On the boundary of Warsaw city south districts Mokotów and Ursynów runs a small river: Potok Służewiecki. The river was frequently causing flooding due to its high degree of urbanisation and rising area of impermeable surfaces in their catchment. Above the frequently problematic part of the river, where floods were occuring, was a pond which lost its retention function due to lowering groudwater levels. The pond was rewitalised with city own funds in years 2013-2015 and later on upgraded with recreation area around in the form of park with use of EU funds. EU funds created also spaces that allow for feeding and breading of migrating birds, EU funds also helped to install a small water turbine (Achimedes tubine - safe for fish) that produces some electric energy - 3kW. The whole investment eliminated the most dangerous floods because water is catched again with the pond. The investment created a new recreation area for the surrounding housing and offices.
Eu funding from regional funds was 6,3 mln zł (67% of 9,4 mln zł for the whole investment).
It is recommended to create surface retention ponds in the cities as a recreation areas. Such surface water areas reduce heat island in the cities. If ponds are created wisely they can reduce river floods or flooding of housing or streets caused by rising intensity of rains. Some locations of the pond can be used for production of electric energy from water flow.
Information sourcesWarsaw City
Description of the renovation of the pond (Polish): https://www.warszawa.pl/sluzewiecki-balaton/ Description of the creation of park surrounding the pond (Polish - page 35): https://um.warszawa.pl/documents/57906/2297782/broszura_wykorzystanie_fe_w_warszawie.pdf/53f7dc1a-9099-1b79-dc68-e46f2f9c7fcc?t=1634497958133 Description ofthe small river power plan on the pond (Polish): https://um.warszawa.pl/-/zielona-energia-potoku-sluzewieckiego