The drought of the last three weeks in particular has had a critical impact on water levels. A southerly air flow starting today will bring relief.
The water levels of inland and sea water have been surprising and worrying Finns throughout the rest of the summer.
For example, the shoreline of Hamina’s Pitkienhiekki sands has receded several metres, revealing barges and rocks. On Saimaa, on the other hand, residents have speculated that the low level of the lake is not simply the result of artificially lowering the water level.
Niittyniemi says that the last three weeks in particular are the reason why it is so dry now.
– It is normal that towards the end of summer the water levels drop and the fall rains starting in August correct the situation.\n Now we are still waiting for the autumn rains. It was really rainless from August.
Sea water level half a metre below zero
An exceptionally low level of sea water has been observed in Etelä Kymenlaakso as well as on other beaches in Finland.
According to Niittyniemi, the total water volume of the Baltic Sea is currently small due to the low runoff. In addition, the north wind pushes the water away from the coast.
– The surface is minus 50 centimeters. According to meteorologists, the reading is relatively rare, only once in 10 years is it this low.
Relief from the drought is expected in a couple of days, when the wind turns to the south. However, it will take a couple of weeks for the sea level to stabilize.
– Rain is the only thing that will fix this situation, but even a small amount of rain will not change the situation. Because the trees still have leaves and the ground is like a dry sponge, runoff does not occur right away, says Niittyniemi.
Saimaa has its own rhythm
Rainfall accounts for water level heights. In the southeast, this year’s precipitation was concentrated during the snowy season.
– Few may remember that there was a lot of snow in the winter for a long time, almost a record amount in the southeast corner. Since then, the amount of precipitation has started to decrease here, says Niittyniemi.
Water bodies of different sizes react differently to low rainfall. For example, Saimaa has its own rhythm for when the water rises and when it falls.
– Now in the middle of September, the surface of Saimaa is 10 centimeters lower than normal. People’s knowledge of the exceptional lowness is due to the fact that in the next few years, Saimaa’s water level has been above average. There is still 40 centimeters to go from the current situation to the lower limit of the normal value.
According to Niittyniemi, large inland waters are therefore not exceptionally low at the moment.
In small bodies of water, on the other hand, the drought appears faster. For example, at flow points, the lack of water can be dramatic.\n In rivers and small streams, it may also have an effect on the spawning of migratory fish.
– If the water is warm and scarce at the same time, the situation is bad for the fish.
Niittyniemi reminds us that water level fluctuations are part of nature. In lakes, the exposure of shores has its own effect, for example, on shore vegetation and species.
– On the other hand, if the water gets really low, for example in lush lakes, the risk of lack of oxygen increases.
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