 1st of April the precipitation has been about 2 TWh lower than normal.

Today's snow + groundwater levels are about 10 TWh higher than normal (= 20-8-2 TWh), which is an all-time-high.  Statistically, a snowpack of 2-3 TWh could survive the summer without melting:

‍Reservoir outlook

We currently estimate that the water filling for Norway as a whole will be 85% by the end of week 29, down from our May forecast of 89%.

We also estimate that a 93%-95% filling will be reached in week 32-33.

We expect 7-9 TWh of water spillage during August, and we don't expect declining reservoirs until the end of September given normal weather conditions. In this calculation we assume that the export capacity from Norway remains reduced.                                          

All in all, despite declining inflows, there is still more than enough snow to be melted for the hydro reservoirs to reach close to full capacity this summer.

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Blog edited by: Morten Munkejord