So the Corps of Engineers turned to a Delft consortium of IHE Delft, Delft Hydraulics (now Deltares) and TU Delft to provide them with an open-source physics-based model. With a small project team we delivered the first version of XBeach which was presented by Dano Roelvink exactly ten years ago at a workshop in Hawaii.

Our approach was new at the time (and now quite common): the software was freely-available and open-source, via All comments, bugs, Easter eggs and hidden features could be seen by anyone. We collected laboratory and field data to test our model and show that it actually worked, published on it in the open literature and at conferences, and we were not afraid to use it in new projects and environments.

From sandy coasts to coral, gravel and vegetated coasts

In this way, the coastal types we could use the model on grew and grew, and the user base grew as well. First, we used the software with European partners to investigate coastal impacts around Europe. Then, we applied it to assess coastal safety in the Netherlands, especially in complicated areas such as strongly curved coasts and urbanized areas with dunes, seawalls and buildings. With the U.S. Geological Survey we used the model for hurricane impact modelling, but also to assess flooding on the entire California coast, and on coral-reef lined Pacific Islands. With support by the U.S. Navy, we can now assess the effects of vegetation and in cooperation with Plymouth (UK) we can compute the deformation of gravel coasts. In a new exciting European project, we will assess climate change impacts along all coasts in Europe.

Figure of coastal types

A lot of ground covered, but challenges are plentiful

Few coastal types are a mystery to us now, but many questions remain. Not only do we need to improve the physics, we also want to apply the model on more complex and larger areas but with using less computational time. The challenge is to solve these seemingly conflicting needs. And this is where our user base comes in.

The original developers are not the only users and developers anymore. We have over 500 registered users who share their experiences about the model. This has led to about 350 scientific papers which use XBeach. The model does not only have an academic impact, consulting firms and dredging companies collaborate in a Joint Industry Project to develop the model for their purposes , and they are using the model more and more in their daily practice. Coastal authorities in the Netherlands, Belgium, USA, Italy and Spain are using the model as well.

All these experiences created a knowledge base which we can employ to set a balanced course to our model development, and to solve coastal storm impact problems together, so that we can keep our populations and coasts save from harm.

Witness for yourself how an open-source community interacts at the XBeachX Conference, to be held 1-3 November at Deltares in Delft. As the software, registration is free.

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