the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Submitted as: development and technical paper 18 Oct 2021
Submitted as: development and technical paper | 18 Oct 2021
Tracing and visualisation of contributing water sources in the LISFLOOD-FP model of flood inundation
- 1Geospatial Research Institute | Toi Hangarau, University of Canterbury, New Zealand
- 2School of Earth and Environment | Te Kura Aronukurangi, University of Canterbury, New Zealand
- 3Department of Geography, Geology and Environment, University of Hull, United Kingdom
- 1Geospatial Research Institute | Toi Hangarau, University of Canterbury, New Zealand
- 2School of Earth and Environment | Te Kura Aronukurangi, University of Canterbury, New Zealand
- 3Department of Geography, Geology and Environment, University of Hull, United Kingdom
Abstract. We describe the formulation of a simple method of water source tracing for computational models of flood inundation and demonstrate its implementation within CAESAR-Lisflood. Water source tracing can provide additional insight into flood dynamics by accounting for flow pathways. The method developed is independent of the hydraulic formulation used, allowing it to be implemented in other model codes without affecting flow routing. In addition, we developed a method which allows up to three water sources to be visualised in RGB colour-space, while continuing to allow depth to be resolved. We show the application of the methods developed for example applications of a major flood event, a shallow estuary, and Amazonian wetland inundation. A key advantage of the formulation developed is that the number of water sources which may be traced is limited only by computational considerations. In addition, the method is independent of the hydraulic formulation, meaning that it is relatively straightforward to add to existing finite volume codes including those based on or developed around the LISFLOOD-FP method.
Matthew D. Wilson and Thomas J. Coulthard
Status: open (until 13 Dec 2021)
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RC1: 'Comment on gmd-2021-340', Anonymous Referee #1, 08 Nov 2021
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The paper presents an algorithm that allows water source tracing and visualisation of water sources for flood inundation. The algorithm and concepts are outlined and described clearly in the paper, and each step of the process is easily understood through the text. The uses and implications of the algorithm that involve contaminant tracing or how inundation water quality is affected by different sources is also briefly discussed but could have been further emphasised in the paper. Having three case studies of varying sizes, flood mechanics and origins, and timescales was good since it showed the algorithm’s flexibility. Overall, the paper is well-written and the algorithm contributes further to the field of floodplain inundation modelling. I would recommend it for publication with minor revisions through adding some additional information to the introduction and discussion, and improving the presentation of some of the results.
Introduction
The LISFLOOD-FP model is briefly described in the introduction (purpose, use, representation of floodplain). The CAESAR model is also mentioned (P2, L33) but it does not get a similar description. It would be good to see a few lines describing the CAESAR model so the reader knows its purpose within the CAESAR-Lisflood model.
It would be good to see a brief review of previous work around tracing flood water sources in flood models in simpler schemes like LISFLOOD-FP. P1 L21-22 says that this ability is presently missing from reduced-complexity models, so have there been other papers that have tried to represent water source tracing in floodplain inundation models?
Methods
P4 L88-89: “Thus, fractions from sources where water is added to the cell are adjusted upwards, while fractions for non-source volumes are adjusted downwards.”
- Why? What would be the physical basis behind this?
P5 L130-131: “… each of the four flow directions”
- What are some of the advantages and limitations when four flow directions are considered? Would using the D8 or D-infinity representations of flow direction meaningfully affect the final results?
Results
For the final layout of the paper, can the maps and graphs for each case study be placed closer to the text of the case study? The UK results are fine, but the NZ and Brazil results are placed further and further from their respective sections. It would be better for the reader if the supporting maps and graphs were closer to the text.
The inundation maps (Fig 5, P13; Fig 7, P16; Fig 9, P19) show a very good overview of where the water sources for the inundation are coming from and how they are mixing. Would it possible to have a scale or legend item showing their respective depths? The text specifies that the darker colours represent deeper depths, but a darkness-depth scale/legend item for the individual colours would be useful.
P14 L220-224: This section outlines the implications of knowing where water that is likely to contain pollutants is being deposited, and its effects on environment and human health. This discussion can be further expanded as this is a very important issue for water resource management. The abstract could also be updated to include one sentence or so about how the algorithm contributes to the mitigation/assessment of water quality issues.
Similar to the New Zealand application, does the Brazil application also have similar water quality issues? Do the Solimões and Purus rivers have similar or differing water quality and how would it affect downstream processes? Have there been water quality issues associated with flooding in the New Zealand and Brazil case studies?
Although the processing time for the case studies is not comparable because of their differing timescales, it would be nice to have a summary table/overview of the three case studies taking about modelling domain size, grid size and number of cells, timescale, time taken to run the simulation, etc.
Discussion
As mentioned previously, it would be good to see discussion about the advantages of considering four flow directions, and if there would be significant changes if the D8 or D-infinity flow directions are incorporated into the model.
It would be good to have more discussions about the implications for water quality/contaminant issues on the environment health and human health, and how the algorithm can contribute to the mitigation of water quality issues. It helps underscore the contribution of the algorithm to modelling and to water resource management.
Testing the model
Please see the supplementary PDF for my notes about testing the model. I encountered some problems with running the Planar Test Case and the supplementary PDF shows the screenshots I encountered.
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CEC1: 'Comment on gmd-2021-340', Astrid Kerkweg, 18 Nov 2021
reply
Dear authors,
in my role as Executive editor of GMD, I would like to bring to your attention our Editorial version 1.2: https://www.geosci-model-dev.net/12/2215/2019/
This highlights some requirements of papers published in GMD, which is also available on the GMD website in the ‘Manuscript Types’ section: http://www.geoscientific-model-development.net/submission/manuscript_types.html
In particular, please note that for your paper, the following requirement has not been met in the Discussions paper:
- "The main paper must give the model name and version number (or other unique identifier) in the title."
If I understand correctly the CAESAR-Lisflood model (version v1.8f) includes the Lisflood-FP model mentioned in the title. Would it be possible to provide a version number for LISFLOOD-FP in the title of your manuscript (in the revised submission to GMD).
Yours,
Astrid Kerkweg
Matthew D. Wilson and Thomas J. Coulthard
Model code and software
CAESAR-Lisflood v1.8f-WS (water source tracing and visualisation) Wilson, M. D. and Coulthard, T. J. https://doi.org/10.5281/zenodo.5541123
Video supplement
Tracing and visualisation of contributing water sources in a model of flood inundation: video supplement Wilson, M. D. and Coulthard, T. J. https://doi.org/10.5281/zenodo.5548535
Matthew D. Wilson and Thomas J. Coulthard
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