Fathom provide flood hazard maps with global coverage. These maps can be retrieved and viewed directly in the Map view. This may be useful as part of your initial site appreciation investigations, for instance.
Accessing Fathom data
Zoom in on the area of interest. The tile downloaded from Fathom will cover the extent displayed on the map view.
On the Results tab, click the Fathom data button.
Note
The first time you access the tool, you will need to provide your Fathom account credentials in the Application Settings.
Select the datasets to download using the drop-boxes provided. Several of these provide multiple options, for example, you can select multiple return periods.
Provide the Project ID. This can be in any text format, e.g. MyProjectID123, and is used as a reference by Fathom for itemised billing to your organisation.
Select the Output folder to which the retrieved datasets will be saved. You can also optionally provide a file suffix.
Click the Retrieve dataset(s) button. This will download the datasets and save them in your specified output folder.
Click the Close button to close the tool.
Add a colour ramp to the flood map to aid with visualisation.
Providing account credentials
The first time you access Fathom data from Flood Modeller, you will need to enter your Client ID and Client Secret into the Application Settings. On the Home tab, click General to open the Application Settings window. Navigate to the Default Settings tab to enter your Fathom settings details.
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If you do not have a Fathom account, fill in the following form and the Fathom team will get in touch: https://www.fathom.global/fathom-jacobs-licence/
Adding colour ramps
When you initially retrieve Fathom datasets, the entire area will be coloured. This is due to the default values used by Fathom. The Layers Panel includes two predefined, Fathom specific colour ramps that can be accessed from the right-click menu. Right-click on your Fathom layer and select Colour Ramps and then choose either Fathom (cm) or Fathom (m) from the displayed list of colour ramp options.
Alternatively a colour ramp optimised for Fathom data can be downloaded and added to your Fathom datasets to resolve this.
To add a colour ramp file:
In the Layers panel, double-click on your Fathom dataset
On the Colour ramp tab, click the yellow folder icon in the top left to Load colour ramp from file.
Navigate to the file above and click Open.
Click Apply and OK to save the changes.
The colour ramp can be customised further as required.
Fathom data FAQs
What units are used for my Fathom datasets?
Raw downloaded Fathom datasets have units of centimetres and valid depths range from 0 to 1000cm. When using the Flood Modeller tools to download new Fathom data or import existing Fathom data, depth data can be returned in either centimetres or metres. If you want to convert a Fathom dataset in centimetres to metres then use the Grid Calculator function to create a copy of your grid with all values divided by 100 (note this will also change the values used for no data flags – so a modified colour ramp will also be required).
Am I charged for using Fathom data?
Yes, you must link to your Fathom account to access the tool, and your account will be charged when datasets are retrieved. You are charged for each call to retrieve data, and therefore it will be more cost effective to select multiple flood maps in a single call.
What tile/extent is downloaded?
The data downloaded will cover the extent currently displayed in the Map view. If the extent displayed is too large, a pop-up will notify you that zooming in further is required.
Can I view my Fathom datasets if I have already downloaded them outside of Flood Modeller?
Yes, absolutely. Use the Convert existing Fathom data option under the Fathom button on the Results tab. This will provide the same conversion options as offered by the new Fathom downloads interface, e.g. convert to ASCII and convert cm to m.
How do I change my Fathom datasets from .tif format to .asc format?
This option is provided as part of the download procedure, via a checkbox. Alternatively datasets downloaded just as geoTIFFs (.tif) can be changed to ASCII (.asc) format using the Layer Convertor tool (Toolbox > Grid Tools). The ASCII format is more customisable in your map view, e.g. it can be made semi-transparent and/or cell value labels can be added.
Why aren't my Fathom datasets automatically loading into Flood Modeller?
The checkbox Load files to map on close of form will be checked by default. This will ensure your retrieved files are automatically loaded into the Map view when you close the window.
How do I create a Fathom account?
If you do not have a Fathom account, fill in the following form and the Fathom team will get in touch: https://www.fathom.global/fathom-jacobs-licence/