Vltava in Prague drops to a third of normal, Slapy keeps falling

Water levels in Czech rivers have dropped to 10–50% of their long-term average, and in some places only a tenth of the usual volume is flowing. In Prague, the Vltava's inflow at the Praha-Chuchle station is currently around 40 cubic metres per second — less than a third of the average annual norm of 134 cubic metres, according to the Czech Hydrometeorological Institute (ČHMÚ).

Vltava near Prague drops to a third of normal

According to ČHMÚ, the hydrological drought threshold at Praha-Chuchle is set at 47.4 cubic metres per second — the current inflow is already below that mark. “Surface and groundwater levels remain significantly, and in places extremely, below the October norm,” said ČHMÚ hydrologist Martin Pecha. Rain in recent weeks has brought only temporary relief: in the south and southwest of Czechia the surface-water drought has barely let up, and reserves in the Lipno, Orlík and Husinec reservoirs have not grown noticeably.

Orlík and Slapy at record lows

The biggest water shortage is on the Vltava cascade — the Orlík and Slapy reservoirs. According to Povodí Vltavy director Petr Kubala, both are now at their lowest level since they were put into operation: their reserve capacity is only 36% full. Lipno is 50% full, with its level close to a historic low. “The level at the Orlík reservoir is stagnating, and the minimum release from the Vltava cascade is now being maintained from Slapy's reserves,” Kubala said. According to him, such a situation has never occurred in the entire time the cascade has operated, although it was anticipated when the reservoirs were designed — something like this can happen roughly once every 50 years.

As recently as spring, Orlík's reserve capacity was 94% full. But since 10 April, the cascade has maintained a minimum release of 40 cubic metres per second below the Vrané dam, while less water has been flowing into the reservoirs than flowing out — so Orlík has been steadily losing its reserves. In early September its level dropped to the set mark of 334.60 metres above sea level, after which Povodí Vltavy began drawing on Slapy's reserves to maintain the minimum release. Without strong rain, Slapy's level will keep falling. Without water from Orlík and Slapy, the Vltava's inflow in Prague would currently be only about 10–15 cubic metres per second — whereas the cascade maintains a release of at least 40 cubic metres per second. This water matters for water abstraction, diluting treated wastewater and sustaining life in the river. At the same time, the low level at Orlík and the drop at Slapy do not mean homes will run out of drinking water: reservoirs used for water supply in the basin are 50–85% full, and according to Kubala, residents will not notice anything at all. Povodí Vltavy does not forecast any restrictions on household water supply even over a longer horizon.

A similar situation on the Elbe

Low inflows are also being recorded by Povodí Labe: rivers in its basin are currently carrying only 10–70% of their long-term average. “The situation is unfavourable,” said Povodí Labe spokesperson Aleš Prokopec. 48 monitored profiles are currently at or below the hydrological drought threshold, with extremely low levels recorded on the Cidlina, Doubrava, Tichá Orlice and the Elbe itself. Because of the water shortage, Povodí Labe continues to use most of its reservoirs to feed the rivers — essentially releasing water to replace the missing natural inflow. This summer, one of the driest and hottest on record, almost all the reservoirs in the basin helped sustain river flow, and most still do so today. According to Prokopec, some are releasing several times more water than they receive: the Hamry reservoir is currently releasing 8 times more water than it takes in, Mšeno 7 times more, and Seč 5 times more. The Rozkoš reservoir has zero inflow at all, yet it still releases two cubic metres of water per second. The reserve capacity of the small Pařížov reservoir has now emptied completely — during the worst of the drought its water was used to feed the Doubrava river.

No significant rain expected for now

Rain in recent weeks has helped the soil and plants, but has not noticeably replenished groundwater reserves — even several rainy days will not solve the long-term water deficit. “From a long-term perspective, we need several consecutive months of above-normal rainfall, ideally across most of the country,” Pecha noted. The coming winter will also be important, he said: if water reserves in the landscape are not sufficiently replenished by then either, the shortage could already be felt next spring. Meteorologists do not expect significant precipitation in the coming week. “Across most of the country, unfortunately, nothing at all will fall. And where there is some precipitation, it will only amount to a few millimetres,” Pecha said. A chance of a change in the weather appears around Friday, but the forecast is still uncertain, and the forecast for the rest of October also shows no precipitation capable of noticeably easing the hydrological drought. Specialists advise treating forecasts beyond 7–10 days with caution.

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Source: seznamzpravy.cz