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Mountain risks and hazards

P.C. Zingari and G. Fiebiger

Pier Carlo Zingari is Director of the
European Observatory of Mountain Forests,
Saint Jean d'Arvey, France.

Gernot Fiebiger is Director of Avalanche,
Torrent and Erosion Control in the Austrian
Forest Technical Service, Salzburg, Austria.

Some approaches for assessing, mitigating and preventing risks in mountain regions.

In the mountains, human lives, property, infrastructures and ecosystems are threatened repeatedly by various hazards and dangerous processes. Natural hazards in the mountains include large-scale hazards such as earthquakes, droughts, eruptions and hurricanes, as well as others originated by small-scale mass movements of water, snow, ice, soil and rock. Dangerous natural processes include avalanches, debris flows, floods, landslides, rockfalls and other disastrous mass movements of soil and rocks. In mountainous regions these processes easily lead to casualties, injuries, destruction of goods and ecological damage.

Mountain hazards affect people and property: victims of a landslide in the Garm area, Tajikistan, in 1998

- FAO/20669/E. YEVES

Humans pursue safety - seek to remove risks or at least to diminish and control them - through both systematic planning and intuitive measures. This article introduces some methods for evaluating the hazards and dangers and for assessing and reducing risks, and describes various types of preventive measures. It emphasizes the role of forests and land use planning in mitigating risk in mountainous regions. It advocates consideration of the traditional risk adaptive measures of mountain communities. The socio-economic conditions of mountain people play an important part in their vulnerability to risk and their ability to prevent and mitigate disaster. The article concludes with a call for integrated, cross-sectoral, participatory approaches to risk mitigation.


The assessment, mitigation and prevention of dangerous processes require reference to a defined area and time frame. The endangered area or zone of the process includes the area in which the process develops, the path of the process and the area of the impact. The assessment of danger and the development of countermeasures must always start with recognition of the whole area.

The size of a dangerous process is described by physical parameters such as intensity, magnitude, duration, energy, pressure, height, volume and impact.

The danger increases with the frequency of the dangerous process during a given period. Every assessment of danger therefore requires investigation of the probability of occurrence and the frequency of the dangerous process.

In terms of succession and duration of dangerous processes, events are commonly distinguished as continuous or episodic; these can be further divided into single or repeating and periodic or sporadic events:

Natural hazards that pose a repeated threat include volcanic eruptions such as this one which took place in 1988 in Réunion



The systematic and integrated planning of safety with consideration of natural hazards has increased during recent decades (Aulitzky, 1974; Kates, 1978; FAO, 2000). The development of a theoretical base and integrated control projects started early (see Burton, Kates and White, 1978; Rowe, 1977; Schneider, 1980) and is in progress (Fiebiger, 1995, 1996; Hewitt, 1996; IDNDR, 2000).

Avalanches not only threaten lives and property, but also cause severe ecological damage; as a result of a large avalanche in winter 1999, the trees in this forest near Zernez, Switzerland, fell like matchsticks


Safety planning can be divided into the steps of risk analysis, risk assessment, planning of countermeasures and implementation.

Risk analysis is followed by risk valuation, in which the culture-specific level of risk acceptance and political attention are considered. The question is "What is allowed to happen?" The answer defines the acceptance of the risk.

If the risk calculated in the risk analysis is greater than the risk acceptance, countermeasures are necessary. Many countermeasures are available to control geomorphologic processes and danger in mountain regions, and their development is under continuous progress (Fiebiger, 2000).

With implementation of the counte-rmeasures the initial risk is reduced to the level of the accepted risk. It must be mentioned that the effective risk always includes an incalculable component.

The risk in a danger area is defined by two components: danger and endangered objects. Countermeasures try to influence one or the other or both of the components:

For both active and passive measures landscape planning is important. It is also neccessary to check the site of danger frequently. The planning of new active or passive measures depends on the development of danger.


Loss of forest cover, if not replaced by other sustainable land use, is often considered an aggravating factor in catastrophic events; it can contribute to increased frequency and severity of floods and landslides. The connection between shrinkage of forested areas and meteorological disasters is not scientifically proved, but it is likely that they are strongly related. Forest resources have an essential, although not sufficient, role in risk mitigation. Depending on the scale considered, forests are directly involved in water quality and quantity control, in protecting soil against erosion, and in snow and debris movement control. Forests in mountain areas always have a multifunctional role. In physical terms, but also in terms of the overall diversity of benefits to livelihood, mountain forests have to be considered as a cornerstone in the prevention of risks and in the rehabilitation of land after disruptive events. Forests contribute greatly to the resilience of mountain communities.

Because of the combination of environmental and human factors, mountain risks related to forest cover, floods and soil erosion are appropriately and carefully assessed and managed in a watershed framework (Hamilton and Bruijnzeel, 1997). The registration of events and collections of data repre-sented, for example, by the online annual flood archives made available worldwide by the Dartmouth Flood Observatory, the 50-year report 1952 to 2002 of the FAO/European Forestry Commission (EFC) Working Party on Mountain Watersheds, and the European Union digital mapping of watersheds (see box on the next page) are concrete tools in risk assessment and management.

Land degradation is a critical issue in risk occurrence. For example, it has been estimated that 50 to 75 percent of the economic losses resulting from Hurricane Mitch - and surely much loss of life - were related to inadequate land use planning. Hurricane Mitch, one of the most powerful and damaging storms ever experienced in Central America, struck between 26 October and 1 November 1998 over a large hilly and mountainous area, affecting five countries, causing overflow of rivers, mudslides and landslides. Some 20 000 people were killed and 3.5 million affected. Mitch caused US$5 billion of damage and left huge tasks of reconstruction, resulting in the loss of decades of development efforts in the region (IADB, 1999). Mountainous terrain and complex river basin systems were found to be the most disaster-prone areas.

Some initiatives and institutions involved in data collection for risk mitigation in mountains

  • Africa Data Dissemination Service:
  • Centro Regional de Información sobre Desastres (CRID):
  • Dartmouth Flood Observatory (DFO):
  • Data Fusion Committee, Geoscience and Remote Sensing Society:
  • European Observatory of Mountain Forests (EOMF):
  • European Union Joint Research Centre (JRC):
  • FAO Forest Resources Assessment (FRA):
  • FAO Global Information and Early Warning System (GIEWS):
  • FAO Land Degradation Assessment for Drylands (LADA):
  • FAO/European Forestry Commission (EFC) Working Party on the Management of Mountain Watersheds:
  • Global Elevation Data:
  • Global Forestry Information System (GFIS):
  • Global International Waters Assessment (GIWA):
  • Hydrological Data:
  • Institut de la Montagne: not yet available on the Web; contact [email protected]
  • Inter-American Geospatial Data Network:
  • International Centre for Integrated Mountain Development (ICIMOD):
  • International Union of Forestry Research Organizations (IUFRO):
  • Local Authorities Confronting Disasters and Emergencies (LACDE):
  • Mountain Forum:
  • ProVention Consortium:
  • ReliefWeb:
  • Swiss Federal Office for Environment, Forest and Landscape (BUWAL):
  • UNEP Global Resource Information Database:
  • United Nations Environment Programme (UNEP):
  • United Nations International Strategy for Disaster Prevention (UNISDR):
  • United States Geological Survey (USGS) EROS Data Center:
  • USGS EROS Data Center International Program:
  • USGS EROS Data Center Distributed Active Archive Center:
  • World Conservation Monitoring Centre (WCMC):

A key lesson that can be drawn from Hurricane Mitch is that to analyse events and their impacts with a view to future mitigation, it is essential to consider the situation prior to the event - in this case an eight-month drought, 1.5 million hectares of devastating forest fires, unsustainable forest practices, deforestation, uncontrolled urbanization and obstruction of river beds. The recorded history of a site is also a key tool in assessing and thus reducing vulnerability.


Social conditions and human activities are predominant factors in catastrophic events. Mountain communities have traditionally developed risk-adaptive cultural patterns and coping strategies (risk reduction methods) which include insurance, diversification, flexibility, liquidity, reciprocation and pooling of resources. But where mountain communities lack sustainable livelihood opportunities, risks cannot be mitigated, with grave consequences. The costs of disasters continue to rise, and the greatest impacts continue to fall on developing countries, countries in transition and poor people (IDNDR, 2000).

Catastrophes in mountain regions affect the security of people both in the mountains and in adjacent lowlands (Hewitt, 1997). Households and communities in developing countries are particularly vulnerable to risks because of many interrelated factors (IDNDR, 2000). These include large populations living in high-risk areas, high incidence of poverty, livelihood insecurity and environmental degradation. The worst effects are often linked to human behaviour and settlement patterns. Poor people often settle on marginal land, particularly along riverbanks and near or on unstable hillsides. In order to reduce vulnerability to hazards, it is crucial to avoid locating human settlements and infrastructure in high-risk areas.

In this regard, involvement of local people is essential; it should precede and accompany technical risk management activities. External technical skills should be merged with local capacities. Local people conserve the memory of events and their locations, and risk management activities should be based on long-term dialogue with inhabitants, resource persons and practitioners. Environmental education is also an essential tool.

Infrastructures such as roads can be both causes and victims of disasters; as shown here in Nepal, inappropriate road construction can result in severe soil erosion and landslides


Infrastructures such as roads, railways, energy lines, dams and settlements - including housing - can be both causes and victims of disasters. Since infrastructures are the result of political decisions and a key concern for local communities, they deserve high attention.

Mountain communities have traditionally developed effective risk adaptive measures, such as these terraces to prevent erosion in mountain agriculture in China

- FAO/20039


Cross-sectoral approaches, decentralized decision-making and the involvement of local communities are key to providing sustainable benefits and mitigating risks. Real integration of resources, land uses, policies and measures and the people and groups concerned may never be attained, but it remains the guiding concept in the management of resources as well as risks.

At the national and subnational levels, framework regulations should help to identify, clarify and link all the sectors involved in risk mitigation. Watershed contributes to risk prevention, response to emergencies and rehabilitation or improvement of land use resources and activities. The national and subnational levels are also appropriate for providing comparative monitoring through criteria and indicators applied to land, resources and activities.

At the local level, the role of community organizations and municipalities, public participation and consultation in disaster prevention and mitigation is crucial. This is illustrated in Switzerland, a mountain-dominated country with long experience in risk prevention, where the federal office in charge of natural dangers is launching a "pragmatic approach for the comparative evaluation of risks" based on dialogue with local people, resource persons and practitioners. Testing on the real scale, in collaboration with the national railway company and local forest services, indicated that dialogue and involvement of local people were cost-effective tools for risk evaluation and mitigation (Greminger and Jordi, 2001).

Mountain hazards can have downstream effects: in Peru, a once-fertile valley has become a deposit of dried mud and stones swept down from denuded mountains during the rainy season

- FAO/12351/I. VALEZ


Risks in mountain regions affect the security of people both in uplands and in adjacent lowlands. The International Year of Mountains - 2002 offers an opportunity to step forward to help mountain households and mountain ecosystems become more resilient to the effects of natural hazards and related technological and environmental disasters, in order to reduce human, economic and social losses.

Mountains show a close linkage between fragile and dynamic eco-systems, environmental degradation, poverty and risk occurrence. International and national actions should therefore consider mountains as a priority for poverty alleviation, environmental rehabilitation and risk mitigation.

Risks in mountainous areas are exacerbated by the nature of the habitats, the topography and limited accessibility. Appropriate local and watershed-based early warning systems are always necessary. For the same reasons, planning, prevention and management of risks in mountain areas are significantly more cost effective than centralized response and recovery after the events.

Land use management has a critical role in reducing vulnerability. Mixed agrosilvipastoral systems developed in mountains worldwide are ecologically and economically resilient. They should be reinforced, restored and supported.

Low-magnitude and high-frequency events deserve the same level of attention as high-magnitude, low-frequency events. While large-scale disasters like Hurricane Mitch draw international attention, many local-scale events cause more damage overall. For example, over 2 400 local events were registered from 1990 to 1995 in Costa Rica, El Salvador and Guatemala (IADB, 1999).

Cultural patterns of prevention and mitigation of risks have been developed by mountain communities around the world. Local people's memory of events and their causes and impacts should be kept as a resource for future generations.


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