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1. Title

RAIN-INDUCED LANDSLIDE SUSCEPTIBILITY: A GUIDEBOOK FOR COMMUNITIES & NON-EXPERTS

ID: DRH 61 Figure 1. Cover page of the guidebook for rain-induced landslide susceptibility assessment by communities and non-experts
Hazard: Landslide
Category:

Process Technology (PT)

Proposer: Daniel Jr. PECKLEY
Country: PHILIPPINES;
Date posted: 02 October 2010
Date published: 22 December 2010
Copyright © 2010 Daniel Jr. PECKLEY (proposer). All rights reserved.

Figure 1. Cover page of the guidebook for rain-induced landslide susceptibility assessment by communities and non-experts

Contact

Daniel C. PECKLEY Jr., PhD
Institute of Civil Engineering, University of the Philippines (UP-ICE)
Diliman, Quezon City 1101, Philippines
Email: dan.peckley@gmail.com
Tel/Fax: +632 4343635

Eduardo T. BAGTANG, DBM
Kalinga Apayao State College
Bulanao, Tabuk, Kalinga 3800, Philippines

Guillermo Q. TABIOS III, PhD
Institute of Civil Engineering, University of the Philippines
Diliman, Quezon City 1101, Philippines

2. Major significance / Summary

This guidebook offers a simplified and graphical assessment procedure for landslide susceptibility. It was prepared for communities and non-experts to enable them to evaluate landsliding susceptibility on their own. The use of this procedure can serve as a preliminary and quick step for a more detailed slope-failure-potential and risk evaluation. This procedure can also facilitate the identification and acceptance by communities of appropriate and cost-effective mitigation measures.

3. Keywords

Rain-induced landslides, susceptibility, communities, non-experts


II. Categories

4. Focus of this information

Process Technology (PT)

5. Users

5-1. Anticipated users: Community leaders (voluntary base) , Administrative officers , Municipalities , National governments and other intermediate government bodies (state, prefecture, district, etc.) , NGO/NPO project managers and staff , International organizations (UN organizations and programmes, WB, ADRC, EC, etc.) , Commercial entrepreneurs , Financing and insurance business personnel , Teachers and educators , Sociologists and political economists , Information technology specialists , Urban planners , Rural planners , Environmental/Ecological specialists

5-2. Other users: Policy makers , Local residents

6. Hazards focused

Landslide

7. Elements at risk

Human lives , Human networks in local communities , Business and livelihoods , Infrastructure , Buildings , Urban areas , Rural areas , Mountain slopes , Agricultural lands , Cultural heritages


III. Contact Information

8. Proposer(s) information (Writer of this template)

Daniel C. PECKLEY Jr., PhD
Institute of Civil Engineering, University of the Philippines (UP-ICE)
Diliman, Quezon City 1101, Philippines
Email: dan.peckley@gmail.com
Tel/Fax: +632 4343635

Eduardo T. BAGTANG, DBM
Kalinga Apayao State College
Bulanao, Tabuk, Kalinga 3800, Philippines

Guillermo Q. TABIOS III, PhD
Institute of Civil Engineering, University of the Philippines
Diliman, Quezon City 1101, Philippines

9. Country(ies)/region(s) where the technology/knowledge/practice originated

PHILIPPINES;

Cordillera Administrative Region
Northern Luzon

10. Names and institutions of technology/knowledge developers

The guidebook was prepared as part of the Department of Science and Technology Grant-in-Aid (DOST-GIA) Project: Development of Non-Expert Tool for Site-Specific Evaluation of Rain-Induced Landslide Susceptibility. This project was undertaken through a financial assistance provided by the DOST Philippine Council for Industry and Energy Research and Development (PCIERD) under Undersecretary Graciano P. Yumul Jr. The governing council of PCIERD, chaired by the Hon. Secretary Estrella F. Alabastro, approved the implementation of this project on its 99th meeting on June 13, 2008.

The project team was composed of the following: Eduardo T. Bagtang, Kalinga Apayao State College (KASC) President and Project Leader; Dr. Daniel C. Peckley Jr., DOST Balik Scientist and Associate Professor of UP ICE; Engr. Jude F. Dakiwag; Engr. Froilan L. Eugenio; Mr. Thomas Carabbacan, Engr. Fides Lovella A. Baddongon; Dr. Lope T. Buen; Engr. Rhonjon Garming; Dr. Arturo S. Daag and Ms. Lucille Rose Del Monte of the Philippine Institute of Volcanology and Seismology (PHIVOLCS); Ms. Fay W. Apil and Mr. Benigno Cesar L. Espejo of the Mines and Geosciences Bureau-Cordillera Administrative Region (MGB-CAR); Engr. Socrates Paat Jr. of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA); and Engr. Clifton D. Valencerina of the Department of Public Works and Highways-Cordillera Admistrative Region (DPWH-CAR). Engr. Baddongon and Dr. Peckley prepared the illustrations in this guidebook. The PCIERD Monitoring Team, composed of Ms. Ruby Raterta, Team Leader; Ms. Laarni T. Piloton; and Mr. Donald Roy B. Gorospe, provided the guidance and assistance required for the implementation of the project and the publication of this guidebook.

A review committee of the assessment procedure and this guidebook provided useful input and insights. This committee was composed of the following: Dr. Benito M. Pacheco, Chair, Philippine Institute of Civil Engineers –Committee on Disaster Mitigation, Adaptation and Prevention Strategies (DMAPS); Dr. Mark H. Zarco, Head, Geotechnical Engineering Group of the UP Institute of Civil Engineering (UP ICE); Dr. Renato U. Solidum Jr., Director, PHIVOLCS; Dr. Prisco D. Nilo, Administrator, PAGASA; Dr. Ben D. Ladilad, Regional Director, DOST-CAR; Dr. Judy F. Sese, Asst. Director, DPWH-Bureau of Research and Standards; Engr. Alexander C. Castañeda, Asst. Regional Director and Cordillera Administrative Region-State of the Nation Project Manager, DPWH-CAR; Dr. Fatima T. Tangan, Officer in Charge-Regional Technical Director, Department of Environment and Natural Resources- Ecosystem Research and Development Services, CAR; Engr. Ferdinand B. Tubban, City Engineer, Local government unit (LGU) Tabuk; Ret. Col. Paulo P. Pagteilan, Provincial Administrator, LGU Mt. Province. While many of their inputs and comments were already incorporated in this guidebook, a few would have to be consirered in future efforts and endeavors on landslide mitigation research.

11. Title of relevant projects if any

Development of Non-Expert Tool for Site-Specific Evaluation of Rain-Induced Landslide Susceptibility.

12. References and publications

[1] Peckley, D. C. et al. (2010), Terminal Report on the DOST-GIA Project: Development of a Non-expert Tool for Site Specific Evaluation of Rain-Induced Landslide Susceptibility. Submitted 28 June 2010.

[2] Peckley, D.C., Bagtang, E.T., and Zarco, M. H. (2010) Development of a Non-expert Tool for Site Specific Evaluation of Landslide Susceptibility, International Symposium and The 2nd AUN/SEED-Net Regional Conference on Geo-Disaster Mitigation in ASEAN, JICA - AUN/SEED-Net, Bali, Indonesia, February 25-26, 2010.

[3] Peckley, D.C. (2006): Business Principles in Geo-hazard Mitigation and Management. Yellowpad Column, BusinessWorld Newspaper, Philippines.

13. Note on ownership if any

With proper acknowledgment and written notice to the authors, all parts of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise.
Individual users are encouraged to document site surveys or investigations in which the assessment procedure presented in this guidebook was applied. The authors would be grateful if this documentation is forwarded to them. Institutional users are encouraged to improve upon whatever is presented in this guidebook. Further enhancements and improvements on the procedure are welcome, especially if such enhancements can save life, limb and property, as well as improve infrastructure.


IV. Background

14. Disaster events and/or societal circumstances, which became the driving force either for developing the technology/knowledge or enhancing its practice

Landslide susceptibility assessment is perceived as a very technical undertaking that only experts such as geotechnical engineers and engineering geologists can do. Given the facts, however, that the Philippines has very few geotechnical engineers and engineering geologists, and that every time a typhoon comes, tragedies and tremendous losses due to rain-induced landslides happen to tens, if not thousands, of communities, it is but practical and cost-effective to enable communities to assess the rain-induced susceptibility of their areas themselves (Peckley, 2005). To enable communities and local governments to do this, a simple and graphical procedure would have to be developed.

The use of such a procedure can serve as a preliminary and quick step for a more detailed slope-failure-potential and risk assessment. This procedure can also facilitate the identification and acceptance by communities of appropriate and cost-effective mitigation measures.

It is for these reasons that the Department of Science and Technology (DOST) of the Philippines funded the Grant-in-Aid (GIA) Project: Development of a Non-expert Tool for Site Specific Evaluation of Rain-Induced Landslide Susceptibility.


V. Description

15. Feature and attribute

 

Guidebook_Cover_r.png

Figure 1. Cover page of the guidebook for rain-induced landslide susceptibility assessment by communities and non-experts.

 

The main objective of this project was to develop a simple, graphical and site-specific assessment procedure that can enable communities and non-experts to assess the rain-induced landslide susceptibility of their areas on their own. This landslide-susceptibility assessment procedure is contained in a guidebook (Figure 1).

The procedure takes off from a very basic idea, i.e., strength or capacity S should always be greater than the applied load L (S>L). This concept could be expressed as a factor commonly referred in engineering as Factor of Safety Fs = S/L, which should always be greater than 1. Figure 2 illustrates the concept.

 Figure2.jpg

Figure 2. Factor of Safety, Fs, for a 30T-capacity bridge.

 

In this guidebook, the S/L ratio is referred to as the Factor of Stability Fs and its basic definition is

           Fsbasic= SRating/aRating                    (1)

where SRating is the strength rating or score of the slope material, while aRating is the rating for the slope angle a. The main force driving landslides is gravity and is directly related to the slope angle a; the higher the slope angle a, the higher the aRating. Figure 3 illustrates Fsbasic for slopes.

Figure3.jpg

Figure 3. Basic Factor of Stability, Fsbasic, for slopes

 

When other factors affecting landslide susceptibility are considered, Fs can be expressed as

Fs = [vFactor*fFactor*(SRating - sRed - dRed)]/[aRating * lFactor]

Here, the vFactor takes into account the vegetation cover of the slope. The fFactor takes into account the frequency of slope failure, presence of cracks and previous failure history. sRed represents the reduction of the shear strength of the slope material due to saturation as indicated by the presence of spring or the elevation of groundwater table due to rainfall infiltration. The dRed factor represents another reduction of shear strength of the material due to saturation due to poor drainage system. The lFactor is a factor that takes into account the existing land use.

To calibrate and validate the assessment procedure, the project team conducted surveys and inspections of 243 landslide and imminent landslide sites in the mountainous region of Cordillera, Luzon, Philippines. These surveys were carried out with assistance from the project cooperating agencies and local governments in the region. Table 1 summarizes the validation carried out for the assessment procedure.

 

Table 1. Levels of stability and validation

Factor of Stability Fs

No. of sites surveyed

No. of sites that failed

%age failure

Fs > 1.2: Stable

2

0

0

1.0 < Fs < 1.2: Marginally stable

8

0

0

0.7 < Fs < 1.0: Susceptible

40

27

68%

Fs < 0.7: Highly susceptible

193

184

95%

Total

243

211

87%


16. Necessary process to implement

A necessary step in this research project was to introduce the proposed assessment procedure to communities through training-seminars. The specific goals of these training-seminars were (1) to determine if communities and non-experts can indeed carry out rain-induced landslide susceptibility assessment using the procedure, and (2) identify aspects and areas of improvement.  

The training-seminars were conducted at eight (8) communities in Benguet and Kalinga, two provinces in Northern Luzon, Philippines, that were severely affected by landslides caused by Typhoon Parma’s heavy rainfall in October 2009.  

These training-seminars consisted of essentially of two parts, namely:
a) A lecture on rain-induced landslide assessment by communities and non-experts, and
b) An on-site landslide susceptibility assessment, where the participants apply the assessment procedure introduced in the lecture. For more details on the contents, please see Reference 1.

17. Strength and limitations

The assessment procedure presented in the guidebook is simple, graphical and site-specific. The approach is basically visual and manual involving simple tests. It does not involve the use of test equipment that can penetrate 30m or more into the ground. Thus, it should be noted that the procedure may only be applicable to shallow landslides, the depth of which is less than 3m. While the possibility of a deep-seated landslide may be detected through this procedure, it should not be used to perform a definitive evaluation of such a landslide. To learn more about how this assessment procedure was developed, see Reference 1 for more details.

18. Lessons learned through implementation if any

The lessons and insights gained from the initial implementation of the procedure, through the above-mentioned training-seminars include the following:

1) Communities and non-experts have the capacity to understand and conduct a supposedly highly technical undertaking such as landslide susceptibility assessment. One attribute of the assessment procedure developed in this study is that it takes off from fundamental and simple ideas, namely:
a)    Landslides are better understood as a “physics” problem rather than as a “chemistry” problem. As a “physics” problem, landslides are about stability, load vs. capacity, strength of materials, slope angle, cracks and discontinuities, and saturation. If it were a “chemistry” problem, it would be about chemical and mineralogical composition, rock origin and classification, age of rocks and soils.
b)    The capacity or strength S should always be greater than the applied load L, as discussed above and illustrated in Figures 2 and 3.
    
Comprehension and reception of the assessment procedure could also have been facilitated by the following:
a)    Conducting the training-seminar and active interaction in the vernacular;
b)    Using the figures and photos prepared for the guidebook, which served as visual aids in classifying rocks and soils;
c)    Presenting the validation of the assessment procedure with the data obtained from the surveys of 243 landslide and imminent landslide sites; and
d)    Giving the participants the opportunity to actually apply the procedure and to present the results to other participants and the trainers/facilitators for feedback and comments.

2) Partnership with NGOs, the concerned LGUs and other institutions greatly facilitate the enabling of communities to conduct landslide assessment on their own, thereby allowing these communities to become more rain-induced landslide disaster-resilient.

3) Wide participation and appreciation can be ensured when the training-seminar is held at the community or village hall, not in some fancy function room or hall far from the community. “High-tech” presentations or seminar facilities may not be available at community halls, thus trainers/facilitators should be capable of giving the seminar using only a board and chalk.

4) Informed and trained communities/non-experts usually lead to open-mindedness and the ability to discern appropriate action/s to protect the community/their families.
For example,
a)    Communities advised by the Mines and Geosciences Bureau to relocate become more rational and objective in considering such advice.
b)    Communities become interested and inquisitive on the proper design and implementation of slope stability works that are appropriate and practical, considering slope material classification and other local conditions.


VI. Resources required

19. Facilities and equipments required

Introducing and conducting the proposed assessment procedure do not require expensive facilities and resources. For participants of up to 60 persons, a minimum of 1-day training-seminar would be required. In this training-seminar, printed copies of the guidebook are essential.

In conducting the assessment procedure, it would be necessary to bring the following:

1)    Camera (cellular phone with camera would suffice)
2)    Measuring tape (preferably 5m or longer in length)
3)    Bond/printing paper (at least 5 sheets)
4)    Pen or pencil
5)    Hammer
6)    Four (4)-inch common wire nails
7)    Shovel and other digging implement/s (e.g. pick axe, hoe)
8)    Bolo/machete for clearing

The following are optional but recommended:
a)    Tiltmeter, anglemeter or any device to measure slope angle
b)    GPS (Global Positioning System) receiver device
c)    Swedish weight sounding test equipment (for sandy, silty and clayey soils) or similar portable in-situ testing equipment

20. Costs, organization, manpower, etc.

The expenses involved in introducing the procedure to communities would depend on the following:

1)      Number of participants;

2)      Cost of printing the guidebook and other hand-outs (pens, papers, etc.);

3)      Honoraria of training-seminar resource persons and organizers; and

4)      Rental of training-seminar hall.

As in any training-seminar, an organizing group or team consisting of three (3) to five (5) persons would have to be created to invite resource speakers and participants, and to prepare the training materials and venue.

The expenses involved in conducting the assessment procedure itself is very limited, as can be inferred in No. 19.


VII. Message from the proposer if any

21. Message

When lives and limbs are at stake, the findings obtained with the use of the landslide assessment procedure presented in the guidebook should be reviewed and validated by a practicing and experienced geotechnical engineer or engineering geologist.


VIII. Self evaluation in relation to applicability

22. How do you evaluate the technology/knowledge that you have proposed?

It is a technology/knowledge that is shown to be effectie based on case studies/experiments in field sites.

23. Notes on the applicability if any

As stated above, the approach employed in this assessment is basically visual and manual, involving simple tests. It does not involve the use of test equipment (e.g., Swedish penetrometer test) that can penetrate 30m or more into the ground. Thus, it should be noted that the procedure may only be applicable to shallow landslides, the depth of which is less than 3m. While the possibility of a deep-seated landslide may be detected through this procedure, it should not be used to perform a definitive evaluation of such a landslide.

 


IX. Application examples

No.1

    E1-1. Project name if available

    Training-Seminar on Community-Based Rain-Induced Landslide Disaster Mitigation at Tublay, Benguet, Philippines


    E1-2. Place

    Tublay Municipal Hall, Tublay, Benguet, Philippines

    Sitio Sto. Niño, Tublay, Benguet, Philippines

    Sitio Coroz, Tublay, Benguet, Philippine

    Photo1.jpg


    E1-3. Year

    2010


    E1-4. Investor

    CFSI
    Team Café by the Ruins
    Alay sa Kapwa Foundation
    LGU of Tublay, Benguet


    E1-5. People involved

    Kalinga Apayao State College
    CFSI
    Team Café by the Ruins
    Alay sa Kapwa Foundation
    LGU of Tublay, Benguet


    E1-6. Monetary costs incurred

    Around PhP70,000.00. (around US$1,600)


    E1-7. Total workload required

    The training-seminar was held for two days. Two resource persons conducted the lectures.


    E1-8. Evidence of positive result

    After the training, the communities took the initiative to further undertake a more detailed landslide risk assessment and implement practical mitigation measures on their own. For the assessment, they dug test pits and were involved in the topographic surveys that were conducted.

    When it was found that their area is only susceptible to shallow landslides (thickness of landslide prone soil layer less is just around 1m), they planted alnus (Alnus japonica) trees and vetiver grasses, the roots of which can penetrate and strengthen this susceptible soil layer.  


No.2

    E2-1. Project name if available

    Training-seminar on Community-initiated Landslide Susceptibility Assessment


    E2-2. Place

    Bgy. Naneng, Tabuk, Kalinga, Philippines

    Photo2.jpg


    E2-3. Year

    2010


    E2-4. Investor

    Department of Science and Technology (DOST)
    Kalinga Apayao State College (KASC)


    E2-5. People involved

    KASC
    Community leaders and members of Bgy. Naneng, Tabuk, Kalinga
    Community leaders and members of Bgy. Lucog, Tabuk, Kalinga
    Community leaders and members of Bgy. Dupag, Tabuk, Kalinga
    Community leaders and members of Bgy. Bagumbayan, Tabuk, Kalinga


    E2-6. Monetary costs incurred

    Around PhP70,000.00 (around US$1,600)


    E2-7. Total workload required

    The training-seminar was held for two days. Two resource persons conducted the lectures.


    E2-8. Evidence of positive result

    Keen interest among the participants on the proper design and implementation of slope stability and drainage works that are appropriate and practical, considering slope material classification and other local conditions.


No.3

    E3-1. Project name if available

    Training-seminar on Community-initiated Landslide Susceptibility Assessment


    E3-2. Place

    Luneta-antamok, Itogon, Benguet, Philippines

    Photo3.jpg


    E3-3. Year

    2010


    E3-4. Investor

    Community and Family Services International (CFSI)
    Alay sa Kapwa Foundation
    Local government unit (LGU) of Itogon, Benguet


    E3-5. People involved

    CFSI
    Alay sa Kapwa Foundation
    LGU of Itogon, Benguet
    Kalinga Apayao State College


    E3-6. Monetary costs incurred

    Around PhP70,000. (around US$1,600)


    E3-7. Total workload required

    The training-seminar was held for two days. Two resource persons conducted the lectures.


    E3-8. Evidence of positive result

    Keen interest among the participants on the proper design and implementation of slope stability and drainage works that are appropriate and practical, considering slope material classification and other local conditions.

    The participants also committed to apply the knowledge gained in finding appropriate relocation sites.


No.4

    E4-1. Project name if available

    Training-seminar on Community-initiated Landslide Susceptibility Assessment


    E4-2. Place

    Labey, Bokod, Benguet, Philippines

    Photo4.jpg


    E4-3. Year

    2010


    E4-4. Investor

    Cordillera Disaster Response and Development Services, Inc.
    (CorDis RDS)


    E4-5. People involved

    CorDis RDS
    Kalinga Apayao State College


    E4-6. Monetary costs incurred

    Around 50,000.00 (around US$1,150)


    E4-7. Total workload required

    One (1) day, two resource persons


    E4-8. Evidence of positive result

    Keen interest among the participants on the proper design and implementation of slope stability measures.

    The participants also committed to apply the knowledge gained in finding appropriate relocation sites.


No.5

    E5-1. Project name if available

    Trainer’s Training on Disaster Risk Reduction and Rain-induced Land Susceptibility Assessment


    E5-2. Place

    Baguio City, Philippines

    Photo5.jpg


    E5-3. Year

    2010


    E5-4. Investor

    Cordillera Industry and Energy Research and Development Consortium (CIERDEC), Baguio City, Philippines


    E5-5. People involved

    CIERDEC
    Technical Education and Skills Development Authority-Cordillera Administrative Region (TESDA-CAR), Philippines
    UP Institute of Civil Engineering, Diliman, Quezon City


    E5-6. Monetary costs incurred

    The organizer (investor) disclosed that around PhP 35,000.00 (around US$800)were spent for this training, where the number of participants was around 30.


    E5-7. Total workload required

    Two days, three resource persons


    E5-8. Evidence of positive result

    While funding for a continued trainers’ training seminar is being sought by CIERDEC, the participants committed to apply and share the knowledge gained in this training-seminar with their respective institutions/agencies.


X. Other related parallel initiatives if any

Message


XI. Remarks for version upgrade

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