The Morava River in Olomouc has taken on a new shape. On the stretch from its confluence with the Mlýnský stream to the railway bridge, the riverbed was revitalised, making it part of a reliable flood protection system. The terraced banks now allow water to spill safely during downpours without threatening the city. In normal times, residents have free access to the water to cool off, and thanks to evaporation and new greenery the neighbourhood’s microclimate has become much more pleasant. Once an inaccessible river has turned into a favourite place to relax.
Positive impact
Flood protection measures on the Morava River became a response to increasingly unpredictable weather: sudden downpours and disruptions to the landscape’s water balance and floods. Although the main goal remained protection from floods, the changes also had a positive effect on the river during periods of drought. The new channel and lowered banks provided better access to groundwater, creating ideal conditions for vegetation.
This helped soften the “heat island” effect characteristic of built-up Olomouc, surrounded by the open fields of Haná (Moravia, Czechia). Additionally planted trees and water evaporation significantly improve the local microclimate. Improving the river’s ecological condition turned an urbanised area into a living oasis in the city.
How does it work?
Increasing the capacity of the Morava riverbed under stage II A covers a stretch 1,437 metres long. It begins at the confluence of the Morava with the Mlýnský stream and ends where the river flows under the railway bridge on the Olomouc–Brno line. Under the project, the river banks were raised by 80 centimetres, and on narrow sections earthen embankments were replaced with walls. At the same time, along 625 metres of the right bank between the Velkomoravská and U dětského domova bridges and along 100 metres of the left bank in front of the U dětského domova bridge, the banks were lowered – they now rise 2 metres above the channel. This makes it possible to safely release flood waters onto undeveloped areas.
The project also included a hydraulic gate on the Mlýnský stream, increasing the volume of water flowing under the Velkomoravská bridge without damaging it, and relocating several engineering structures. Before construction began, 832 metres of the main sewer collector, 1.8 metres in diameter, had to be relocated – it was moved outside the potential flood zone.
The structure has not only technical but also ecological significance. It includes dividing the edge of the shoreline, alternating calm and turbulent sections and building shelters for fish. Thanks to the new parallel channel, a 350-metre-long island has appeared.
The starting situation
Before the works began, this stretch of the Morava could safely withstand only a flood with a 20-year recurrence. The river was deeply cut into the terrain, and the banks were cut off from the surrounding space and hard to reach.
Operation and maintenance
The reliable operation of the protection system depends on regular care of the walls, barriers and other flood-protection methods – both the vegetation and the technical condition of the engineering structures.
The new routes along the landscaped stretch of the river have become much more popular: pedestrians and tourists use them to reach the city centre, and people ride bicycles and roller skates. According to the 2017 traffic census, 669 cyclists pass through here every day.
Why was this particular measure chosen?
Modifying the Morava channel became part of a comprehensive project to restore the floodplain’s water-retention capacity in the river’s lower reaches, and was also included in the “Master Plan for Flood Protection in the Morava River Basin”. The project was tested using numerical calculation models. Hydraulic calculations compared three options for the section of the right bank levee between the U dětského domova bridge and the railway bridge. Following negotiations with the owners of neighbouring private gardens, the city of Olomouc, together with the river basin administration, chose a combination of a bank levee and a flood wall.
Obstacles and challenges
The main task was to develop a high-quality design and see it through to the end. Construction went ahead without serious complications, and the entire stage II A was completed on time.
How much did it cost?
The total cost of the works was 330 million Czech crowns (€13 million). Funding was provided by the river basin authority Povodí Moravy, s.p. and the city of Olomouc. The Ministry of Agriculture also provided a grant to support flood-protection measures. Their estimated service life is 100 years.