the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 21 May 2025
The effect of different landslide mapping approaches on the geomorphological assessment of landslide hazard
Abstract. Despite various methodologies proposed in the last decades, there are still no standard for estimating landslide hazard. Consequently, practical applications for territorial management have to assimilate in a single cartography information obtained at local level with different methods, with negative consequences on the quality of derived products. Here we proposed a new methodology – based on well-established hazard matrices – to assess landslide hazard, which starts from a landslide inventory, and introduces a new method for estimating the landslides frequency. We apply this new method to three landslide inventories compiled with increasing detail. They are: (i) a basic-historical inventory, (ii) a generational-historical inventory (a detailed version of a simple historical inventory), (iii) and a composite multi-temporal inventory (which includes the generational-historical inventory plus the multi-temporal inventory). Results are then compared each other, and to independent measures from Persistent Scatterer Interferometry. Our results highlight the importance to base landslide hazard analysis on a generational-historical inventory that adequately characterizes the complexity of landslide clusters, whereas indicate that multi-temporal mapping is not decisive for the purpose. Overall, our procedure puts landslide mapping back at the center of the hazard assessment chain, raising questions on the reliability and availability of landslide inventory maps.
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RC1: 'Comment on egusphere-2025-2096', Anonymous Referee #1, 19 Aug 2025
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I started to read the manuscript with great interest as in the abstract the paper claims to create a new method to assess landslide hazard and puts inventory at the center of landslide hazard assessment. However, I am not satisfy those claims are substantially supported by the manuscript and my major observations are as follows:
1. The literature review/introduction part of the manuscript is very weak as it does not properfly define the rational behind this research and does not explain the research gaps (why this work needs to be done) and what are the existing gaps in the scientific literature. For example, recent works on physically based analysis for small regions and statistical/ML approaches for large regions has significantly well defined the landslide hazard in terms of exceedence probability, susceptibility and hazard itself. Gap on those works must be stated and your work must be well posed to solve those gaps. (e.g. why your work is needed when the work of Guzzetti 2005 on probabilistic approach or recent improvements on that can define landslide hazard).
2. The method defined for this work needs to be clarified as method section ends abruptly at the section comparing with PS points. I did not understand what is the end goal of your landslide hazard assessment. does it provide landslide hazard zonation (like class low medium high) or does it provide quantitative measure. From the introduction section my impression is that you have semi-quantitative approach for defining hazards.
3. Can we define landslide hazard just based on the frequency of past landsldies? Major issue that I have with the approach is that you assume the landslide will occure in the same zone if it has occured in the past observation and vice versa. I would asuume the landslides often change the terrain characterstics changing the landslide dynamics and frequency, thus changing the hazard.
4. How is the landslide volume/kinetic energy estimated? is it through sterio-images or based on the area of landslide polygons. Since area can be a proxy of volume why not use area itself, which can be measured with higher precision and accuracy?
5. Your workflow primarily maps frequency and then treats it as hazard for planning (“frequency counting”, “landslide frequency zonation” and “LHZs” are the operative layers). That’s consistent with the classic geomorphological tradition, but it does not explicitly model when landslides are likely to recur. Therefore, it looks more like landslide inventory analysis to understand their spatial frequency.
6. The manuscript introduces PS within LHZs “to identify active settlements,” but the role of PS in the hazard inference remains vague (screening? validation? conditioning?). Spell out: (i) PS processing settings; (ii) deformation thresholds that define “active”; (iii) how PS density/velocity modifies frequency classes; (iv) how you treat layover/vegetation decorrelation; and (v) how PS evidence is integrated with inventory (e.g., Bayesian updating of activity state vs. a qualitative overlay). Without this, PS risks being read as a visual add-on rather than a quantitative component.
7. The paper discusses reasoning behind frequency mapping but does not present a formal validation (e.g., chrono-validation, forward validation against a held-out recent period, or cross-regional transfer). I would consider some quantitative validation by some sort of chrono validation.
8. How would you assess the uncertainties in the hazard zones, and how better is it compared to geomorphic zonation by expert based analysis where expert looks at the geomorphology and defined the landslide zones. I think this needs to be discussed extensively.
Citation: https://doi.org/10.5194/egusphere-2025-2096-RC1
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