DHI experts and visiting researcher Professor Qin Jim Chen are leading the development of new science-based models to enable improved coastal decision-making. Together, they are investigating ways to account for coastal vegetation and its relevance for wave attenuation and coastal circulation in the design of nature-based solutions (NBS).

Dr. Qin Jim Chen is a professor at Northeastern University in Boston where he focuses his research on coastal processes and nature-based solutions using field campaigns, numerical modelling and physics-informed neural networks. However, it all started when Dr. Chen worked for two years with DHI 30 years ago as part of his PhD study on Boussinesq models at the ICCH (International Research Centre for Computational Hydrodynamics). Later, his career took him to Louisiana State University and now Northeastern University in Boston; always with focus on coastal hydrodynamics. Now 30 years later, he has returned to DHI – and the Technical University of Denmark – to renew collaboration as part of his academic sabbatical.

‘The increase in extreme weather events around the world makes it imperative that we have multiple lines of defence for coastal communities and critical infrastructure. Nature-based solutions are one such critical line of defence. However, the challenge is that there are no official or universal design guidelines for NbS, so how can we make robust decisions on when and where to implement which nature-based solution?’ explains Dr. Chen about his motivation for research in NbS.

‘Ultimately, the goal is to assign values and strength to different types of NbS and to have a science-based framework for decisions on e.g. what type of extreme event the NbS should withstand such as tropical storms or hurricanes. In other words, the engineering community and decision makers need a framework that enables more efficient and objective decision-making surrounding the complex design of NbS and at the same time allows for cost efficiency and adaptability in a changing climate.’

Dr. Chen will collaborate with DHI experts on testing the accuracy of DHI’s wave modelling solutions with his field data. The end goal is to remove subjective decision-making in coastal and marine engineering projects by increasing confidence in modelling tools such as MIKE 21 SW  and MIKE 3 Wave FM.

Collaboration will close research gap between field conditions and modelling

Niels Gjoel Jacobsen, Principal Engineer at DHI, elaborates on the close collaboration, ‘The work of Dr. Chen is an important part of the foundation for developing new tools to predict the effectiveness of nature-based solutions. By comparing the results of our modelling predictions with his field data, we hope to convince even more in the engineering community of the validity of using such quantitative modelling tools when designing nature-based solutions.’ 

The two researchers are currently working on the comparison between field data and numerical predictions on wave attenuation through marshlands under the landfall of a tropical storm. The aim is to improve on the swaying effect through analytical models so that extrapolation to field conditions is easily achieved and can be incorporated in MIKE Powered by DHI’s practical engineering models.

There is a need for a more holistic approach to nature-based solutions

‘There needs to be a more complex and holistic approach to NbS where we also include the value of ecosystem services as one example of co-benefits. The perspective on NbS should include other co-benefits than simply the value of reducing the risk of e.g. flooding or erosion, and this is why we need to have a broad range of experts in such matters on board.’ 

Dr. Chen adds, ‘The great thing about working with DHI is that they have a strong team of marine biologists and ecologists, so we can leverage their expertise on the seasonal characteristics of specific species of seagrass or mussel banks, for example. By combining this knowledge with advanced engineering models, we will hopefully be able to contribute to more resilient nature-based solutions as a part of climate adaptation measures.’