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EQ survey of NO2 reservoirs shows they are nearly full with a high risk of spillage

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

As 2020 represents an extreme hydropower situation in Norway (partly in Sweden and Finland as well), we have made the extra effort to inspect with our own eyes – and camera! – several hydro reservoirs in the NO2 price zone.

EQ operate hydrology models for all price-zones in the Nord Pool area. These models are based on aggregated values for all variables such as precipitation, inflows and hydro reservoir content, quantified into GWh, MWh or TWh units.              

Aggregated numbers are essential, but sometimes it’s worth the effort to – almost literally – dip your feet in the water to see if reality matches the models.

Having visited and gauged the water levels of nine reservoirs in the NO2 price area, we are able to confirm that levels are high and likely to rise further.

Combining our own observations with available official information we have been able to estimate the energy content (TWh + %) for these reservoirs, which represent 28% of the total reservoir capacity for NO2 (ref table below).                                                                                                                        

The filling level in the observed reservoirs varies between 74% and 96%, corresponding to an average of 88.1% at the end of week 27, or 8,282 GWh of max 9,402 GWh.

The average 88.1% figure for this selection of well-regulated reservoirs is slightly higher than the NO2 official average of 85.7% which indicates that NO2's two largest multi-year reservoirs, Blåsjø and Svartevatn, have lower filling levels, perhaps closer to 80%.  

Regulation capacity: Max Reservoir capacity (GWh)/Yearly inflow (GWh). MASL = metres above sea level

The chart below shows the average reservoir filling for all of NO2 up until week 27. We estimate that these reservoirs will be around 90% full by week 29, which equals the maximum level for the 2000-2019 period.                                                

Some of the nine observed reservoirs are likely to be completely filled by week 29, and with an expected 95% average filling we are likely to see water spillage to avoid the risk of flooding going into August.

Reservoirs likely to reach 90% of max capacity by wk 29

Seeing is believing. We are therefore happy to share some of our observations from our tour of the NO2 reservoirs below (all photos: Eylert Ellefsen).

Estimated filling: 86%. 5m from max.  Nearly 1.5 TWh capacity
Estimated filling: 91%. 10m from max. Nearly 2 TWh capacity.
Water spillage from reservoir. We expect more spillage from several reservoirs in August.
Still snow left to be melted. Lake level: 1,000 masl.
Lake level: 500 masl. Very little snow in sight, but the inflows must come from somewhere...
The water level is in this reservoir was too difficult to assess, but looks high...

Edited by: Morten Munkejord

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