Title: “The Landslide Handbook—a Guide to Understanding Landslides”: A Landmark Publication for Landslide Education and Preparedness

By: Peter Bobrowsky, Geological Survey of Canada

Lynn Highland, U.S. Geological Survey

Abstract

The International Program on Landslides (IPL) aims to conduct international cooperative research and capacity building on landslide risk mitigation, notably in developing countries. To this end, a proposal was submitted to the IPL project committee by landslide researchers from the Geological Survey of Canada and the U.S. Geological Survey. The proposal entitled “A Best Practices Handbook for Landslide Mitigation” and was accepted by the ICL/IPL Board of Representatives (BOR) in 2002. As the project evolved, the aim of the Handbook became more comprehensive and the target audience clarified as those charged with emergency management, landslide mitigation, and public education in both developed and developing countries, including those lay persons interested in a comprehensive introduction to Landslide Hazards. The final product and volume entitled “The Landslide Handbook--A Guide To Understanding Landslides” was written by Lynn Highland, U.S. Geological Survey (Landslide Program) and Peter Bobrowsky, Geological Survey of Canada. This handbook is now helping home-owners, community and emergency managers, and decision makers to take the positive step of encouraging awareness of available options and recourse in regard to landslide hazard. As of 2011 The Handbook has been published in 4 additional languages: Mandarin Chinese, Japanese, Portuguese, and Spanish.

Introduction

The Landslide Handbook began as a project proposal titled “A Best Practices Handbook for Landslide Mitigation” and was accepted by the ICL/IPL Board of Representatives (BOR) in 2002. As the project evolved, the aim of The Handbook became more comprehensive and the target audience became more targeted as those charged with emergency management, landslide mitigation, and public education in both developed and developing countries, including those lay persons interested in a comprehensive introduction to Landslide Hazards. The title of the book is “The Landslide Handbook--A Guide To Understanding Landslides” written by Lynn Highland, U.S. Geological Survey (USGS) Landslide Program, and Peter Bobrowsky, Geological Survey of Canada (GSC). This handbook now helps home-owners, community and emergency managers, and decision makers to take the positive step of encouraging awareness of available options and recourse in regard to landslide hazard. Each year since the proposal (2002), the progress of the book was presented both in written form and meeting presentations, and as it was a large undertaking, the volume went through a process of several peer and editorial reviews. It was decided that the first release of the publication would be as a USGS Circular, whose series is immediately made available to all free of charge. The equivalent Canadian version is now in preparation.

The original document was written in English and since first release in 2008 it has been translated into 4 additional languages: Mandarin Chinese, Japanese, Spanish and Portuguese. The English version was posted online through the USGS’s website in a downloadable form, and an additional 1,000 hard copies were printed and distributed free of charge. Approximately 150 copies were distributed to the world landslide research community related to the ICL, shortly after publication. At the present time, all printed copies in English have been distributed, and it is only available in its online version. As for the translations, the Chinese version was translated by Dr. Fawu Wang, Shimane University, Japan, and is available in print and online through the China Geological Survey. Dr. Yueping Yin of the China Geological Survey was instrumental in getting this translated version of The Handbook edited and printed. The Japanese version, translated by Dr. Tamotsu Nozaki, is now online, through the Japan Landslide Society’s website. The Spanish version was translated by the World Bank’s Disaster Global Facility for Disaster Reduction and Recovery (GFDRR), Washington D.C. It is accessible online at the World Bank website, and also in print from the World Bank. The Portuguese version was translated by Dr. Paulo Rogerio, a geotechnical Engineer in Pomerode, Brazil, and edited by the World Bank. This latter version is also available on online, and in print version. In 2011 the Geological Survey of Canada will release an updated version of the handbook, as landslide science and information changes and evolves.

Examples of Information found in The Handbook

There are several examples of previous efforts to provide basic landslide information to lay audiences, but a literature search by the authors revealed that nothing comprehensive at an introductory level has been published since the 1980’s. There are a number of landslide “practice” books published by the landslide academic/research/consulting community; and notable examples are Cornforth (2005), Sidle (2006), and Turner and Schuster (1996). However, these works are aimed at the professional landslide community and though informative and useful, are not aimed at a lay audience. There are also many other publications dealing with topical landslide information such as, landslide mapping, engineering, mitigation, monitoring, and safety, but nothing available that combined all of these aspects, in a public-friendly format. The only information that was up-to-date and readily available on landslide hazards was basic safety information, i.e. what to do if threatened by a landslide, how to evacuate, etc. These types of publications were released by Federal Emergency Management Agency (FEMA), the Red Cross, and certain communities in countries that regularly experience landslides.

The philosophy behind The Landslide Handbook begins by assuming that the user knows nothing about landslides, either scientifically or practically, and thus starts by introducing very basic landslide nomenclature and classification of types. There are detailed graphics and illustrations so that the user can more easily visualize landslide processes, which have multi-dimensional aspects and complex relationships with geology, weather, climate, soil-types, geomorphology, and human activities on the surface and under-water areas of the earth. Figures 1 and 2 show examples of some of the illustrations and captions that are part of the basic facts concerning landslides. Figure 3 shows an example of the multi-hazard nature of landslides and how they can result from other types of hazards such as flooding, and also how landslides are actually the cause of other hazards such as tsunamis. The section on mitigation gives examples of basic slope, debris-flow, and rock fall hazards, and some basic information about actions that homeowners and/or community decision-makers can take to lessen the impact of these hazards. As such, Figure 4 shows an example of a debris-flow basin, as one way of mitigating the hazardous effects of debris flows. The book features illustrations and photos from all over the world, in order to show the universal nature of landslide hazards. The book includes a glossary of terms which are commonly used to describe landslide processes, and which include some of the engineering terms most commonly associated with landslide mitigation techniques.

Growing populations may be limited in their geographic expansion, except to occupy unstable, steep, or remote areas. Often, stabilizing landslide-scarred areas is too costly, and some inhabitants have no other places to relocate. Fortunately, simple, “low-tech” precautions and

actions can be adopted to at least ensure an individual’s immediate safety, and this handbook gives a brief overview of many of these options. We strongly suggest that, where possible, the assistance of professional engineers/geologists or those experienced in the successful mitigation of unstable slopes be consulted before one embarks on actions. There is one section that was originally published by the Los Angeles County, California (USA) Public Works Office about steps a homeowner can apply to reduce the erosion and debris flows (Figures 5 and 6). The procedures in this section use materials that are readily available to many people, including plywood, sand bags, and shovels. The section on rock fall illustrates some of the methods that communities use to mitigate the hazard from rock fall, which is frequently a problem on roadways and thoroughfares.

One of the sections of The Handbook discusses environmentally-friendly approaches to landslide mitigation. Though there will always be engineered solutions to landslide hazard involving professional consulting companies, substantial earth-moving and shoring up of slopes using expensive, but effective materials such as concrete, drains and anchoring, there is a need for basic erosion control that uses locally-available tools, are low tech in nature, and that will not have too many adverse effects on the environment (Figure 7).

Unprotected natural or constructed earthen slopes are a major point source erosion problem that can result in serious sediment flows to lower catchment sites, contamination of rivers and streams, water quality reduction, slope failure and slippage that often result in landslides, economic damage to property, and loss of life. The Vetiver System can effectively and at low cost actually protect slopes by stopping or significantly reducing the risk of slippage, and thus prevent downstream water contamination. This is because Vetiver grass roots have a high tensile strength (average 75 MPa) shown in places to increase shear strength of soil by a factor of 40, and also because when planted on slopes Vetiver grass may reduce slope hydraulic pressures through the absorption of water. It is this combination of slippage prevention (mass wastage of soil) and its sediment filtering ability that results in very clean water moving through the catchment. (From Vetiver Grass website, http://www.vetiver.org) One example of a positive effect that The Handbook has had on landslide mitigation is from Brazil. Southern Brazil is very landslide-prone and people traditionally used a different type of grass to help stabilize slopes. The grass was not that effective, and a local geotechnical engineer having read The Handbook section about Vetiver grass, purchased and then applied shoots to several test slopes and as a result obtained superior slope protection (Figures 8 and 9). The use of Vetiver grass and its effectiveness is now spreading to surrounding areas in Brazil, and is being eagerly adopted as a low-cost, environmentally-friendly solution for erosion on slopes, that may eventually result in a landslide. The Handbook introduces several other methods of “bio-engineering” which includes but is not limited to, Vetiver grass.

In all sections of the handbook there appear many cautionary statements advising that, where possible, people should secure a professional engineering geologist, civil engineer, and/or geotechnical engineer for advice on optimal landslide hazard mitigation measures. As each landslide is unique, there is also cautionary language about the fact that conditions vary from site to site, and landslide causes and behavior may be very unique and different in each area, although appearing to be the same on the ground surface. The volume also stresses that surface conditions may mask what is really going on at various depths of a slope and that understanding the geology, soil type, and water drainage is very important. The book acknowledges that its’ content is primarily for education, introducing people to the science of landslides, as well as introducing them to methods that can reduce the hazard, but not necessarily eliminate the problem. The following is a partial list of the Table of Contents, showing a small portion of the topics that the Handbook covers:

Part II – Evaluating and Communicating Landslide Hazard

Part A - Evaluating landslide hazards

1. Observation and/or Inspection 2. Technological Tools for Evaluation of Landslides –Mapping, Remote Sensing, and

Monitoring a. Map Analysis

b. Aerial Reconnaissance

c. Field Reconnaissance

d. Drilling

e. Instrumentation

f. Geophysical Studies

g. Acoustic Imagery and Profiles

h. Computerized Landslide Terrain Analysis

Part B - Communicating landslide hazard Safety Information

1. Building and Construction Information 2. Suggested Local government Outreach for Landslide Hazard Evaluation and Communication 3. Examples of Hazard Warning Signs

Part III – Mitigation Concepts and Approaches

Part A - Overview of Mitigation Methods for Various Types of Landslide hazards

1. Soil Slope Stabilization 2. Rock fall Hazard Mitigation 3. Debris- Flow Hazard Mitigation 4. Landslide Dam Mitigation 5. Methods of Biotechnical Mitigation

Part B - Simple Landslide Mitigation Techniques for Home and Businesses, Managers and Citizens

As illustrated in Figure 10, in order to motivate residents to heed evacuation warnings for example, the residents must first be aware of the hazard. Second, they must understand the impacts an event may have on their family, dwellings and community. Third, they must accept the idea that not following a warning message can result in injury or death. Finally, they must take action and respond to the warning to evacuate. The success of a warning rests in the public’s or individual’s awareness, education and understanding, and acceptance of their risk. If the intent is behavior change or action, then public outreach must focus on moving the public through the initial stages of awareness, education and understanding, and acceptance. The Handbook provides a crucial tool for public education about landslide hazards and together with videos, films, newspapers, brochures, training and other educational media, are a necessary requisite for hazard mitigation and community support for such.

In early 2011, a Customer Satisfaction Survey was performed on The Landslide Handbook by a U.S. Geological Survey economist. Such surveys are performed for various selected publications to obtain feedback on the quality and usability of USGS publications. Questions are sent to those individuals to whom a copy was sent, to those who obtained a copy from the USGS Publication store, and/or read/downloaded the online version. Respondents were asked which portions of The Landslide Handbook they found especially useful, how they use the Handbook, what decisions are influenced by information in the Handbook, and if they have suggestions to improve the Handbook. The survey was administered via email, and respondents linked to a webpage to complete the questionnaire online. The authors were sent the result of the Handbook Satisfaction Survey. Figures 11 and 12 summarize the general results of the survey.

Some of the comments appearing on the Customer Service Satisfaction survey were:

• It`s great to have it available as a pdf. • Love the large number of photos and illustrations. • Marvelous photos!!!! • Most aspects of the handbook are very well written.

• Nicely illustrated and useful to the public who may not have the technical background. • Being a promoter of disaster risk management in developing countries, I found the

handbook to be very useful. In developing countries there is a gap in knowledge concerning hazards, including landslide hazard, this handbook should be promoted as a useful reference. The handbook should be an ideal tool for those who have some responsibility in land-use planning and risk-management. It is my impression that this handbook has captured very well the technical aspects concerning landslides and how to deal with them. In this sense, it should assist those decision makers in identifying the set of measures required to deal with the technical side of landslides.

• Consider partnering to generate versions in other languages. • I believe this book is almost perfect, but perfect translation is impossible. I hope that the

way of usage of technical terms and some of the content will be allowed to change depending on the circumstances of each country, area or society.

Dr. Steve Gillespie, the Economist who engineered the Customer Satisfaction Survey reports: “Aggregate customer satisfaction on all (USGS) products we've surveyed is over 90%. With an overall simple satisfaction of 100%, the Landslide Handbook is higher than the average.”

Translations of the English version of the Handbook

Currently, the Landslide Handbook has been translated into 4 languages, from the original English version. This has made this handbook particularly useful to a wide audience around the world. The distribution of these translated versions include print copies, internet links for all versions, and the distribution by the World Bank to government and community users in Brazil (Portuguese version) and other areas in Latin America (Spanish version). The terminology and glossary aims to familiarize users around the world with the commonly-used nomenclature for landslide science, and will be extremely useful in describing landslide characteristics and behaviors that can be understood by a wide variety of global users. The extensive illustrations and graphics are extremely useful for illustrating landslide concepts and events, and framing the multi-hazard, and multi-dimensional aspects of the study of landslides. The support of the International Consortium on Landslide scientific project sponsorship (IPL) has been crucial in providing support and a framework in which to write and publish the Handbook. The Handbook enhances the diverse range of projects supported by the IPL and is in some way related to all of them, past and future.

Acknowledgments The authors thank their respective employers, the Geological Survey of Canada the US Geological Survey for their support over the years in the development and delivery of this project. Our thanks to Lionel Jackson for the technical review of the manuscript. This is contribution #?? for the Geological Survey of Canada.

References:

Cornforth DH (2005) Landslides in Practice—Investigation, Analysis, and Remedial/Preventative Options in soils, John Wiley & Sons, Inc., Hoboken, New Jersey USA, p 596

Gillespie, S (2011) Customer Satisfaction Survey for The Landslide Handbook—A guide to understanding

landslides, USGS unpublished report Highland L M, and Bobrowsky, P (2008) The Landslide Handbook: A guide to understanding landslides.

U.S. Geological Survey Circular 1325, p 129 online: http://pubs.usgs.gov/circ/1325/ Los Angeles County Department of 20 Public Works, Board of Supervisors, 1993, Homeowner’s

guide for flood, debris, and erosion control: Alhambra, California, in English and Spanish. Online: http://dpw.lacounty.gov/wmd/Homeowners/index.cfm

Sidle RC, and Ochiai H (2006) Landslides: Processes, prediction, and land use. Water Resources

Monograph 18, American Geophysical Union, Washington, D.C., p 312 Turner AK, and Schuster RL (1996) Landslides—Investigation and mitigation. National Research Council,

Transportation Research Board Special Report 247, National Academy Press, Washington, D.C., p 673

University Corporation for Atmospheric Research (UCAR) and National Center For Atmospheric Research

(NCAR) http://www2.ucar.edu/

Varnes DJ (1978) Slope movement types and processes, in R.L. Schuster and R.J. Krizek, eds.: Landslides: Analysis and Control, Transportation Research Board Special Report 176, National Research Council, Washington, D.C. , p. 11-23

Mandarin Chinese Translation: http://www.cgs.gov.cn/ZTlanmu/qita/zzbaodao/XTqu/XTqu/744_8056.htm Japanese Translation: http://www.landslide-niigata.org/handbook.html Portuguese Translation: Spanish Translation: Vetiver Grass website: http://www.vetiver.org

Figures

Figure 1.--A simple illustration of a rotational landslide that has evolved into an earthflow. Image illustrates commonly used labels for the parts of a landslide (from Varnes, 1978).

Figure 2—Cross section graphic of a Debris-flow (top) together with a photograph of damage to the city of Caraballeda, located at the base of the Cordillera de la Costa, on the north coast of Venezuela. In December, 1999, this area was hit by Venezuela’s worst natural disaster of the 20th century. Several days of torrential rain triggered flows of mud, boulders, water, and trees that killed as many as 30,000 people. (Photograph by L.M. Smith, Waterways Experiment Station, U.S. Army Corps of Engineers)

Figure 3--An example of a mulit-hazard event. Photograph shows an aerial view of Lituya Bay, Alaska, USA. On July 9, 1958, an earthquake occurred which caused a landslide to enter the bay. The landslide in turn, caused a tsunami wave that had a run-up of 174 meters on the opposite shore, and a 30-meter wave passed beyond Lituya Bay. It is the largest landslide-generated wave ever documented. Note the extent of the nonforested areas of land lining the shore of the bay, which marks the approximate reach of the tsunami wave. (Photograph by D.J. Miller, U.S. Geological Survey)

Figure 4--Aerial photograph of a debris-flow basin, constructed at the bottom of a slope in San Bernardino, California, USA. (Photograph by Doug Morton, U.S. Geological Survey).

Figure 5 – Schematic of an unprotected home, Figure 6 – Schematic example of a house with In the path of a debris flow and (or) “mudslide.” Protective structures in place. Shows construc- (Los Angeles County, 1993) tion of deflection walls and debris fences. Because of extreme force of impact associated with some debris flows, these and similar struc- Should be carefully engineered and constructed. (Los Angeles County, 1993)

Figure 7-- A Vetiver grass system is being used in the Democratic Republic of the Congo for gully control in urban areas and for highway stabilization. These gullies are a major problem in this area and other West African countries (top); the same slope now has improved drainage, and the slope has been planted in Vetiver grass (middle); this planting of Vetiver grass is about 3 months old (bottom). Photos from Vetiver Grass website: http://www.vetiver.org)

Figure 8--This residence in Brazil was planted with Vetiver Grass, as a slope Stability tool. The grass was first introduced in the handbook. As the people in this area were using another, less effective Batatais grass. The top photo shows the slope before planting, the Bottom photo is Vetiver that has been established. (Photos by Paulo Rogerio, Brazil)

Figure 9--These photos from Pomerode, Brazil show the use of Batatais grass (short length grass in top photo) which has very shallow roots. This grass was being widely used in the past, and not very effectively, as a slope stabilizer. The top photo also shows the initial planting of vetiver grass, on the bare slope. In the bottom photo, the long shoots are vetiver grass which has now established itself. Vetiver has very long roots, and has been found to be a superior erosion control/slope stability tool. Photos by Paulo Rogerio.

Figure 10 – The steps necessary for communities to be aware of the effectiveness of life-saving actions, such as evacuation and preparedness. Graphic from COMET, University Corporation for Atmospheric Research and National Center For Atmospheric Research, http://www2.ucar.edu/

Figure 11--Results of USGS Customer Satisfaction Survey for the Landslide Handbook. Survey respondents were asked to rate which part of the Handbook they found especially useful.

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Appendix D (safety info)

Appendix B (evaluation tools)

Appendix A (glossary of terms)

Section 2 (evaluating hazard)

Appendix C (stabilization)

Section 1 (landslide types)

Section 3 (mitigation)

Percentage especially useful

Portions of Handbook especially useful

Figure 12-- Results of Customer Satisfaction Survey showing percentages of those who indicated levels of satisfaction with the Handbook: Very satisfied, Satisfied, and dissatisfied.

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Organization

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Content

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Illustrations

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