qgis_port

Floodwater Depth Estimation Tool (FwDET) QGIS Processing Script

A QGIS Processing script to implement FwDET v2.1

Tested against QGIS 3.34.5

1 Installation Instructions

Install QGIS with GRASS

download and install the QGIS version shown above (other versions may also work) and ensure you have the GRASS processing provider enabled.

download the scripts

download processing_scripts/fwdet_21.py script to your local machine

add to your QGIS profile

In the QGIS Processing Toolbox, select the python icon drop down , and Add Script to Toolbox... then point to the downloaded script. This should load new algorithms to the Scripts/FwDET group on the Processing Toolbox.

2 Use

Instructions are provided on the algorithm dialog

3 Example Data

Example DEM and inundation polygon are provided in the test_case\PeeDee folder (see Issue #12).

5 Development

create a virtual environment from the supported QGIS version and the ./requirements.txt file.

6 Known Issues and Limitations

• verify that the filtering/smoothing operations match the ArcPy equivalents
• could not find a QGIS pre-installed equivalent to ArcPy's CostAllocation. Instead, we use grass7:r.grow.distance which provides a similar result with a neutral cost surface. This is also quite slow. A better alternative would use WhiteBoxTools; however, this adds a dependency.
• the algorithm is sensitive to tiny holes in the inundation polygon. These could be fixed through pre-processing to remove small holes.
• did not test a coastal scenario