Augustenborg Ekostaden — Malmö's Open Stormwater Retrofit of a 1950s Housing Estate

Augustenborg, a 1948–52 housing estate in Malmö suffering flooding, high tenant turnover and unemployment, was retrofitted from 1998 under the 'Ekostaden' programme led by the municipal housing company MKB with the City of Malmö. Total investment was about SEK 200M (~€24M), roughly half from MKB, SEK 24M from the national LIP programme and SEK 6M from EU LIFE (Botanical Roof Garden).
The open stormwater system (6 km of channels, 10 retention ponds, over 11,000 m² of green roofs) has handled around 90% of stormwater from roofs and impervious surfaces since 2001, and cut annual runoff by about 20% versus a conventional system. The district was reported unaffected by the 2007 50-year rainfall event that cut off much of Malmö, and avoided severe damage in the 2014 100 mm/6 h event.
Reported social outcomes include roughly 20% lower tenant turnover, unemployment falling from 30% to 6% (1998–2002) and election turnout rising from 54% to 79%; about one fifth of tenants took part in the dialogue. These are before/after figures without a control group, so attribution to the programme is not proven.
Documented limits: maintenance costs roughly double those of a conventional sewer system, limited space, safety concerns near schools and for elderly or disabled residents, and algae in ponds.

Read the full analysis: https://climate-adapt.eea.europa.eu/en/metadata/case-studies/urban-storm-water-management-in-augustenborg-malmo/