The complexity of flow or how to show water the way

Prof Dr Andreas Schlenkhoff and the Department of Water Management and Hydraulic Engineering.

In the US action film "Hard Rain", heavy rainfall causes the water level to rise so that an entire city has to be evacuated. A disaster scenario that many people would like to see in the cinema but would never want to experience. And it is precisely this topic that the engineer Professor Dr Andreas Schlenkhoff has been working on for 30 years. Born in the Ruhr region, he is familiar with the anxious questions from citizens who are happy to turn to the expert in heavy rainfall and flood protection following press reports on flooding. "Because we have the Wuppertal Dam here," he says, "many people believe that heavy rain or flooding can't affect us." But far from it. Schlenkhoff says quite frankly: "We don't need to wait for climate change. We actually have permanent flooding! And we have to face up to it." Society lives with a risk, he emphasises, which is why he never tires of regularly informing the public about it.

Father, grandfather and many relatives worked in mining

The 58-year-old scientist has a strong family background in mining, which he has known since his earliest childhood through his grandfather and father. But even as a teenager, he realised that working in the tunnels would not offer him a future. So, through a friend, he came to Wuppertal in 1980 to study civil engineering. There he flirted with the subject of tunnelling for a long time and deepened his knowledge of geotechnics until a key experience led him to water management.

Schlenkhoff smiles as he recalls an IGAW (Institute for Foundation Engineering, Waste and Water Management) excursion to Karlsruhe in 1985. "And then we were on a tunnel construction site (the Karlsruhe/Basel rapid construction site) and after a hundred metres the air got thick. I got a headache and couldn't see a thing. And then I asked the site manager: 'How can the men work here? Today, the construction site would be closed immediately. Today, everything is ventilated. Back then, they were blasting, diesel lorries were driving around and I thought: Oh dear."

But the next day he visited a hydraulic engineering site in Bavaria.

"We had great blue and white weather, it was a large construction site, on the river of course, a concrete factory, next to it a wood workshop, all nicely set up in tents, and they had also built a dining hall for the 1000 employees."

That was the initial spark. From then on, Schlenkhoff focussed his scientific studies on water management, was offered a job as an assistant by his hydraulic engineering professor in Wuppertal, became a senior engineer and then worked in Indonesia, India and Australia before moving to an engineering office for a few more years. And hydraulic engineering and water management have always been his focus. The engineer was in charge of responsible projects. For example, he designed flood retention basins and dykes and was largely responsible for the construction of Lake Phoenix, an artificial lake on the former Phoenix-Ost steelworks site in Dortmund's Hörde district. He says proudly: "This engineering office was one of the leading ones. I was there at the right time, the projects were challenging and interesting."

The student returns to the university as a teacher

And yet it is still the case in the engineering office that one project follows another, a team of 70 people has to be constantly busy and questions cannot be answered in full because the new offer is already available. He comments in consternation: "It wasn't nice, but that's the way it was." So after a few years, the engineer decides to return to the university. And as the appointment negotiations sometimes take longer, he looked after the engineering office's branch in Cologne in the meantime and was involved in the flood protection concept developed by the city of Cologne at the time.

Since 2003, he has been head of the Department of Water Management and Hydraulic Engineering at the Institute for Foundation Engineering, Waste and Water Management at the University of Wuppertal. Here he was able to return to the open questions that remain at the end of a project. Schlenkhoff and his team of five now only work on special projects.

How to show the water the way

One project that deserves special mention involved him working with the technical operations of a Bergisch town. Schlenkhoff took on the investigation of a sewer problem, as water was flowing over the road during heavy rain instead of running into the half-filled gullies. Due to its budget situation, the city was unable to meet the Ministry's costly requirements and turned to the Wuppertal expert for help. Schlenkhoff made his first calculations in this research project with a small budget and experimented in his mini-laboratory. Further research applications followed and the project developed a momentum of its own - partly due to a television report - which resulted in other external companies also approaching the University of Wuppertal.

MeierGuss in the Minden-Lübbeke district is one such company that, together with the teaching and research department, developed a drainage gully that enables water to flow better into the street drain. In their promotional film, they point out, among other things, the needs-based road attachment, the good absorption properties and the simple installation of the product. By modifying the grate struts and rotating the geometry by 90 degrees, a significantly improved inlet was ensured. Schlenkhoff used three-dimensional models for flow simulations and says: "Without the physical tests, we wouldn't have been able to do it." He has also initiated a legal opinion on the basis of which the city is now proceeding with implementation. He says: "In any case, our project partners are now building the first road where the water remains on the surface as planned. And that is a revolution. They don't realise it now, but the city planners don't need to renovate the canal, they just need to do something on the surface. And then the water can be channelled into the nearby stream." This transfer service is directly accessible to the citizens.

The country needs new men

The professor would like to see a higher proportion of men studying in his field. "There are fewer baby boomers now and you have to observe the development," he says, "we have incredibly good women." Schlenkhoff is constantly trying to establish good collaborations and summarises: "I can promise everyone who works for me or does their Master's thesis that they will definitely get a job."

Schlenkhoff knows that Wuppertal will lose half of its managerial staff in the next ten years and oracles: "If digital administration doesn't materialise, then we're screwed. We urgently need planners and engineers."

Ever since Günther Jauch's 2008 programme "Who Wants to Be a Millionaire", we have known that Wuppertal is the rainiest city in Germany. Where, if not here, would the teaching and research field of water management and hydraulic engineering find the best working conditions? Students can only benefit from this.

Uwe Blass (interview from 06.12.2017)

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Prof Dr Andreas Schlenkhoff studied civil engineering at the University of Wuppertal. In addition to working abroad in Indonesia, India and Australia, he also worked in a renowned engineering office. In 2003, he took over the teaching and research area of water management and hydraulic engineering at the Institute for Foundation Engineering, Waste and Water Management at the Faculty of Architecture and Civil Engineering.