Spatial Analysis of Maritime Disasters in the Philippines: Distribution Patterns and Identification of High-Risk Areas

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The introduction provides an overview of maritime disasters in the Philippines and their impact and introduces analytical tools such as GIS and Maxent. However, it does not sufficiently elaborate on how these tools have been used in previous studies or what novelty this paper brings. It is recommended that a more detailed discussion of the state of the art and how this article contributes to filling existing gaps be included.

 

The research design is robust and relevant, combining spatial analysis tools such as Kernel Density and Maxent with key environmental variables. Comparing two datasets (PCG and IMO) strengthens the methodology and ensures greater validity of the results. However, a more explicit justification could be included for selecting these tools over alternatives.

 

Although the methods are detailed, some technical aspects could benefit from clarity. For example:

 

Coordinate integration by geocoding could explain more precisely how errors or missing data were handled.

 

Including a brief explanation of the cross-validation process and the choice of threshold values would be helpful. In addition, although tools such as ArcGIS and the SDM Toolbox are mentioned, details on specific configurations that could be relevant for replicating the study are lacking.

 

The results are well organized and supported by clear visualizations, such as density maps and risk models. Explanations are consistent and aligned with the study objectives. However, some graphs could benefit from further contextualization. For example, the results of the contribution of variables in Maxent could be included in a larger analysis to discuss how these variables influence maritime security policies.

 

 

The conclusions are consistent with the results obtained and reflect the implications of the analysis for improving maritime security. The article highlights high-risk areas and suggests specific actions, such as implementing vessel traffic management systems (VTMS). However, it would be valuable to include specific recommendations for future research, such as integrating dynamic data (e.g., real vessel traffic in real-time).

Comments on the Quality of English Language

• Corrected verb agreement ("waters... are" instead of "is").

• Improved sentence flow and coherence.

• Clarified the timeline ("Between 2000 and 2012" instead of "from 200 to 2012").

• Added precision by specifying "passenger ferry" instead of only "Dona Paz incident."

Author Response

Reviewer 1:

Comments and Suggestions for Authors

Comment 1: The introduction provides an overview of maritime disasters in the Philippines and their impact and introduces analytical tools such as GIS and Maxent. However, it does not sufficiently elaborate on how these tools have been used in previous studies or what novelty this paper brings. It is recommended that a more detailed discussion of the state of the art and how this article contributes to filling existing gaps be included.

 

Response: Text was revised as follows:

This work characterises the spatial patterns of maritime incidents in the Philippine archipelago to provide quantitative estimates of the likelihood component of risk assessment. It seeks to contribute knowledge on the application of geospatial tools and approaches for a geographical area where published literature is sparse with very limited reported research covering the focus and methodology used in this paper. The combination of a grid-based approach, the geostatistical tools including kernel density and hotspot analysis together with the machine learning tool Maxent is meant to provide a convenient means to cross check the outputs of each tool and provide confidence in the results. This novel approach provides confidence in the final risk mapping output. More importantly, the resulting map products aimed at contributing to the knowledge base required for improved maritime safety of the country.

 

Comment 2: The research design is robust and relevant, combining spatial analysis tools such as Kernel Density and Maxent with key environmental variables. Comparing two datasets (PCG and IMO) strengthens the methodology and ensures greater validity of the results. However, a more explicit justification could be included for selecting these tools over alternatives. 

Response: Text was revised as follows:

The Kernel Density tool in ArcGIS Pro [55] was used to describe the spatial distribution of the locations of incidents and provide a visualisation of the magnitude per unit area of the original incident locations derived from the data source. Default values for the tool was used for this analysis. Its use in this study is based on its robust depiction of incident distribution as reported on related work to characterise and identify high risk maritime locations in Malaysian waters [21], fishing and maritime traffic incidents in the Atlantic waters of Canada [56], incidents in Fujian Province of China [57] as well as global patterns of maritime accidents [25].

Maxent: Maxent was selected as the most suitable tool due to its capability to use only presence-only data, robust model outputs and applicability to a wide range of domains [33, 38, 39].

 

Comment 3: Although the methods are detailed, some technical aspects could benefit from clarity. For example:

 

Coordinate integration by geocoding could explain more precisely how errors or missing data were handled.

 

Response: Text was revised as follows:

In cases where geographic coordinates were not explicitly available, the names of places from the reports describing the vicinity of the incident was used as input for the Ge-ocoding tool in ArcGIS Pro. The resulting coordinates were verified manually in Google maps with reference to well-known routes and adjusted for accuracy and consistency. News media reports on the incidents were another source of information to cross-check the coordinates.

Comment 4: Including a brief explanation of the cross-validation process and the choice of threshold values would be helpful. In addition, although tools such as ArcGIS and the SDM Toolbox are mentioned, details on specific configurations that could be relevant for replicating the study are lacking.

Response: Text was revised as follows:

Maxent parameters to evaluate performance include turning on Random Seed and setting the test percentage to 20%, using Subsample for the replicate type and setting the maximum itera-tions to 10000. There were no thresholds rule set for the modelling

 

Comment 5: The results are well organized and supported by clear visualizations, such as density maps and risk models. Explanations are consistent and aligned with the study objectives. However, some graphs could benefit from further contextualization. For example, the results of the contribution of variables in Maxent could be included in a larger analysis to discuss how these variables influence maritime security policies.

Response: Additional text was added: 

This result provides a guide for further research focused on these variables with the end in view of supporting management decisions on a national scale.

 

Comment 6: The conclusions are consistent with the results obtained and reflect the implications of the analysis for improving maritime security. The article highlights high-risk areas and suggests specific actions, such as implementing vessel traffic management systems (VTMS). However, it would be valuable to include specific recommendations for future research, such as integrating dynamic data (e.g., real vessel traffic in real-time).

Response: Text was added:

The use of real time position data and big data from AIS together with machine learning and Artificial Intelligence (AI) approaches [71-73] further provide opportunities for developing effective solutions to improve the management and control systems to enhance the country’s maritime safety as mandated by national policies [74].

Reviewer 2 Report

Comments and Suggestions for Authors

1. This manuscript uses advanced spatial analysis techniques to examine key issues in maritime safety. It can inform policy and maritime management practices in the Philippines and other regions. Meanwhile, the manuscript is well-structured and clearly written. However, some sections would benefit from more detailed descriptions of the methods and their implications for maritime risk management. There are some suggestions as follows.
2. On page 1, line 32, the author may have mistakenly planted it, but it should be 2000.
3. In the abstract part, the work clearly states the key findings and how they can be used to improve maritime safety. However, the abstract emphasizes methodology, not outcomes. It is suggested that the authors emphasize the outcome of this study. Moreover, the author could provide a brief of policy implications or potential applications of the findings.
4. Most of the references need to be more recent research information. Updating or providing recent research to support the research statement or providing international readers with follow-up is recommended.
5. For the figures, it is recommended to supplement the related legend, such as information on latitude and longitude, scale bar, and description to ensure all figures are legible and include captions explaining their relevance to the study.
6. It is suggested that the authors could use consistent terminology throughout the whole manuscript when referring to datasets, tools, and variables (e.g., avoid switching between "distance to land" ( on page 1, line 22; page 5, line 193; page 7, line 213; page 10, line 282) and "land distance" on page 6, line 199; page 7, line 219; page 8, line 228 ).
7. For the Discussion part, it is suggested that the authors propose specific interventions based on the findings. For example, enhanced navigational aids in high-risk zones should be recommended, or vessel traffic management systems (VTMS) should be prioritized at identified hotspots. Moreover, the authors could Discuss how findings can support international maritime safety frameworks or national policies, such as the Philippine Maritime Industry Development Plan.
8. In conclusion, it is suggested that the authors highlight how the findings directly contribute to enhancing maritime safety in the Philippines and highlight specific steps for applying the study's findings to improve maritime safety. To demonstrate the contribution of this research to maritime safety.

Author Response

Comment 1: In the abstract part, the work clearly states the key findings and how they can be used to improve maritime safety. However, the abstract emphasizes methodology, not outcomes. It is suggested that the authors emphasize the outcome of this study. Moreover, the author could provide a brief of policy implications or potential applications of the findings.

Response: Text was edited as follows:

The maps developed depicts spatial pattern of maritime accidents in the country and identifies areas of high risk consistent among the different geospatial tools used. Results provide an approach and maps that support efforts for the improvement of maritime safety.

Comment 2:

Most of the references need to be more recent research information. Updating or providing recent research to support the research statement or providing international readers with follow-up is recommended.

Response: Recent references were added in the use of the tools including Maxent and in the discussion section.

Comment 3: For the figures, it is recommended to supplement the related legend, such as information on latitude and longitude, scale bar, and description to ensure all figures are legible and include captions explaining their relevance to the study.

Response: The scale bar is consistently present in all figures. There is no need for latitude and longitude information as all the maps have the same extent covering the area of study.

Comment 3: It is suggested that the authors could use consistent terminology throughout the whole manuscript when referring to datasets, tools, and variables (e.g., avoid switching between "distance to land" ( on page 1, line 22; page 5, line 193; page 7, line 213; page 10, line 282) and "land distance" on page 6, line 199; page 7, line 219; page 8, line 228 ).

Response: Corrections done

Comment 4: For the Discussion part, it is suggested that the authors propose specific interventions based on the findings. For example, enhanced navigational aids in high-risk zones should be recommended, or vessel traffic management systems (VTMS) should be prioritized at identified hotspots. Moreover, the authors could Discuss how findings can support international maritime safety frameworks or national policies, such as the Philippine Maritime Industry Development Plan.

Response: This is mentioned in the discussion.

Comment 5: In conclusion, it is suggested that the authors highlight how the findings directly contribute to enhancing maritime safety in the Philippines and highlight specific steps for applying the study's findings to improve maritime safety. To demonstrate the contribution of this research to maritime safety

Response: This contribution is now included in the abstract and conclusion.

Reviewer 3 Report

Comments and Suggestions for Authors

This is an excellent paper, and a very good analysis of the patterns of marine accidents in the Philippines. There is a comendable awareness of the global literature in the field applied not only in the marine context, but also an awareness of the literature in land-based contexts. The methodology is explained in detail, and the results fully illustrated with a very good set of maps. Viewed on the desktop the maps are not all that clear -if magnified there is a very good colour key ssytem used for all the respective maps. The discussion and conclusion highlights the key risk factors and places these in a geographical context.

Author Response

Comment 1: This is an excellent paper, and a very good analysis of the patterns of marine accidents in the Philippines. There is a comendable awareness of the global literature in the field applied not only in the marine context, but also an awareness of the literature in land-based contexts. The methodology is explained in detail, and the results fully illustrated with a very good set of maps. Viewed on the desktop the maps are not all that clear -if magnified there is a very good colour key ssytem used for all the respective maps. The discussion and conclusion highlights the key risk factors and places these in a geographical context.

Response: Thank you for the comments above. As an online article, the figures can be zoomed in to show details.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The author has added or revised that there are no additional comments.