FastFlood Docs
Mitigation
Mitigation features
Using the vector feature editor, you can add line segments, polygons and rectangles. For all of these, a height (either negative or positive) can be defined by clicking on the feature outside of the shape editor. The features are included in the elevation model when you run a simulation.
Adding a polyline feature can be done easily.
The height of the barrier can be specified.
When adding reservoirs or barriers, don’t forget to enable ‘account for depressions’ in the settings. Otherwise, the storage in reservoirs is not accounted. Once set up, you can use [shift]+[r] to quickly run the model again.
After simulating flow again, we see a reservoir is filled by the flow.
We can edit the barrier later and quickly simulate again.
Painting can be done for more custom design of mitigation. By selecting the painting tool, you can click within the elevation dataset and paint elevation increase (for barriers, dams and reservoirs) or elevation decrease (for channels, reservoirs and buffers).
Then, after simulating again, the new channel definition is incorporated in the simulation.
You can erase painted features using the same tool.
You can choose to paint only a single pixel at a time in the elevation data, or paint with a smooth brush (surrounding pixels are influenced as well).
By checking the erase button, the paint tool erases and changes made. Use the clear-all button to remove all changes. Once set up, you can use [shift]+[r] to quickly run the model again.
Mitigation through land cover an infiltration properties
If you aim to implement alternative land-cover and soil processes as mitigation, these can be filled in through their respective inputs. For example, forestation for hydrolgical improvements can be entered through an appropriate increase in infiltration rate (see literature on how increased organic matter might cause this), and an increase in Mannings surface roughness coefficient, which lowers the discharge response peaks.