Climate-adaptive design in existing urban neighbourhoods

How can existing urban neighbourhoods be made resilient to intense rainfall, drought and high groundwater levels? Rotterdam aims to regenerate its existing urban neighbourhoods and make them climate-adaptive. Under a multi-year framework agreement, Iv is supporting the municipality in addressing this challenge. Each neighbourhood requires a tailored approach. Iv investigates how rainwater can be retained locally, where opportunities exist to introduce more green space and how vulnerable foundations can be protected. This work is carried out in close coordination with the municipality, water authorities and other stakeholders.

Neighbourhoods vary considerably in terms of soil composition, foundation type and elevation. Older foundations are particularly vulnerable to fluctuating groundwater levels, while public spaces often show significant settlement, in some cases amounting to several tens of centimetres. Groundwater levels and ground conditions play a crucial role in this. Replacing ageing combined sewer systems requires smart, phased solutions that minimise disruption for residents.

The challenge is to strike the right balance between retaining and draining water. Rainwater should be retained locally wherever possible, but excessive infiltration can create problems for vulnerable foundations as well as damp crawl spaces and basements.

Iv has carried out area assessments for a range of neighbourhoods. Based on these assessments, several design options were developed and evaluated using a multi-criteria analysis, taking into account factors such as the water management challenge, technical feasibility, cost and the impact on the surrounding area.

In densely built-up neighbourhoods, for example, permeable paving may be selected to promote local infiltration, while in greener areas, drainage via verges or swales is often the more appropriate solution. The installation of drainage, infiltration and transport pipelines (DIT sewer system) also enables groundwater levels to be managed more effectively during both dry and wet periods. In this way, Iv delivers well-founded, future-proof solutions that can be replicated across other neighbourhoods in the city.