the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 17 Apr 2025
Multiscale Modeling for Coastal Cities: Addressing Climate Change Impacts on Flood Events at Urban-Scale
Abstract. This study presents an integrated modeling framework designed to bridge scales from regional to urban, enabling a detailed assessment of the impacts of future climate scenarios on three European coastal cities: Massa (Italy) and Vilanova (Spain) in the Mediterranean, and Oarsoaldea (Spain) in the Atlantic. Conducted as part of the SCORE EU Project (Smart Control of Climate Resilience in European Coastal Cities), the framework employs a novel, non-standard downscaling approach to translate large-scale atmospheric outputs from the EURO-CORDEX regional model ALADIN63 (for Historical, RCP4.5, and RCP8.5 scenarios) into high-resolution simulations of storm surges, wave climate, and river discharge using SHYFEM, WAVEWATCH III, and LISFLOOD models.
The framework achieves coastal resolutions on the order of 100 m, providing time series of water levels and wave runup, which are combined into total water levels. These results, together with extreme value analysis of river discharge and projected relative sea level rise (RSLR), are used as boundary conditions for an urban-scale hydrodynamic model with resolutions as fine as 2–20 m. This multi-scale integration allows for detailed analysis of changes in flooded areas and volumes under RCP4.5 and RCP8.5 scenarios, relative to historical conditions, highlighting the influence of shifting extremes, RSLR, and site-specific features.
Results show that in Massa and Vilanova, increased extreme river discharges are projected, while moderate changes in extreme water levels are overshadowed by RSLR, particularly for Massa. Oarsoaldea, well protected from storm surges, is expected to experience a slight reduction in extreme river discharge. This work demonstrates the capability of the integrated framework to address climate change impacts at urban scales, providing valuable insights for the development of localized adaptation strategies.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
(2739 KB)
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Supplement
(2087 KB)
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(2739 KB) - Metadata XML
-
Supplement
(2087 KB) - BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2025-270', Anonymous Referee #1, 05 Jun 2025
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AC1: 'Reply on RC1', Carlo Brandini, 22 Jul 2025
We sincerely appreciated the insightful and constructive comments by the reviewer, which led to a deeper understanding of some key aspects and pushed us to better clarify and strengthen the paper.
Please find our detailed replies to each comment in the attached zipped response files.
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AC1: 'Reply on RC1', Carlo Brandini, 22 Jul 2025
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RC2: 'Comment on egusphere-2025-270', Goneri Le Cozannet, 10 Jun 2025
This paper provides an example of flood modelling in two coastal cities due to storm surge and river discharge. The paper is well written and is relevant to NHESS. Some uncertainties - e.g. on compound events - are well discussed, but not all. However, before publishing this work, I recommend to:
- provide more elements about the validation of this work
- assuming a proper validation of the total water levels at a tide gauge and waves offshore, the key uncertainty will result from the use of an empirical formula for the wave setup, which requires a high resolution shallow water bathymetry. It would be important to discuss it as the ambition is to provide a high resolution flood model, as illustrated by the use of a Lidar topographic data.
- the context about sea-level rise is not well explained; it would be important to discuss what we know from sea-level rise, e.g. commitments over decades to centuries, the fact that meters of sea level rise can not be avoided on the long term and that this could happen earlier than projected in case of an ice sheet collapse - see e.g. the IPCC report WG1 published in 2021. Based on this review, I recommend to reconsider the statements starting lines 605 regarding future flooding in Massa.
- The data used on sea-level projections are not clearly presented (no unit in Table 3, no source associated to the table). This should be precisely clarified.
- Overall the paper would have more impact with a one or a few clear key messages that could be taken forward - e.g. that precise flood hazard assessment is required to assess future sea level rise impacts in coastal cities, that this can not be achieved at broad scale yet (no global Lidar DEM) and requires local assessments;
These comments are moderate, but provided elements on the validation can be provided, they coulb be handled as minor comments.
I hope that this review is useful
Sorry for submitting this review late
Gonéri Le Cozannet, BRGM, 10/06/2025Citation: https://doi.org/10.5194/egusphere-2025-270-RC2 -
AC2: 'Reply on RC2', Carlo Brandini, 22 Jul 2025
We sincerely thank the referee for the constructive and insightful comments, which have significantly contributed to improving the quality and clarity of our manuscript.
In the attached file, we provide detailed responses to each of the points raised. For clarity, the referee's comments are reproduced in blue italic font, followed by our replies.
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AC2: 'Reply on RC2', Carlo Brandini, 22 Jul 2025
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2025-270', Anonymous Referee #1, 05 Jun 2025
This study introduces a comprehensive modeling framework to assess the impacts of climate change on coastal and riverine flooding in European coastal cities. By integrating atmospheric data from the ALADIN63 regional climate model under the EURO-CORDEX project, researchers simulate future flood scenarios under RCP4.5 and RCP8.5 climate pathways. The modeling chain employs a wave model, storm surge model, river discharge model based on rainfall-runoff processes, and HEC-RAS for hydrodynamic simulations to assess flood extents and depths. The findings underscore the importance of high-resolution, integrated modeling approaches to accurately project and manage future flood risks in coastal urban areas.
Please find my review in the attached file.-
AC1: 'Reply on RC1', Carlo Brandini, 22 Jul 2025
We sincerely appreciated the insightful and constructive comments by the reviewer, which led to a deeper understanding of some key aspects and pushed us to better clarify and strengthen the paper.
Please find our detailed replies to each comment in the attached zipped response files.
-
AC1: 'Reply on RC1', Carlo Brandini, 22 Jul 2025
-
RC2: 'Comment on egusphere-2025-270', Goneri Le Cozannet, 10 Jun 2025
This paper provides an example of flood modelling in two coastal cities due to storm surge and river discharge. The paper is well written and is relevant to NHESS. Some uncertainties - e.g. on compound events - are well discussed, but not all. However, before publishing this work, I recommend to:
- provide more elements about the validation of this work
- assuming a proper validation of the total water levels at a tide gauge and waves offshore, the key uncertainty will result from the use of an empirical formula for the wave setup, which requires a high resolution shallow water bathymetry. It would be important to discuss it as the ambition is to provide a high resolution flood model, as illustrated by the use of a Lidar topographic data.
- the context about sea-level rise is not well explained; it would be important to discuss what we know from sea-level rise, e.g. commitments over decades to centuries, the fact that meters of sea level rise can not be avoided on the long term and that this could happen earlier than projected in case of an ice sheet collapse - see e.g. the IPCC report WG1 published in 2021. Based on this review, I recommend to reconsider the statements starting lines 605 regarding future flooding in Massa.
- The data used on sea-level projections are not clearly presented (no unit in Table 3, no source associated to the table). This should be precisely clarified.
- Overall the paper would have more impact with a one or a few clear key messages that could be taken forward - e.g. that precise flood hazard assessment is required to assess future sea level rise impacts in coastal cities, that this can not be achieved at broad scale yet (no global Lidar DEM) and requires local assessments;
These comments are moderate, but provided elements on the validation can be provided, they coulb be handled as minor comments.
I hope that this review is useful
Sorry for submitting this review late
Gonéri Le Cozannet, BRGM, 10/06/2025Citation: https://doi.org/10.5194/egusphere-2025-270-RC2 -
AC2: 'Reply on RC2', Carlo Brandini, 22 Jul 2025
We sincerely thank the referee for the constructive and insightful comments, which have significantly contributed to improving the quality and clarity of our manuscript.
In the attached file, we provide detailed responses to each of the points raised. For clarity, the referee's comments are reproduced in blue italic font, followed by our replies.
-
AC2: 'Reply on RC2', Carlo Brandini, 22 Jul 2025
Peer review completion
Journal article(s) based on this preprint
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Michele Bendoni
Francesca Caparrini
Andrea Cucco
Stefano Taddei
Iulia Anton
Roberta Paranunzio
Rossella Mocali
Massimo Perna
Michele Sacco
Giovanni Vitale
Manuela Corongiu
Alberto Ortolani
Salem Gharbia
Carlo Brandini
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(2739 KB) - Metadata XML
-
Supplement
(2087 KB) - BibTeX
- EndNote
- Final revised paper
This study introduces a comprehensive modeling framework to assess the impacts of climate change on coastal and riverine flooding in European coastal cities. By integrating atmospheric data from the ALADIN63 regional climate model under the EURO-CORDEX project, researchers simulate future flood scenarios under RCP4.5 and RCP8.5 climate pathways. The modeling chain employs a wave model, storm surge model, river discharge model based on rainfall-runoff processes, and HEC-RAS for hydrodynamic simulations to assess flood extents and depths. The findings underscore the importance of high-resolution, integrated modeling approaches to accurately project and manage future flood risks in coastal urban areas.
Please find my review in the attached file.