An integrated, replicable Landslide Early Warning System for informal settlements &ndash; case study in Medell&iacute;n, Colombia

Gamperl, Moritz; Singer, John; Garcia-Londoño, Carolina; Seiler, Lisa; Castañeda, Julian; Cerón-Hernandez, David; Thuro, Kurosch

doi:https://doi.org/10.5194/nhess-2023-20

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https://doi.org/10.5194/nhess-2023-20

Preprints

20 Feb 2023

| 20 Feb 2023

Status: this discussion paper is a preprint. It has been under review for the journal Natural Hazards and Earth System Sciences (NHESS). The manuscript was not accepted for further review after discussion.

An integrated, replicable Landslide Early Warning System for informal settlements – case study in Medellín, Colombia

Moritz Gamperl, John Singer, Carolina Garcia-Londoño, Lisa Seiler, Julian Castañeda, David Cerón-Hernandez, and Kurosch Thuro

Abstract. Due to climate change and growing urbanization, fatalities from landslides are rising worldwide, and thus solutions for people at risk are needed. This is especially the case for the Andean cities which are often expanding into the steep slopes surrounding them. In Medellín, Colombia, a combination of landslide-prone dunite rock and steep slopes in the east of the city creates a high-hazard scenario for about 87,000 residents, most of whom live in informal settlements. We developed a landslide early warning system (LEWS) which can be applied in such semi-urban situations. The LEWS consists mainly of a measurement system of horizontal and vertical sensor lines across the slope and autonomous point-sensors in between these lines. All parts of the LEWS, from hazard assessment to the monitoring system and the reaction capacity, are supported by extensive activities together with the local community to gain trust and create synergies. This also includes local authorities, agencies and NGO's. To test such a system, a prototype has been installed in a neighborhood in Medellín in 2020–2022. The experiences of this installation resulted in a framework for LEWS's of this kind which we have compiled on a wiki-page to facilitate replication by people in other parts of the world. Hopefully, this can stimulate a lively exchange between researchers and other stakeholders who want to use, modify and replicate our system.

Received: 07 Feb 2023 – Discussion started: 20 Feb 2023

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Moritz Gamperl et al.

Status: closed

RC1:
'Comment on nhess-2023-20', Anonymous Referee #1, 17 Mar 2023

The paper presents an important issue regarding the rising fatalities from landslides due to climate change and urbanization, and the need for solutions for people at risk, in Andean cities such as Medellín. The authors propose a landslide early warning system (LEWS) which has been developed and tested in a neighborhood in Medellín, and a framework for LEWSs has been set.
The paper lacks details on the technical aspects of the system and its effectiveness in reducing fatalities. The rainfall/velocity thresholds are not even set yet. The paper also does not provide a thorough evaluation of the system's performance during the testing phase. Lastly, the manuscript seems to have a report-like structure, not really suitable for a research paper.

Citation: https://doi.org/10.5194/nhess-2023-20-RC1
- AC1: 'Reply on RC1', Moritz Gamperl, 27 Apr 2023
  
  Dear reviewer, thank you very much for your comment. We agree regarding the lack of rainfall and velocity thresholds in our case study in Medellín, Colombia. However, the focus of the paper is the distribution of the open-source elements (hardware and software) of the system and the illustration of the installation of these elements, and thus, it was not the goal to elaborate more on the system’s performance. These aspects will be discussed in other articles on the project, when more data from the measurement system is available (e.g. after two years of running the system) However, to give a more complete picture, we will add some more information about data analysis and interpretation in the revised manuscript.
  Regarding the lack of technical aspects, we partly agree. All aspects regarding the technical details have been published in Gamperl et al. 2021, as referenced in line 100 f. All changes that occurred since (and are not published elsewhere) are included in the manuscript. As stated prior, the focus was not on the technical details but on the framework and its reproducibility, and the social integration, as mentioned in the abstract and the introduction (36 ff.). So, the technical aspects regarding the sensors are referenced. However, as mentioned above, some more of the technical aspects regarding data analysis and interpretation will be included in the next version of the manuscript for a more complete picture. After the recent period of running the LEWS we are now also able to give preliminary thresholds, which we will do in the revised manuscript. It is clear that the relevance of warnings will only be increased after running the system for some time. Hence, we could present the outline of the LEWS now and can present more data of the monitoring system after a longer period of time, in a separate paper that focuses on this issue and thus will have a different emphasis than the current manuscript. We would like to emphasize that such a large and complex system can not be described in full detail in one research article, which is why we decided to focus with this manuscript on the interaction of the social and technical aspects, as well as the reproducibility of the system, while only shortly describing the topic of data analysis and interpretation, the details of which will be the topic of a future research paper.
  Following the intention of our paper, it was not possible to follow the structure of a common research paper. We felt the need for this structure due to the focus on the wiki page and the do-it-yourself aspects. With this paper, a researcher would be able to pursue a similar development path to elaborate their own monitoring and early warning system for their specific area or case study, using also the provided information on the wiki page. We don’t think that this – maybe unorthodox structure – is an argument against a research contribution for the NHESS journal. Quite the opposite, it was needed to convey the need for an LEWS with both a social and a technical emphasis.
  
  Citation: https://doi.org/10.5194/nhess-2023-20-AC1
RC2:
'Comment on nhess-2023-20', Anonymous Referee #2, 21 Mar 2023

In the paper “An integrated, replicable Landslide Early Warning System for informal settlements - case study in Medellin, Colombia” the authors describe an example of participatory, replicable landslide early warning system (LEWS), which was installed in Medellín (Colombia). The peculiarity of the LEWS is to combine the technological (measurement of physical parameters through a network of low-cost sensors) and social aspect (contribution of the involved stakeholders), in view of improving the system efficiency through a participatory approach. The case study is certainly interesting and promising but, in my opinion, the manuscript cannot be considered for publication as an original research paper. In detail, at the end of section 1.3 the authors assert that: “the scope of this contribution is to expand the concepts for a monitoring system as published in Singer et al. (2021); Gamperl et al. (2021b) and show them in the larger picture of the whole LEWS, including also the social angle”. However, the current structure of the work does not help in clarifying the novelty of the work. To be honest, the article has a very conversational tone, but great part of the reported information has been already published in the two above-mentioned articles, and only few, new things (i.e., Inform@Risk wiki, community and social integration of LEWS) have been added, which are not sufficient to significantly improve the scientific quality of the article. For instance, section 3 just describes the installation of the monitoring system in Medellín which, in turn, is a replication (with few modifications) of that installed in southern Germany and already described in Gamperl et al., 2021b.

At the beginning of Section 5.1, the authors assert that: “Detailed investigations of the data produced by the system and their analysis and interpretation are out of scope for this publication and will be published in the future”. Well, my suggestion is to focus on this specific issue instead, since I am convinced that the significance and reliability of the entire LEWS will benefit from it.

Citation: https://doi.org/10.5194/nhess-2023-20-RC2
- AC2: 'Reply on RC2', Moritz Gamperl, 27 Apr 2023
  
  Dear reviewer, thank you for your comments. We understand that the article’s goals should be made clearer in the introduction in order to show the novelty of the contribution.
  We understand the reviewer’s comment regarding the elements in the article which have already been published before and were referenced. To that time, the principal goals and structures were described in a very early stage of developing the LEWS. The current manuscript shows the stage after full installation of the system, going into details of the installation process, which haven’t been published before. Besides, we described the open source hardware and software on the Inform@Risk wiki for the first time. With this paper, a researcher would – for the first time – be able to pursue a similar development path to elaborate their own monitoring and early warning system for their specific case study, using also the provided information in the wiki page.
  The clear novelty of this research contribution is, that we describe details on the combination of the technical parts of the system with the community and social integration parts, to provide this information in newly developed open-source formats for other researchers and communities. This is an effort that has – to our knowledge - never before been undertaken – and published – in such areas. Most technical descriptions of LEWS lack the “last mile” and therefore stop before it comes to social integration. On the other hand, community oriented early warning systems usually lack the technical part.
  We do not agree with the following statement: The installation of the monitoring system in Medellín is described as a ‘replication of a system which before has been installed in southern Germany and described in Gamperl et a. (2021b)’. The system in Germany was only a very small prototype with six sensor nodes, no drillings and no line CSM/TDR measurements (costs: approx. 500 €). Also, the site is not inhabited, so only the technical part was tested before application to a large area at risk. This small-scale installation was only supposed to test the sensor functionality, as explained in Gamperl et al. (2021b). The described system in Colombia, on the other hand, is a large and complex monitoring system that covers about 38 ha and comprises 120 sensor nodes, several kilometers of horizontal and vertical TDR/CSM lines, four deep drillings (2 x 50 m and 2 x 30 m) and three gateways (costs of approx. 100.000 €). Additionally, the area is very densely populated and thus the social integration becomes a large part of the system, as first described in the manuscript.
  In the revised manuscript, we will work out the differences to the smaller system in Germany more clearly and highlight the novelty of the work.
  We will include more details regarding data analysis and interpretation in the next version of the manuscript. However it is clear, that the relevance of warnings will only increase after the system has been in operation for a longer period of time. Hence, we think it is worthwhile to present the outline of the LEWS and it’s social integration now and only include the detailed sensor data analysis and interpretation after some time in a separate paper. The latter would then be a very different focus from the present manuscript.
  
  Citation: https://doi.org/10.5194/nhess-2023-20-AC2

Status: closed

RC1:
'Comment on nhess-2023-20', Anonymous Referee #1, 17 Mar 2023

The paper presents an important issue regarding the rising fatalities from landslides due to climate change and urbanization, and the need for solutions for people at risk, in Andean cities such as Medellín. The authors propose a landslide early warning system (LEWS) which has been developed and tested in a neighborhood in Medellín, and a framework for LEWSs has been set.
The paper lacks details on the technical aspects of the system and its effectiveness in reducing fatalities. The rainfall/velocity thresholds are not even set yet. The paper also does not provide a thorough evaluation of the system's performance during the testing phase. Lastly, the manuscript seems to have a report-like structure, not really suitable for a research paper.

Citation: https://doi.org/10.5194/nhess-2023-20-RC1
- AC1: 'Reply on RC1', Moritz Gamperl, 27 Apr 2023
  
  Dear reviewer, thank you very much for your comment. We agree regarding the lack of rainfall and velocity thresholds in our case study in Medellín, Colombia. However, the focus of the paper is the distribution of the open-source elements (hardware and software) of the system and the illustration of the installation of these elements, and thus, it was not the goal to elaborate more on the system’s performance. These aspects will be discussed in other articles on the project, when more data from the measurement system is available (e.g. after two years of running the system) However, to give a more complete picture, we will add some more information about data analysis and interpretation in the revised manuscript.
  Regarding the lack of technical aspects, we partly agree. All aspects regarding the technical details have been published in Gamperl et al. 2021, as referenced in line 100 f. All changes that occurred since (and are not published elsewhere) are included in the manuscript. As stated prior, the focus was not on the technical details but on the framework and its reproducibility, and the social integration, as mentioned in the abstract and the introduction (36 ff.). So, the technical aspects regarding the sensors are referenced. However, as mentioned above, some more of the technical aspects regarding data analysis and interpretation will be included in the next version of the manuscript for a more complete picture. After the recent period of running the LEWS we are now also able to give preliminary thresholds, which we will do in the revised manuscript. It is clear that the relevance of warnings will only be increased after running the system for some time. Hence, we could present the outline of the LEWS now and can present more data of the monitoring system after a longer period of time, in a separate paper that focuses on this issue and thus will have a different emphasis than the current manuscript. We would like to emphasize that such a large and complex system can not be described in full detail in one research article, which is why we decided to focus with this manuscript on the interaction of the social and technical aspects, as well as the reproducibility of the system, while only shortly describing the topic of data analysis and interpretation, the details of which will be the topic of a future research paper.
  Following the intention of our paper, it was not possible to follow the structure of a common research paper. We felt the need for this structure due to the focus on the wiki page and the do-it-yourself aspects. With this paper, a researcher would be able to pursue a similar development path to elaborate their own monitoring and early warning system for their specific area or case study, using also the provided information on the wiki page. We don’t think that this – maybe unorthodox structure – is an argument against a research contribution for the NHESS journal. Quite the opposite, it was needed to convey the need for an LEWS with both a social and a technical emphasis.
  
  Citation: https://doi.org/10.5194/nhess-2023-20-AC1
RC2:
'Comment on nhess-2023-20', Anonymous Referee #2, 21 Mar 2023

In the paper “An integrated, replicable Landslide Early Warning System for informal settlements - case study in Medellin, Colombia” the authors describe an example of participatory, replicable landslide early warning system (LEWS), which was installed in Medellín (Colombia). The peculiarity of the LEWS is to combine the technological (measurement of physical parameters through a network of low-cost sensors) and social aspect (contribution of the involved stakeholders), in view of improving the system efficiency through a participatory approach. The case study is certainly interesting and promising but, in my opinion, the manuscript cannot be considered for publication as an original research paper. In detail, at the end of section 1.3 the authors assert that: “the scope of this contribution is to expand the concepts for a monitoring system as published in Singer et al. (2021); Gamperl et al. (2021b) and show them in the larger picture of the whole LEWS, including also the social angle”. However, the current structure of the work does not help in clarifying the novelty of the work. To be honest, the article has a very conversational tone, but great part of the reported information has been already published in the two above-mentioned articles, and only few, new things (i.e., Inform@Risk wiki, community and social integration of LEWS) have been added, which are not sufficient to significantly improve the scientific quality of the article. For instance, section 3 just describes the installation of the monitoring system in Medellín which, in turn, is a replication (with few modifications) of that installed in southern Germany and already described in Gamperl et al., 2021b.

At the beginning of Section 5.1, the authors assert that: “Detailed investigations of the data produced by the system and their analysis and interpretation are out of scope for this publication and will be published in the future”. Well, my suggestion is to focus on this specific issue instead, since I am convinced that the significance and reliability of the entire LEWS will benefit from it.

Citation: https://doi.org/10.5194/nhess-2023-20-RC2
- AC2: 'Reply on RC2', Moritz Gamperl, 27 Apr 2023
  
  Dear reviewer, thank you for your comments. We understand that the article’s goals should be made clearer in the introduction in order to show the novelty of the contribution.
  We understand the reviewer’s comment regarding the elements in the article which have already been published before and were referenced. To that time, the principal goals and structures were described in a very early stage of developing the LEWS. The current manuscript shows the stage after full installation of the system, going into details of the installation process, which haven’t been published before. Besides, we described the open source hardware and software on the Inform@Risk wiki for the first time. With this paper, a researcher would – for the first time – be able to pursue a similar development path to elaborate their own monitoring and early warning system for their specific case study, using also the provided information in the wiki page.
  The clear novelty of this research contribution is, that we describe details on the combination of the technical parts of the system with the community and social integration parts, to provide this information in newly developed open-source formats for other researchers and communities. This is an effort that has – to our knowledge - never before been undertaken – and published – in such areas. Most technical descriptions of LEWS lack the “last mile” and therefore stop before it comes to social integration. On the other hand, community oriented early warning systems usually lack the technical part.
  We do not agree with the following statement: The installation of the monitoring system in Medellín is described as a ‘replication of a system which before has been installed in southern Germany and described in Gamperl et a. (2021b)’. The system in Germany was only a very small prototype with six sensor nodes, no drillings and no line CSM/TDR measurements (costs: approx. 500 €). Also, the site is not inhabited, so only the technical part was tested before application to a large area at risk. This small-scale installation was only supposed to test the sensor functionality, as explained in Gamperl et al. (2021b). The described system in Colombia, on the other hand, is a large and complex monitoring system that covers about 38 ha and comprises 120 sensor nodes, several kilometers of horizontal and vertical TDR/CSM lines, four deep drillings (2 x 50 m and 2 x 30 m) and three gateways (costs of approx. 100.000 €). Additionally, the area is very densely populated and thus the social integration becomes a large part of the system, as first described in the manuscript.
  In the revised manuscript, we will work out the differences to the smaller system in Germany more clearly and highlight the novelty of the work.
  We will include more details regarding data analysis and interpretation in the next version of the manuscript. However it is clear, that the relevance of warnings will only increase after the system has been in operation for a longer period of time. Hence, we think it is worthwhile to present the outline of the LEWS and it’s social integration now and only include the detailed sensor data analysis and interpretation after some time in a separate paper. The latter would then be a very different focus from the present manuscript.
  
  Citation: https://doi.org/10.5194/nhess-2023-20-AC2

Moritz Gamperl et al.

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Short summary

We developed a system which can help improve the resilience of informal settlements in mountainous areas against shallow landslides. This system comprises a monitoring system which is specially designed for such areas and an according social system, the goal of which is to include the local residents in every step. We here present this system and the tools for it's further improvement by and with the scientific community, as well as endangered on-site communities.


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