Neighbourhood-scale sustainable urban drainage (SUDS), Pankow, Berlin, Germany

The site is a 117-hectare residential neighbourhood in Berlin's Pankow district, combining multi-storey apartment buildings from the 1920s and 1930s with taller post-war residential blocks. Its population density and age structure make it a typical Berlin neighbourhood; the population stood at 23,276 in 2017. The area has a high proportion of sealed surfaces — buildings, streets, parking areas and railways — which increases stormwater runoff and puts pressure on drainage infrastructure. Research cited in the study found that parts of Berlin with high urban heat also tend to generate significant stormwater pollution, and that demand for the services green infrastructure provides is greatest in the most densely built-up districts.

The KURAS project aimed to develop and compare practical options for managing stormwater at neighbourhood scale, retaining water at source rather than conveying it rapidly away. The scenarios were designed to meet local requirements around groundwater management, urban climate and biodiversity, and were then evaluated economically to identify which combination of measures offered the best value.

Challenges addressed

The SUDS packages address climate change adaptation, managing stormwater to reduce flooding during heavy rainfall.

Costs of NbS

The study designs three complete SUDS packages for a neighbourhood in Berlin-Pankow, combining green roofs, façade greening, tree drains, swales, ponds, permeable pavements, rainwater cisterns and retention soil filters. Façade greening dominates the costs, accounting for most of the installation and maintenance spending in Scenarios A and C. Over 50 years, total costs are about EUR 89.8 million for Scenario A, EUR 46.3 million for Scenario B and EUR 131.1 million for Scenario C (2023 prices, 3% discount rate). Scenario B is cheapest because it uses far less façade greening and more ponds and tree drains, with installation of about EUR 18.5 million and maintenance of about EUR 1.1 million per year.

The SUDS packages reduce runoff and flooding, recharge groundwater and save drinking water through rainwater harvesting. Green elements clean the air, store carbon, create habitat, cut heating and cooling needs and extend the life of buildings, while a greener streetscape raises property values. Present-value benefits over 50 years are about EUR 64 million (A), EUR 62 million (B) and EUR 109 million (C) (2023 prices). Including wider social benefits improves the results only slightly.

Benefit–cost ratio

Only Scenario B pays off, with a BCR of 1.33; Scenarios A (0.71) and C (0.83) cost more than they return. The right mix of measures is therefore decisive for economic feasibility.

The KURAS project partners, working in separate groups of stakeholders, planners and interest groups, drew up three independent stormwater management scenarios for the study site. Each set out a different extent and spatial arrangement of measures, from swales and ponds to green roofs, tree drains and permeable paving.

Climate and land-use data were organised on an 8 m × 8 m grid, recording how each parcel of land is used and the level of daytime heat stress at pedestrian height. Grid cells containing green infrastructure were identified so that their effects could be assessed separately from the wider drainage measures.

An economic valuation followed, covering installation and maintenance costs alongside monetised ecosystem services and health benefits. Costs were taken from an interim report on the economic side of the KURAS project, and results were expressed as net present value and benefit–cost ratio over a 50-year horizon. A Monte Carlo analysis with 10,000 iterations tested how sensitive the results were to variations in costs and valuations.

Daniel Johnson, ESCP Business School Berlin — djohnson@escp.eu

Study overview

This case study examines how a Berlin neighbourhood could manage stormwater sustainably using sustainable urban drainage systems (SUDS). It draws on the KURAS project, a German research programme on urban stormwater management and sewer systems funded by the Federal Ministry of Education and Research.

Conventional drainage in dense cities moves stormwater away as quickly as possible, often through separated sewers that discharge into nearby water bodies while carrying dust, heavy metals and organic trace substances from construction and traffic. SUDS take a different approach, retaining stormwater at or near the source and replicating natural processes in the water cycle. This reduces runoff, eases pressure on sewers and treatment plants, and improves the quality of receiving rivers. Because the measures are green, they also deliver other benefits, including cooling.

Working with local stakeholders, the KURAS project developed three independent stormwater scenarios for a 117-hectare residential neighbourhood in Pankow, Berlin. Each combined different mixes and placements of measures, including extensive green roofs, façade greening, urban trees, swales, swale-trench systems and beds, ponds, permeable paving, rainwater harvesting cisterns and retention soil filters. The scenarios reflected local priorities such as groundwater management, urban climate and biodiversity, alongside feasibility.

Researchers then assessed the economics. Over 50 years, the present value of costs ranged from €36.0 million to €114.4 million. All three scenarios produced positive net present values and benefit–cost ratios above one, meaning benefits outweighed costs. The cheapest performed best financially, with a net present value of €32.8 million and a benefit–cost ratio of 1.91, largely because it favoured measures with low maintenance costs.

Runoff reduction alone was worth €2.3 million to €4.6 million per scenario in discounted terms. Berlin's rainwater fee of €1.804 per m² of sealed surface, which can be halved where such measures are installed, gives property owners a direct financial incentive.

The study's central message is that placement matters more than quantity: a smaller, well-targeted set of measures can match the performance of a much larger green retrofit.