Population and Landslide Risk Evolution in Long Time Series: Case Study of the Valencian Community (1920–2021)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study presents a procedure aimed at estimating the population exposed to landslide risk. In particular, a susceptibility map and data on the population are used. The procedure is applied in the Valencian Community (Spain) in the period 1920-2021.

Although the paper presents an interesting study with a certain degree of novelty, some issues need to be addressed before considering this paper suitable for publication (see the following comments).

 

MAIN COMMENTS

 

As a general comment, the authors need to carefully check the guidelines of the journal about the format of the citations.

 

2. GENERAL METHODOLOGY: This Section needs to be carefully reviewed, as a logic and rigorous structure is missing. The main issues are the following:

• the first part of the Section describing the main aim of the paper (lines 107-111) should be moved in the Introduction;
• the general framework showed should be presented at the beginning of Section 2. To this aim, you could move here Figure 4 and its description (lines 326-336);
• a more logic structure of the Section could be: 2.1 General framework; 2.2 Status and trend indices;
• improve the description of the examples reported in Figure 1 (lines 180-184), as it is not well explained the differences between the three cases reported.

 

3. CASE STUDY: VALENCIAN COMMUNITY: In this Section it is assumed that you should describe the study area and the dataset. Thus, I suggest moving Section 3.2 in Section 2 in order to describe the procedure followed for estimating the population at risk and the calculation of the indices.

 

6. CONCLUSIONS: Some insights and the “lessons learned” from the study reporting the best practices to be followed for urban planning and land use in the study area should be provided.

 

Finally, some minor errors and typos should be corrected throughout the manuscript and a careful revision of English language is highly recommended.

Some (not exhaustive) examples:

 

Line 122: Change “enormity” with “magnitude”

 

Title of Section 3 should start with a capital letter

 

Figure 9: Highlight the visualization of the three provinces, as they are not clear in the current version (I recommend adding the names of the provinces and using different colours for the borders)

 

Line 459: Change “signifies” with “indicates”

 

Lines 584: Delete “the study cited above”

 

Line 598: Change “the scope studied” with “this study”

 

Line 603: Change “any study of this kind” with “other studies”

 

Lines 613-614: Delete “(panoramic views, etc.)”

Comments on the Quality of English Language

The English language needs to be improved

Author Response

We sincerely appreciate all the comments from the reviewer, which have significantly contributed to improving the quality of the presented work.

 

Comments 1: As a general comment, the authors need to carefully check the guidelines of the journal about the format of the citations.

Response 1: Thank you for pointing this out. We have changed the citation format to comply with the journal requirements.

 

Comment 2. GENERAL METHODOLOGY: This Section needs to be carefully reviewed, as a logic and rigorous structure is missing. The main issues are the following: the first part of the Section describing the main aim of the paper (lines 107-111) should be moved in the Introduction; the general framework showed should be presented at the beginning of Section 2. To this aim, you could move here Figure 4 and its description (lines 326-336); a more logic structure of the Section could be: 2.1 General framework; 2.2 Status and trend indices; improve the description of the examples reported in Figure 1 (lines 180-184), as it is not well explained the differences between the three cases reported.

Response 2:

Regarding the main comments, Section 2 GENERAL METHODOLOGY has been reorganized following the reviewer's suggestions.

The description of the examples in Fig. 1 (now Fig. 2) has been improved between lines 180-184. This paragraph now reads:

“To illustrate this, Figure 2 shows an example with three different UADs covering a rectangular enclosure with a built-up area of 100 area units. Each circle represents a group of inhabitants (for the RPD calculation, 1 inhabitant). The three defined indices are calculated together with RPD under different scenarios: a) change in population distribution; b) change in number of affected inhabitants.”

 

Comment 3. CASE STUDY: VALENCIAN COMMUNITY: In this Section it is assumed that you should describe the study area and the dataset. Thus, I suggest moving Section 3.2 in Section 2 in order to describe the procedure followed for estimating the population at risk and the calculation of the indices.

 

Response 3:

In Section 3 CASE STUDY, the study area and the dataset used are described. We believe that obtaining specific data for the study area following the procedure established in Section 2 on general methodology is more appropriate, as it is an application of this methodology to a specific area. Therefore, we understand that it is better explained if the methodology and its application are differentiated and separated into different sections.

 

 

Comment 3: 6. CONCLUSIONS: Some insights and the “lessons learned” from the study reporting the best practices to be followed for urban planning and land use in the study area should be provided.

 

Response 3: In the CONCLUSIONS section, the following text has been added after the 3rd paragraph:  

“Indeed, there are a number of municipalities identified in this paper whose spatial planners should be more vigilant. They should do so by applying greater control on areas where urban development extends into mountainous areas. These areas are highlighted in Fig. 12 and are mostly located in the region of La Marina, in the north of the province of Alicante. These municipalities are close to the coast, receive high-income tourists and have limited possibilities for urban expansion. The new constructions end up occupying land with a higher risk of landslides, among other problems that are not inconsequential in nature (environmental, infrastructural, etc.).”

 

Comment 4: Finally, some minor errors and typos should be corrected throughout the manuscript and a careful revision of English language is highly recommended. Some (not exhaustive) examples: Line 122: Change “enormity” with “magnitude” Title of Section 3 should start with a capital letter Figure 9: Highlight the visualization of the three provinces, as they are not clear in the current version (I recommend adding the names of the provinces and using different colours for the borders) Line 459: Change “signifies” with “indicates” Lines 584: Delete “the study cited above” Line 598: Change “the scope studied” with “this study” Line 603: Change “any study of this kind” with “other studies” Lines 613-614: Delete “(panoramic views, etc.)”

 

Response 4: The typographical errors have been corrected in the text, and the visibility of the 3 maps has been improved by adding their geographic coordinates and indications of the location of provinces.

 

Comment 5: The English language needs to be improved

 

Response 5: The entire text in English has been reviewed again, and we accompany it with a certificate of the professional category of translator of the article.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors focused on hot topics and evaluated landslide disasters using new methods.

(1) The Abstract is incomplete and lacks results. Furthermore, in the end of Abstract, what does' patterns of variation and possible causes' specifically refer to?
(2) Line 26, this sentence is unrelated to the topic of this article.
(3) The content of lines 33-39 is hollow, and it is unclear what the author intends to convey by citing these references. Please cite some of the viewpoints, data, methods, and results specifically.
(4) Line 98, this sentence is very abrupt. Why did you choose this place as your research area? In addition to complex terrain and diverse urban layouts, what is more important is that it has already suffered from disasters. So at least the past disaster situations should be mentioned here.
(5) To be honest, I haven't seen any research gaps.
(6) Add latitude and longitude to Figures 3, 9, and 12.
(7) Why isn't the grid data of 100m2 shown in Figure 3? Administrative scale statistics will weaken spatial attributes.
(8) The data source needs to be more detailed.
(9) Discussion, suggests using different subheadings to separate. And also suggests adding comparisons with other methods, and shortcomings and prospects.

Author Response

We sincerely appreciate all the comments from the reviewer, which have significantly contributed to improving the quality of the presented work. Below, we provide our comments on the suggestions made for the review.

 

Comment 1: The Abstract is incomplete and lacks results. Furthermore, at the end of the Abstract, what does 'patterns of variation and possible causes' specifically refer to?

Response 1: The last sentence of the abstract has been changed to:

“The risk to the population has been found to be stable or decreasing slightly over the entire historical series in the study area. However, the intensive tourism in some coastal municipalities in the north of Alicante has led to the construction of holiday homes in unsuitable locations in mountainous areas and with it to an appreciable increase in risk.”

 

Comment 2: Line 26, this sentence is unrelated to the topic of this article.

Response 2: We want to emphasize that the increase in risk is due to both natural causes and those caused by human activity. In our own city (Valencia), we suffered a severe flood last October where both reasons were unequivocally manifested. In any case, we have improved the wording of this paragraph:

“In recent years, society has seen an increase in damage caused by natural hazards. Floods stand out in particular for their visibility, extent, intensity and frequency, in which climate change is presented as a primary triggering agent. In the case of landslides, with unequal influence but marked by unprecedented meteorological events (Chen et al., 2024; Gariano & Guzzetti, 2016; Haque et al., 2019), one important factor is the increased exposure to risk of susceptible elements: population, buildings, infrastructure (Moore & McInnes, 2016).”

 

Comment 3: The content of lines 33-39 is hollow, and it is unclear what the author intends to convey by citing these references. Please cite some of the viewpoints, data, methods, and results specifically.

Response 3: It is true that this paragraph is general, indicating some references that deal with different risk management and mitigation systems, as well as the most appropriate evaluation methodologies according to the available data. Specifically, the summary offered by Corominas (2014) in his article is highly recommended. However, it is true that they contribute little to the process developed in this work, and therefore, it seems advisable not to include it.

 

Comment 4: Line 98, this sentence is very abrupt. Why did you choose this place as your research area? In addition to complex terrain and diverse urban layouts, what is more important is that it has already suffered from disasters. So at least the past disaster situations should be mentioned here.

Response 4: In Spain, landslides are generally translational and severe; only some cases of flows have caused major disasters with a high number of victims. From the official record available for our entire national territory, 2927 events are presented. 3% of these events have occurred in the study area, which corresponds to 5% of the total Spanish surface area, with very few victims but significant damage to infrastructure and homes. The Valencian Community has been considered as our work area due to its varied orography and the different population dynamics it presents, an aspect that has allowed us to verify if there are differences in the evolution of risk to permanent or second homes. Therefore, the first part of this paragraph is changed to:

“In accordance with the stated objective, a working area needs to be chosen that is affected by landslides and with different population dynamics. The case of the Valencian Community, which takes up 5% of the total surface area of Spain, is adapted to these population conditions. It also represents 3% of the landslides in the whole of Spain, in accordance with its surface area, which have caused significant material damage, fortunately with very few victims.”

 

Comment 5: To be honest, I haven't seen any research gaps.

Response 5: Thanks you very much.

 

Comment 6: Add latitude and longitude to Figures 3, 9, and 12.

Response 6: We agreed, we have included geographic coordinates in all maps.

 

Comment 7: Why isn't the grid data of 100m2 shown in Figure 3? Administrative scale statistics will weaken spatial attributes.

Response 7: We have preferred to work at an administrative scale which, although more heterogeneous, is easier to identify and provides indications about joint municipal management. Indeed, part of the information is lost, but this is assumed when applying a “bottom-up” method that better integrates and generalizes data that cannot be highly accurate (the 100x100m population grid comes from the application of a “top-down”). This aggregation turns out to be more efficient and realistic for drawing conclusions. On the other hand, the 100m grid is too dense to include in such a small-scale map, which, for better readability of the article, we prefer not to increase.

 

Comment 8: The data source needs to be more detailed.

Response 8: The data has been obtained from three main sources. We understand that dedicating two pages to population and cadastral data may be sufficient, as it pertains to the specific Spanish case, but it could be detailed much more. The susceptibility mapping comes from a previous article by the same authors, which can also be expanded, but the reference to the article is provided for full consultation.

 

Comment 9: Discussion, suggests using different subheadings to separate. And also suggests adding comparisons with other methods, and shortcomings and prospects.

Response 9: We agreed with this suggestion, we will separate this section into two subsections for better understanding: 1. Variable Correlation and 2. Cluster Analysis. On the other hand, our main intention in this article is to obtain a homogeneous distribution of groups for the different municipalities that make up the study area. This way, it is easier to make comparisons and determine where the priority action areas are. Between the correlation analysis and the subsequent cluster analysis, we obtain this result. Its weakness lies in the appearance of “outliers,” but it is possible to filter them by their special geographic characteristics. A linear regression analysis could also be performed to understand temporal trends or geographic neighborhood using Moran's autocorrelation index. But we believe that they cannot offer more information than the overall view provides, in addition to not having found references in the bibliography.

Author Response File: Author Response.pdf