Simulate flooding using big data and smart algorithms

An example of Water Board Vechtstromen

Suppose a levee threatens to fail. Can I simulate the situation within 1 hour and determine the possible consequences? Water Board Vechtstromen has developed a method to quickly and comprehensively simulate flood scenarios and share the results with the Safety Region. Read below about this project.

Crisis management

Early assessment of the effects of a failing levee in the event of a calamity is crucial. If flood defences fail and flooding occurs in the management area of the Water Board Vechtstromen, the Safety Region wants answers as quickly as possible. For example, it is important to know where the power will fail and where people and livestock will have to be evacuated.

The Water Board Vechtstromen therefore started at the end of 2019 with training sessions to learn how to work with the flood module of the Tygron Platform. The aim was to quickly simulate a flood (within half a day) and to share the results with the Safety Region during a disaster.

The project started with the ‘theory’: how does the water module of the Tygron Platform work? The  company Aveco de Bondt, showed therefore a number of theoretical and practical examples, explained. The following training sessions focused on the practical side: how to use the Platform and how to model a scenario.

Simulation of the failure of the levee at the diversion channel (Dinkel). On the left you can see the water depth. The orange arrow (Diversion channel near the Beuningerveldweg) indicates the failure of the levee (the location of the breach). On the right you see the flow velocity.

Tygron, together with a number of Water Boards, has developed software to quickly simulate levee breaches using big data. The calculations are performed on a GPU supercomputer, which allows results to be generated at a very high level of detail. With the results of the calculations the impact of a possible flood can be determined accurately. And this in turn is important for the safety regions. For more information about the use of this water module, please visit: https://www.tygron.com/en/2020/02/12/the-water-module/.

The Tygron Platform is now widely used by water boards, municipalities, provinces and consultants. The Water Board Vechtstromen has been working with the software for performing stress tests for several years now. See also: https://www.vechtstromen.nl/@37742/stress test city/

Testing

Hydrologists from the Water Board Vechtstromen have tested what the most important factors are that determine the effects of a failing levee. From there it was determined which assumptions and choices have to be made in simulations. After all, during a calamity there is limited time to build a model.

An important choice concerned generating a new Tygron Platform project or using existing projects and configuring them during a calamity. The first option was chosen, because then you always have the most up-to-date data at your disposal. These and other choices have been incorporated in a step by step plan and corresponding explanation document to model a flooding scenario.

A test that has been done is about the importing of culverts. Culverts with a standard diameter of 1 m are imported automatically (if available). After the test, it appeared that it is important to import culverts with their actual diameter. This can give a different flooding image. In the image above the effect of culverts on the flooding is shown.

Tygron then processed the step by step plan and explanation document into a manual and a template project. With the template project, a new project can be quicly created and configured. This is because certain default settings are already configured automatically. Think of legend colours, attribute names of the data that has to be imported, the result map layers that you eventually want to use and more. Vechtstromen has prepared the data sets to be used for the entire management area of the Water Board. This allows experienced users of the Platform to create a flooding simulation within half an hour during a calamity.

Results

In the last training the manual and the template project were tested. A number of locations where a fictitious levee breach was simulated were the Midden Regge near Den Ham, the Hoogeveense Vaart, the Vecht near Hardenberg and the Stieltjeskanaal. Results were , with the use of the manual the trained Vechtstromen employees were able to simulate flooding scenarios at the various locations in their management area within the set time. Also, the results could be exported and shared with the Safety Region.

Important for the Safety Region, for example, is the maximum water depth per location (see figure above). This and more results can be exported from the Platform in different ways and formats and shared with the Safety Region.

 

The manual is posted on the Wiki of Tygron where also the documentation of the software can be found. In this way, the manual can be (re)used by everyone, including other Water Boards. The fact that other Water Boards are also working on this topic is shown by the reaction of a hydrologist from the Water Board Rijn en IJssel on our forum. Rijn en IJssel also created a manual on how to simulate a flooding scenario using the Tygron Platform. It is interesting to see that these manuals contain many similarities in choices and assumptions.

Responses

Sjon Monincx, senior advisor at Water Board Vechtstromen and project leader of this project, presented the approach of Water Board Vechtstromen in the PCWMN[1]. He presented a quay breakage of the Vecht near Zwolle. Reactions from hydrologists and crisis management advisors were positive. Hydrologists found it interesting and were interested in the calculation model of the software. People from crisis management were particularly surprised by the realistic 3D images. They indicated that the directors from the steering committee should definitely see this.

The question ‘how do you know the results are right?’ was also asked. It is important to always realise that a model remains a simplification of reality and not the reality itself. The hydrologist who is is configuring the model must be well aware of how the model calculates, what it does and does not contain, what limitations there are and how realistic the results are as a result.

Curious about the manual of the Water Board Vechtstromen? Check it out on our Wiki page: https://support.tygron.com/wiki/Falen_keringen_template

For the explanation document, see: https://support.tygron.com/wiki/Uitgangspunten_falen_keringen_template.

See also the manual of Water Board Rijn en IJssel: https://community.tygron.com/forum/discussion/254/calamiteiten-falende-keringen-simuleren-stappenplan#latest.

1] Platform Crisisbeheersing Waterschappen Midden Nederland
(Platform Crisis Management Water Boards Central Netherlands)