Elimination of the effects after the flood of 2 and 3 June 2013 - revised version after ICOMOS´s and ICCROM´s review

Objectives

Beginning of June 2013, Prague was struck by a "50-year flood". The anti-flood barriers (at the total length of 20 km) proved effective as they protected most of the (historic) centre of the city. Major problems were caused by smaller water courses, namely Botič, Rokytka and Šárecký Brook at few heritage sites for which the inclusion in the anti-flood protection system had not been feasible. The Botič stream (and its tributaries) flows through the Průhonice Park, which is part of the Historic Centre of Prague World Heritage property, and forms one of the main compositional axes of the park. The flood silted the watercourses, ponds and tops of weirs, damaged the emergency spillways, weirs, retaining walls and bridges, caused bank erosion, severely damaged the park paths and caused extensive waterlogging and subsequent falling of the waterlogged trees.

The project aimed at eliminating the effects of the flood of June 2013, in particular on the Botič stream, by

• addressing the damage to the paths, meadows and the existing vegetation of Průhonice Park;
• improving the ecological condition of the watercourses in the Průhonice Park and stabilising the flow rates in the Botič basin above the park.

Results

The following activities were undertaken:

• Stabilisation of the Botič stream bank (300 m) and of of the Dobřejovice stream bank (600 m) by stone (October-November 2014): the most eroded banks were stabilized with tightly packed large rocks that should make these parts of the banks withstand the pressure of water during extremely high flow-rates.
• Restoration of damaged 610 m of park paths (October-November 2014): the reconstruction work comprised the breaking up and repair of the base layers, ballast bed adjustment with additions of appropriately-sized aggregate and its covering with a packed-gravel surface. The area along the paths was landscaped and grassed over.
• Repair of spillway of Sádkový pond (April 2014): all unusable parts of the damaged spillway were removed, the walls were reinforced with local stone (slate) and the whole spillway was re-pointed. Concrete strip foundation was laid along the right bank of the Botič stream adjacent to the spillway and retaining walls were built with local stone, which stabilized not only the right bank of the Botič stream, but also the whole slope between the Botič and the Sádkový Pond. The Botič streambed was cleaned up. Under the spillway and near it a sill was built of large stones. The area around the spillway was landscaped and grassed over. The right and left banks of the Botič stream under the emergency spillway were landscaped and stabilized with rock riprap.
• Planting of new trees (April-May 2015): 48 new trees were planted, mostly in the floodplain areas of the Park along the banks of ponds and watercourses, to replace the trees that fell or were damaged during the flood. The species mix was chosen with a view to enhancing the dendrological value of the Průhonice Park.

The Průhonice Park reopened and its long-term preservation against floods was improved through the stabilisation of the flow rates in the Botič basin.