SEAMLESS-WAVE
SEAMLESS-WAVE is a developing “SoftwarE infrAstructure for Multi-purpose fLood modElling at variouS scaleS” based on "WAVElets" and their versatile properties. The vision behind SEAMLESS-WAVE is to produce an intelligent and holistic modelling framework, which can drastically reduce iterations in building and testing for an optimal model setting, and in controlling the propagation of model-error due to scaling effects and of uncertainty due statistical inputs.
Downscaling coarse-resolution DG2 flood maps
As opposed to piecewise-constant data representation used in first-order methods like FV1, the DG2 solver represents data as piecewise-planar per element defined by three coefficients: an average-coefficient and two slope-coefficients in X and Y directions (Shaw et al., 2021). When the model is run using the DG2 solver, even though the data are inherently considered as piecewise-planar, the output water depth maps are only generated based on the average-coefficients. This might lead to crude flood maps when using the DG2 solver on coarse grids.
To improve this crudeness, a post-processing toolkit, named DG2downscale, is provided in the postprocess directory of LISFLOOD-FP-trunk repository, to artificially increase the resolution of the generated flood maps in a process called downscaling.
The left panel in the figure below shows a schematic view of the piecewise-planar representation of the DG2 data (like water depth) over a coarse cell. If four subdivisions are assumed on this coarse cell, using the piecewise-planar representation, it is possible to evaluate the data on the centres of each subdivision. These evaluated data, form the piecewise-constant representation on one level finer resolution, are shown in the right panel in the figure below.
The toolkit is obtained after compiling the LISFLOOD-FP code, following the instructions within “Compilation”. It will be generated as an executable file with the name DG2downscale.exe on a Windows platform and the name DG2downscale on a Linux-based platform, in the same directory where the LISFLOOD-FP executable is generated.
The toolkit requires the availability of the three coarse DG2 water depth or free-surface elevation files: the average-coefficient files .wd or .elev and the slope-coefficient files .wd1x and .wd1y or .elev1x and .elev1y. These files must be placed in the same directory where DG2downscale is generated.
In this directory, clicking on the location bar of the Windows Explorer, then typing cmd and pressing Enter, will open the Command Prompt Window. To run the toolkit, the name of the executable must be entered in the Command prompt, followed by the name of the coarse DG2 average-coefficient file, i.e. .wd or .elev:
DG2downscale.exe file_name.wd
or
DG2downscale.exe file_name.elev
Note that the slope-coefficient files will be read by the code automatically. After running the DG2downscale toolkit, the downscaled water depth or free-surface elevation Esri ASCII raster file will be generated within the same directory. This file will be saved with the same name as the coarse DG2 average-coefficient file but with the added extension of DScaled (i.e. for example file_name.wdDScaled or file_name.elevDScaled).