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Is there a way to quickly investigate 2D results?

Yes, there are tools to extract time series (from a user specified point) and section data (from a user defined section line) directly from the map when 2D results are loaded.

What functionality does Flood Modeller Free provide?

Flood Modeller Free provides the same great functionality as Flood Modeller Pro for use on smaller projects, limited to 250 1D nodes and 100,000 2D cells; across all three 2D solvers (ADI, TVD and FAST).

Does Flood Modeller generate flood maps automatically?

Flood depth grids (or flood extent polygons) can be generated automatically. For 1D flood mapping, a TIN needs creating and will influence the quality of the resulting flood map.

Is there a restriction on model building in Flood Modeller Free?

You can only build 1D models up to the 250 node restriction within Flood Modeller Free, however there are no restrictions when building a 2D model.

Flood Modeller Free restricts you from running model simulations that are greater than 250 1D nodes and 100,000 2D cells.

There are also no restrictions when viewing models or their results.

Could you lower ground elsewhere to accommodate flood plain compensation?

Yes this is an alternative option that could be investigated with additional model scenarios. You can draw a polygon and assign a revised level and add this to the model to override your ground elevation data.

Can I define different mesh sizes for different 2D domains in the same model?

Yes, you can define different mesh sizes for each different domain. Multiple domains can be adjacent (linked by a 1D model) or completely separate.

Does the GIS interface support both TAB and SHP file formats?

Yes, both TAB and SHP formats are supported.

Are tutorials or model data available for new users?

Yes, tutorials and example data sets are available under the 'Help and Support' section on our website and from within the software installation.

What are the governing equations used in Flood Modeller?

Full solution Saint Venant (1D) and Shallow Water Equations (2D) as well as a simplified solution in the FAST solver. Full details are provided in the technical documentation.

What are the output formats of the flood depth grids?

Flood depth grids can be exported in a range of formats including ESRI ASCII and binary FLT formats.

Does Flood Modeller work with coastal flooding (i.e. storm surges)?

Yes, Flood Modeller works with coastal flooding, including surge, sea level rise and overtopping of defences.

Is there a limitation on the 2D area size within Flood Modeller Free where direct rainfall can be applied?

In Flood Modeller Free you can apply direct rainfall on a digital terrain model (DTM) using the full 2D solver as long as the 2D domain is no more than 100,000 cells. In terms of the area of coverage, this is dictated by the selected cell size you choose.

In Flood Modeller Pro you have the ability to run larger 2D models.

What's the difference between computational area and active area?

A 2D model extent must be defined by a rectangular array of cells, which is the computational area. However, in most cases you will know areas within this extent that will not flood (i.e. high ground) so performing calculations in every cell of the computational area would be inefficent and time consuming. Therefore you can define areas within the computational area in which calculations will be performed. These are the active areas and are defined by polygon shapefiles. They are optional in your 2D model but using them can greatly improve model performance.

Can you create a triangulated mesh based 2D model instead of a grid based 2D model ?

The 2D solvers in Flood Modeller are based on a rectangular grid.

What is the 2D FAST solver?

The 2D FAST Solver uses simplified hydraulics and has been developed to enable rapid assessment of flooding. It provides maximum flood depths in the quickest time possible – up to 1,000 times faster when compared to traditional 2D solvers.

The software works by identifying depressions on the floodplain then routing water through these depressions. Water depths in the depressions are determined by the volume of water flowing into each one, the level at which water can spill into neighbouring depressions and the water level in the neighbouring depressions.

What is the 2D FAST Dynamic solver?

The 2D FAST Dynamic solver uses similar simplified hydraulics as the 2D FAST solver. However, the 2D FAST Dynamic solver allows you to incorporate timesteps within your model which provide information on flow paths and the build-up of flooding during the storm.

The FAST Dynamic solver is a prototype development that works well in specific situations. However we recommend that users check results against other solvers and do not use the FAST Dynamic results in isolation.

Should I use the 2D FAST solver or 2D FAST Dynamic solver?

The 2D FAST solver provides maximum depths for a flood event. If you require greater detail of how the storm and associated flooding develops, the 2D FAST Dynamic solver could be used to provide estimates of the evolution of the flood event.

The FAST Dynamic solver is a prototype development that only works well in specific situations. We recommend that users check results against other solvers and do not use the FAST Dynamic results in isolation.

In general it is advised that the 2D FAST solver is used instead of the 2D FAST Dynamic solver.

Can Flood Modelller convert ASCII files to SHP files (e.g. for converting TUFLOW results for use in Flood Viewer) or can Flood Viewer use ASC files?

Flood Modeller has a tool called "Layer Convertor" which can convert an ASCII depth grid into a flood extent shapefile - it traces around all non-zero (non missing data) areas of the grid to form an extent outline.

What do I do if Bing Maps stop working?

You can reset the map functionality by pressing the default Bing Map key button in the General Settings window (and then restarting Flood Modeller to apply the change).

How large is my model and is my licence sufficient?

With 2D models, it is also possible to find out the number of cells your model has by multiplying the cells in ‘Number of Cols’ and ‘Number of Rows’ from the ‘Domain Details’ tab within the ‘Domains’ tab of the 2D Simulation Window. This window shows the contents of the 2D simulation project XML file, which you need to load into Flood Modeller first.

Running your 1D and/or 2D simulation will also reveal the number of nodes and/or cells in your model. If your model crashes, the .log or .zzd files produced will list this information.

What is the difference between 1D and 2D flood modelling?

1D modelling solves the 1D equations of flow in channels. A single water level, velocity and flow rate is calculated for each cross-section/node within the model. It also includes 1D equations for 'point features' such as weirs, bridges, sluices and other structures.

2D modelling solves the 2D equations of flow using a variety of methods (e.g. Alternating Direction Implicit or Total Variation Diminishing). It is usually carried out to calculate water depth and 'depth averaged' velocity on a grid or mesh. 2D modelling requires a digital terrain model (DTM) and/or bathymetry of channels.

Click here for an overview of 1D and 2D flood modelling.

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