Tallinn Soodla water reservoir drying up due to climate change

This summer, the Soodla reservoir released so much water into Lake Ülemiste that, combined with natural causes, the reservoir's water level decreased by 2.5 meters.
This summer, the Soodla reservoir released so much water into Lake Ülemiste that, combined with natural causes, the reservoir's water level decreased by 2.5 meters. Source: The Tallinn University Institute of Ecology

The Tallinn University Institute of Ecology has discovered that half of the Soodla water reservoir has evaporated. As the situation is critical, residents of Tallinn are advised to start using water sparingly.

Jaanus Terasmaa, a professor of eco-hydrology at the University of Tallinn, explained on the morning program "Terevision" that the Soodla reservoir is exactly what its name implies: a water storage place. Even if there would be less water than usual occurring naturally, the residents of Tallinn could have access to safe drinking water and hydroelectricity could be generated.

Terasmaa said that the reservoir is often full with water in the winter, while the soil naturally dries out in the spring. However, in order to restore the ecosystem's equilibrium the following year, certain basic conditions must be sustained.

"If we allow it to become completely dry and the water ecosystem disappears, we will lose its vital function: the ecosystem's ability to purify itself," the professor continued, and added that "water prices would hike as a result of the need to purify more water."

"Water levels are absolutely critical for preserving ecological balance," the professor said, and explained that the Soodla reservoir is unique in that its water levels cannot be restored artificially; the reservoir must be able to replenish itself.

The reservoir depends on the flow of the river Soodla for its water supply. In the first eight months of the year, from January to August, the river basin received under 300 millimeters of precipitation, Terasmaa said, while the normal range is about 500 millimeters.

The Soodla water reservoir is located in the municipality of Anija, Harju County, 2022. Source: The Tallinn University Institute of Ecology

The professor said that due to the new state of the reservoir, we should begin thinking about water conservation because water is becoming increasingly scarce.

"In Estonia, we tend to believe that we get a lot of rain and that the issue is that we have to divert water quickly. Reading Tammsaare, for instance: only a ditch is in making. Climate change, on the other hand, has made precipitation patterns more volatile," he said.  

Although the annual amount of rainfall in Estonia is about the same as in the past, Terasmaa explained that when it rains is also a significant factor. The prolonged heavy rainfall following a time of drought is of little benefit because the water is quickly carried to the sea, with little soaking in and replenishing the groundwater basin.

"As a society, we must start adapting to climate change. Water consumption is inevitable, yet water conservation is vital and attainable. Too long have we been accustomed to a water-abundant and water-absorptive lifestyle," he said.

Simple lifestyle changes can help to conserve water: for instance, everyone can turn off the tap while brushing their teeth or let the water run only after their hands are already soaped, Terasmaa said, adding that it makes good practice to begin with these small steps.

"Climate change has begun and what we are doing now as a species, such as reducing greenhouse gases, or at least attempting to do so, will not help our generation any longer. The changes that have begun are ongoing and we must be adapting to them fast," he said.  

Terasmaa emphasized, however, that Estonia is unlikely to end up in a severe water supply urgency, citing the models analyzed at the University of Tartu, which predict that the quantity of precipitation in Estonia would grow by around a fifth by the end of the century.

"However, we should keep in mind the overall water balance. As the temperature rises and evaporation increases — the water disappears faster," he said.

A month's worth of perspiration could now downpour all at once as the rainfall pattern became uneven. Warming winters are also a cause for concern because, at our latitudes, winter is when water replenishes the most.

"Snow falls with minimum evaporation, melts in the spring, fills reservoirs and nourishes groundwater abundantly. When this doesn't occur, as during warm, dry winters, our water supply begins to run out."

Cost, the professor added, is the greatest incentive for conserving both electricity and water. "The higher the price, the greater the savings. Unfortunately, that's how things are."

The reservoir's near future will be determined in the coming months, Terasmaa said. "The coming winter will be decisive whether the reservoir will look different next summer."

The Soodla reservoir is located in the municipality of Anija, Harju County. Next to Lake Ülemiste, both the Soodla and Paunküla reservoirs provide water to the residents of Tallinn.

The Soodla water reservoir is located in the municipality of Anija, Harju County, 2022. Source: The Tallinn University Institute of Ecology

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Editor: Kristina Kersa

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