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  Events of winter 1999 and the resulting consequences for the Alpine area

Mario BROGGI - Director of the Federal Institute of Research on Forests, Snow and landscape, Birmensdorf , Switzerland

 

 

The 1998/1999 winter was extraordinary for the whole of the European alpine area. In particular, the northern slopes of the Alps from Savoie to the Tyrol were covered by intensive falls of snow and affected by avalanches with grave consequences throughout almost the entire region. The example of Switzerland is used to illustrate this winter of avalanches and several lessons are proposed.

What type of event was involved ?

As far as fresh falls of snow and the extent of their effect were concerned, the situation in February 1999 was exceptional. The phenomenon of continuous snowfall over a period of approximately one month recurs about every 80-100 years on the northern slopes of the Swiss Alps. In some measurement centres, the total depth of snow reached record levels : in Elm (Glarus), for example, more than 4 m of snow fell over nine days, and even more than 8 m over 30 days. The frequency of recurrence of such quantities of snowfall varies from region to region but is around 30-50 years.

Damage report

The avalanches in February 1999 resulted in the death of at least 100 people in the Alps, mostly in Galtür (Tyrol) with 38 dead, in Evolène (Valais) with 12 dead and Chamonix (France) with 12 dead. In Switzerland over the whole winter season 34 people died in avalanches, 17 of whom were in houses or on the streets. The total cost of the damage exceeded figures for damage caused by other avalanches this century. In Switzerland, around 1000 avalanches have damaged approximately 1700 buildings, vehicles, etc., including around 230 houses. The direct damage to property was estimated at around 250-300 million Swiss francs and the indirect costs through companies closing down and loss of earnings were estimated at 200-250 million Swiss francs. The Gotthard motorway was completely closed to traffic for more than one week. Damage to houses and cars in the Tyrolean Paznaun valley was estimated at 24 million Swiss francs. In Gargellen in the Vorarlberg valley, for instance, tourist damage was calculated at 10 million francs.

The disastrous avalanche winter of 1950/1951 in the Swiss Alps resulted in 98 dead and damaged 1500 buildings. In February 1999, with a similar number of avalanches, approximately four times as many tourists and 1.5 times as many inhabitants were staying in the affected mountain areas. That the damage was not worse was not just a matter of luck. The targeted progress of an integral avalanche protection programme over the last fifty years is equally responsible.

Assessment of current integral avalanche protection

The integral avalanche protection encompasses all organisational, planned, technical and biological provisions. The steps carried out until today have proved to be good or very good. With regard to the protection of inhabited areas, progress in the last ten years has been extensive, while with regard to the protection of the main traffic routes the full extent of the continually increasing risk is probably not yet known. It is worth recording in detail:

Planning provisions

The cartography of avalanche danger provides the elements to be able to take into consideration the potential, long-term avalanche danger in the planning for use of an area. The danger is classified in four zones according to frequency and pressure strength. In the red zone, it is forbidden to build. Although Federal law regarding forests and hydraulic engineering has made it compulsory to produce maps of danger zones and to keep an event land register for the canton, not all districts in danger of avalanches have yet produced such maps. In places where they exist, the 1999 avalanche corridors were in most cases found to be correct. Avalanches exceeded the forecast area marked on the danger zone maps only in isolated cases. In Valais, for instance, the blue zone (restricted building under certain conditions) must be extended in approximately 10 avalanche paths, and the red zone in two danger area maps.

Further research is necessary to develop further the methods for avalanche forecasts with regard to powder avalanches and the combined descending and powder avalanche.

Technical provisions

A reduction in construction in areas where avalanches start, in their fall path and in avalanche settlement areas is considered to be part of construction avalanche protection. The aim of these steps is the protection of inhabited areas and main traffic routes. In Switzerland, over 650 km of support work is being carried out. Since 1951 approximately 1.5 thousand million francs has been invested in protecting buildings against avalanches. The support construction has largely fulfilled the expected requirements. There is no known case of a destructive avalanche starting from a supported area. Thanks to galleries, several main traffic routes could be kept open. However, in some cases, such galleries have been proved to have been built too short.

In addition to avalanche warning and closing and evacuating areas, starting avalanches artificially is a very important operational solution.

In many places, the safe use of ski areas and to some extent keeping open traffic routes that are in the avalanche danger area can no longer be envisaged without relying on starting avalanches artificially.

Avalanche starting points above areas where people live are only blasted in exceptional cases because of the possible danger of extensive damage. The case of Leukerbad in the winter of 1999 remains vivid in our memory.

Organisational provisions

In winter, the Swiss Institute for Snow and Avalanche Research in Davos provides the general public with daily information about avalanche dangers, including in regional avalanche reports. Thanks to the early warning system, the warning time in the avalanche winter of 1999 was long enough for even those emergency avalanche services that were not fully prepared to be sufficiently operational. Although personnel operating avalanche-warning services in Switzerland are well trained, the training of decision-makers must be intensified. Just in the worst affected cantons, Valais and Bern, the local crisis units had to evacuate almost 8000 people from their homes and close dozens of streets because of the danger. The inter-cantonal measurement and information system is also important, because it supplies the elements for a multitude of continuous measurement data to be assessed on the spot.

Biological provisions

During the events in February 1999, no avalanches causing serious damage started in the forest. The mountain forest has in this sense fulfilled its protective function of preventing avalanche from starting.

The technical construction work of an area where avalanches start costs around 1 million Swiss francs per hectare. A national study puts the economic value of the protective effect of mountain forests at up to 4 hundred thousand million francs per year. The maintenance of mountain forests is important for efficient protection of inhabited areas and roads.

How can we reduce the economic losses in the case of extreme natural events ?

The changes in the use of mountains and the increased traffic, both local and in transit, lead to constantly changing threatening scenarios and risks. The latter must be periodically checked and the protection measures changed accordingly. Integral risk management with the inclusion of all possible provisions and their various combinations (organisational, planning, technical, biological) has the greatest implication. For more effectiveness and efficiency when drawing up future protection plans, all possible measures that serve to reduce risks should be given equal consideration. Risk prevention and short-term, organisational provisions (warnings, alarms, etc.) have even greater implication in the future due to the technical and economical limits of the feasibility of protection projects. The improvement of the understanding of avalanche dynamics and the recurrence of single events should also be improved. Accordingly, adjustment in the organisations, targeted training of local avalanche services and appropriate work with the general public are necessary. Overcoming crises is therefore above all a question of experience.

The guidelines to estimate avalanche danger for activities that have an influence on the surroundings should be updated and supplemented with elements concerning planning decisions for evacuation and precautionary closure of connecting roads. Through an early consideration of planned and structural provisions, the risk of avalanches for tourist transport facilities can be greatly reduced.

Recommendations are required for projects, construction and use of such facilities.

With all these efforts to protect people and property in the Alps, we must not be deceived by an illusion of absolute protection. In the Alps, not everything is possible for economical and ecological reasons.

Natural catastrophes such as those in the avalanche winter of 1999 should therefore be taken as a warning. Consequently, society is right to adapt itself to natural realities by opting for precautionary risk management.