the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 08 Oct 2024
Earth observation informed modelling of flash floods
Abstract. More frequent extreme rainfall events in a changing climate increase the risk of flash flooding that is affecting populations globally. However, the flood hazard modelling required to reduce disaster risk in populated urban environments is often limited by the availability of data required for model calibration and validation. In this study, we use a historical flood event captured by 5 m resolution satellite imagery to quantify the effects of flood model complexity and inform flood hazards under future climate scenarios in the West Bank, Palestine. Flooding in January 2013 affected over 12,500 people and large areas of cropland. Vegetation loss and damage during the event were captured using satellite imagery and a normalised difference vegetation index (NDVI), and used as a reference flood extent. The physics-based HEC-RAS flood model best reproduced this NDVI-derived inundation extent (F1 score = 0.76), although the FastFlood model was able to produce a similar inundation pattern (F1 score = 0.74) over 300 times faster. Simulated flood depths from both models were similar; FastFlood displayed a mean difference of -0.03 m and a mean absolute error of 0.51 m when compared to HEC-RAS. Climate analysis revealed that the January 2013 rainfall corresponded to a historical return period of between 1 in 5 and 1 in 10 years. In comparison, a 1 in 100-year rainfall event (RX1day (maximum 1-day precipitation) of 148 mm) based on historical data (1985–2014) could increase by almost 40 % (to 205 mm) in the mid-future (2041–2060), which could cause 23 % (4 km2) greater inundation compared to the 2013 event. Although the patterns of future precipitation in the region are uncertain, our flood hazard maps can support urban planning and infrastructure development to manage storm water runoff, particularly where ephemeral channels, or wadis, intersect the road network.
- Preprint
(2954 KB) - Metadata XML
-
Supplement
(712 KB) - BibTeX
- EndNote
Status: closed
-
RC1: 'Comment on egusphere-2024-2722', Anonymous Referee #1, 07 Apr 2025
In this study three hydrological models are applied to on the West-Bank of Palestine. Because of little data availability, satellite images of the inundation extent of a flash flood in 2013 are used to validate the models. Future rainfall scenarios for the West-Bank are derived from GCMs via down-scaling and then used as input for these models to investigate possible future flood scenarios.
The manuscript is well written, clearly structured and to the point. At the same time the manuscript provides enough detail to follow the methodology and deals thoroughly with the data, e.g. the use and comparison of different DEMs.
Providing solid flood risk management in regions with little data availability is an important topic, especially in regard to climate change and the expected increase of flood magnitudes. This study points out that creative solutions in these regions are required and offers the use of satellite imagery as one possible solution.
While I really like the practical and applied nature, I also have some questions and criticism to address, mainly the use of apparently uncalibrated models which are even more simplified with the use of just one (?) mannings roughness value for the whole study area.
However, after discussing following aspects, I recommend this manuscript for publication.
See the detailed comments in attached document.
- AC1: 'Reply on RC1', C. Scott Watson, 07 Jul 2025
-
RC2: 'Comment on egusphere-2024-2722', Anonymous Referee #2, 29 Jun 2025
I found the manuscript to include several interesting elements, but I struggled to grasp a clear central message. It seems to be trying to do three things at once: (1) demonstrate how NDVI-based satellite observations can be used to support flood model validation in data-scarce areas, (2) compare three flood models of different complexity in terms of their performance and efficiency, and (3) simulate future flood hazard under changing climate conditions. All of these are relevant and useful topics, but the way they are presented together in the same paper feels unfocused. It’s unclear which of these is the main contribution.
The title emphasizes “Earth observation informed modelling,” which suggests that the novelty lies in using NDVI (and potentially other EO data) to support flood model validation where traditional in-situ observations are unavailable. This is potentially a very valuable idea and an important contribution. However, the paper spends a lot of time comparing three models and running future scenarios, and those parts — while well executed — feel somewhat disconnected from the core innovation. If the goal is to highlight the value of NDVI as a validation tool, then that angle needs to be brought forward much more clearly, both in the framing and the discussion. If, instead, the authors are more interested in benchmarking models or demonstrating a future risk pipeline, then the paper might need a different title and narrative altogether.
As it stands, the paper tries to be a methods paper, a modelling comparison, and a climate risk study all at once — and as a result, the reader is left unsure what the takeaway is. I would encourage the authors to clarify their core message, streamline the structure around that message, and remove or reduce content that is not essential to it. A more focused version of this study could be very publishable, but in its current form I would recommend substantial revision and resubmission.
Citation: https://doi.org/10.5194/egusphere-2024-2722-RC2 - AC2: 'Reply on RC2', C. Scott Watson, 07 Jul 2025
Status: closed
-
RC1: 'Comment on egusphere-2024-2722', Anonymous Referee #1, 07 Apr 2025
In this study three hydrological models are applied to on the West-Bank of Palestine. Because of little data availability, satellite images of the inundation extent of a flash flood in 2013 are used to validate the models. Future rainfall scenarios for the West-Bank are derived from GCMs via down-scaling and then used as input for these models to investigate possible future flood scenarios.
The manuscript is well written, clearly structured and to the point. At the same time the manuscript provides enough detail to follow the methodology and deals thoroughly with the data, e.g. the use and comparison of different DEMs.
Providing solid flood risk management in regions with little data availability is an important topic, especially in regard to climate change and the expected increase of flood magnitudes. This study points out that creative solutions in these regions are required and offers the use of satellite imagery as one possible solution.
While I really like the practical and applied nature, I also have some questions and criticism to address, mainly the use of apparently uncalibrated models which are even more simplified with the use of just one (?) mannings roughness value for the whole study area.
However, after discussing following aspects, I recommend this manuscript for publication.
See the detailed comments in attached document.
- AC1: 'Reply on RC1', C. Scott Watson, 07 Jul 2025
-
RC2: 'Comment on egusphere-2024-2722', Anonymous Referee #2, 29 Jun 2025
I found the manuscript to include several interesting elements, but I struggled to grasp a clear central message. It seems to be trying to do three things at once: (1) demonstrate how NDVI-based satellite observations can be used to support flood model validation in data-scarce areas, (2) compare three flood models of different complexity in terms of their performance and efficiency, and (3) simulate future flood hazard under changing climate conditions. All of these are relevant and useful topics, but the way they are presented together in the same paper feels unfocused. It’s unclear which of these is the main contribution.
The title emphasizes “Earth observation informed modelling,” which suggests that the novelty lies in using NDVI (and potentially other EO data) to support flood model validation where traditional in-situ observations are unavailable. This is potentially a very valuable idea and an important contribution. However, the paper spends a lot of time comparing three models and running future scenarios, and those parts — while well executed — feel somewhat disconnected from the core innovation. If the goal is to highlight the value of NDVI as a validation tool, then that angle needs to be brought forward much more clearly, both in the framing and the discussion. If, instead, the authors are more interested in benchmarking models or demonstrating a future risk pipeline, then the paper might need a different title and narrative altogether.
As it stands, the paper tries to be a methods paper, a modelling comparison, and a climate risk study all at once — and as a result, the reader is left unsure what the takeaway is. I would encourage the authors to clarify their core message, streamline the structure around that message, and remove or reduce content that is not essential to it. A more focused version of this study could be very publishable, but in its current form I would recommend substantial revision and resubmission.
Citation: https://doi.org/10.5194/egusphere-2024-2722-RC2 - AC2: 'Reply on RC2', C. Scott Watson, 07 Jul 2025
Viewed
| HTML | XML | Total | Supplement | BibTeX | EndNote | |
|---|---|---|---|---|---|---|
| 451 | 106 | 118 | 675 | 74 | 34 | 50 |
- HTML: 451
- PDF: 106
- XML: 118
- Total: 675
- Supplement: 74
- BibTeX: 34
- EndNote: 50
Viewed (geographical distribution)
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1