2/2007 T T N N E E M M N N O O R R I I V V N N E E 4 ENVIRONMENT 2/07 NATURAL HAZARDS

NATURAL HAZARDS IN THE ALPINE REGION at a glance

The hazard situation in the Alpine country of Switzerland is influenced by the significant differences in altitude over a small area and relatively high precipitation volumes as com- pared with the rest of western Europe. Floods, in particular, can arise almost everywhere as water run-off per square meter is almost four times the global mean.

Switzerland lies in the temperate cli - Swiss Central Plateau is one of the most around 65,000 kilometres, and due to mate zone of the centre of western Eu - densely populated areas in Europe. the extreme differences in altitude of rope and borders on France, Germany, up to 4,000 metres over a relatively Austria, Liechtenstein and . It’s ter - High levels of runoff small area between the and the ritory totals 41,285 square kilometres Due to the prevailing westerly winds Central Plateau, floods can occur al - (km 2), of which almost two thirds are and the country’s proximity to the At - most everywhere in Switzerland. More - located in the Alpine region. The inten - lantic Ocean, the Mediterranean Sea over, the steepness of the terrain exac - sively developed residential and eco - and the North Sea, a lot of humid air is erbates erosion and hence, also, the nomic zone is concentrated on the rel - blown towards the Alps. Rain fronts of - risks posed by landslides and debris atively flat Central Plateau which only ten accumulate for days in front of this flows. Warmer periods, when the sea - accounts for 23 percent of the coun - meteorological barrier, giving Switzer - sonal snow and glacier melt in the try’s territory. Nestled between the Jura land above-average annual precipita - Alpine region coincide with intensive mountains in the north west and the tion volumes of 1,457 litres per square storms or orographic precipitation, are foothills of the Alps in the south, this metre (m 2). A good two thirds of this, particularly critical. In this situation, plain, which ranges from 50 to 100 i.e. almost 1,000 litres per m 2, is dis - rivers and lakes often break their banks kilometres in width, extends in a charged to other countries through an and flood the valley plains. north-east direction from Lake intricate network of streams and rivers. to . The mean water runoff in Switzerland Wide range of hazards is almost four times higher than that in in the mountains Densely populated Central Plateau the rest of Europe and the world. Thus, However, the mountain regions are The vast majority of Switzerland’s pop - a total of 40 billion cubic metres of wa - significantly more vulnerable to natur - ulation of around 7.5 million people ter flow into the Mediterranean, North al hazards than the Central Plateau. live in the lowland. In addition to the Sea and the Black Sea via the Heavy snowfall and unfavourably centres of industrial production, the rivers, i.e. the , Rhone, structured snow cover create a risk of majority of the important service oper - (via the Po) and (via the ). avalanches at high altitudes, while ations and the main road, rail and avia - This explains Switzerland’s crucial role heavy rainfall during the warmer sea - tion infrastructure, all of the major as a water reservoir for western Europe. sons can trigger landslides and debris cities, i.e. Geneva, Lausanne, Bern, flows. Rock fall and rock slides can also , Zurich and Basle, are located Almost countrywide flood risk put both settlements and important here. Thus, with a population density Due to the extensive network of water transport routes at risk, as demonstrat - of almost 600 people per km 2, the courses, whose combined length totals ed, for example, by the blocking of the ENVIRONMENT 2/07 NATURAL HAZARDS 5 Land Use in Switzerland

Settlement Agriculture (not including Alpine farming) Alpine farming Basle Lake Constance Rhine Forest Zurich Water bodies Glaciers, firn Other unproductive areas Aar Lucerne Berne

Lausanne

Lake Geneva Geneva Rhone

Lugano

Federal Statistical Office FSO, GEOSTAT / FOEN

Gotthard motorway, a key cross-Alpine land, however when they arise they forests and water bodies, hazard map - road axis between northern and south - represent the natural hazard with the ping and the planning, construction ern Europe, in 2006. The above-average greatest potential for damage. Individ - and maintenance of protective struc - climate warming in the Alpine region ual areas such as Valais and the Basle tures – however they receive financial and the resulting thawing of the per - region are at greater risk from earth - and expert support from the federal au - mafrost and retreat of the glaciers will quakes than other parts of the country. thorities. The Federal Office for the En - cause greater volumes of loose material vironment is responsible for the strate - to be mobilized in the future, a devel - Safety as a public service gic management of these tasks and opment which represents an additional The protection of the population and guarantees safety at national level on threat to settlements, transport routes important material assets against nat - the basis of uniform standards. It is up and other infrastructure. Longer peri - ural hazards is provided as a public to the 26 cantons to decide whether to ods of drought also increase the risk of service by the state. In the federal state organize these tasks centrally or to del - forest fires, particularly in the south of of Switzerland, this task is perceived as egate some of them to the political mu - Switzerland. Overall, climate change is the joint task of the Confederation, nicipalities, of which there are over expected to increase the intensity of cantons and municipalities. The auth- 2,700 in Switzerland. Thus, the system precipitation and storms, prompting orities on all three levels work closely accommodates the cultures of political the need for more measures to limit the with each other in this area, which re - cohabitation which vary from region extent of the damage caused by floods, quires close cooperation. Thus, for ex - to region. hail and severe storms. Earthquakes ample, the 26 cantons are responsible tend to be a rare occurrence in Switzer - for the maintenance of the protection Beat Jordi 6 ENVIRONMENT 2/07 NATURAL HAZARDS

HAZARD PREVENTION There is no such thing as absolute safety

As a mountainous country with considerable variations in altitude over a relatively small area, Switzerland is particularly vulnerable to the various types of natural hazards. Swiss society is in a position to reduce existing risks to human life and material assets to an acceptable level, however there is no such thing as absolute safety.

On the night of 23 August 2005, the extreme events, its discharge corridor houses on the alluvial fan bordered swollen Glyssibach torrent burst its in the village is being widened consid - directly on the old torrent bed. The narrow banks and discharged thou - erably to 18 to 21 metres and secured families affected by this measure found sands of tonnes of debris and mud into by means of massive dikes. An even alternative solutions and were compen - a neighbourhood of Brienz in the can - wider channel is needed in the flatter sated for the loss of land by the munic - ton of Bern. Following heavy rain estuary area where the Glyssibach tor - ipalitiy. throughout the Alpine foothills, nu - rent deposited its debris on a number merous landslides were triggered on of occasions in the past. For reasons of The renunciation of land use the steep slopes of the Brienzer Rot- space, it will be necessary to sacrifice in high risk areas horn mountain, the contents of which some of the existing development land As in Brienz, a row of 14 houses in were conveyed down to the valley at in this case as some of the destroyed Chippis near Siders on the river Rhone top speed by the mountain torrents. continued on page 8 Ten buildings failed to withstand this force of nature and were completely Flood damage in Switzerland between 1972 and 2002 destroyed by the deluge of debris and water from the Glyssibach, and a fur - ther 18 houses suffered extensive dam - age. Two people lost their lives on the night of the disaster, however the ma - jority of people who were taken by complete surprise by the event – and, in some cases, roused from their sleep – managed to make it to safety in good time.

More space for mountain torrents Just a short time after the devastating debris flows, the Bernese cantonal au - thorities responsible for flood protec - tion in the region decided – in consul - tation with the federal authorities and the affected municipality – that some of the houses destroyed by the flood WSL should not be rebuilt in the same loca - tion. To create sufficient space for the As demonstrated by an analysis of flood damage between 1972 and 2002, large areas of torrent’s bed load in the case of future Switzerland are flood-prone. Each blue dot on the map marks a loss event. ENVIRONMENT 2/07 NATURAL HAZARDS 7

Swiss Air Force

The destruction of part of Brienz village in the by debris flow from the Glyssibach torrent during the storm of August 2005.

Flood damage in Switzerland between 1972 and 2005

annual damage (adjusted for inflation) cumulative damages (adjusted for inflation) The scale of the damage caused by annual damage cumulative damages floods is increasing. The storms in million CHF in million CHF of August 2005 – with heavy 3000 15 000 flooding in Central Switzerland and – were the most expensive extreme event ever 2500 suffered by Switzerland.

2000 10 000

1500

1000 5000

500 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 0 0 0 0 0 0 0 0 9 9 9 9 9 9 9 0 7 7 7 7 7 7 7 7 7 7 8 8 8 8 8 8 8 8 8 8 9 9 9 0 9 2 1 FOEN 8 ENVIRONMENT 2/07 NATURAL HAZARDS

Which natural hazards represent a threat to Switzerland? CHF 1.8 billion per year

floods 15% extreme temperatures 21% geological mass movements 4%

avalanches 11%

gales 16% 12% earthquakes

storms 21%

PLANAT, Katarisk, BABS

The total cost of the risk posed to Switzerland by all natural hazards is CHF 1,800 million per year. AURA Keystone

Avalanche damage in Goms near Damage caused by Storm Lothar Selkingen, canton of Valais, February 1999. in December 1999.

in the canton of Valais had to give way zones by keeping them free of develop - mobility and communications require - to provide sufficient discharge capacity ment is also supported by the insur - ments. “The situation is aggravated by for the confined river in the event of ance companies which have had to pay the increasing intensity of extreme flooding. This measure is included in out large compensation sums in recent weather events arising from climate the plans for the Third Rhone Correc - decades, in particular as a result of the factors caused by the greenhouse effect, tion. These two examples herald a repeated floods – in some cases in the which is exacerbated by human activ- turning point in the approach to natur - same location, as was the case, for ity,” explains Markus Nauser from al hazards in Switzerland. “We can no example, in the Matte neighbourhood FOEN’s Climate Section. “As an Alpine longer cling to existing land-use prac - of Bern on the bank of the river . country, Switzerland is affected partic - tices in high risk areas at any price,” Since 1972 alone, the total cost of flood ularly severely by the effects of climate says Hans Peter Willi, Head of FOEN’s damage in Switzerland exceeds CHF change.” The rising freezing level is Hazard Prevention Division. “Swiss so - 11 billion (adjusted for inflation). At causing glaciers and permafrost in the ciety should consistently avoid using around CHF 3 billion, the large-scale high mountains to melt which, in turn, areas where human life and material havoc wreaked by the storms of August aggravates the risks posed by debris assets cannot be protected at a reason - 2005 generated the highest costs. How - flows, rock fall and rockslides. In gener - able cost for development and give ever, the scale of damage arising from al, the increased water and energy con - them back to nature or agriculture.” natural disasters is constantly increas - tent of the atmosphere at higher tem - This renunciation of land use in high ing, not only in Switzerland, but also in peratures promotes more intensive risk areas may well be advisable if this other countries. The main reasons for precipitation and heavier storms. measure ensures greater safety for this are the general expansion of settle - buildings in adjacent areas. ment areas, the associated appreciation Identifying the hazards and of development land values in areas taking action Increasing damage potentially at risk, the greater vulnera - “In order to be able to provide better The concept of safeguarding hazard bility of infrastructure and increasing protection to people and important ENVIRONMENT 2/07 NATURAL HAZARDS 9

Swiss Air Force

Thanks to a discharge corridor, which channels the water from the rising Engelberger Aa river across the airfield into in the event of flooding, Buochs, canton of , (right) was protected from flooding in August 2005. Ennetbürgen, canton of Nidwalden, (left) was partly flooded because the protective dike, which has now been completed, was not finished due to project delays arising from planning objections.

material assets against risks we must to unacceptable risks to the point the case of a hazard event. The destruc - first record and assess the different nat - where the target-protection objectives tive effects of large earthquakes, which ural hazards on the basis of uniform are not fulfilled, additional measures are admittedly very rare in Switzerland criteria adopted nation-wide” says must be undertaken to improve the sit - but constitute the natural hazard with Hans Peter Willi. The hazard maps uation. These measures may be struc - the greatest potential in terms of the which are co-financed by the federal tural in nature – as in the case of extent of the damage they cause, can authorities and are due to be complet - avalanche sheds, rock fall nets, debris only be prevented through the imple - ed by 2011 will serve this purpose. flow barriers and flood dikes. For finan - mentation of such structural protection “These should highlight areas that cial, technical and ecological reasons, measures in the relevant building or fa - should not be developed for safety rea - however, the state cannot afford to cility, i.e. earthquake proofing. Gener- sons, on the one hand, and possible protect all buildings and infrastructure ally, the owner is liable for the cost of protection deficits in existing settle - against natural hazards by constructing all types of proofing. However, some ment and infrastructure areas, on the expensive protective structures. Spend - buildings insurers have recently begun other.” ing of up to 20 percent of the value of to invest in prevention as this enables The state guarantees the provision the goods at risk on protective struc - them to avoid large compensation pay - of basic safety services – as a public ser - tures is seen as a worthwhile invest - ments for a relatively small outlay. The vice – over a wide area, in particular ment. significant increase in the excess paid through the maintenance of the pro - for household contents insurance from tection forests and through appropriate Increasing individual responsibility CHF 200 to CHF 500 also provides a fi - hydraulic engineering measures and Depending on the situation, the imple - nancial incentive for the promotion of the maintenance of watercourses. If, mentation of local protection measures private damage protection. despite these measures, people, resi - (proofing) appears to offer an obvious dential buildings, transport links and solution to reducing the vulnerability Prevention pays other important facilities are exposed of individual buildings and facilities in According to a survey commissioned 10 ENVIRONMENT 2/07 NATURAL HAZARDS

by the Federal Council, i.e. Swiss gov - landslides and avalanches by protec - gency services and the affected popula - ernment, and published by the tive structures. To be able to save as tion must be fully aware of existing PLANAT expert commission in 2006, many human lives as possible and lim - weaknesses and know how to behave Switzerland already spends CHF 2.9 bil - it the scale of the damage in the event in such serious situations. For this pur - lion or 0.6 percent of gross domestic of a natural hazard, the local emer - pose they are dependent on reliable product annually on measures to pro - warning and alarm systems which can vide protection against natural haz - also function in emergency situations ards. This corresponds to barely 1.2 accompanied by breakdowns in power tenths of a percent of the total value of supplies and communications links. all of the country’s buildings and their The event analysis of the storms of contents. Of this expenditure, 60 per - August 2005, which has not yet been cent falls to private entities and the rest completed, has highlighted some is made by the state. Flood protection deficits in this regard which the federal and storm protection account for most authorities now aim to resolve through of the money spent. Almost half is used targeted measures to improve hazard for prevention. How effective these in - warning and alarm systems. Switzer - FOEN vestments in the safety of our environ - land already spends around CHF 400 ment can be, is clearly demonstrated One-stop office million annually on provisions for by the flood events in the Buochs area for all natural hazards such intervention. (canton of Nidwalden) during the storms of August 2005. Hydraulic engi - As the leading authority at federal The community of solidarity neering measures carried out to mod - level with responsibility for this area, of the insured ernize and improve flood protection on FOEN has been dealing with all natur - Considerably more money, i.e. almost the Engelberger Aa river and completed al hazards and the associated safety CHF 1.1 billion per year, is spent on shortly before this event at a cost CHF issues since 2006. Its strategy in this provision for recovery. Insurance pre - 26 million helped to prevent flood area, which was developed jointly miums account for three quarters of damage in excess of CHF 100 million. with expert organizations and can - this sum. The well developed com- tons, is aimed at safeguarding the munity of solidarity among insured Organizational safety measures lives and livelihoods of individuals and parties with buildings insurance en - Because it is impossible to provide ab - communities . ables regions, companies and individu - solute protection against extreme Through integrated risk manage - als severely affected by natural disasters events, the organizational measures ment based on the principle of sus - to survive economically and finance imposed by crisis management com - tainability, FOEN aims to guarantee a their new start – as, for example, in mittees – such as evacuation and block - high level of protection for the popu - Brienz where, 20 months after the dis - ing of roads and rail links – play a key lation and important material assets aster, few traces remain of the disas - role in situations of imminent danger. throughout Switzerland on the basis trous night of August 2005. They are particularly important at local of uniform safety standards. Impor - level in areas that are inadequately tant areas of activity in this regard Beat Jordi shielded against floods, debris flows, include the development of basic prin - ciples, consultancy and quality control services for hazard protection projects, INFO LINKS education and training for actors at all Hans Peter Willi www.bafu.admin.ch/naturgefahren (only available levels, the exchange of experience Head of Hazard Prevention in German, French and Italian) with other countries and engagement Division, FOEN www.planat.ch in a societal risk dialogue. Tel. + 41 (0) 31 324 17 39 www.swissworld.org [email protected] ENVIRONMENT 2/07 NATURAL HAZARDS 11

INTEGRATED RISK MANAGEMENT A sustainable approach to risk

Providing protection against natural hazards is the shared task of many stakeholders. In addi - tion to the state, private institutions and all potential victims are also involved in this endeavour. The planning of protective measures should be tailored to individual situations and be as sustainable as possible. The example of the river demonstrates the criteria, on the basis of which FOEN evaluates such projects.

Swiss Air Force To protect , the capital of the canton of , against floods of this kind (August 2005), it is intended to increase the flow capacity of the river Sarner Aa.

Sarnen, the capital of the canton of Ob - taries caused extensive damage to vironments of several thousand people, walden, was flooded for the third time houses, industrial buildings and infra - the urgent need for measures to im - since 1999 on 23 August 2005. Within structure to a tune of over CHF 200 prove safety in the valley of the Sarner 36 hours, the water in rose million. Over 1,000 debris flows and Aa is uncontested. “We want to protect a good two metres to a level of 472.42 accumulations of debris on 450 hectares human life, livelihoods and important metres, thus exceeding the previous of land were recorded throughout the material assets at an acceptable cost,” record from 1999 – another year of ex - canton. The main transport axes were says Gian Reto Bezzola, Head of the tensive flooding – by 1.14 metres. The blocked by floods, debris deposits and Risk Management Section at FOEN. crisis management authorities ap - landslides with the result that a num - “The degree of protection provided pealed to the population to leave the ber of municipalities were cut off from should be consistent with standards in ground floors of their houses, seek their surroundings. the rest of Switzerland.” The process in - refuge in the upper floors and prepare volved in providing protection against for evacuation. Throughout the Sarner Effectively minimizing risk natural hazards is based on clearly de - Aa valley, the main river, which was in Given the deficits that exist in the pro - fined steps. First, experts assess the rel - full flood, and its overflowing tribu - tection of the living and economic en - evant risks on site – starting inter alia 12 ENVIRONMENT 2/07 NATURAL HAZARDS

t Intervention

n Alert Warning e

v Rescue Information E Damage mitigation Preparation Information/ Instructions Organisation Resource planning Deployment planning Insurance Recondition Provisional Repair Supply and disposal Transport Systems Prevention Communications Land use planning Financing Technical measures Emergency legislation Biological measures

Reconstruction Definitive repair Reconstruction Strengthening of resilience Financing

Source: The Federal Office for Civil Protection

The cycle of integrated risk management: an integrated and holistic risk management assumes that all types of measures for natural disaster reduction are considered. Generally, measures of preparedness, response and recovery (reconstruction) should be equally implemented. from experience with previous hazard protective structures, the preservation with a specific protection objective in events. Based on the existing natural of the flow capacity of watercourses mind. The associated residual risks hazards, current and planned land uses and the maintenance of protection must be minimized with the help of and the ecological status of the loca - forests. “Particular priority is given to suitable precautions. Alarm-raising and tion, the second step involves the joint spatial planning measures,” notes Gian evacuation, local proofing of assets and definition by all stakeholders of the ac - Reto Bezzola. “This means that riverine insurance cover for eventual damage tion that needs to be taken. The ques - zones, retention areas and discharge constitute important elements in tack - tion as to what can be allowed to hap - corridors can be kept free for extreme ling residual risks. pen as a result of a hazard event is events, thus enabling them to make an answered with the help of a risk evalu - important contribution to the preven - A touchstone for the concept of ation which takes the relevant social, tion of an unchecked increase in dam - sustainable hydraulic engineering economic and ecological factors into age potential.” Structural measures are The protection objectives defined for account. Depending on the defined only considered when these measures the Sarner Aa valley can only be ful - protection objectives, experts identify prove insufficient. However, it is not filled with the help of structural mea - the optimum combination of protec - possible to provide complete protec - sures. One possible solution would be tion measures from the catalogue of tion against hazard events. Moreover, the construction of a bypass tunnel available measures. Priority is given rare large-scale events can exceed the from Lake Sarnen to Lake Wichel, here to the appropriate maintenance of capacity of the measures implemented which is located around four kilome - ENVIRONMENT 2/07 NATURAL HAZARDS 13

AURA (2), FOEN (4)

Integrated risk management incorporates all measures that contribute to the reduction of damage caused by natural hazards: for example, emergency management during disasters, the maintenance of protective structures, repair work, the maintenance of protection forests and structural measures.

tres further down in the valley. This outside of developed areas. “Thus, the of the order of CHF 5 million. This is would mean that once the water in the capacity of the existing watercourse still significantly less than the differ - lake reaches a certain level, the water could be increased and the section of ence in price between the two variants. would be channelled underground the river outside the settlement area Thus, FOEN favours the cheaper option through the mountain ridge to the east would be ecologically upgraded at a and proposes that the additional risk of Sarnen without affecting the valley significantly lower cost,” explains Gian be covered by insurance. “Economical - river. Based on current information, Reto Bezzola. “In view of the limited fi - ly acceptable and environment-friend - this solution would cost around CHF nancial resources available which ly hazard prevention ultimately in - 67 million. oblige us to adopt the most sustainable volves the acceptance of damage in the Another solution, which would cost solutions possible, in the case of the case of rare large-scale events,” says CHF 47 million, involves the deepen - Sarner Aa, a number of factors support Gian Reto Bezzola. Beat Jordi ing and widening of the Sarner Aa. The an over-ground solution.” river would be deepened by up to two This variant affects many more INFO metres and widened by a maximum of stakeholders, and would, therefore, Gian Reto Bezzola 20 metres downstream of Lake Sarnen. take longer to implement. Due to po - Head of Risk Management Additional embankments are planned tential damage arising from another Section, FOEN to provide flood protection to residen - flood event, a delay of around two Tel. + 41 (0) 31 324 16 59 tial areas as well as targeted flooding years would generate an additional risk [email protected] 14 ENVIRONMENT 2/07 NATURAL HAZARDS

HAZARD MAPS Experts survey all risk areas Thanks to the hazard maps, we should know by 2011 where and to what extent human beings and important material assets in Switzerland are at risk from natural hazards. The maps, which are being compiled by experts, help to ensure that areas at risk are kept free from develop - ment. They also constitute an important basis for the planning of protective structures and for emergency planning for crisis situations.

As the saying goes “a rolling stone gath - is smooth and moss-free. “It has not rock’s descent. The forest stands on ers no moss,” and, given that it is the in - been lying there long,” says geologist loose limy soil. Other evidence of rock spiration behind the name of the Markus Liniger. The boulder fell loose fall activity is provided by the many eponymous rock band, it must be true. from a ledge 50 metres higher up. Using marks in the bark of the trees. They gen - Sure enough, the block of limestone ly - his geologists’ compass, Markus Liniger erally lie at a height of around one and a ing on the foot of a beech tree on the establishes the dip direction and slope half metres. It may be concluded from south-eastern flank of the Urmiberg inclination. The slope is 42 degrees this that the stones descend towards the above Brunnen in the canton of Schwyz steep yet the tree was able to block the valley in smallish hops. The limestone

Hundreds of houses in Sörenberg in the canton of Lucerne are located in the red hazard zone and, therefore, in the high risk category (left). Nünalpstock, the unstable peak above the village poses a risk of a major rock falls and slides. The threat to a large part of the settlement is now to be averted by means of structural protection measures. As part of the project (right) it is planned to construct barriers and channeling elements on the slope (dark green) and a training dike (brown). The future hazard map reflects the risk reduction following the implementation of the hazard protection project. Fachbereich Naturgefahren, canton of Lucerne ENVIRONMENT 2/07 NATURAL HAZARDS 15

Beat Jordi, Biel (2006), Fachbereich Naturgefahren, canton of Lucerne (1911)

Sörenberg im Entlebuch was built after 1970 on the piles of rubble deposited by major rock slide events. Other major rock slides have occurred since the slide of 1910 (right) – the last one in 1999.

Hazard maps as a source of dispute

The red area on hazard maps largely indicates areas where de - from the intensity and probability of the individual hazard velopment is banned. Planning permission is not granted types. Uniform quantifiable indicators exist for the definition here: buildings that are destroyed are not rebuilt and very few of the intensity categories. “The procedure has proven optimal conversions or extensions are allowed. The owners must there - in numerous projects,” reports Roberto Loat from FOEN. “This fore accept a loss in the value of their property and have no is further substantiated by the low number of objections. An right to compensation. As a result, hazard maps can easily be - important reason for this is that a risk dialogue between the come a cause of dispute and this makes their meticulous com - authorities and local residents is initiated at an early stage in pilation all the more important. The hazard category is derived the project.”

lies in layers parallel to the slope and is dence of this in his notebook. How of - cant need for populations to be aware strongly fissured. The geologist mea - ten does this happen, how large are the of the hazard situation in their locali - sures the existing joint faces in the rock falling bodies, how far do they travel ties. By 2011, hazard maps indicating and identifies the potential falling bod - and at what kind of force? It is impor - the areas in which avalanches, floods, ies. He will enter these values – along tant to know the answers to these ques - slides and rock fall could represent a with other data such as the slope incli - tions because the land at the foot of risk to human life and important mate - nation, fall height, absorbability and mount Urmiberg is used for settlement rial assets should be available for all coarseness of the surface, tree stem den - and other purposes. residential areas in Switzerland. sity and mean stem thickness – into the This hazard assessment was com - According to a survey carried out by computer and generate a simulation of missioned by the canton of Schwyz. FOEN on the status of the hazard map - the rock fall process. Together with information from the ping process, with two thirds of the natural hazards database, the site find - area to be mapped already covered, Assessing the hazards ings, calculations and rock fall simula - avalanche risk emerges as the best doc - The protection forest at the Urmiberg tions will be used in the compilation of umented risk. In addition to this, 30 currently does a very satisfactory job. the “Rock fall” hazard map to be creat - percent of flood hazard areas, 29 per - Beeches, pines and spruces grow on the ed on a scale of 1:5000. cent of rock fall areas and 23 percent of sunny scarp and numerous holly trees areas affected by landslide activity, attest to the mild local climate. An ac - Avalanches, floods, landslides, rock fall have been mapped. cess road was built in the 1990s to facili - The cantons are currently working on tate the maintenance of the protection the systematic surveying of their haz - Four hazard categories forest or enable its establishment in the ard areas. They are doing this, first, to The Swiss hazard maps specify four haz - first place. However, it is still possible fulfil an obligation defined in the for - ard categories: for stones to crash down across the for - est and water engineering legislation • Areas at “serious risk” from hazards est edge. Markus Liniger records the evi - and, second, because there is a signifi - are marked in red. Buildings in these 16 ENVIRONMENT 2/07 NATURAL HAZARDS

locations could be completely de - “Used in conjunction with intensity acceptable cost. In areas classified in the stroyed by natural hazard events, thus maps and other documents, hazard blue hazard category, new buildings are people are also at risk here even inside maps constitute a basic prerequisite for generally only authorized in conjunc - the buildings. making hazards and risks understand - tion with stringent safety requirements. • The areas marked in blue are at “medi - able to the authorities and stakeholders,” However, these spatial planning mea - um risk.” People are usually protected says Roberto Loat from FOEN’s Risk Man - sures come too late in many areas. What if they remain inside solidly built agement Section. happens if buildings or important infra - houses, but not if they go outside. structure has already been built in haz - Damage to buildings may be expect - Spatial planning instrument ard areas and risks exist? In such cases, ed, but they would not be expected to The area in which the hazard maps are the level of safety required and the level collapse if they have been constructed most effective as an instrument is spatial of damage that should be accepted must in accordance with the relevant stan - planning at municipal level, which is first be clarified. “If people or significant dards. binding on land and property owners. material assets could be affected, the pro - • Areas marked in yellow are character - Thus, no more development zones tection objective is set at a higher level ized by a “low risk” to human life but should be designated in the areas marked than for less important material assets considerable material damage is still a in red on hazard maps. If not already in with limited damage potential,” says possibility. force, zoning bans should be considered Roberto Loat. • A residual risk exists in yellow-white in areas in which the state can only pro - hatched areas. vide an adequate level of safety at an un - Rock-slide risk in Sörenberg Seven hundred residential units stand underneath a slope in Sörenberg in the Hazard map for flooding, status 2006 canton of Lucerne which is sliding at a rate of two centimetres per year. The res - idential settlement in question origi - nates for the most part from the early 1970s. “The housing was built at the time in full knowledge of the risk situa - tion,” says René Graf, Director of the Natural Hazards Department at the Lucerne Cantonal Authority for Agri- culture and Forest. The area is called “Laui” which is derived from the Ger - man term Steinlawine, i.e. rock slide or rock avalanche. However, the collective memory of the rock slide of 1910 – with debris flows that extended right down to the now developed area – had been sup - pressed. Sudden slope failures, which can 66 – 100% arise as secondary events in mobile 33 – 66% 5 – 33% slopes (see page 19), represent a real risk Percentage of mapped area per canton 0 – 5% at present. Two larger debris flows were FOEN ENVIRONMENT 2/07 NATURAL HAZARDS 17

Percentage of Swiss territory covered by hazard maps based on hazard types

% Hazard maps 100 not available 90 16 40 40 54 some available stroyed but nobody was hurt.” The En - 3 80 gelberger Aa river provides another such 15 under development 70 example. Based on the hazard maps, available 60 13 part of the flood discharge was forced to 17 available and implemented in 50 20 relation to spatial planning spill over and deliberately inundate un - 40 13 15 developed areas. This overflowing water 11 53 30 8 could then be channelled and conveyed 16 20 16 13 to Lake Lucerne without causing dam - 10 14 age. Uncontrolled flooding would have 13 10 0 resulted in the inundation of Buochs Avalanches Flooding Rock fall Landslides and Ennetbürgen in the canton of Nid - BAFU walden. “On average, we calculate that it costs CHF 5,000 per square kilometre triggered in 1999. Human life is at risk safeguard the houses. “Today, the ad - to compile a hazard map. This figure when debris flows penetrate to residen - vance warning time for debris flows is can, of course, vary significantly, notes tial areas. For this reason, the Lucerne two hours – barely enough time for Roberto Loat. “Compared with the po - cantonal parliament authorized an evacuation. One day, it will be 24 hours tential damage caused by an extreme overall structural measures concept or longer.” Despite these measures, hazard event, this is a very small sum. costing CHF 14.2 million. The buildings some houses will still be located in the The storms of 2005 caused damage to - will be protected in future by two large red zone and should the worst case arise talling over CHF 100,000 per square sediment retention basins and a 1.8 or should they be destroyed as a result kilometre in the affected areas.” kilometre-long, five-metre-high training of a different event – for example a fire – dike. All going smoothly, work will start planning permission will not be granted Hansjakob Baumgartner on the project in 2007. The cost will be for their reconstruction in the same lo - met jointly by the Confederation, can - cation. ton, municipalities and owners of the LINKS affected houses. René Graf estimates Practical test passed www.bafu.admin.ch/naturgefahren > Umgang mit that the house owners’ contribution will Overall, the hazard maps already avail - Naturgefahren > Gefahrenkartierung und range between a few hundred and a few able passed their practical test during planerische Massnahmen (only available in thousand francs per residential unit. the storms of August 2005. The experts German, French and Italian) were around 80 percent correct in their Avoiding harm to human life hazard assessment. The knowledge pro - www.planat.ch > Risk Management > Preparedness > Prevention It is also intended to monitor and con - vided by the maps proved life-saving in trol the conditions in the rock-slide some instances. Roberto Loat is aware of area with the help of a permanent several such cases. “Thanks to the haz - recording system. “The aim of these ard map, for example, it was known that INFO measures is to avoid harm to human several houses on Lake Lucerne in Weg - Roberto Loat life,” says René Graf. This means that it gis (canton of Lucerne) were at risk from Risk Management Section will be possible to know when there is a landslide. Thus, the affected people FOEN risk of a disaster in areas where the pro - were evacuated. The slope slid shortly Tel. + 41 (0)31 324 16 57 tective structures are not sufficient to afterwards. Three buildings were de - [email protected] 18 ENVIRONMENT 2/07 NATURAL HAZARDS

LANDSLIDES Entire mountain slopes on the move The sliding of slopes is an essential fact of the earth’s unending geological history. Permanent landslides have been under way in several areas of Switzerland for thousands of years now. The thawing permafrost soils at higher altitudes are now increasingly on the move too. A satellite monitoring system is assisting in the timely identification of this hazard and its avoidance.

The tower is slightly crooked, but noth - rain is shaped by the accumulated slide by far the most severely affected. When ing else about the church in Peiden in material and fresh cracks, landslides the movement of the ground is deep, Val (Lugnez) in the canton and rock falls bear witness to the fact steady and slow, buildings are barely of Graubünden betrays the fact that that an ongoing chapter of geological affected. This is not the case, however, this house of God is on the move. Over history is being written here.* if the speed of the movement is higher the past century, its position has shift - at the front of the building than that at ed to the south-east by over 16 metres On the move for millennia the back. The houses in Peiden are neat and it has subsided by four metres. Pei - The landslide process in the valley, and fully intact, but some of them den is located in a 30-square-kilometre which has been populated since the show traces of repeated repair work. Re - slide area with a slate sagging. The left , started several thousand pairs have not been carried out for side of the valley from to years ago. Due to its location in a zone years on one particular building. Wide , which stands on a nappe with subject to what are known as differen - cracks gape open in the masonry of the a 15 degree gradient, is creeping valley - tial movements, of the eight villages lo - derelict house. wards at a rate of between 1 and 20 cated on the landslide body, Peiden is The proximity of the village to the centimetres per year. On a geological river (Glenner), which is eroding * The hike from the «Valgronda» post-office timescale, this is a brisk speed. Anyone car stop outside Cumbel via Peiden – Bual Sut – the foot of the slope one hundred me - who hikes from Peiden to Vignon will Degen takes a good two hours. tres further down, is also unfavourable. experience a geological drama. The ter - Map 1:25 000, sheet 1214 (Glion). Following floods in the late 1920s, the

Near-surface slope failures

If the slip surface of a landslide is near the surface, vegeta - tion can also influence the process. The root system of some tree species can extend to as many as two or more metres underground. Deep rooting trees and bushes draw water from the soil and hence the crucial lubricant. Meadows also stabilize the soil. Because the presence of numerous types of plants on a small surface creates a greater variety of soil anchors, plant cover with a high lev - el of biodiversity provides better protection against erosion than a homogenous species community. The fertilizing of steep slopes – whether intentional or the result of nitrogen emissions from the air – diminishes their stability as it re - duces biodiversity and promotes flat-rooting species. N E O F

www.waldwissen.net > Natural Hazards > Erosion Destructive landslide in Lutzenberg, canton of Appenzell, 2002. ENVIRONMENT 2/07 NATURAL HAZARDS 19

Hans Rudolf Keusen, Geotest AG, Zollikofen

The Stieregghütte (mountain chalet) at the foot of Mettenberg mountain near in the canton of Bern fell victim to this moraine slide in 2005. ground began to slide so strongly that the website of the municipality of therefore, at “serious risk” (see page Peiden almost had to be evacuated. Re - , to which Peiden belongs, “fear 14). The situation is less critical in oth - settlement was considered but the in - of the forces of nature fuelled by over- er parts of the valley where the slide habitants did not want it. The popula - pessimistic forecasts prompted many activity is deep-seated and steady. It is tion at the time was 87, it is now 11. The families to leave Peiden.” possible to build there, although safety adverse geological location, hastened requirements must be fulfilled. “A migration from the village. According to Well known landslide area strong reinforced concrete substructure Lugnez is a textbook example of a large may be necessary, for example,” says Crack in a building as an indicator of landslide area. Measurement data from Hugo Raetzo from the Landslides, the large-scale landslide in Peiden, canton the area go as far back as 1887. Like Avalanches and Protection Forest Sec - of Graubünden. major rock falls, deep-seated landslides tion at FOEN. can rarely be halted by human inter - vention or only at a disproportionate Monitoring of areas at risk cost. However, deceleration has been The safety of the population in a land - achieved with the help of underground slide area is at risk if the process accel - drainage, even in the case of very large erates, if differential movements dam - landslides (see «Drainage as a recipe for age houses or if secondary landslides success» page 21). develop spontaneously. The latter can Drainage, corrections of the river move rapidly in the direction of the Glenner and the construction of the valley and just a few thousand cubic Zervreila dam in its watershed area metres of rock is enough to destroy have also alleviated the situation in buildings. Slope-type debris-flows have Lugnez somewhat. No further signifi - also caused fatalities in Switzerland in cant acceleration has been observed for the past. Dozens of people die in rapid decades. However, the slope continues landslides in Italy every year. In addi - to slide. Peiden would not be built tion, debris flows can develop from the again today. The village is located in landslide areas, and, due to the high the red zone on the hazard map and is, volumes of bed load they carry, these FOEN 20 ENVIRONMENT 2/07 NATURAL HAZARDS

Ground movements (encircled in red) can be recognized using satellite images as, for example, in the Arolla area in the canton of Valais. represent a risk to settlements located ble slopes and rock sections will slide or as far as several kilometres away from strong rainfall will trigger debris flows. the landslide area. Because landslide As recent studies show, the increase in movements can accelerate abruptly, temperature in the 20th century has al - their development should be moni - ready given rise to mass movements, in tored. Today, FOEN uses the most mod - particular since the late 1980s. Slopes ern resources available, such as radar have started to slide and rock glaciers interferometry, for this purpose. Using consisting of frozen debris and ice are radar waves, it is possible to obtain creeping faster towards the valleys. maximum-precision distance measure - Although this mainly occurs in ments at every point on the earth’s sur - locations far removed from inhabited face from satellites located 800 kilome - areas, landslides and rock falls in these tres away. Boulders, roads and locations can represent a – direct or in - buildings are suitable reflective mea - direct – risk to traffic routes and settle - suring points as vegetation covers the ments in the valleys. For example the ground conditions in the radar images. rock glacier in the forefield of Glacier A dozen such points in Lugnez are FOEN de Tasarmine in Lower Valais, which caught by the eye of the satellite. The had been inert for a long time, has be - resulting data produce an accurate im - “Radar interferometry offers enor - come active in recent years. Satellite age of the landslide and enable the mous potential for hazard identifica - data show that it is creeping towards identification of the zone of differen - tion and risk management. Despite the valley at a rate of 0.8 to 1.5 metres tial movements. This technology also costing less, the information obtained per year, and as much as two metres provides geologists and engineers with using this large-scale analysis instru - per year at the front of the rock glacier. valuable insights into other well known ment is more detailed” says Hugo Raet - The findings coincide fully with the landslide areas such as Grächen in the zo. This method opens up new possibil - values obtained – with far greater diffi - canton of Valais, Grindelwald in Bern, ities, particularly in unpopulated areas, culty – from the ground measurements. Lauterbrunnen in Bern, Schwarzsee in i.e. high mountain areas where mea - Moreover, the satellite brought previ - Fribourg and Villars-Leysin in Vaud. surement networks do not exist or ously unknown ground movements to The results of these observations are where measurement costs would be ex - light: a laterally connected debris slope now incorporated, inter alia into the cessive. at mount Dent de Perroc has also start - hazard maps which, in turn, act as a ba - ed sliding. sis for the definition of hazard zones New risks from melting permafrost The road to Arolla in the canton of and areas in which development is This new technology is badly needed, Valais crosses the valley eight hundred banned in local zoning plans. not least in relation to the new risks metres further down. “We clearly need arising from climate change. In the to know what is going on in the Alpine European partnership permafrost area – at altitudes greater permafrost zone,” says Hugo Raetzo. The European Space Agency (ESA) has than 2,300 metres above sea level – the “Radar interferometry provides excellent been collecting radar data by satellite ice which binds the unconsolidated opportunities in this regard which are since 1991. As part of its cooperation sediments is melting. As a result there also acceptable from a cost perspective.” with the ESA, Switzerland is authorized is an increasing risk that previously sta - to use this archive. Envisat, the Euro - Hansjakob Baumgartner pean earth observation satellite, has LINKS been flying over every location on INFO earth at intervals of 35 days since 2002. www.bafu.admin.ch/naturgefahren > Rutschungen (only available in German, French and Italian) Thanks to the support provided by the Hugo Raetzo Space Affairs Service at the State Secre - www.planat.ch > Natural Hazards > Mass Movement Landslides, Avalanches and tariat for Education and Research, > Landslide Protection Forest Section, FOEN FOEN also has access to the latest radar www.vallumnezia.ch > Informationen A-Z > Geologie Tel. + 41 (0)31 324 16 83 data from the Alps. (only available in German and Romantsch) [email protected] ENVIRONMENT 2/07 NATURAL HAZARDS 21

Disregarded warnings in Falli Hölli

The first sign was a fault with the drinking-water supply. In The name March 1994, a water pipe in the Falli Hölli holiday house de - says it all: velopment near Plasselb in Fribourg had become displaced the demo- and needed be repaired twice. The western flank of mount lished Falli Hölli, i.e. Schwyberg had started to creep. Thirty-three million cubic Hell Fall, metres of debris and mud were slowly sliding down the valley. holiday t o

Boreholes revealed that the slip surface lay at a depth of 37 development h p u c o

metres. This quickly eliminated any hope that the slope could in 1994. D / N E O

be stabilized with the help of engineering measures. Thirty- F seven houses were completely destroyed – moved 200 metres, torn apart, overturned and buried by the falling masses of earth. The landslide reached its maximum speed of six metres per day by the end of July, from October no further obvious Schmid stated: “It is safe to say that the ground conditions displacements could be observed. pose a serious disadvantage to the stability of the structure.” Boreholes also brought pieces of wood to light, the relics of Today, the canton does not grant planning permission in previous mass movements. The determination of their age us - the area although, at a rate of 1 centimetre per year, current ing carbon dating revealed that the western slope of mount movements are small. The ban on building is justified by the Schwyberg had been active in the past 5,000 years. The Falli possibility of the renewed acceleration of the landslide. From a Hölli development was not planned until the 1960s. Every - geological perspective, this argument could have been used thing was done by the book and planning permission had decades ago – even without the help of the hazard map. been obtained, however geological reports compiled at the “However, even today, too little attention is paid to the accel - time did contain warnings. In a report produced for the eration scenarios associated with unstable slopes in Switzer - Fribourg Cantonal Planning Authority, geologist Gottfried land,” notes FOEN geologist Hugo Raetzo.

Drainage: a recipe for success

At the back of the Valle di Campo – a through channels. If the Rovana runs tinuous erosion of the foot of the side valley of the Maggia Valley in the high, the water now flows through a slope. Following the implementation canton of Ticino – a huge slide mass of newly constructed diversion tunnel. of this measure, the landslide along 800 million cubic metres with an area Thanks to this tunnel, it was possible the slip surface practically came to a of around six square kilometres was to prevent – for a large part – the con - standstill. moving on a slip surface of up to 170 metres depth. It not only imperilled Stabilized slide mass in the Campo valley, canton of Ticino. the villages Campo and Cimalmotto lo - FOEN cated on it, but also risked causing an afflux in the Rovana River which could have triggered catastrophic flood waves and floods right down to Lo - carno and Ascona. These risks have largely been elimi - nated thanks to engineering measures. High water pressure in the body of the landslide emerged as the main cause of the movements. Thus, a 1,800-metre long drainage tunnel was constructed below it, from which drainage bore- holes lead directly into the slide. The water is also drained on the surface 22 ENVIRONMENT 2/07 NATURAL HAZARDS

EARTHQUAKE PROTECTION If the earth were to shake tomorro w...

Despite what people may think Switzerland is not immune to strong earthquakes with enormous potential for damage. As things stand, the country would be -prepared for such an event. Preventive measures could go a long way towards mitigating the disastrous effects of a major earthquake. These would involve providing better protection for buildings and infrastructure and suitable insurance cover for the resid- ual risks.

pare as well as possible for its occurrence. New buildings and infrastructure must be designed and built in compliance with the rules of earthquake-resistant design.”

A largely underestimated hazard Unlike storms and floods, earthquakes cannot be forecast. Based on historical e n o t

s data, experts at the Swiss Seismologial y e K Service at the Swiss Federal Institute of Historical depiction of the strong earthquake of 1356 in Basle and photo of the collapsed roof Technology Zurich (ETHZ) can, howev - of a church as a result of seismic shaking in the Siders area of the canton of Valais (1946). er, predict the probability of their occur - rence. The areas of Switzerland most at “I got the fright of my life,” reports ge - Fortunately, earthquakes of this level risk from earthquakes are the canton of ologist Marcel Burri when asked about of intensity have not re-occurred in Valais, the Basle region, central Switzer - his recollection of events on the Switzerland in recent decades. For this land, the mountain valley and evening of 19 January 1946 in Siders in reason, such recollections are fading the Rhine valley upstream of Lake the canton of Valais. “I was on my way from the collective memory. However, in Constance. Approximately 500 seismic home from school. We were violently view of the very real risk posed by earth - shocks are recorded in Switzerland each jolted around. Everyone was screaming. quakes, such a carefree attitude is mis - year. Most of them occur in these re - The electricity supply failed and fires guided. “Given the growth in population gions, however, the population is only started all over the place. We ran home and increasing value of material assets, aware of around two percent. These through the rubble to our parents. We the risk has actually increased signifi - events are triggered by an abrupt release were very afraid and did not know when cantly,” stresses Blaise Duvernay, Manag - of energy stored in the earth’s crust it would finally end or how strong the er of the Federal Coordination Office for caused by the collision of the African next tremor would be. That was my first Earthquake Mitigation at FOEN. “For this and Eurasian tectonic plates. Statistical - sleepless night.” reason it is important to make people ly, an earthquake measuring 5 on the aware of this natural hazard and to pre - Richter scale can be expected in Switzer - ENVIRONMENT 2/07 NATURAL HAZARDS 23

Earthquake risk in Switzerland

In the European context, Switzerland is at medium risk from earthquakes. Strong earthquakes are possible here, but are far less common than in typical risk areas such as Turkey. As indicated by the scale of possible ground accelera- tion (m/s 2), the earthquake risk in Switzerland is greatest in Valais and in

the Basle region. The lower the value the FOEN lower the hazard.

land every ten years and an event of a magnitude of 6 may be expected every 100 years. The intensity of the tremors in Siders in 1946 is estimated at 6.1 and that of the disastrous earthquake in Basle in 1356 at 6.9. A comparable earthquake in the Basle region today would probably claim around 1,500 lives and cause direct damage to prop - erty ranging between CHF 60 and 100 billion. Damage on a scale of between CHF 2 and 5 billion could be expected in Siders. “By way of comparison, the direct damage to buildings and infra - structure arising from the floods of Au - gust 2005 totalled around CHF 3 bil - Switzerland lion,” says Blaise Duvernay. “Thus, in terms of damage potential, earth - Project Sesame low middle high very quakes are among the most significant high natural risks facing Switzerland.”

Patchy precautions adopted its SIA Standard 160 contain - specifications in force within the EU. Contrary to the widely held view that ing provisions on earthquake resistant Compared with the older standard, the earthquake resistant construction is ex - construction which take modern ad - new ones take better account of the pensive, the additional costs associated vances in this area into account. This crucial influence of local geological with such measures in new buildings was followed by the adoption of SIA factors and introduce structural design represent at most 1 percent of the value Standards 260–267 in 2003 which con - concepts which enable the provision of of the building. In 1989, the Swiss En - tain more stringent requirements for a high level of protection at an accep t- gineers’ and Architects’ Association load-bearing structures in line with the able cost. Ninety percent of buildings 24 ENVIRONMENT 2/07 NATURAL HAZARDS

Thomas Wenk, Zurich (2)

The Swiss Confederation is having all of its important buildings and infrastructure inspected for earthquake resistance and retro - fitting them where necessary – for example the Ganterbrücke bridge on the A9 national highway in the Simplon area of Valais and the lecture hall at the ETH Zurich which has been retrofitted with steel columns.

necessary. In addition, the SIA earth - quake regulations must be implement - ed in all new federal buildings. Inspec - tions – and proofing, if necessary – are also mandatory for all major conver - in Switzerland were constructed before Switzerland’s parliament building: sion or restoration projects. The prime 1989, however, and are not, therefore, a shining example example of the work carried out by this specifically designed to resist strong There is no constitutional basis for programme is the Swiss Bundeshaus, seismic shocks. The deficits in masonry earthquake hazard mitigation in the Federal Parliament building, where buildings with more than four to five Switzerland. However, a programme of the earthquake resistance was im - floors are particularly obvious. Serious measures for federal buildings and proved as part of its renovation in 2006 weaknesses also exist in the old mason - structures which are financed or re - and 2007. “The most important struc - ry buildings with wood floors and in quire the authorization of the federal tural measure involves the connection typical town houses, in which almost authorities has been in existence since of the facade to the floor/ceiling slabs,” all of the load-bearing walls have been 2000. The objective of the Federal Co - explains Blaise Duvernay. “In addition, removed to create space for retail busi - ordination Office for Earthquake Miti - where possible, low-resistance floor/ nesses. gation, which was established in 2001 ceiling slabs are being replaced by rein - In most cantons, the application of and is affiliated to FOEN, is to monitor forced concrete ones.” the seismic requirements of the struc - and improve earthquake safety in Blaise Duvernay puts this progress tural design codes are neither explicite - buildings which are the responsibility into context, however, by explaining ly demanded nor controlled and this of the Confederation. It also coordi - that the 3,000 public federal and can - makes the task of ensuring comprehen - nates working groups which harmo - tonal buildings inspected by the end of sive prevention more difficult. Further - nize the measures necessary for critical 2006 represent less than two tenths of more, architects, engineers and clients infrastructure, cultural assets and seis - a percent of Switzerland’s total build - often lack the necessary information mic monitoring and for intervention in ing stock of over 1.8 million structures. and training. Because many clients do the event of an earthquake. Between “Thus the cantons are required to im - not specifically request earthquake re - 2001 and 2004, experts inspected over prove this situation in the years to sistant buildings, the number of build - 300 federal buildings and 690 major come through the introduction of in - ings that are vulnerable to strong bridges belonging to the national road spection procedures for private con - tremors is constantly on the increase, network. A further 500 buildings and struction projects and, in particular, even today. Thus, the risk posed by around 3,300 bridges are to be inspect - the inspection of buildings involving a earthquakes in Switzerland increases ed by 2008. If the experts encounter serious risk to human life.” daily, in particularly in private new problems in the course of these inspec - buildings. tions, the structures must be surveyed Valais is moving in detail and earthquake-proofed if Earthquake mitigation in Switzerland is ENVIRONMENT 2/07 NATURAL HAZARDS 25

FOEN/E. Ammon, AURA Simulated earthquakes

The canton of Valais is also working on raising its population’s awareness of earthquakes. For example, a 300 square metre stand at the 2006 Valais Fair in Martigny was devoted to this na - tural hazard. For the first time in Switzerland, 15,000 people were able to test FOEN’s earthquake simulator and experience at first hand the effect of earth tremors measuring 6 to 7 on the Richter Scale at their epicentre. Since then, the simulator has been used at exhibitions and fairs throughout the country. A school classroom shaken by the earthquake simulator.

the responsibility of the cantons. Up to the case of an earthquake in the Rhone Next step: mandatory earthquake now, however, only Valais and Basle- valley has increased significantly since insurance? City have included the corresponding 1946, several microzoning studies have Nowhere in the world is the popula - preventive measures in their legislation been carried out in recent years in Brig, tion better insured than in Switzerland. and introduced them into their plan - Visp and Monthey. Sitten and Mar - This observation does not apply, how - ning authorization procedures. Valais tigny are due to follow suit in 2007 and ever, to damage caused by seismic has assumed a pioneering role in the 2008. Further studies of this nature shocks. With the exception of the can - Swiss context. In 2004, the cantonal have also been carried out in other ton of Zurich, there is no guaranteed government made compliance with the parts of Switzerland, i.e. in the canton cover in Switzerland for damage to SIA earthquake standards 260–267 of Basle-City and on the Ecublens cam - buildings caused by earthquakes. Since mandatory and defined inspection pro - pus of the Swiss Federal Institute of early 2005, the Swiss Insurance Associa - cedures for public and private build - Technology Lausanne (EPFL) and the tion (SVV) and the Association of Can - ings. The canton has been equally ac - campus of the Swiss Federal Institute of tonal Fire Insurance Companies (VKF) tive in the compilation of maps of Technology Zurich (ETHZ). By the end have been working on a project to es - subsoil classes which facilitate the of 2006, ten cantons had compiled tablish nationwide mandatory insur - earthquake resistant design of new maps of soil foundation classes for their ance of earthquake damage under the buildings. The same applies to the most densely populated areas with the supervision of the Federal Office of Pri - studies carried out on microzoning help of the federal authorities. The re - vate Insurance (FOPI). What is involved which are used to establish the behav - sults can be downloaded free of charge here in practice is the extension of cur - iour of the substratum in the event of from: www.bafu. admin.ch > Naturge - rent mandatory buildings insurance. seismic shocks. As a result they provide fahren > Erdbeben > Erdbebenge - “The product is not clearly defined engineers with better design bases fährdung der Schweiz > Geologische at the moment. When this stage has which are specific to the local situation Standorteffekte > Karte der Baugrund - been reached it will have to be ap - and are more comprehensive than the klassen nach SIA 261. proved by the cantons and authorized general standards. by the Federal Council,” says Blaise The effects of an earthquake on a Duvernay. “Earthquake insurance will building depend not only on its magni - be introduced in 2008 at the earliest.” tude and the distance of the location LINKS from the epicentre, but to a large ex - Cornélia Mühlberger de Preux www.bafu.admin.ch > Naturgefahren > Erdbeben tent also on the local properties of the substratum. Thus, soft soil heightens www.seismo.ethz.ch INFO the intensity of seismic shocks. This is www.sgeb.ch (German) Blaise Duvernay true, for example, of the loose sedi - www.planat.ch >natural hazards >earthquake Prevention of Major Accidents ment deposits from rivers and lakes in and Earthquake Mitigation www.crealp.ch > Dangers naturels > Séismes the Rhone plain. Whereas in the past Section, FOEN (French) the valley floor was mainly used for Federal Coordination Office for www.seisme.ch (French) agricultural purposes, today it is dense - Earthquake Mitigation ly populated and heavily industrial - www.bebende.ch (German and French) Tel. + 41 (0) 31 324 17 34 ized. Because the damage potential in www.rheintal06.ch (German) [email protected] 26 ENVIRONMENT 2/07 NATURAL HAZARDS

Presentation from the exhibition “Le Valais bouge” (i.e. “Valais is How Valais proofs moving”): earthquake risk should be established before building starts and its buildings taken into account.

The canton of Valais is a pioneer in the area of earthquake resistant construction. ENVI - RONMENT spoke to engineer Xavier Mittaz To what extent are critical buildings to find out exactly what earthquake proofing and structures like hospitals, schools involves. As an expert in the area, he in - and dikes protected in Valais? spects the earthquake resistance of building The canton launched its “Lifelines” inspection campaign in projects on behalf of the canton. the late 1990s. Measures to improve earthquake resistance have already been implemented in acute hospitals. The ENVIRONMENT: What measures must be taken in the design same applies to the control centre of the Valais cantonal po - and construction of a building to ensure maximum earth - lice force. Several administrative buildings and schools are quake resistance? currently being inspected with a view to future conversion. Xavier Mittaz: The load-bearing elements which absorb the The safety of dams is monitored by the Confederation. seismic forces must be continuous and as regularly spaced as possible, both in the plan and elevation. This means that Do architects and engineers have access to specific training? the architect and construction engineer must work together Courses in earthquake resistant construction have been on in the design phase. In Valais, seismic calculations must be offer in Valais since 2003. In 2005, the Swiss Society for submitted as part of the planning authorization procedure Earthquake Engineering and Structural Dynamics (SGEB) or - for new buildings with more than two floors above ground- ganized a further training course on earthquakes and exist - floor level. The same applies to projects involving the com - ing structures and the corresponding SIA 2018 standard. In prehensive renovation of existing buildings. French-speaking Switzerland, training opportunities are also available at the College of Technology and Architecture in Which older buildings pose the most problems? Fribourg. The buldings that cause most problems are those built be - Interview: Cornélia Mühlberger de Preux tween 1950 and 1970. Savings were often made in the area of building materials at the time, and the increasing use of reinforced concrete made it possible to construct ceiling Recommended reading slabs with greater spans and hence reduce the number of load-bearing walls. Older houses with a lot of thick walls • Erdbebensicheres Bauen in der Schweiz, BAFU, 2006. Orders: often prove less vulnerable if they have not been altered too www.umwelt-schweiz.ch/div-7523-d. extensively. • Ist unser Haus erdbebensicher? Faltprospekt, BAFU, 2007. Orders: www.umwelt-schweiz.ch/div-7527-d. ENVIRONMENT 2/07 NATURAL HAZARDS 27

FLOOD PROTECTION The deceptive safety of channelized Pioneering achievements in the field of hydraulic waterways engineering have made a crucial contribution to Switzerland’s economic development. However, the old flood control structures often fail to satis - fy the requirements of sustainable flood protec - tion. Thus, expensive rehabilitation work needs to be carried out on many water courses to im - prove safety levels.

FOEN/E.Ammon, AURA

Interrupted railway track and inundated alluvial plain following dike failure in the upper reaches of the river Aare near in the canton of Bern in August 2005.

Some 60 billion cubic metres of water of Switzerland. Dreaded diseases like itate agriculture and settlement in the fall from the sky in Switzerland every malaria were still prevalent in marshy valleys without continuous setbacks, year. In terms of the country’s total areas – such as the Bernese Seeland – the unpredictable meandering water area this represents a precipitation vol - into the 19th century. In the alluvial courses had to be tamed using the re - ume of almost 146 centimetres. This plains, untamed rivers repeatedly laid sources available at the time. abundance of water has always repre - waste to harvests, destroyed settle - sented a mixed blessing for the people ments and swept bridges away. To facil - continued overleaf 28 ENVIRONMENT 2/07 NATURAL HAZARDS

Christian Meuli, ARGE Hochwasserschutz, canton of

Rivers need space: the diverted and rehabilitated bed of the river Flaz in Oberengadin provides better flood protection to in Graubunden.

A pioneering era in hydraulic Swiss Confederation. Individual regions dikes had been constructed on both engineering and cantons would not have been able to banks of the river. Even at low water, the Thus, the first major river correction in - cope with the floods or bear the financial river filled the 70-metre space between volving the diversion of the river Kander burden of these major infrastructure pro - these dikes and this resulted in the depo - into Lake Thun was carried out almost jects alone. The action against the forces sition of considerable volumes of debris. 300 years ago. The real boom in hy - of nature required not only solidarity be - With time, the river bed aggraded and draulic engineering in Switzerland did tween upstream and downstream popu - the dikes risked overflowing in the event not begin, however, until the 19th cen - lations, but also financial commitment of a flood. tury when almost all of the important on all levels of the state. This problem was remedied by the Alpine rivers – such as the Rhine, Linth, Thanks to straightening, deepening second Rhone correction which took Reuss, Aare and Rhone – were channel - and diking, the water courses could safe - place between 1930 and 1960. The river ized and diked. ly accommodate greater volumes of wa - channel was adapted to the lower flow The guiding principle behind the hy - ter and there were fewer floods in the and narrowed, a measure which in - draulic engineering measures imple - valleys. Combined with gradual reaf - creased the flow velocity and improved mented at the time was the realization forestation in the headwaters, torrent bed-load transport significantly. As the on the part of engineers that straight - control also made a crucial contribution most recent studies show, however, even ened channels had greater flow and bed- to the improvement of the situation to - these measures could not increase the load-transport capacity. This means that wards the end of the 19th century. This transport capacity of the Rhone suffi - the rivers deposit less bed load on gentler gain in safety led to a rapid expansion of ciently. Thus, a targeted long-term ap - stretches and cannot burst their banks so industry in the alluvial plains: new settle- proach to bed-load management was re - easily. The main engineering feats of this ments arose in the areas protected by the quired. period included the diversion of the river dikes and agriculture gained fertile allu - Linth into Lake Walen and the first train - vial land. The neglect of excess load ing of the Jura waters which diverted the Almost all of Switzerland’s large water river Aare into Lake Biel through the New insights gained over time courses were tamed using the same prin - construction of the Hagneck Canal. The inadequacies of these protection ciple as that used for the Rhone: i.e. measures became evident, however, over based on the calculation of rare flow A nation united against floods the course of the decades – for example peaks – for example, with a return period Like the re-occurring floods, the river in the Rhone valley in Valais. As part of of 100 years – the dimensions of the nec - corrections also made a central contribu - the first Rhone correction, which was essary river channel were determined tion to the cohesion of the then young carried out between 1863 and 1890, and reinforcement dikes constructed. ENVIRONMENT 2/07 NATURAL HAZARDS 29

“The weaknesses of this system came to due to be carried out on numerous ma - clude, for example, the targeted man - light in recent decades with the in - jor water courses over the coming agement of bed load, the use of spatial creased occurrence of extreme flood decades. This process offers the hy - planning instruments to keep hazard events,” says Simone Hunziker of draulic engineering experts an oppor - zones free of development and the rais - FOEN’s Hazard Prevention Division. “A tunity to remedy the existing deficits ing of bridges, where the accumulation society that depends on flood protec - and implement the principles of sus - of floating debris could hinder water tion structures to protect its settle - tainable flood protection. flow. Moreover, computer simulations ments and infrastructure against a one- Where possible, the water courses of possible flood events help in the hundred-year flood will suffer even are widened again and liberated from identification of unpopulated corridors greater losses if a water course exceeds their narrow constraints, because the for use in cases of excess load: volumes this calculated value.” In such cases of higher the dikes the greater the risk of of water that exceed the capacity of a excess load dams can collapse or be flooding during an extreme flood event river bed can be discharged there under overtopped, settlements flooded and which exceeds the designed capacity of controlled conditions. Examples for so - transport links destroyed. the protection structures. River widen - lutions of this kind that have already ing increases flow capacity, decreases been implemented include sections of A new protection philosophy the maximum water level and reduces the recently rehabilitated Engelberger The bank protection structures and the flow rate. On the other hand, how - Aa river, the diversion of the river dikes in often extensively narrowed ever, it also creates valuable habitats Flaz to protect Samedan in the canton rivers are showing their age in many lo - for plant and animal species which de - of Grisons and the river Reuss in cations today. In some cases, for exam - pend on periodic flooding. Urnerland before it enters Lake Lucerne. ple on the river , the water shoot - The motorway, which is closed during ing down into the straightened bed has The combination of different measures flooding, acts as an ad-ditional eroded and deepened the riverbed In addition, modern flood protection drainage corridor when the riverbed is which has resulted in the partial under - combines different measures which im - no longer able to discharge the vol - cutting of the bank structures. As a re - prove the protection of human life and umes of water present. sult, urgent rehabilitation projects are important material assets. These in -

Widened rivers or rivers with fewer flood protection structures – Low bridges often become critical bottlenecks in the case of like this stretch of the Rhone in Pfynwald forest between Leuk flooding. Driftwood can block the flow, as in this example of the and Siders in the canton of Valais – provide diverse habitats and Rhone near Naters in Valais in October 2000. popular recreational areas.

(2) Keystone 30 ENVIRONMENT 2/07 NATURAL HAZARDS

FOEN flood statistics Somewhat conflicting concerns Experts can use statistical methods to estimate the frequency of ex - Settlements, industrial zones, roads, rail - treme flood events on the basis of previous maximum values. Com - way lines and other valuable infrastruc - bined with hydrological analyses and model calculations, flood sta - ture take priority in the implementation tistics represent an important hydraulic engineering tool. They can of flood protection structures. In addition be used to design the river-bed dimensions necessary to achieve to hydraulic engineering measures, target - protection objectives in the rehabilitation of water courses. How- ed local flood proofing and the adapted ever, uncertain factors such as climate change must be taken into use of buildings at risk contribute to the account as it is questionable whether the data available from the reduction of vulnerability. Given that the past will also apply in the future. occasional flooding of pasture or forest ar - Since the late 1950s, the large reservoirs in the canton of Valais, eas that can recover from floods relatively have exercised an attenuating effect on the flow in the Rhone, par - quickly, is hardly likely to cause signi- ticularly in the case of small and medium-sized flood events. With- ficant damage, this is more likely to be out this retention capacity, the flooding of the main valley that allowed to happen. To optimize the pro - occurred in the major flood years of 1987, 1993 and 2000 would tection objectives and proposed measures, have been more disastrous. the interests of all stakeholders must be www.bafu.admin.ch > water > hydrological foundations and data carefully considered – taking their some - times conflicting concerns into account – in the context of river rehabilitation pro - jects. “Possible conflict arises today mainly Annual peak flows of the river Rhone due to the conflicting interests of flood at the FOEN measuring station in Sion in cubic metres per second

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Canton of Valais

The planned Third Rhone Correction (description below) is intended to give the river more space again.

protection, nature conservation and at worst, 14,000 hectares of land in the widening is planned upstream and agriculture,” says Jean-Pierre Jordan, main valley would be flooded. The cur - downstream of this stretch of the riv - consultant for the Third Rhone Cor - rent cost of the damage arising from er,” explains Jean-Pierre Jordan. The re - rection at FOEN. “Agricultural land has such an event would be around CHF 10 habilitation measures are ultimately to be sacrificed for the widening of the billion, and the destruction of major being carried out with long-term devel - Rhone. This measure was initially con - industrial plants – for example Alcan opments in mind. “Even if there is an troversial even within the federal admi - and Lonza – would account for half of acceleration in climate change and a nistration – the Federal Office for Spati - this sum. general increase in flows, the system al Development (ARE) and the Federal would be able to cope with the new re - Office for Agriculture (FOAG) expressly Priority measures in critical areas quirements with the help of minor demanded that good agricultural land The implementation plan for the Third adaptations.” be protected. “All of the authorities Rhone Correction, which was autho - now support the solution that has been rized in summer 2006, specifies the Lucienne Rey, Beat Jordi found: thanks to integrated land recla - framework for the entire rehabilitation mation which suits the farmers and im - of the river and ensures that the neces - proves their production conditions, the sary spatial coordination is carried out. LINKS loss of this land is largely compen- The technical details of the work to be www.rhone-thur.eawag.ch (German) sated.” carried out as part of the General www.vs.ch/rhone (French and German) Rhone Project, which is due to be pre - Potential damage totalling sented for consultation in 2008, are de - www.alpenrhein.net (German) ten billion francs fined. It is planned to implement prior - www.wwf.ch > Unsere Themen > Wasser (German, The Third Rhone Correction is the ity measures costing a total of CHF 360 French and Italian) largest and most expensive river reha - million in the five sectors of Visp, www.svv.ch > Publikationen > Wenn das bilitation project currently under way Siders, Sion, Fully and Aigle to improve Wasser kommt in Switzerland. Over CHF 1 billion will the level of safety in critical areas. In have to be invested in this measure the case of Visp, an eight-kilometre- INFO over the coming 30 years. Simulations long subsection of the river is involved. Jean-Pierre Jordan of the effects of a flood which would be The flow capacity on the town perime - Flood Protection Section statistically expected to occur every ter, where widening is not an option, FOEN 100 years show that this represents a will be increased through the deepen - Tel. + 41 (0) 31 324 17 52 good investment. In an extreme event, ing of the river bed. “Considerable [email protected] 32 ENVIRONMENT 2/07 NATURAL HAZARDS

FLOOD PROTECTION AND NEW FINANCIAL EQUALIZATION

Reduction of unacceptable risks takes priority

Under the New Financial Equalization frame - and maintenance of avalanche barriers and rock fall nets work, from 2008, federal spending on protec - and the production of the hazard maps. tion against natural hazards in Switzerland will be specifically effect-oriented. As part of this Risk-based criteria approach, the federal authorities will take the “In future, money will be allocated to the cantons on the risk situation in the relevant regions, the asso - basis of priority,” explains Christian Schuler from the FOEN ciated damage potential, the corresponding Hazard Prevention Division. “The reduction of unaccept - rehabilitation requirements and the sustain - able risks is particularly important in this context.” In order ability of the proposed measures into account. to ensure that urgent projects which can prevent large- scale damage are implemented as quickly as possible, from In order to protect settlement areas against disastrous 2008, funding will focus more specifically on the existing floods, the Confederation, cantons and municipalities will risks. The corresponding potential damage can be deter - have to spend several billion Swiss francs on flood protec - mined, inter alia with the help of the hazard maps. tion in the coming decades. The Third Rhone Correction alone will cost CHF 1 billion, and rehabilitation measures Financial incentives for worthwhile projects totalling CHF 600 million are planned in the Alpine foothills In addition to the general funding for the development of as a result of the floods of August 2005. To these are added general hazard information, such as hazard maps, smaller equally urgent projects on the large Alpine rivers Aare, projects and periodic maintenance tasks, important pro - Reuss, Linth and Alpenrhein. In order to be able to finance jects are processed, evaluated and financed on an indi- the currently planned flood protection measures within the vidual basis. All projects must fulfil certain minimum desired time frame, the federal and cantonal authorities requirements. The Confederation also wishes to promote will need increased funding. FOEN’s regular annual budget optimized solutions by granting higher subsidies. It is in this area is CHF 67 million. In accordance with the New hoped that better quality and the targeted improvement Financial Equalization, the allocation of resources will be of structural flood protection measures can be achieved based on new criteria from 2008. This also applies to the in this way. In addition to risk-oriented criteria, the Confed - funding of other hazard prevention measures by the Con - eration will also take the issue of sustainability into consid - federation, i.e. protection forest maintenance, construction eration.

Optimized flood protection through the widening of the river Thur. Amt für Umwelt TG ENVIRONMENT 2/07 NATURAL HAZARDS 33

EXTREME WEATHER Climate change aggravates natural hazards

As an Alpine country Switzer - land is affected more than most by climate change. It must adjust to the fact that the risks posed by floods, debris flows, rock fall, winter storms and heat waves are increas - ing. Thus, new approaches are needed to improve hazard prevention. A R U A / N E O F

Flood damage in Oey-Diemtigen, canton of Bern, following the storms of August 2005. More extreme weather events may be expected as a result of climate change.

Since November 2006, the heating sys - struction of this heating system is an of CO 2 concentration means that the tems in 40 houses in Oey-Diemtigen in excellent example of how something frequency of floods and winter storms the canton of Bern no longer run on oil good and sustainable can come out of a increases by a factor of three to five but on wood. The construction of a dis - difficult situation,” says Hans Küng, and the frequency of heat waves may trict heating system in this municipal - one of the project initiators. even increase by multiples of these,” ity in the Bernese Oberland is related says Martin Grosjean, Executive Direc - to climate change. Oey was one of the More energy in the atmosphere tor of the Swiss National Centre of areas particularly badly affected by the It is not possible to prove scientifically Competence in Research on Climate storms of August 2005 – half of the vil - whether the flood of 2005 was actually (NCCR Climate). lage was buried under metre-high piles a result of climate change because – in - of debris. Hans Küng, the President of cluding other factors – the measure - Future climate forecast the municipality, recalls that the deci - ment series are not long enough. How - Despite uncertainties regarding the sion not to replace the heating systems ever, there are clear indications of a speed at which climate change is tak - destroyed in the flood individually, but link between global warming and the ing place, researchers on the Schweiz to substitute them with a shared wood frequency of extreme climate events. 2050 project have created a forecast of chip burner, arose at an early stage in There have been 16 major flood events Switzerland’s future climate. Their the aftermath of the disaster. Wood is in the past 200 years; of these, seven model calculations are based on an av - available in abundance in the Diemtig - occurred during the period of warming erage emissions scenario. According to tal valley. As a result of the flood, re - from the mid-1970s. The energy and them, the temperatures in the entire newable energy sources and CO 2 sud - water content of the atmosphere is in - country are rising – and, moreover, denly became a focus of interest among creasing due to the greenhouse effect. faster than hitherto. As compared with the population. After some to-ing and As a result, the probability of extreme the late 20th century, the increase in fro-ing, the heating system was eventu - weather phenomena also rises. “We go winter temperatures is around two de - ally installed in record time. “The con - by the rule of thumb that the doubling grees and three degrees in summer 34 ENVIRONMENT 2/07 NATURAL HAZARDS

temperatures. Winter precipitation vol - due to a rock fall event. These “dramat - al hazards in general. The state cannot umes are increasing by around 10 per - ic developments in many places” come guarantee absolute safety to the popu - cent, however they are declining by as no surprise to geologist Hans Rudolf lation and does not make any claim to around 20 percent in the hot season. Keusen. For example, since 1980, aver - do so (it is not an automatic right in Stronger deviations may be expected age temperatures on the Jungfraujoch any case). “Natural hazards cannot be from year to year, both in relation to (the lowest point on the ridge linking brought under control with the help of temperatures and precipitation. Thus, the Mönch and Jungfrau peaks) have technical measures alone,” says Hans Switzerland must adapt to events such risen by up to two degrees. Periods Peter Willi, Head of FOEN’s Hazard Pre - as the heat wave summer of 2003. The with a zero-degree limit above 4,000 vention Division. “On the contrary, cli - consequences at the time were almost metres are increasing and the nights mate change highlights the need for 1,000 fatalities, large-scale harvest fail - are also getting warmer at high alti - comprehensive risk management ure, problems with overheated or tudes. “The thawing of the permafrost which requires a broad range of risk-re - parched water courses and an increase makes the rocks unstable. This leads to duction measures in addition to robust in forest fires, as demonstrated by the more rock falls and more frequent rock protective structures that can cope large-scale destruction of the protec - slides,” explains Hans Rudolf Keusen. with cases of excess load.” tion forest above Leuk in August 2003, Mountain climbers must adjust to the which involved arson. fact that, as a result of this, some routes Increasing damage potential will become “objectively more danger - The level of the financial burden al - Increased rock fall hazard ous.” To this is added the fact that the ready posed by natural hazards was More and more mountaineers are expe - rapid retreat of the Alpine glaciers, in demonstrated clearly in August 2005. riencing the effects of the increasing particular on steep mountain slopes, is With damage totalling CHF 3 billion, temperatures in the mountains at first mobilizing large volumes of scree and the floods of August 2005 in Switzer - hand. Climbers on the this aggravates the risk of debris flows, land were the most expensive natural mountain and the Eigernordwand in particular. disaster of the past 100 years. The (north face of the Eiger) were injured greater vulnerability as compared with by rock fall in the very hot July of 2006 There is no such thing previous flood events is directly linked and there were three fatalities on the as absolute safety to the increasingly intensive use of west flank of the Jungfrau peak. The In the future, the situation facing land in the areas at risk. emergency services also had to rescue mountain climbers in the Alps today, In terms of the extent of the dam - 25 mountaineers on the Matterhorn will be increasingly applicable to natur - age they cause, of all the climate-relat -

Fighting a large-scale forest fire near Leuk in the canton of Valais in August 2003 and rock fall on the Gotthard motorway near in the in May 2006. Climate change aggravates the risk of forest fires, in particular in Valais and Ticino. The risk of rock fall and rock slides is also increasing.

E. Ammon, AURA (2) ENVIRONMENT 2/07 NATURAL HAZARDS 35

Modelling of potential permafrost distribution in the Swiss Alpine region (below) and view from the Schafberg to the Berninatal valley with , canton of Grisons. The Giandains avalanche and debris flow bar - rier, which was completed in 2003, is intended to protect the village from, inter alia, the conse - quences of the thawing permafrost on the disintegrating Schafberg. The municipality of Pontresina tackled the possible consequences of climate change at an early stage and was the first mountain municipality in Switzerland to implement comprehensive hazard protection measures. ed natural hazards, floods already rep - resent the greatest risk in Switzerland today. This risk will tend to increase further as a result of climate change. “First, as a result of the rising zero-degree limit, precipitation is in - creasingly falling in the form of rain instead of snow, even at higher alti - tudes,” explains FOEN climate expert Markus Nauser. “During extreme weather events, this increases the runoff in water courses with Alpine wa - tershed areas and, therefore, the flood risk in the Swiss Central Plateau.” Second, the increase in precipitation intensity and extremes forecast by the experts from the Schweiz 2050 project Beat Jordi, Biel supports the expected rise in floods, landslides and debris flows.

Water courses need more space These predictions also have an impact on flood protection. In order to be able to channel the expected runoff peaks and water volumes without causing damage, water courses, which are con - fined in many locations, will require far more space in the future. “There is significant need for action because the existing protection measures no longer meet the increased requirements,” explains Gian Reto Bezzola, an expert FOEN on floods at FOEN. “The protection Local permafrost possible Extensive permafrost likely 36 ENVIRONMENT 2/07 NATURAL HAZARDS

structures are often ineffectual in cases tions where dike failure could occur plementing a targeted policy of depop - exceeding the design load and can only and the water could overflow in the ulation when individual residential be adapted to changing requirements first place. Based on the different possi - buildings and manufacturing plants at a considerable cost.” ble scenarios, preventive measures are can no longer be adequately protected then taken and emergency concepts at an acceptable cost. In such cases, the Expecting the unexpected developed. “Our aim is to ensure that state assumes a significant proportion An overview of the protection deficits in the case exceeding the design load a of the costs arising from the abandon - will be available when the hazard maps river will overflow at a location where ment of affected properties. have been completed. As part of the the water will cause least damage,” says FOEN is currently examining the es - hazard assessment process, which is Hans Peter Willi. tablishment of a national prevention supported by the federal authorities, fund which could be used to finance the experts must examine the potential Containing new hazards similar measures. “We must expect the outcome of an extreme event for each As a result of climate change, our soci - unexpected,” says Hans Peter Willi. hazard. This enables the recognition of ety will have to abandon certain sensi - “With the help of a smart adaptation weaknesses and risks which should be tive land-use practices in hazard zones. strategy we aim to minimize the possi - fully remedied in accordance with the Thus, for example, the authorities in ble economic consequences of climate principles of integrated risk manage - the Aosta valley in Italy are already im - change and to limit new risks to an ac - ment or reduced to an acceptable level. ceptable level.” A balanced and aware approach to Kaspar Meuli risk differs from previous hazard de - LINKS fence concepts whereby hydraulic en - www.bafu.admin.ch/klima > Publikationen gineering based the dimensioning of (only available in German, French and Italian) protective dikes on rarely attained peak INFO flows. It was merely hoped that future www.occc.ch > Projects + Publications floods would not inundate the dikes. www.meteoschweiz.ch Markus Nauser “As opposed to this, today, possible www.hitzewelle.ch (only available in German Climate Section, FOEN weak points and bottlenecks such as and French) Tel. + 41 (0) 31 324 42 80 bridges where driftwood can block a www.swissre.com > Research & Publications > [email protected] river bed are inspected,” explains Hans Top Topics view > Focus report > The effects of Peter Willi. Experts also inspect loca - climate change Hans-Peter Willi, see page 10

Global warming represents an additional stress factor for the forest: scientific measurement of the sap flow of a pubescent oak (left). Experts from the University of Bern drill ice cores from the depths of the Piz Zupo glacier to reconstruct the climate of the past 500 years (right).

Medienstelle NFS Klima, Bern ENVIRONMENT 2/07 NATURAL HAZARDS 37

Keystone

Descent of a powder avalanche over Evolène in the canton of Valais on 22 February 1999. Twelve lives had already been lost on the previous evening due to another major avalanche in the region.

PROTECTIVE FOREST Well maintained forests provide greater safety

Switzerland’s mountain forests protect hundreds of settlements and transport routes against natural hazards such as avalanche and rock fall. The long-term maintenance of the tree stands that make up this biological protection system is expensive. The Swiss Confederation supports these protection measures to a tune of CHF 50 million annually – for example, in the “Bawald” forest over Ritzingen in the Goms region of the canton of Valais.

High above Ritzingen in Valais, in the forester Fredy Zuberbühler, manager of One day, when the two-hundred- steep “Bawald” forest which protects the the Mittelgoms forestry operation. year old members of the same species village against avalanche and rock fall, a “They were bent over like the runners are no longer standing, these young group of young conifers stands in a on a Davos sledge. It was a pitiful sight.” trees will stabilize the snow mantle and small clearing at 1,700 metres above sea- At the time, he gave up on the trees and actually prevent avalanches from start - level. Just a few metres further down, was already thinking about what should ing in the first place. The foresters had there are massive spruce trees, which are be done to close the resulting gap. How - to give nature a helping hand in the over 250 years old. “In the very snowy ever, the trees recovered and stand high upper part of the slope. Avalanches, winter of 1999, a snow slab crashed and straight today as though nothing some of which penetrated down to the down over the young fir trees,” reports had ever happened to them. valley floor, repeatedly formed here 38 ENVIRONMENT 2/07 NATURAL HAZARDS

where the snow can pile up metres lowed to happen in locations where creep of the snow masses which can high. Thus, the forestry service in - settlements or transport routes require move valleyward by up to five metres stalled wooden snow rakes ten years protection. in the course of a winter and thus put ago. The young trees can now develop From 1950, the protective forests in considerable pressure on the young undisturbed and in a few decades they many locations were no longer man - trees. will replace these temporary structures aged as it was feared at the time that in their protective function. human intervention would weaken Sustainable protective forest them. This approach resulted in a trend maintenance Growth under extreme conditions for the development of over-aged tree The insights gained in the Bawald were However, such interventions should re - stands with an unbalanced species applied in the FOEN project “Sustain - main exceptional. Fredy Zuberbühler, composition. “Mountain forest re - ability and Success Monitoring in the who knows the 100-hectare protective quires a good horizontal and vertical Protective Forest” which provides the forest better than anyone else, says mix of varieties and age classes to be relevant foresters with basic informa - that, in over 20 years of working in the able to fulfil its protective function on tion and practice-based working papers Bawald, the one thing he has learned is a continuous basis,” says Forest Inspec - in the form of a manual. “The knowl - patience: “Living things – be they tor Norbert Carlen from the Cantonal edge we have today is far more de - plants or animals – develop formidable Office for Forest and Landscape in Sit - tailed,” says Philipp Gerold from the strength that enables them to survive ten. For this reason, the forestry ser - Forest Maintenance Section in the can - in these extreme conditions.” Drought vices in the mountain regions have in summer and snow pressure in winter professionalized forest maintenance make life very difficult for them. over the past two decades. The spruces, which represent 90 The threat percent of the forest stand here, grow Goms protective forest of air pollution so slowly in the early years that, 20 as experimental ground In addition to maintenance, air years ago, the foresters thought they The Swiss Mountain Forest Mainte - pollution has a considerable im - should close the gaps in the stand nance Group (Schweizerische Gebirgs- pact on the vitality of protective by planting seedlings. However, while waldpflegegruppe) – an expert body – forests. Over 90 percent of forest almost all of the planted seedlings used the Bawald forest as experimental locations in Switzerland are died, the robust naturally-occurring ground for the development of general - currently affected by excessive ni - seedlings survived because they were ly applicable guidelines for protective trogen inputs. This results in the better adapted to the harsh conditions. forest maintenance. According to an gradual acidification and over-fer - Fredy Zuberbühler shows a photo of a initial stand survey, around two thirds tilization of the soil, which, in the young group of small slightly bushy fir of the forest area was over-aged. Over long term, causes the eluviation of trees which grew around a fallen tree the following years, the forestry service important minerals and, hence, 20 years. Today, they are “out of the created small gaps to provide light and the imbalanced supply of nutrients woods” and, at almost 50 years of age, space for the next generation of trees to the trees. have reached the size of majestic by means of targeted logging. The re - This gives rise, inter alia, to nega - Christmas trees. sponse to this measure was positive in tive effects on the root system and terms of regrowth. However, even to - vulnerability of the trees to wind - The aim is to achieve a good mix day, 20 years later, it is necessary to throw, drought, diseases and harm - “Nature cannot manage things in the look very carefully to be able to identi - ful organisms. Moreover, the direct mountain forest on its own, however,” fy the tiny trees in the sometimes tall input of pollutants – for example explains Marzio Giamboni from FOEN’s grass. The annual increment of the through ozone – represents an addi - Landslides, Avalanches and Protectiv e young trees at this altitude is just a few tional stress factor for the trees. The Forest Section. “If the stands were left centimetres. To protect them, logged or reduction in air pollution targeted to their own devices, we could expect fallen trees are left in the forest. Stabi - by the federal authorities alleviates the large-scale collapse that occurs in lized by their own snags, they compact these threats to the protective for - virgin forests.” This must not be al - the snow and thus prevent the dreaded est. ENVIRONMENT 2/07 NATURAL HAZARDS 39

Fredy Zuberbühler, Ritzingen/Dienststelle für Wald und Landschaft des Kantons Wallis

The “Bawald” forest over Ritzingen in the Goms region of the canton of Valais protects the village against avalanches and rock fall. On the cantonal map of the forest functions, the top priority protective forests are indicated in red and the second priority ones are indicated in orange. ton of Valais. “In the past, we were lim - the significant role of the forest as a (GIS), which records all of the natural ited to the recording of removals. To - central component of integrated risk hazards that can be warded off by these day, we observe the protective forest management. forests. and know exactly where action is re - According to the modelling which quired.” After two decades of working The SilvaProtect-CH project has now been completed, 21.2 percent in the Bawald forest, Fredy Zuberbühler FOEN funds the maintenance of pro - of Switzerland’s protective forest is is satisfied. “We intervened where it tective forests to the tune of around located in the canton of Grisons, 18.3 was absolutely necessary. Now we can CHF 50 million annually to ensure the percent in Valais, 17.5 percent in Tici - leave the forest to its own devices for long-term protection of settlements no and 12.3 percent in the canton of the next quarter of a century.” and transport routes against natural Bern. The findings are currently be ing hazards. An important condition for discussed with the cantonal forestry Immensely beneficial protective effect the allocation of federal funding is the services. Harmonized criteria for pro - In terms of the area covered, at alti - delineation of the corresponding tective forest delineation are due to be tudes up to the natural tree line, i.e. forests by the cantons. However, due to adopted by late 2007. Implementation around 2,000 metres above sea level, the lack of a standard method, the data at cantonal level is due to take place by evergreen coniferous forest is the main recorded since 1991 are inconsistent. late 2010. source of avalanche protection – as is On the request of the cantons and in the case with the Bawald forest above consultation with them, in 2004, FOEN Urs Fitze Ritzingen. Unlike most technical pro - launched its own system for the mod - tection structures, mountain forests in elled delineation of forest areas with a INFO steep terrain also provide protection protective function. The system, which against other natural hazards such as is known as SilvaProtect-CH, is based Marzio Giamboni (SilvaProtect- rock fall and near-surface slope failure. on a geographical information system CH), Landslides, Avalanches and Based on Switzerland’s closed forest Protection Forest Section, FOEN area, which totals around 10,850 Tel. + 41 (0) 31 324 86 40 square kilometres, FOEN estimates that [email protected] the proportion of forest area with a LINKS protection function is between 40 and André Wehrli (protective forest) www.bafu.admin.ch > Naturgefahren > Schutzwald 60 percent. A previous National Re - Landslides, Avalanches and (only available in German, French and Italian) search Foundation study calculated the Protection Forest Section, FOEN economic value of this effect at around www.forestknowledge.net Tel. + 41 (0) 31 323 93 98 CHF 4 billion per year, which explains www.wsl.ch > search > protective forest [email protected] 40 ENVIRONMENT 2/07 NATURAL HAZARDS

PROTECTIVE FOREST LEARNING PATHS Recognizing the importance of the protection forest

The purpose of the learning paths in nine Swiss mountain regions is to raise public awareness of natural hazards on high ground and the effect of the protective forest. The Schutzwald Schweiz (“Protection Forest Switzerland”) group, which is funded by the federal authorities, has chosen to do this by means of sensory experience.

The Swiss population’s conception of the forest has changed which provides far more direct access to the topic. The aim is radically, even in the mountain regions. Whereas it was once to ensure that the importance of the protection forest be - seen as an important source of raw material and income and comes rooted in the participants’ thoughts and actions in the as a shield against natural hazards, today it is frequently long term. viewed as an amenity area, even by local residents. However, Participants have to overcome challenges at different instal - the importance of the protection function of mountain forests lations along the paths. For example, they must negotiate a has actually increased due to the spread of settlement areas point with loose rocks and, having overcome this hurdle, they and proliferation of transport routes. The “schutz.wald. can then learn about the topic of rock fall on an information mensch” (protective.forest.man) project was launched in panel. Thus, participants do not encounter the topic as passive 2002 to update this imbalanced image of the forest. Its aim is readers but as observers who access information first and fore - to link the recreational and useful aspects of the forest, thus it most through their own experience and reasoning. combines pleasant walks in the forest with the raising of awareness of natural hazards. Signs of natural forces The nine learning paths in Moléson (Fribourg), Adelboden First-hand experience (Bern), Bettmeralp (Valais), Grafenort/ (Obwalden), Learning paths represent a proven but now rather jaded Altdorf (Uri), Wägital (Schwyz), Werdenberg (St Gallen), awareness-raising instrument. Thus, in this case, a concept Poschiavo (Graubunden) and Arosa, (Graubunden, from Au - was consciously chosen that differs from the usual approach gust 2007) have different installations on topics such as to learning paths, says biologist and environmental trainer avalanches, landslides and forest maintenance. Vivid examples Klemens Niederberger, who developed the project on behalf are provided on site alongside the traces of natural forces left of the Schutzwald Schweiz group. The emphasis here is not on by rock falls, rock slides, torrents, debris flows, floods, land - signposted information panels, but on sensory experience slides and avalanches. www.schutz-wald-mensch.ch

The learning paths in the nine mountain forests enable participants to experience at first hand natural hazards in the mountain regions, the functions of the protection forests and the enormous significance of forest maintenance. SILVIVA ENVIRONMENT 2/07 NATURAL HAZARDS 41

FOEN

More space for the previously channelized river Magliasina in Ticino: the new river bed is protected against erosion using bioengineering methods.

PROTECTION IN HARMONY WITH NATURE Greater safety through reserved open spaces Structural measures for protection against natural hazards often impact heavily on landscapes and habitats. However, modern hydraulic engineering is moving away from the drive to tame rivers with the help of structural flood controls. It is giving water courses more space and combining flood protection concerns with those of nature-oriented landscape management.

Turquoise water meanders along its came an unexpectedly destructive force. The structural flood controls on a good course to Lake Lugano in the half-shade The torrential river damaged the trans - two kilometres of the river were re - of the alluvial forest. This idyllic land - port routes, buildings and facilities that moved, the riverbank was flattened out scape near Caslano in the canton of had increasingly encroached on its somewhat and parts of the river bed Ticino is, however, a recent develop - banks in recent decades. extended to twice its previous width. ment: as recently as the 1990s a narrow Native shrubs and trees protect the canal kept the small mountain river More space for nature embankment from erosion. Willow Magliasina in bounds to protect a golf The flood damage of around CHF 7 mil - seedlings, lying willow branches and co - course on the flood plain from flooding. lion prompted a review of the previous conut nets provide stability for steeper However, when an unusually heavy protection concept. Just a few months sections of the river bank. These bio - storm broke in Ticino in September later, the municipalities involved agreed engineering safety measures have not 1998, the channelized water course be - to give the river Magliasina more space. only made the river banks more attrac - 42 ENVIRONMENT 2/07 NATURAL HAZARDS

tive for leisure-seekers, they have also Significant need for action was used on wet ground during the created a diverse habitat for plants and As part of ecomorphology investiga - clean-up operation. “Driving at exces - animals. As model calculations show, tions on the structure of water courses, sive speed on flooded fields immediate - thanks to the extra space, the owners of which are co-funded by the federal au - ly after the drain off of flood water fre - properties bordering the area are largely thorities, the cantons have collected quently causes further damage through protected against flooding, even in the data on rivers and streams with a total soil compaction which is often more se - event of a peak flow exceeding that of a length of almost 27,300 kilometres. Of rious than the damage caused by the one hundred year flood. this, around 10,000 are significantly re - natural hazard in the first place,” ex - stricted, unnatural or culverted. Renatu - plains Jürg Zihler from FOEN’s Soil Sec - Expensive infrastructure – ration with widening is required to rem - tion. It is also a matter of economic self- costly damage edy these deficits. “However, this is only interest, not to lapse into blind activism Floods become a social problem when possible if the land along the water but allow the soil to settle and dry for a they put human life and important ma - courses is available,” says Markus Thom - few days. “Even in cases involving cont - terial assets at risk. “The significant in - men. The need for action is greatest in amination with organic substances – for crease in built infrastructure is a one of highly developed settlement and eco - example oil – in our experience, the soil the main reasons for the enormous nomic zones because, in the past, water recovers relatively well,” notes Alexan - damage caused by floods,” notes Markus courses in these locations were often se - der Imhof, Director of the Department Thommen from FOEN’s Landscape and verely restricted so as to provide addi - for Pollution Control at the Uri Canton - Land Use Section. tional land for development. al Office for Environmental Protection. This applies in particular in the The question arises, however, as to “It is amazing how quickly the plants mountain region where the steep terri - whether society is actually prepared to shoot up through the layers of mud.” tory increases the momentum of the curb its development activities to im - However, if the alluvium cover is more water courses – and hence also their de - prove flood protection and upgrade the than 15 centimetres thick, it must be re - structive power in the event of a flood. habitat quality of the water courses. moved – preferably using a caterpillar The damage potential is rising here due Jean-Michel Gobat from the Institute tracked vehicle. to the continuing improvements in the of Botany at the University of Neuchâ - quality of the infrastructure. The feder - tel has explored this issue as part of Lucienne Rey al authorities alone, spend almost CHF Swiss National Research Programme 100 million annually on structural im - 48, Landscapes and Habitats of the provements such as access roads, barns Alps. According to the project findings, and farm buildings. “In the storm of ecological flood protection projects LINKS 2005, in addition to public transport have the best chance of being imple - routes and inhabited buildings, numer - mented if the memory of a flood event www.umwelt-schweiz.ch/naturgefahren > Publika - ous farmland improvements as well as is still current as this makes people tionen > Hochwasser > Fallbeispiele Wasserbau > Malcantone (German, French and Italian) forest roads were damaged,” notes more receptive to radical measures. Markus Thommen. To minimize the www.rhone-thur.eawag.ch (German) damage arising from such events, na - Working with nature ture must be given more space again. It is not only important to work with INFO “In some cases, it would make more nature in the context of hazard preven - Markus Thommen sense to leave areas which are particu - tion, it also pays to do so in the after - Landscape and Land Use Section larly vulnerable and can only be pro - math of a loss event. After Storm Lothar, FOEN tected at a very high cost entirely to serious soil degradation arose in numer - Tel. + 41 (0) 31 322 80 78 the devices of nature.” ous forests because heavy machinery [email protected] ENVIRONMENT 2/07 NATURAL HAZARDS 43

ALERTING Timely warning when danger threatens The extent of the damage caused by natural disasters can be significantly reduced if crisis management units, emergency services and other stakeholders are warned in good time. Emergency planning provides more time to move people, animals and mobile assets to safety and to organize the preparedness measures for damage reduction. For this reason, Switzer - land aims to improve its warning and alert systems.

Evacuation arrival a few days or hours in advance. of a resident Experts at MeteoSwiss (Swiss Weather from the Service), the Swiss Federal Institute for flooded Matte Snow and Avalanche Research (SLF) in neighbourhood Davos and FOEN monitor weather de - of Bern in velopments with the help of the very August 2005. latest technologies. Based on model calculations and their experience, they can often predict critical weather situa - tions and their possible effects in good time. In exceptional situations, they collaborate with the National Emer - gency Operations Centre (NEOC) in Zurich which informs the crisis task forces at cantonal level and, if neces - sary, instructs the population via elec - tronic media.

Improving warning and alerting systems “The weaknesses that emerged in Au - gust 2005 showed that there is room for improvement in our natural hazard warning and alert systems,” says Hans Peter Willi. Thus, the federal authorities aim to optimize the cooperation be - tween the different expert bodies, create a shared natural hazards internet plat - form (gemeinsame Informationsplatt-

Beat Baumann, Wasserwirtschaftsamt, canton of Bern form Naturgefahren/GIN) and improve the operational reliability of the measur - Several thousand cars sank in the wave Peter Willi, Head of the Hazard Preven - ing devices. “In the case of extreme of storms of August 2005. The flood tion Division at FOEN. events, the action undertaken in the damage to motor vehicles in Switzer - With the exception of strong earth - early hours is often crucial for the fur - land alone totalled almost CHF 100 quakes which can occur without any ther course and extent of the damage,” million. “If the population had been warning, most of the natural hazards explains Hans Peter Willi. “The decision warned on time, people could have that represent a threat to Switzerland – is taken at this point as to whether the moved numerous parked cars to safety for example heavy storms, avalanches damage can be limited through suitable without running any risk,” says Hans and floods – announce their imminent organizational measures.” 44 ENVIRONMENT 2/07 NATURAL HAZARDS

Good preparedness reduces FOEN’s automatic alarm annunciators the fire services in large industrial con - the damage Early warning based on detailed precip - cerns. Depending on the watershed To ensure that things do not get out of itation and run-off forecasts and alert - area of a river and the respective control when a hazard event exceeds ing based on water level measurements threshold value, which is defined in the capacity of existing protective often play a crucial role. To this end, advance in consultation with the structures, emergency planning which the FOEN Hydrology Division has al - client, those responsible have one to is tailored to the situation is required in ready equipped 26 of its water mea - two hours time to implement the nec - the hazard zones. This includes, in par - surement stations on larger water essary emergency measures. Thus, for ticular, the advance raising of public courses and lakes with alarm annuncia - example, FOEN has installed seven ad - awareness, the thorough training of tors. If the Rhine, Aare, Lütschine, ditional alarm annunciators in its mea - crisis management units who are famil - Emme, Reuss, Linth, Limmat, Töss, Sit - suring stations on the Aare from Lake iar with the weaknesses of the local ter, Thur, Ticino or Maggia reach a crit - Brienz to its outlet from Lake Biel since structural safety concepts and well pre - ical water level, these devices send an the flood of 2005. The measures under - pared emergency services with the nec - automatic alert to the appointed secu - taken in cooperation with the Bernese essary operating resources. If the fire rity company Certas. From there, Water Management Office and the can - brigade, police and other emergency FOEN’s clients are notified around the tonal police are intended to facilitate services are mobilized in good time, de - clock by telephone and kept informed the timely alerting of the crisis man - pending on the risk involved, they can about the critical water level. The main agement units and emergency services close threatened transport routes, evac - subscribers to this service are the can - in neighbouring municipalities. uate people and animals, install tem- tonal and municipal crisis manage - porary protection measures and – in ment units, the emergency services and Beat Jordi the case of flooding – keep bottlenecks on water courses free from debris and LINKS INFO driftwood. If those affected by the haz - www.bafu.admin.ch > Hydrology > Hydrological Beat Sigrist ard are given prior warning, they will foundations and data > Forecasts and alerts (Automatic Flood Alert) have time to move vehicles and other www.meteoschweiz.ch > Danger Hydrometry Section, FOEN material assets to safety without Tel. + 41 (0) 31 324 76 39 www.slf.ch putting their lives at risk. [email protected] www.naz.ch

Hans Peter Willi, see page 10

Road blocks (left: For Pedestrians/Caution!/Danger of Avalanches/Road closed) and temporary protection measures are important ways of reducing the extent of the damage caused by natural hazards in critical situations. Keystone/Vereinigung Kantonaler Feuerversicherungen VKF, Bern ENVIRONMENT 2/07 NATURAL HAZARDS 45

Swiss Air Force In August 2005, the industrial zone on the Reuss plain near in the canton of Uri was flooded for days. The emergency services had to pump out large volumes of contaminated mud.

MAJOR ACCIDENTS CAUSED BY NATURAL HAZARDS When chemical stores are flooded

Some industrial concerns and businesses which work with environmentally hazardous sub - stances are located in hazard zones. In the absence of adequate protection measures, harmful chemicals could be released there in the event of flooding, rock fall or an earth - quake. Such locations will now be surveyed and assessed systematically with the help of FOEN’s new databases.

On 22 August 2005, the torrents from toxic substances also stored there, such risk from natural hazards, thus in the the Uri tributary valleys deposited as chromates, perchloroethylene and event of flooding, rock fall or an earth - tonnes of debris on the Reuss plain. other chlorinated solvents, had also quake the release of hazardous sub - The material deposed by the Schächen leaked. However, fortunately, the con - stances poses an additional risk,” re - torrent near Schattdorf blocked the tainers with the environmentally haz - ports Daniel Bonomi from FOEN’s overflowing stream and the resulting ardous substances remained intact and Prevention of Major Accidents and water mass formed a lake in the indus - were successfully recovered by the Earthquake Mitigation Section. In ad - trial zone, flooding 201 industrial op - emergency services. Where time al - dition to the increasing pressure from erations employing over 2,000 people, lowed, some containers had been land use – in particular in the highly including large industrial premises, moved to safety before the flood. industrialized Central Plateau, the such as those belonging to the RUAG Basle region and in the plains of the corporation and Dätwyler rubber fac - Pressure from land use large Alpine valleys – operational fac - tory. The chemical emergency re - exacerbates risks tors also play a role in the problematic sponse teams were deployed for days; Due to their handling of hazardous choice of these locations. For example, once the water had retreated they had substances, around 2,300 plants in chemical works are often located near to pump large volumes of mud conta - Switzerland are subject to the provi - large water courses because they need minated with leaked oil and various sions of the Federal Ordinance on Ma - cooling water and because, in the past, chemical substances. It could have jor Accidents (Störfallverordnung, the water courses provided a very been worse if some of the particularly StFV). “Some of these locations are at convenient means for the disposal of 46 ENVIRONMENT 2/07 NATURAL HAZARDS

Vulnerable industrial zone at the foot of the eroded scarp near Preonzo in the Leventina district of Ticino. their polluted waste water. “As a result, these companies unintentionally ex - posed themselves to the risk of flood - ing,” concludes Daniel Bonomi.

Registration of operations at risk The application of the provisions of the ordinance on major accidents (StFV) in relation to stationary plants is basically the responsibility of the cantons. During their inspections of the relevant plants, they must also check whether industrial accidents could be triggered by natural hazards and identify the preventive measures that must be taken by the owners. A national overview of the extent of this problem is still lacking. However, with the ERKAS risk register and the newly established SilvaProtect (see page 39) and Aquaprotect databases, which contain a spatial breakdown of the risks posed by avalanches, landslides and floods, FOEN already has a nation - wide basis for a systematic assessment. This is due to be carried out for the first time in 2007 and is expected to Canton of Ticino provide indications of potential prob - lem cases. Whether a particular indus - trial zone is actually at risk from natur - formations on the crumbling scarp heavy storm on 13 June 2000, the al events, should also be indicated by right at the foot of Alpe di Roscioro Feldbach torrent pushed large volumes the hazard maps to be developed by represent a permanent threat to safety. of water and debris through the vil - the cantons. “If these facts had been In May 2002, following heavy rainfall, lage. The first and second basements of known, some factories probably would around 150,000 cubic metres of rock the factory were flooded by around not have been built in their current lo - plummeted down to the valley. Some 35,000 cubic metres of mud and water, cations,” says Daniel Bonomi. “The of the boulders actually reached the 30- giving rise to CHF 20 million worth of best way to provide protection against metre-high and 120-metre-wide protec - damage. The wastewater treatment major accidents caused by natural haz - tive barrier which was being construct - plant and the chemical store contain - ards is to avoid building potentially ed at the time. The slope is now ing toxic cyanides and heavy metal dangerous plants in areas at risk from permanently monitored by measuring salts were also flooded. “Thanks to a natural hazards.” probes. major operation lasting several days, the emergency services succeeded in Industrial zone under a crumbling crag Lessons learned from damage ensuring that the contaminated water The industrial zone of the municipality The managers from the company did not reach Lake Constance nearby,” of Preonzo, which lies between BERNINA International, which pro - says Bruno Hertzog, who is responsible and in the canton of duces sewing machines in Steckborn in for major accident prevention at the Ticino, is a rather unsafe location the canton of , also learned Thurgau Cantonal Office for the Envi - which would probably not be zoned for some valuable lessons from damage ronment. After this event, the munici - development today. The unstable rock caused by a natural hazard. After a pality of Steckborn optimized its struc - ENVIRONMENT 2/07 NATURAL HAZARDS 47

tural flood protection. The company Visp in the canton of Valais – one of tory of the works – almost all of the affected by the flood also upgraded the Switzerland’s biggest chemical plants – over 2,000 employees were evacuated. protection of its chemical store, radi - the safe operation of the plant is also a Hours beforehand, production process - cally reduced the volumes of haz - matter of concern for the owners of es had been shut down and operation ardous substances stored there and adjacent properties. The company ceased as the cooling water supply was consistently separated substances land, which was built on one hundred no longer guaranteed. If the dike had which react strongly with each other. years ago, is dissected by the Rhone to been flooded or breached, the works “The implementation of such opera - the north and is bordered on the west could have been inundated by up to tional safety measures is primarily in by the Vispa, a tributary from the Saas 2.5 metres of water and the town of industry’s own economic self-interest and Matter valley, which enters the Visp would also have been flooded. because through these measures it can valley river at this location. Several protect itself against expensive damage alarming flood events have occurred Improved flood protection and long breaks in production due to here over the past two decades, i.e. in The implementation of structural natural hazards,” notes Daniel Bono - 1987, 1993 and, most recently, 2000. flood protection on water courses is mi. “At the same time, they also pro - Kurt Gimmel, Director of Emergency basically the task of the state. Thus, vide a service to the population and en - Services at Lonza Visp, recalls 20 Octo - the Rhone dikes upstream and down - vironment as they prevent additional ber 2000 with horror. “Just another 20 stream of the company land were damage through the release of haz - centimetres and the rising Rhone raised and reinforced again in 2001. It ardous substances.” However, at pre - would have breached the dike crest is even planned to equip the nearby sent empirical values are still lacking and flooded the plant.” Fortunately, town of Visp and, hence also, the in - which would enable the assessment of this did not happen because the can - dustrial zone to withstand a one-thou - their extent as compared with the over - ton had raised the dike crest along the sand-year event in the future. Thus, all damage caused by natural hazards. 1.5 kilometres of the company premis - the canton of Valais is planning com - es by 60 centimetres back in 1993. De - prehensive protection measures in the A narrow escape spite this, the situation was so serious vicinity of the Lonza plant. As part of In the case of the Lonza AG works in that – for the first time in the long his - the Third Rhone Correction, from

Flood safety in the vicinity of the Lonza Plant in Visp (left) is being significantly improved by the Third Rhone Correction. The company has already implemented various measures to improve earthquake safety. Thus the blue steel frame protects the spherical tank used to store liquefied gas against heavy seismic shocks.

FOEN/Stefan Hartmann, Zurich 48 ENVIRONMENT 2/07 NATURAL HAZARDS

2008, the dikes will be reinforced again metres, the alarm is raised in accor - proofed. For example, the columns and the flow capacity of the river in - dance with the new protection con - supporting a spherical tank containing creased through the deepening of its cept. If the water level rises by a fur - liquid gas were reinforced with a steel bed. The channel will be widened to ther 20 centimetres, production is frame and the 26 concrete columns of the east and west of the company completely shut down and the plant the spherical ammonia tank have now premises and the confluence of the secured, an operation which takes been fitted with special hard rubber Vispa with the Rhone will also be sig - around eleven hours to complete. This buffers and a concrete slab so that they nificantly widened. As opposed to this, task includes, for example, the secur - are better able to withstand seismic it will not be possible to widen the ing of storage tanks and vats to pre - waves. Rhone river bed in the direct vicinity vent them from floating and breaking of the company premises as the plants free. Mobile objects such as tank wag - Stefan Hartmann, Beat Jordi on both sides of the river practically ons containing chemicals are removed border on the existing dikes. in good time and containers of sub - stances that are hazardous to water are Company flood protection concept moved to higher storage locations. LINKS Because all structural protection mea - Evacuation of the plant personnel www.bafu.admin.ch > Themen > Stoerfallvorsorge sures have their limits, companies also would begin two hours before a threat - ( German and French) need to implement technical and orga - ened flood. www.vs.ch/rhone.vs ( German and French) nizational measures to mitigate dam - www.kgvonline.ch ( German and French) age if affected by a natural hazard. Structural protection measures Lonza AG has a permanently manned As part of the risk analysis carried out INFO alarm centre for this purpose which in 1993, Lonza AG also assessed the constantly monitors the Rhone water company’s earthquake risk. It emerged Daniel Bonomi level, the weather situation in the wa - from this analysis, that some chemical Prevention of Major Accidents tershed area of its tributaries and the plants from the 1970 and 1980s did and Earthquake Mitigation run-off from hydroelectric power sta - not fulfil the applicable earthquake Section, FOEN tions in the tributary valleys. If the wa - safety requirements. Thus, vulnerable Tel. + 41 (0) 31 322 93 98 ter in the Rhone reaches a level of 2.6 areas of the plant were earthquake- [email protected]

The cooling water from the Rhone is crucial for the Lonza plant in Visp. During flooding, the supply of the plants is no longer guaranteed due to the debris. In extreme cases, Kurt Gimmel, Director of the company’s emergency services, must order the suspension of production.

Stefan Hartmann, Zurich ENVIRONMENT 2/07 NATURAL HAZARDS 49

www.bafu.admin.ch/naturgefahren (mainly D, F, I) www.meteoswiss.ch > danger Protection against natural hazards Weather warnings As a federal authority, FOEN’s mission is to protect the Swiss MeteoSwiss, the Swiss meteorological service, has deve- population and important material assets on the basis of uni - loped a modern multi-level storm warning system in collabo - form nation-wide safety standards. FOEN is responsible for ration with the cantonal civil protection authorities and the protection against the entire range of climatic, geological National Emergency Operations Centre (NEOC). The website and technical hazards. The careful maintenance of water provides direct information in the form of maps on the risks courses and protection forests constitutes a key element of posed by storms, heavy rainfall, heavy snowfall and forest FOEN’s safety strategy. fire. www.planat.ch (E, D, F, I) www.naz.ch > English > Themes > Natural hazards National Platform for Natural Hazards (PLANAT) Alerting the population The extra-parliamentary commission PLANAT was commis - The National Emergency Operations Centre (NEOC) is the sioned by the Swiss government to develop a strategy to im - Swiss federal centre of expertise for exceptional emergency prove protection against natural hazards throughout Switzer - events. Its core tasks include the issuing of early warnings and land through optimized risk management. Its website alerts in the event of suspected or increased radioactivity, presents the results of its work and also acts as an informa - chemical accidents and dam ruptures. It also redoubles its ef - tion platform and central point of contact. It provides docu - forts in these areas to protect the population and livelihoods mentation, images, contact and internet information on the in the event of a natural disaster. entire topic of natural hazards. www.praeventionsstiftung.ch > En www.wsl.ch > en > Research > Projects > Natural Hazards Providing better protection for buildings Centre of excellence in research In recent years, storms, hail and floods were responsible for 95 The Swiss Federal Institute for Forest, Snow and Landscape percent of the damage caused to buildings in Switzerland and Research carries out basic research and supervises a large covered by insurance. The Cantonal Public Building Insurance number of applied projects in the area of natural hazards. Its Companies’ KGV Prevention Foundation would like to reverse key focus areas include mountain hydrology and torrents, this trend for increasing damages in the long term and, thus, snow and permafrost, avalanches, landslides and rock fall, promotes buildings-related risk management. and hazard alerting and prevention. Current avalanche warn - www.swissre.com > Research & Publications ings can be found at www.slf.ch. > Top topics view > Natural catastrophes www.seismo.ethz.ch (E, D, F) Natural hazards throughout the world Seismological Service As a globally active reinsurer, Swiss Re is particularly affected The website of the Swiss Seismological Service provides infor - by the increasing damages being paid as a result of natural mation on the risk of earthquakes in Switzerland. The earth - disasters. The company’s detailed analyses provide a sound in - quake hazard map shows that the canton of Valais and the troduction to the global problem of natural disasters. Basle region are particularly vulnerable to earthquakes. The www.unisdr.org seismological events recorded in the Earthquake Lists go back to the 13th century. International Strategy for Disaster Reduction The International Strategy for Disaster Reduction ISDR aims www.katarisk.ch (E, D, F, I) at building disaster resilient communities by promoting Risk assessment increased awareness of the importance of disaster reduction In terms of civil protection, the military threat to Switzerland as an integral component of sustainable development. has been eclipsed by the risks posed by natural disasters and societal emergencies. The Katarisk project analyses and eval - uates these risks using a standardized method. The website also provides information (in German, French and Italian) on practical risk management. Natural Hazards online 50 ENVIRONMENT 2/07 NATURAL HAZARDS

INTERNATIONAL COOPERATION Worldwide exchange of experience

The natural hazard protection concepts developed in Switzerland attract interest beyond the country’s borders. Thus, the expertise developed in Switzerland is used in the context of bilateral cooperation with various other countries. Switzerland also benefits from this international exchange of experience.

The United Nations International va, also deals with the development eas where possible can also be imple - Strategy for Disaster Reduction (ISDR) and implementation of strategies for mented in developing and emerging aims to contribute to the building of the prevention of natural disasters. nations at a relatively low cost,“ ex - disaster-resilient communities by pro - The WMO focuses on early warning plains Hans Peter Willi, Head of moting increased awareness of the systems in this context. Thus, for ex - FOEN’s Hazard Prevention Division. importance of disaster reduction as an ample, its Hydrology and Water Re - The selected approaches are also suit - integral component of sustainable de - sources Programme (HWRP) promotes ed, however, to industrial countries, as velopment. To this end, 168 states the assessment of flood risk and fore - demonstrated by their application in adopted the Hyogo Framework for Ac - casting through expert consultation the German federal state of Saxony tion at the international conference in and cooperation projects. The aim of and in the Czech Republic. Kobe, Japan in January 2005. The Swiss the Associated Programme on Flood The European Union’s new Floods Agency for Development and Coopera - Management (APFM), which is also a Directive will oblige all Member States tion (SDC) promotes the implementa - WMO initiative, is the implementa - to produce flood hazard maps for high tion of the Hyogo Framework in vari - tion of flood management based on risk areas. Together with France, Swit- ous countries. It also supports the ISDR the Integrated Water Resources Man - zerland is joint director of the Euro - secretariat in Geneva. Switzerland is agement approach. The WMO works pean Exchange Circle on Flood Map - also involved in various other interna - closely with Switzerland in this area ping (EXCIMAP), the aim of which is tional and regional organizations, for and the planned initiatives include a to formulate a recommendation incor - example it acts as an Advisor Country pilot project in Mexico. porating good-practice methods for to the Asian Disaster Reduction Centre high-quality hazard maps. (ADRC) whose headquarters are in Promotion of hazard maps Kobe. The latter aims to facilitate the As part of its bilateral international de - Bilateral contact with Asia exchange of information and experi - velopment work, SDC supports pro - Switzerland has been involved in a ence between experts and institutions jects for protection against natural technical exchange of experience in in all member countries, to provide in - hazards in several countries. The con - the area of flood protection with Japan formation on disaster prevention and cepts developed in Switzerland provide for 20 years. Another bilateral coopera - to promote international cooperation. a valuable complement to the infor - tion relationship was recently estab - The World Bank and regional develop - mation and experience available local - lished with the Chinese Ministry for ment banks are also becoming increas - ly. For example, hazard maps, which Water Resources which is interested in ingly active in the area of disaster re - show natural hazards such as floods adapting the Swiss Federal Law on Hy - duction and Switzerland supports the and landslides in selected areas have draulic Engineering for the People’s corresponding endeavours. been produced in various countries, Republic of China. The dynamic con - for example the Latin American states tact between the two countries also Cooperation with the WMO of Nicaragua and Ecuador. “Our strat- gave rise, inter alia, to a project for im - The World Meteorological Organiza - egy of identifying areas at serious risk proving flood forecasting and alerting tion (WMO), which is a specialized from natural hazards in good time and on the Yangtze, for which Switzerland agency of the UN and based in Gene - of avoiding their use as settlement ar - provided crucial support. ENVIRONMENT 2/07 NATURAL HAZARDS 51

Publication details 2/2007, June 2007

The FOEN publication UMWELT, on which this special English-language edition is based, appears quarterly in German and French; subscriptions are available free of charge. ISSN 1424-7186.

Published by: Federal Office for the Environment (FOEN). FOEN is the federal government’s centre of environmental expertise and is part of the Federal Department of the Environment, Transport, Energy and Communication (DETEC)

General project management: Bruno Oberle, Andreas Stuber

Keystone/EPA Concept, editing, production, marketing: Georg Ledergerber (project manager/ managing As seen here on the Rio Bilampi in Nicaragua, settlements and human life are at risk editor), Flavia Castelberg (deputy managing editor), from flooding in many developing countries. Hazard maps, which register the risk Simone Hunziker, Hans Peter Willi (keynote); Hansjakob Baumgartner, Cornélia Mühlberger de posed by such natural hazards, are being compiled in various regions with the help Preux; Beat Jordi (coordination of keynote and of Switzerland. English-language edition)

External collaborators: Exchange of experience tions and authorities in the Alpine re - Urs Fitze, Stefan Hartmann, Kaspar Meuli, Lucienne Rey in the Alpine region gion as well as Japan and Taiwan. It The Platform for Natural Hazards of aims, in particular, to promote inter - English translation: Susan Cox the Alpine Convention (PLANALP) in - disciplinary research on the protection English content editor: Markus Zimmermann volves representatives from all of the of living space against floods, avalan- Production and layout: Alpine countries, the European Union ches, landslides and other mass move - Atelier Ruth Schürmann, Lucerne and various NGOs. The aim of ments. To this end, Interpraevent analy - Editorial deadline: 30 April 2007 PLANALP, which was established in ses th e causes of natural disasters and 2004 and is chaired by Andreas Götz, derives preventive, damage-limiting Editor’s contact details: FOEN, Communication, Vice Director of FOEN, is the develop - protective measures from the informa - Redaktion UMWELT, CH-3003 Bern, Tel. +41 (0)31 322 93 56, Fax +41 (0)31 322 70 54 ment and implementation of hazard tion obtained and develops the re - e-mail: [email protected] prevention and adaptation strategies search findings with a view to their Internet: The editorial content of the magazine is throughout the Alpine region, for ex - practical implementation. available on the FOEN website at: ample through the creation of expert www.environment-switzerland.ch networks on the level of research and Beat Jordi Subscriptions, changes of address and administrative bodies. The platform is ordering of back issues: intended to promote the cross-border UMWELT, Postfach, CH-4501 Solothurn, Tel. 031 324 77 00, Fax 032 624 75 08, exchange of experience, improve early LINKS [email protected] warning systems and firmly establish www.unisdr.org integrated risk management through - Paper: Cyclus Print, 100% recycled paper from www.adrc.or.jp sorted printers’ offcuts and office waste out the Alpine region. The Swiss mountain forest maintenance group, www.worldbank.org > Topics > Urban Development Circulation of special English-language issue: > Hazard Risk Management 6,000 copies Schweizerische Gebirgswaldpflege - gruppe (GWG), which was established www.deza.ch > English > Search: natural hazard Printer: Vogt-Schild Druck AG, Derendingen in 1981 with international involve - www.apfm.info Copyright: ment, pursues similar objectives in the www.cepri.fr > English version Reprints permitted with citation of source and area of protection forest management. copy to the Editors www.planat.ch > E > Services > Publications > The promotion of international Flood Risk Reduction in China Note networking is also the aim of the Inter - The UMWELT magazine is conceived as a forum for www.planat.ch > E > PLANAT > PLANALP praevent research society, which was the discussion of conservation and environmental www.iksr.org > Floods protection issues. For this reason, some of the founded in 1968. The society unites views expressed may not necessarily coincide with natural hazard experts from organiza - www.interpraevent.at the position of FOEN.