Dr. Darla Nickel

“Rain will be the downfall of climate change!” (“Niederschlag dem Klimawandel!”) This is the motto of the Berlin Rainwater Agency (“Berliner Regenwasseragentur”) – a joint project of the Senate and the Berlin Water Works that aims to turn Berlin into a sponge city. Dr Darla Nickel, technical environmental protection engineer and head of the agency, has as much oomph as the agency’s motto. Born in California to a family with roots in agriculture, Dr Nickel was raised to see rain as a cause of both joy and concern; whether here or in California, too much or too little rain leads to hot weather, droughts and floods. Countering this – by retaining, draining and evaporating rainwater for use in irrigation, for example – has thus been impressed on her since birth.  And that is exactly what she and her team of eight at the Rainwater Agency want to bring home to property owners, planners, administrators and housing companies – by providing information, consultation and education as well as through dialogues, public relations and a host of digital tools.

Dr Nickel, the Berlin Rainwater Agency is celebrating its fifth anniversary this year – congratulations! Five years of working to foster and implement sustainable water management measures in the city. When you look back, what have your greatest successes been?

We have given rainwater a new image. Obviously not on our own, but I do think we play a part in people today seeing rainwater as a valuable resource. And their actions confirm this: since 2022, for example, we have been cooperating closely with the Sponge City task force within housing management company BIM Berliner Immobilienmanagement. Their aim is to embed a comprehensive strategy for decentralized rainwater management at existing properties in their company. To do so, members of the task force provide information on the sponge city concept, organise trainings, initiate pilot projects, change work flows and structures and include everyone involved in construction management within the company in the process. One thing is certain: major companies such as BIM with its 5,000 state-owned properties play a pioneering role. If they embed rainwater management in their strategies, it sends a powerful signal.

What position do other housing companies take when it comes to rainwater management?

Berlin’s housing sector is water-conscious: 85 percent of Berlin’s housing companies believe that water management is key for the city and 81 percent have already implemented according measures. We obtained these figures from a  survey (German only) we conducted among member companies of and in cooperation with BBU, the Association of Housing Companies in Berlin and Brandenburg, in February 2022.

What projects or activities could have gone better? And what are the key findings you have taken away from them?

We help the Senate and districts give public roads, spaces and green areas a new, water-conscious design. In projects like these, it is a matter of course to examine and harness the potential for decentralized rainwater management today. However, there is often a lot of competing space and not always a lot of potential. “Old patterns”, standards and financing options frequently also cause us to fail. That’s why our successes are often not quite as great as we would like and as they really need to be. To resolve these problems, we would like to invest even more in the exchange of professional expertise in future.

In spring you called for applications for the competition entitled “10 Ideas for the Sponge City Berlin” (“10 Ideen für die Schwammstadt Berlin”) for the first time and received a slew of submissions. What impressed you the most?

First of all, we were surprised by the incredible number of applicants. We had hoped for 30 submissions; in the end, we had 75. Most of them were that good that we struggled to make a selection – as did the jury – which goes to show how many people are giving some serious thought to how to retain rainwater in our city. At the closing event we could feel a community coming together. Berlin’s State Secretary for the Environment, Britta Behrendt, was there as well and later called the event an encouraging one, adding that she was inspired to see so much positive energy in one room. We want to continue to strengthen this community.

What are the next steps for the winners of the competition? What support can the Rainwater Agency offer to implement their projects?

The competition (German only) itself has already helped the winners take the next step. Rhea Rennert’s suggestion – a rainwater storage facility for public areas that is shaped like a bench – got so much positive feedback during and after the event that she decided to found a start-up. The state of Berlin is working on regulations and a funding programme for the utilisation of rainwater in public spaces, which will directly benefit her concept as well. We organised an exchange of expertise with representatives from the Neukölln and Spandau districts for Laura Tams and Björn Kluge. They are both researchers at TU Berlin and want to provide trees with more water through “puddles” on the innermost edge of pavements towards the streets “Gehwegunterstreifen”. Together with the districts, the two are now looking for a suitable location to test their idea. And Sven Hähnichen is advancing cross-property solutions. Prior to the competition, he had already been commissioned by the Senate Department for Urban Mobility, Transport, Climate Action and the Environment to conduct a corresponding study. We are helping him wherever we can – for example by steering the advisory board, organising the closing event and implementing another cross-property project in Charlottenburg. 

Can you give us an outlook on the next five years? Where do you see Berlin’s most pressing problems on its way to becoming a sponge city with sustainable rainwater management measures?

The focus of the next years will definitely need to be on existing buildings, in other words, on the inner city area, which is already densely populated and heavily sealed. The problems we aim to counter with the sponge city concept are most severe in these areas: during heavy rains, particularly high quantities of water flow into the canalisation here and overload it. On the other hand, these areas lack green spaces during hot weather and droughts and plants don’t get enough water.

Which brings us to our next question: what current projects will you and your team be working on over the next weeks, months or even years?

We consult property owners on all matters around the planning, construction and operation of decentralised rainwater management measures. In 2022, we processed 300 requests for consulting; this year, we are approaching 400, a number we expect will increase. We have also developed powerful digital tools to make things easier for key actors such as planners, districts and housing companies. These include a cost calculator (German only), an overview of funds (German only) and a project database (German only) with examples to model one’s own projects on. Currently, we are developing another offer which will allow us to help property administrators identify profitable projects more purposefully. We are working on helping all actors get to know these tools and integrate them into their work.

Our “blockbusters” also include project support, from larger undertakings up to district developments. We want every district to become a sponge city district. Currently we support about 30 projects: accelerating the transfer of knowledge, supporting the introduction of new solutions, resolving conflict and optimising urban-development processes. In November 2023, two new employees joined our team: an environmental engineer and a landscape architect, both of whom are helping us expand our offer.

In the broadest sense, rainwater management concerns urban space. What solutions does a smart city offer in this respect?

Successfully planning and giving an existing road or public space a new design, for example, requires an intensive exchange of expertise between responsible parties and stakeholders. To support this participative process, the Rainwater Agency and the Berlin Water Works have cooperated with a specialist for multi-user systems to develop an interactive planning table (German only). What makes this digital planning tool so special is the fact that all relevant actors can sit down at one physical table where they have all available information at their fingertips and can plan things together in direct contact. This provides an easier and quicker way for them to find a common thread and balance interests. We also see great opportunities in visualisation techniques. Using 3D or augmented reality, we can demonstrate how we can change spaces for the better and thus help people feel less afraid of change. 

What do you think the city of the future will look like??

People in sponge cities (German only) will store, use, evaporate and seep rainwater locally, thus protecting their city, their residents and nature against the consequences of climate change such as hot weather, droughts and heavy rains. And they will increase quality of life by creating attractive spaces with lots of green and healthy waters.

Please complete the following sentence: “Berlin is a smart city, because...”

... so many people are putting their heart and soul into the idea of the sponge city becoming a reality. (vdo)

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