Scientists say Estonia lacks comprehensive stormwater drainage plan

Estonia lacks a comprehensive plan for managing excess rainwater, although solutions are available, researchers at the Estonian University of Life Sciences told ERR. The warning follows a weekend of heavy rainfall that exceeded a month’s average in several parts of the country and flooded streets in some areas.

Rainfall in Estonia has become more frequent and more intense over short periods, making flooding increasingly common in densely populated urban areas. A study by the university found that rainfall intensity has risen by 4 percent over the past decade and is likely to increase further.

Researcher Ottar Tamm said responsibility for excess water currently rests mainly with water utilities, although property owners and local governments also have responsibilities during intense rainfall.

“Rainfall is becoming more intense, but the pipes are not getting larger. The water must have somewhere to go, and if the pipes cannot contain it, routes must be planned for it,” Tamm said.

He said cities should plan pathways for excess water, including when new streets are built. In Tartu, the Emajõgi River receives the city’s stormwater, but a flood barrier means the water remains on the city side of the barrier. Tamm said the city should pay particular attention to the Supilinn neighborhood when planning new streets.

Tartu is currently testing a nature-based stormwater solution in the harbour railway area. The project involves creating detention areas, such as ditches, where water can remain temporarily before being directed into pipes. This helps prevent pipes from being overwhelmed when large volumes of water arrive at once, Deputy Mayor Kertu Vuks said.

Such solutions are not suitable for the most densely built-up parts of cities. Rain gardens being tested by the university to retain excess water would be best suited to areas where housing is still being developed, Tamm said. He suggested that stormwater measures such as rain gardens could be included in comprehensive plans from the outset.

“We have not made this mandatory so far, but looking ahead, it could certainly be an additional alternative, considering how much rain can fall at once,” Vuks said.

Tamm said solutions for collecting and directing excess water also exist in densely populated areas, although they cannot be applied everywhere. University researchers are expected to complete a more detailed guide for engineers and local governments by the end of autumn.