Flood Control at Rivers and StreamsWegleitungen des BWG Directives de lOFEG Direttive dellUFAEG Guidelines of the FOWGBerne, 2001

1In cooperation with:Federal Office for Spatial DevelopmentSwiss Agency for the Environment, Forests and LandscapeFederal Office of Agriculture

Flood Control at Rivers and Streams

Obtainable from: SFBOL, Distribution of Publications, CH-3003 Berne, www.bundespublikationen.chOrder number: 804.801.eng

Wegleitungen des BWG Directives de lOFEG Direttive dellUFAEG Guidelines of the FOWGBerne, 2001

Eidgenssisches Departement fr Umwelt, Verkehr,Energie und KommunikationDpartement fdral de lenvironnement, des transports,de lnergie et de la communicationDipartimento federale dellambiente, dei trasporti,dellenergia e delle comunicazioniFederal Department of Environment, Transport, Energyand Communication

2RDB;

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EditorFederal Office for Water and Geology FOWGLndtestrasse 20PostfachCH-2501 Biel

Editing CommitteeHans Peter Willi (FOWG)Jean-Pierre Jordan (FOWG)Ulrich Roth (Sigmaplan AG; Berne)Bernhard Frei (Advokaturbro Keller, Mesmer,Frei, Degiorgi; Berne)

TranslationLyn Shepard, FilisurMartin Jaeggi, Ebmatingen

Conception and RealizationFelix Frank, Berne

QuotationFederal Office for Water and Geology:Flood Control at Rivers and Streams.Guidelines of the FOWG, 2001 (72p.)

FOWG, Biel 2002

12.02 1000 84293

3Contents

Strategy Where Do We Stand? 7 What Do We Want? 8 Principles for Flood Protection 9 How Can These Demands Be Fulfilled? 10

Action Recognizing the Need for Action 13 Ascertaining the Hazard Situation and Damage Potential 14 Assessing the State of a River or Stream 15 Setting Protection Objectives 16 Determining the Necessary River Space 18 Defining the Need for Action 20

Procedure Responsibilities 23 Legal Standards 24 Framework Conditions 26 Federal Subsidies 27 Regular Procedure 28 Accelerated Procedure 30 Participation 32 Overcoming Conflict 33

Project Design The Sequence of Project Design Work 35 Conditions in the Catchment 36 Uncertainties of Basic Data 38 Hydraulic-Engineering Conditions 40 Types of Hazard and Influencing Factors 42 Assessing Hazards 44 Graphical Presentation of Hazards 46

Measures Order of Priorities 49 Appropriate Maintenance 50 Forestry Aspects 52 Alluvial Zones 53 Land-Use Planning Measures 54 Off-Limits Zones 56 Object Protection 57 Protective Structures 58 Construction Methods 60 Emergency Planning 62 Emergency Organization 63

Appendix Glossary 65 Checklists 68 Contact 72

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The first edition of the guidelinesFlood Control at Rivers and Streamswas edited in 1982. Since then the le-gal and professional framework haschanged considerably. However, al-ready then the federal counsellor LeonSchlumpf wrote in the preface, thatfor interventions made for flood con-trol reasons more attention has to begiven the other functions of a river orstream. With their varied riparianvegetation they subdivide landscapeand enhance its value. They offer habi-tats for animals and plants and theirnatural value makes them an idealplace for relaxation.

5Editorial

The disastrous floods of the year 1987 remain not only in the memoryof those immediately hit by the events. For a new way of flood riskassessment as well, the year 1987 has become a milestone: the analysisof the causes of those events led to considerable new knowledge whichin the meantime had a strong influence on the related legal bases.

The strategy of the Federal Department ofEnvironment, Transport, Energy and Com-munication is governed by the principle ofsustainability. This results in the follow-ing objectives: to protect and maintain the naturalconditions and natural resourcebases for social well-being (ecologicalsustainability); to provide up-to-date services in trans-port, energy, water resources, postalservice, telecommunications, and elec-tronic media that benefit the populationand the economy in such a way that thefinancial burden on the state and theeconomy is acceptable (economic sus-tainability); to ensure access to the natural resourcebase and to public services for the entirepopulation and all parts of the country un-der equitable conditions and to protectpeople from hazards and health risks(social sustainability).

BasicsFlood protection plays a major role in sus-tainable development. Appropriate floodprotection has been and continues to be abasic condition for a prosperous society. Intheir efforts to fulfil the common task offlood protection, the cantons and munici-palities receive financial support from thefederal government through the federallaw on flood protection policy, datingfrom 1877.The recent Federal Law on Flood Con-trol (Wasserbaugesetz, WBG, 1991) pro-vides a new basis for hazard assessment,differentiation of protection objectives, ad-equate planning of measures, and limita-tion of remaining risks (emergency plan-

ning). The respective Ordinance onFlood Control (Wasserbauverordnung,WBV), revised in 1999, regulates thesegeneral considerations.

Increased demandsIn recent decades, stream and river train-ing have contributed much to the generaleconomic development of many areas inSwitzerland. Only in recent years has floodprotection policy been updated. The 1987flood disasters in particular proved thatthere is no absolute safety from floods.These disasters triggered a complete re-view of flood protection policy, whichconcluded that a sustainable policy re-quires land-use practices that take accountof existing natural hazards and minimizedirect impacts on rivers and streams.This is possible only when sufficient con-sideration is given to the multitude offunctions fulfilled by rivers and streams.Reduction of damage following extremeevents presupposes that these events betackled in detail. The results have to beconsidered in emergency planning proce-dures as well as in structural and land-useplanning.Therefore, a modern flood protectionpolicy will not only take account of safetyaspects but consider other aspects of sus-tainable development as well. Environ-mental concerns and economic factorsmust be included in the planning processas early as possible.The present manual is designed to con-tribute to the solution of complex tasks inthis context. It was developed in a waythat should allow the principles involvedto remain valid for a long period of time.We hope that it will meet the expectations

of all present and future readers. No stan-dard solutions are presented, however. Onthe contrary, this manual is intended tohelp the authorities, associations and hy-draulic experts concerned with flood pro-tection schemes to ask the right ques-tions.Landowners and insurance companies areaddressed as well; they can also contrib-ute much to reducing damage potential.This should make it possible to approachflood protection in a way that satisfies allthe parties concerned.

Christian FurrerDirector of the Federal Officefor Water and Geology FOWG*

*Former Federal Office for Water Management

Strategy

7UFA

EGF

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G

Where Do We Stand?

Legal standards

hazard assessment, differentiation of pro-tection objectives, adequate planning ofmeasures, and limitation of remaining risk(emergency planning).The Ordinance on Flood Control(Wasserbauverordnung, WBV) representsan additional cornerstone. It came into ef-fect in 1994 and was revised in 1999. Inaccordance with these laws, the cantonsdelineate hazard zones and the necessaryspace to be allocated to rivers and streamsfor flood control reasons, but also in orderthat they can fulfil their ecological func-tions. This means that the areas in ques-tion must be included in structural andland-use planning and be considered in allland-use activities.

Loss of diversityThere are other deficiencies besides thesesafety aspects. In the past, the space allo-cated to rivers was limited to a narrowchannel. From an ecological point of view,such rivers are deficient and can no longerfulfil various functions for the followingreasons: Geometrically lined channels are mo-notonous landscape elements. Intense land use up to the border of ariver or stream does not leave enoughspace for natural dynamic changes tohappen.

A new orientationThese problems have been recognized andhave led to a conceptual reorientation offlood protection. The 1987 flood eventsand subsequent analysis of theircauses provided a decisive impulse for abasic reconsideration of flood protectionand development of new strategies.Safety for everyone and everything is notpossible. This is not only a question of lim-ited financial resources owing to budgetconstraints in the public sector. The valueof the goods at risk has also increasedenormously. Therefore, defence againsthazards is no longer the only issue. Whatparticular risks are accepted or may be ex-pected to be accepted also needs to be dis-cussed: What might happen, and wheremight it happen?

The legal frameworkAll of the above findings have had legalconsequences. The new Federal Law onFlood Control (Wasserbaugesetz, WBG)came into effect on January 1, 1993. It pro-vides a strategic basis for comprehensive

Numerous river training projects in Swit-zerland, including additional construc-tions, have considerably improved floodsafety and contributed extensively to theeconomic development of large areas infloodplains.Despite the efforts of many decades andlarge investments, there is no absolutelyfull protection against floods. This wasdefinitely proven by the major flood disas-ters of 1987, 1993, 1999 and 2000. In ad-dition, all the minor floods of recent yearshave indicated again and again that struc-tural measures have a limited effect onexceptional natural events.

The need for concrete actionReducing the impacts of floods on socio-economic life will require major efforts infuture if the amount of economic damageis to be held in check. In particular,damage potential should be reduced.There are numerous reasons for rapid ac-tion: Economic development frequently takesplace in hazardous areas, particularly infloodplains. Flood damage is steadily in-creasing in these areas. Flow is accelerated in canalized riversand streams. The peak discharge increasesin the downstream reaches. In general, there are not enough deten-tion areas available for incoming waterduring extreme events. The maintenance of river channels is of-ten neglected. Thus, hazardous conditionsmay suddenly change and new areasmight be threatened. The risk of hazards could generally in-tensify in coming decades due to externalinfluences (e.g. global climate change).

Hazard: Condition or process from which danger canarise for human beings, the environment, and/or property.

Risk: Size and probability of potential damage.

Residual or remaining risk: Risks that remain aftercompleting all foreseen protective steps.

Streams and rivers not only cause floods.During an average 340 flood-free daysper year they fulfil other functions that shouldalso be considered in flood protection.

8Fran

k

Strategy

Action

Procedure

Project Design

Measures

Appendix

What Do We Want?

Recommended reading

FOWG (flyer, 1995): Demands on FloodProtection

BWG (flyer, 2000): Raum den Fliessgews-sern! [Space for Rivers!]

Up-to-date flood protection is not limitedto complete and maintain existing rivertraining works. On the contrary, major ef-forts have to be made to include flood pro-tection aspects in the planning and co-ordination of all land-use activities.This includes the legitimate demands of allconcerned partners and of activities suchas water quality control, fishery, forestry,agriculture, protection of landscapes, wa-ter supply, and hydropower generation.Flood protection today is facing numerousdemands that reflect conflicts of interest.In order to devise good solutions, floodprotection must fulfil a number of require-ments: Living space and the economic en-vironment must be adequately pro-tected. Further economic damage must be lim-ited by means of a comprehensive pre-vention strategy. Handling of uncertainties needs to beimproved and included in flood protectionconcepts. Rivers and streams have to be regardedand respected as an essential link elementin nature and the landscape.

Continuous processThe federal law and the federal ordinanceon flood control clearly emphasize theserequirements. Only a minimum of floodprotection activities is allowed along riv-ers and streams. Flood prevention hasa high priority. Despite preventive meas-ures, functional emergency planningand emergency organization are indis-pensable.On this basis a number of flood protectionprinciples can be formulated (see p. 9).Sustainable flood protection can only beachieved if these principles are put intopractice. Consequently, the will to col-laborate and achieve consensus among allparticipants in this process is indispens-able.In addition, federal policies pertaining toflood protection, water quality control,conservation of nature and landscape,fishery, forestry, hydropower generation,etc., are in a process aimed at better co-ordination.Step-by-step revision of the respectivelaws has a common aim that can besummarized under the heading ofsustainability: Impacts on nature andlandscape must not endanger living con-ditions for future generations.

Requirements

Residential and commercial spaceshould be protected properly.

Comprehensive preventionshould allow costs of damagenot to continue to increase.

Handling natural dangers shouldbe improved and consideredin flood protection concepts.

Rivers and streams should berespected as vital and integratedparts of nature and the landscape.

9Principles for Flood Protection

Flood

Crisismanagement

State of ariver channel

Catchment

Damagepotential

Meteorology

DamageVulnerability

Danger

Event

Two main strategies must be pursued to prevent an exponential increaseof flood damage in the near future: (i) priority should be given to land-useplanning in order to reduce vulnerability and damage potential, and (ii)emergency planning to reduce flood damages should also be undertaken.

Analyse the hazards. Comprehensive knowledge of hydrological and hydraulic conditions and prevailing hazards withinrivers is necessary if protection requirements are to be properly evaluated. Existing hazards and conflicts can be understood bydocumenting flood events, by making complete event inventories, and by establishing hazard-index maps. The hazard situationshould be updated regularly. The existing hazards are to be considered in structural and land-use planning.

Assess and eliminate ecological deficiencies. Sustainable flood protection supports abundant riparian vegetation andprovides ample space for the development of natural diversity in the aquatic, amphibian, and terrestrial ecosystems. It pro-vides links between habitats.

Differentiate the protection objectives. Flood protection concepts are based on a clear differentiation amongobjectives. Areas and objects of high value require a greater degree of protection than those of lower value. According to thissimple rule, agricultural land and individual buildings require less protection than towns, industrial plants, or infrastructure.Furthermore, no specific protection may be necessary for low-intensity agricultural areas. However, assessment of possibledamage may result in different weightings. Thus, the measures taken have to be evaluated and judged according to theirappropriateness.

Retain where possible, let pass where necessary. In order to dampen flood peaks, flood discharge should be retardedwithin detention areas wherever possible. Therefore, natural detention areas should not only be maintained but also re-estab-lished wherever appropriate. Flood waves should only be allowed to be passed downstream without dampening where thelocal situation requires it, e.g. in narrow settlements. Flood corridors should be established there or kept free in order to pro-vide enough space for extreme events.

Minimize impact. Cross sections with sufficient flow capacity are a basic condition for securing flood protection, to keep thesediment regime in equilibrium, and to guarantee drainage of an area. Nevertheless, flood safety should be provided withminimum impact on natural habitats.

Check possible failure points. Natural uncertainties have to be considered carefully. In consequence, the safety of protec-tion structures needs to be adapted and optimized. Moreover, their functioning and structural safety need to be checked foroverstress during extreme events. Possible failure points might be recognized and eliminated in time through periodic checksof the fitness and usefulness of existing structures.

Guarantee maintenance. Appropriate maintenance of river and stream channels is a permanent task. It ensures mainte-nance of the substance of existing protection structures and of corresponding discharge capacity.

Secure the necessary space of a river. A stream must be more than a simple gutter and a river more than a canal. Landuse in their vicinity requires respect of sufficient distance. The cantons are obliged to determine the necessary space for rivers,to establish it within the structural or land-use plan, and to consider it for all activities affecting land use.

Respect needs. For many people streams and rivers serve as recreational areas for leisure or relaxation. These demands haveto be considered along with demand for sustainable use of water resources, particularly for hydropower generation.

10

http://www.bwg.admin.ch

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How Can These Demands Be Fulfilled?

Area of sustainability

Environmental aspects:protecting nature and the environment

Social aspects:protecting the public

Economic aspects:ecological and economic proportionality

* This procedure corresponds to the VSEGuideline (2000): Der regionale Entwsserungs-plan REP [The Regional Drainage Plan REP].

Every flood protection project is biased ac-cording to conditions determined by (i)the prevailing natural hazards, (ii) existingor projected land use, and (iii) the hydrau-lic and ecological conditions of the river inquestion. On the other hand, the federallaw on flood protection determines prior-ity among respective measures. Sustain-able measures have a clear priority: Flood protection is to be guaranteedthrough proper maintenance of theriver or stream channel. This also includesthe maintenance of forests with a protec-tive function throughout the entire catch-ment. Land-use planning measures topreserve open space along rivers and pre-vent uncontrollable increase of damagepotential on floodplains have the same pri-ority as maintenance of river channels. Ur-ban development that considers existingnatural hazards is a better form of preven-tion than expensive protection works toprotect thoughtlessly delineated buildingzones. Structural measures are only to beconsidered when maintenance work andplanning measures cannot provide thenecessary safety. Determination of priorities requires con-sideration of other measures such asflood-proofing of buildings and otherexisting structures.

Guiding principlesfor flood protectionThe particular need for concrete actionmust be determined with the cooperationof all parties concerned, based on a pre-determined framework. This is only possi-ble when (i) knowledge of the prevailinghazards is available, (ii) the hazards areproperly assessed, (iii) the various interestsare coordinated, (iv) the relevant laws arefollowed, and (v) the priorities are set: Holistic planning is necessary for ten-able solutions. The result is a package ofmeasures that considers all types of natu-ral hazards and incorporates all land-useactivities. These measures have to beadapted to existing development plans.* The current state of the river or streammust be preserved through maintenanceworks and land-use planning, providedthat the degree of safety is sufficientfrom the point of view of flood protectionand ecological conditions are acceptable. A plan for measures to be undertakenhas to be established if deficiencies arerevealed by a safety assessment. Measureshave to be adapted to local conditions. Inthe process, flood safety as well as ecologi-cal deficiencies must be taken into ac-count. These are of equal importance inguaranteeing appropriate flood safety andmaintaining the ecological functions of theriver or stream. Flood protection is no longer just limitedto the prevention of overbank flooding andinundation by any means. Streams and riv-ers are ecosystems that host a variety ofanimals and plants, as well as excellentrecreational sites. Therefore, up-to-dateflood protection needs to show considera-tion for the numerous functions of the

river or stream and must try to preserveand strengthen them wherever possible. Every flood prevention concept has to beassessed in terms of technical, economicand ecological balance. If a particularproject is disproportionate in this respect,then land-use or protection objectiveshave to be reconsidered. A detailed project must be estab-lished if the measures are deemed propor-tionate. Residual risks always remain. These re-sidual risks must therefore be assessedand the planned measures supplementedby emergency planning and relatedemergency organization (includingwarning concepts and evacuation plans).The efficacy of the measures in place needsto be examined in case of overstress dur-ing extreme events. This integral examina-tion leads to living being conscious of pos-sible hazards in the sense of a global riskculture.

Strategy

Action

Procedure

Project Design

Measures

Appendix

11

Hazardoussituation

Use(existing

or planned)

Rivercondition

Emergency planning and emergency organization

Measures implemented

Measures are proportionatePreserving

actual status

Propermaintenance

Land-use planning steps

Preservingactual status

Cultivation

Land-use planning steps

Setecological

goals

Determineprotection goal

Deg

ree

of

pro

tect

ion

su

ffic

ien

t

Go

als

ach

ieve

d

Goals unfulfilled

Planning of measures

Cultivation steps

Land-use planning steps

Restoring nature

Planning of measures

Proper maintenance

Protective forestcultivation

Land-use planning steps

Protective structures

Protection deficit present

Residual risk

Measures aredisproportionate

Assessmentof steps taken

Determineusage goal

Action

13

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Recognizing the Need for ActionWeighing interests

Many risks are obvious, but others can hardlybe recognized without precise examination.Flood risk particularly falls into oblivion afterlong periods without threatening events.

Determining the need for action depends on the following points:

Ascertaining the risk situation and damage potential.

Assessing the state of a river.

Setting protection objectives.

Determining the necessary space for rivers and streams.

Setting ecological development goals.

Confirming existing or planned land use.

Flood control and ecological concerns arenot in conflict, but are equal priorities inany flood control plan.

The need for action from a floodcontrol standpointFrom a flood control standpoint, a hazardassessment must be made before as-sessing the need for action. One may rec-ognize possible protection deficits byweighing the risk situation against the ex-isting or planned land use.If a deficit exists, the next step is to ascer-tain the degree of potential damage. If theexisting risk is great, the protection deficitmust be offset by plans of measures.If no deficit exists, maintenance workshave to be ensured. Suitable areas shouldbe examined if they can be safeguarded aspotential flood detention areas orfloodways.

The need for action from an en-vironmental standpointFrom an environmental standpoint, thestream or river reach in question must bechecked for ecological viability, andthe ecological development goals must beset in order to assess the need for action.Rivers and streams have multiple func-tions. They are not only habitats for localfauna and flora but also network corri-dors. Therefore, the situation at the upperand lower reaches must also be consid-ered.Monotonous, heavily trained river chan-nels do not fulfill these functions (or onlyin a limited sense). Hence, maintenance orrestoration of conditions close tonatural also belongs to the flood controltasks: rivers should become evident as

landscape-forming elements, and a watercycle close to natural should be main-tained as much as possible. Moreover,greater attention should be given to thepopulations recreation needs.

The key role of farmingWhen weighing the interests of land-usedemands and environmental concerns,farming plays a key role. This is becauseecological compensation measures de-manded for infrastructure projects oftenuse up agricultural areas. Yet solutions canstill be found that serve both farming and

flood protection. Thus, farmers affectedmust be involved in planning from the out-set. They may take over maintenanceworks on the river in question, getting ap-propriate remuneration.In addition, financial incentives rewardnearly natural use of areas adjoining wa-terways. Ecological compensation areasare taken into account for a performanceassessment, and areas of low intensityfarming adjoining rivers are priority areasfor which bonus payments may be re-ceived in keeping with the Eco-Quality De-cree (EQD).

14

9000

8000

7000

6000

5000

4000

3000

2000

1000

0

72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00

1800

1600

1400

1200

1000

800

600

400

200

0

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Ascertaining the Hazard Situationand Damage Potential

Dam

ages

per

yea

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Tota

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amag

es

Values in millions of Swiss francs (adjusted to include inflation)Strategy

Action

Procedure

Project Design

Measures

Appendix

Flood and sediment disasterdamage in Switzerland since 1972.

The major events of 1978, 1987,1993, 1999, and 2000 are crucial.

The effects of a flood in a specific area arebasically determined by three factors: by the processes occurring, by their intensity, and by their duration.Therefore, the degree of potential damagein a defined area is not a fixed amount butdepends on a series of assumptions whichoften cannot easily be verified.Wrong hypotheses obviously lead to mis-judgments. Hence, a variety of sce-narios have to be elaborated that are jus-tified by the broad spectrum of potentialflood processes. Only in this way is it pos-sible to obtain usable results that allowobjective and comprehensive cost/ben-efit ratio comparisons. All those involved technical experts, design engineers, andrepresentatives of municipalities, the can-tons and the federal government shoulddebate those scenarios and agree on them.The hazard situation ascertained in thismanner enables assessment of a floodspotential consequences i.e., the numberof people at risk, the amount of mate-rial damage, the degree of collateraldamage (interrupted production, productsubstitutions), and the degree of environ-mental damage.

VulnerabilityWater penetrates into buildings mainlythrough entrances, cellar openings, or ga-rage doors. Therefore, building vulnerabil-ity to damage depends largely on the el-evation of these potential weak pointscompared to the level of the surroundingterrain. The sealing of the external surfacesof a building, the supply equipment andelevator facilities are also potential weakpoints.

Ascertaining damageA rough assessment of potential damagesuffices generally. Basic data are particu-larly available in the case of material dam-age. It is often very difficult to assignmoney values for other categories. Usuallydamages for specific land-use categoriesare ascertained in costs per area unit.However, sensitive individual objects mustbe given special attention.

Special risksSpecial risks include chemical and biologi-cal production plants, storage sites, rub-bish incineration plants, dumps, switchingcenters, and production plants housingmachinery of above-average cost. Specialprecautions are also necessary in case ofdisaster for important infrastructure sitessuch as command centers, hospitals, andemergency shelters.Usually investigations of special risks havealready been undertaken in connectionwith the ordinance on major accidents andmay be used. Otherwise they must be or-dered. Detailed studies are justified only ifthe economic viability of a flood con-trol project becomes the focus of discus-sion.

15

Assessing the State of a River or Stream

Rivers or streams imbedded in culverts present a special problem.Whenever possible, they should be opened and their channeltransformed back into a state close to natural. New culvertsshould only be permitted in compelling cases, and their numberought to be restricted to an absolute minimum.

Recommended reading

BUWAL (Mitteilungen zum GewsserschutzNr. 27): Methoden zur Untersuchung undBeurteilung der Fliessgewsser komor-phologie Stufe F [Methods for Examiningand Assessing Rivers and Streams Ecomor-phology Grade F]

A natural stream and river landscape con-sists of a mosaic of different habitats.Flowing and still water, deep and shallowreaches, as well as periodically and epi-sodically flooded bank areas are foundclose to each other on a narrow space inrivers or streams that have remained natu-ral or have been laid out close to a naturalstate. Hence they provide a large habitatdiversity for plants and animals.Yet these transitional areas betweenwater and land areas that perform mul-tiple functions have disappeared in manyregions due to the pressure of heavy landuse. Therefore, all flood-control projectsmust take seasonal flow variation and va-riety of currents into greater account. Inorder to ascertain the need for action fromthe standpoint of both the ecology andflood control, three factors stand in theforefront: Does the river or stream have a varietyof structures? Have existing migrationobstacles or training works diminished thisstructures variety? How much room does the stream orriver need to fulfill its ecological func-tions? What cross section does the river needto evacuate flood flow?

Ecomorphological assessmentThe need for action concerning a riversnatural functions can be derived froman ecomorphological assessment. Whenplanning flood control measures, this needfor action should be considered in pre-cisely the same way as protection objec-tives for land use.The term ecomorphology covers the en-tirety of structural conditions in and at

the river channel, i.e., both training works(e.g., bank protection, weirs, or bedstabilization structures) as well as the con-dition of nearby surroundings (cultures,land use, vegetation, and river or streamspace).The related assessment can be carried outwith varying degrees of detail. In case of aregional assessment of rivers or streams(the so-called grade F), five main char-acteristics are sampled: average bed width; variation of the free surface width; bed stabilization structures

(and stream migration barriers); bank toe protection works; bank width and bank characteristics.

16

Setting Protection Objectives

Hold it back when you can, let it pass when necessary. The general use of onespecific design flood no longer has any general validity. Instead, the protection objectivesshould focus on specific objects and the damage potential at hand. Yet the 100-yearflood (Q100 ) in settlement areas is now, as in the past, an important reference value.Higher protection should be the aim in case of very high damage values and special risks.

Strategy

Action

Procedure

Project Design

Measures

Appendix

Protection objectives are set differently,depending on the type of hazard thatcould endanger a specific location andwhat form of protection is needed: wherehuman lives or high material damage val-ues may be at stake, the protection ratingis set higher than it may be in areas usedfor farming or forestry. Thus, a few objectsmay be flooded often, others seldom, stillothers as far as possible never.This is a crucial innovation in comparisonto past planning. In the past, flood controlmeasures were often designed for a spe-cific event. Hence, a 100-year event(Q 100) was usually selected. Almost fullprotection was guaranteed for this event.Yet this procedure led to disproportion-ately expensive solutions in many areas.And the effects of an event exceeding thisdesign flood were usually not ascertained.

New planningIn the meantime the following procedurehas proven its value: Defining protectionobjectives should occur in relation to landuse and objects to be protected.This has resulted in a so-called protec-tion objective matrix that forms thebasis of methodology and differentiationin setting protection objectives. Such aprotection objective matrix was firstgraduated by object categories after theflood event in Uri canton of 1987. This ex-ample has also proved itself in other loca-tions.

Differentiation of protectionobjectivesFlood control efforts concentrate on re-ducing and preventing damage. Incase of high material values, the degree of

Main parametersThe protection objective is basically linkedto probability of occurrence, and this ischaracterized by specific parameters. Thequantity parameter used most often is thepeak discharge Q expected for a certainreturn period. The damage limit Qa refers to a dis-charge that should run off without caus-ing damage to objects requiring protec-tion. The hazard limit Qb refers to a dis-charge that, when exceeded, can lead toan uncontrolled flow situation. The secu-rity of objects to be protected is no longerguaranteed. Flood processes for flood dischargeamounting between the damage limit Qaand the hazard limit Qb may cause limiteddamage, but neither objects to be pro-tected nor flood control structures shouldnormally be destroyed. For certain object categories, the designdischarge must be raised from the damagelimit Qa to the hazard limit Qb, if the pro-cess involved induces high danger. In case of differing object categories, thedefinitive protection objective should beascertained by assessing the residual risks.If a project leads to disproportionate costsor impacts, the protection objectives or theland-use practice must normally beadapted. The concerns of other domains af-fected (e.g., farming, protection of natureand the landscape, settlement develop-ment, and energy production) must beconsidered when weighing interests.

protection is set higher than for low val-ues. According to this principle, the protec-tion objective is graduated by the value toprotect, whereby the processes involvedshould be considered. The most importantobject categories are: Closed settlements. They shouldusually be protected against rare events. Industry and trade. The same princi-ples apply for these facilities and installa-tions as for closed settlements. Theyshould usually be protected against rareevents. Infrastructure facilities. Differentia-tion occurs here between installations ofnational, regional, or local importance.The protection objective will be higher orlower, depending on its value, as well asits vulnerability. Cultivated areas. It is better to pro-tect intensively cultivated areas than lowintensity cultivation areas. There is also agreat difference to be made between theprocesses that reduce land fertility andthose that lead to a one-time crop loss inthe worst scenario. Special objects. These must be as-sessed individually, but again, the prin-ciple has to be used that the higher thepotential for damage, the higher the pro-tection goal.

Qa

Qa

Qa

Qb

Qb

Qb

Qb

Qb

Qa

Qa

Fran

kA proposal for a protection objective matrix

Qa Damage limit

Qb Hazard limit

FQ1 Annual flood

FQ100 Flooding occurring only onceevery 100 years (100-year flood)

EFQ Flooding occurring for extremein hydrological and meteorological situations

PMF Probable maximum flood

Nature landscapes

Low-intensityfarming areas

High-intensityfarming areas

Single buildings; localinfrastructure facilities

Infrastructure facilitiesof national importance

Closed settlements;industrial facilities

Special objects;special risks

No design discharge

To be determined case by case

Full protection

Limited protection

No protection

Object categories Q1 Q10 Q20 Q50 Q100 EFQ PMF

Differentiating protection objectivespermits suitable reaction to the flood

hazard based on local danger factors. Thiscuts costs while enabling even extreme

events to be handled. Such a protectionobjective matrix was used for the

first time in Uri canton (after a devastatingflood of the Reuss river in 1987).

Dependence on the processesinvolvedThe protection objective not only dependson how a specific area is used (object cat-egories) but also on the frequency andcharacteristics of floods occurring there.Therefore, important parameters besidepeak flow must always be considered. Incase of bank erosion or debris flow,the protection objectives must be in-creased according to the hazards of thesedangers. Definitive parameters linked tothe various processes can set for the re-lated scenarios: In case of inundation, the main pa-rameter is the volume of water flowing outof the channel and the duration of flood-ing. In case of erosion and deposition,the decisive quantity is not so much thepeak discharge, more the duration of theflood. In case of debris flow, the volume isoften more crucial than the peak dis-charge.

18

Determining the Necessary River Space

Minimum space needed from an ecological standpoint.Minimum space needed from flood protection standpoint.

Bank area Bank areaNaturalchannel bed

Slope1:2

Slope1:2

Maintenancestrip (3m)

Legallypre-

scribeddistance

frombuildings Bank area Bank area

Legallypre-

scribeddistance

frombuildings

Requiredchannel

bed width(hydraulic)

Maintenancestrip (3m)

Qd

Strategy

Action

Procedure

Project Design

Measures

Appendix

Recommended reading

BWG (flyer, 2000): Raum den Fliessgews-sern! [Space for Rivers!]

Any project presents a crucial question:How much space does the stream or riverneed? Basically the minimum necessaryriver space includes the channels bed andthe bank area. The stream or river can re-work this space. It makes itself availablefor flood flow, and it usually remains freeof any kind of use (buildings and facilitiesmay only restrict the minimum river spacein well-justified exceptions). Moreover, theanswer to the question about the neces-sary space can be derived from the follow-ing needs: The flood control standpoint.Given the hydrologic basics and the pro-tection objectives set, a river space tobe secured in the long-term must be de-fined. The corresponding design flood per-mits determining hydraulically the re-quired theoretical bed width whenconsidering local framework conditions.When considering a 1:2 bank slope and amaintenance strip of 3m that ensures ac-cess, the minimum space required can beestimated from the flood control stand-point. The ecological standpoint. Streamsand rivers are not only habitats of a variedflora and fauna native to the location. Theyare also a link in networking the habitats.They form the landscape, they contributeto self-purification of the water, and theyprovide a crucial contribution to regener-ating groundwater. From the ecologicalstandpoint, a simple method of calculation a key curve is available to set theminimal necessary space. It ascertains thewidth of the bank area. This working aid isapplicable for small and medium-sizedstreams that comprise a major part of thewater network.

Minimum necessary spaceThe larger of the two river spaces deter-mined this way is finally definitive. Build-ings and facilities should basically main-tain the legally prescribed distance to theriver space ascertained in this manner.

Other space requirementsWhere leisure activities are expected, rec-reational space complements the spacerequirement of rivers and streams. In rarelyused areas, necessary space can be ex-panded by the meander width of a natu-ral channel. Setting up a buffer zone cor-responding to the meander width makesspace available for dynamic developmentof rivers that are close to nature.

Approach to secure spaceA wide range of planning measures canassure the necessary space for rivers andstreams to secure flood control and eco-logical functions: Acceptance in cantonal guidelinesor action plan (imperative): it maintainsthe primary hydraulic engineering funda-mentals valid in the long run and providesguidelines binding on the authorities. Consider in cantonal or municipalityland-use plans (imperative): defineflowing waterways space by clearly identi-fied parcels and property lines (e.g., by re-lated frontage lines). Consider in a municipality structuresordinance (optional): also define riverspace by clearly identified parcels andproperty lines. Define a municipality planning zone(optional): rapid temporary assurance ofthe required river space to prevent furtherrestrictions.

Acquire land through the publicsector (optional): assures space perma-nently for rivers and streams. Transfer land (optional): relievesproperty owners of disproportionate re-strictions. Resolve through contracts (op-tional): governs management and care ofbank areas as well as compensation forthese ecological services. Legally prescribe distance tobuildings in urban areas (recom-mended): In order to maintain leisurespace in river areas, we recommend thatthe defined river space benefits from theusual legally prescribed distance to build-ings (i.e., from the bank area onwards).

15

10

5

0

0 2 4 6 8 10 12 14 16 18

19

Fran

k (2

); Sc

hub

lin (

1)

Natural channel bed. Corresponds at meanflow to the water level width and serves as thedecisive parameter for calculating the bank areaand meander width.

A natural channel bed indicates a marked varietyin width. If natural comparative stretches aremissing, the following multipliers apply: With limited variety in width

Factor 1,5 With lack of variety in width

Factor 2,0

Natural bed width in meters

Ban

k w

idth

in m

eter

s

Bank width to secureflood protection

and ecological functions

Bank width for ensuring biodiversity

Bank area. The bank area required for river orstream functionality is determined by the keycurve. Depending on the width of the channel bedon both sides of the river, it amounts to a mini-mum of 5 m. This consists of the minimum nu-trient buffer zone that is set at 3m accordingto the material decree. In areas with excessivenutrients input from neighboring farming regions,this buffer zone should be extended.

Leisure space. An additional space of 3m isrecommended globally (e.g., for paths) near set-tlements and on traditional hiking and bikingroutes. Furthermore, enough room must be fore-seen for rest areas and camp grounds.

Meander. In little used areas, a stripe corre-sponding to the meander width of a natural chan-nel can be superimposed on the bank area, and itcan be widened accordingly. Its width amounts tofive or six times the width of the channel bed .

Settlement areas. Even under limited-spaceconditions, flood control and ecological net-working should also be secured to the maximum.

Key curve. The decisive parameter in ascertain-ing the necessary space of a river is the naturalbed width. The bank areas recommended mini-mal width can be derived from this: Even in caseof brooks, it amounts to at least 5m. At a width of15m, a bank strip can function as an independ-ent biotope. In case of smaller streams in parti-cular it makes sense to determine a wider bankarea (hatched green line). This will promote bio-diversity the natural variety of plants and an-imals along the stream.

20

Des

air;

Doc

umen

ta N

atur

a

Defining the Need for Action

Expansion of river space has a positiveimpact in a great variety of areas: It

reduces risks of flood damage. It enablesmore cost-effective solutions for flood

control structures. It protects rivers andstreams from input of undesirable

ingredients and improves water quality. Itcontributes to maintenance of natural

habitats. And it upgrades recreation space.

Strategy

Action

Procedure

Project Design

Measures

Appendix

After a hazard situation has been identi-fied, the damage potential ascertained, thestate of the river assessed, the protectionobjectives set, and the necessary spacedetermined, the decision must be taken onthe degree of planning measures neces-sary. Four individual cases or combinationsof these individual cases can be distin-guished.

Case A:No flood control deficitCurrent use is in harmony with the hazardsituation posed by nature. This fortunatesituation should be secured over the longterm. Therefore, it is necessary to imple-ment it in structure and land-useplanning. The maintenance already guar-anteed should be continued, and the func-tionality of protective structures on hand(and their susceptibility to hazards) shouldbe checked periodically.

Case B:Flood control deficitIf a flood-control deficit is identified,studies within planning corrective mea-sures must determine how to eliminate orreduce it. Possible ecological deficitsshould be considered at the same time.After the measures have been realized, re-maining hazards must be identified. Ahazard map should be compiled for thispurpose to be implemented in structureand land-use planning. Residual risksshould be clarified and should be consid-ered in emergency planning and organiza-tion. Maintenance of protective structuresand of river channels must be secured overthe long term.

Case C:No ecological deficitThere are no land-use conflicts, and theriver is in a condition close to natural. Thisshould be assured in the long term throughstructure and land-use planning. Themaintenance and care already carried outare to be guaranteed and continued.

Case D:Ecological deficitIf ecological deficits are identified, withinplanning of corrective measures must alsobe determined how the situation can beimproved. Flood control concerns mustalso be taken into account. After improve-ment of the situation has occurred, it mustbe secured for the long term. If deficits re-main that cannot be eliminated immedi-ately, the necessary land for it must at leastbe secured in a land-use planningsense.

21

AB

C DNo flooding deficit

recognizable

Flooding deficitpresent

Long-term guarantee

No ecological deficitrecognizable

Ecological deficitpresent

Planning measuresin the environmental sector

Planning measuresin the flood control sector

Planning measuresin the flood control

as well asenvironmental sectors

Need for action

Need for action Need for action

Procedure for planning corrective measures andintegrating ecological demands. A sustainableflood control project basically treats both aspects.

Procedure

23

Keys

tone

The Federal Law on Flood Control (Wasserbaugesetz, WBG)sets the following framework conditions:

the goals of flood control;

the order of priorities in planning and when carrying outflood control measures;

qualitative requirements in case of unavoidable interven-tions in the river space and maintenance.

Responsibilities

All flood control measures but especiallyplanning and construction measures lead tocomplex decision-making processes in whicha number of standards should be noted.

The federal government has broadsweeping legislative authority in the floodcontrol sector. Yet each canton is respon-sible for related projects. This task isbroad-ranging and includes both riverchannel maintenance and land-useplanning as well as structural measures.The cantons are also responsible foremergency planning and emergency or-ganization.Accordingly, the cantons carry out federalflood control laws and enact regulationsnecessary to implement them. In particu-lar, they regulate inner-cantonal responsi-bilities (task distribution between the can-ton, the districts, and the municipalities)and the applicable procedures for planningand realizing the measures needed.*

Distribution of tasksThe cornerstones of federal law mark outthe material framework that the can-tons fulfill on their own. For its part, thefederal government must provide compen-sation regarding certain flood controlmeasures and may give financial aid forriver restoration (no legal claim). The fed-eral government also promotes training

and continuing education for peopleentrusted with flood control. And it carriesout surveys of interest to all Switzerlandon flood control matters and hydrologicconditions.Furthermore, the responsible Federal Of-fice for Water and Geology (FOWG) pro-vides the basic data and manuals requiredfor suitable and sustainable flood control.It also advises the cantons as well as otherinstitutions. The FOWGs opinion is neces-sary (see below) for certain projects. In allother cases the cantons may opt to seekthe FOWGs opinion.But in case subsidies are sought, earlycontact with the FOWG is recommended.

Federal supervisionA central federal task is to supervise can-tonal enforcement of federal law. TheFOWG is also responsible in this area. Itchecks conformity of flood control projectswith federal legislation particularly envi-ronmental law and looks after appropri-ate use of federal resources.Before they make a decision, the cantonspropose their flood control projects to theFOWG for federal comment. This appliesespecially in case of projects that: affect a river forming a national border, affect flood control measures of othercantons, require an environmental impact study, affect a protected area or an object onthe national inventory.

Procedural coordinationAll decisive cantonal and federal law pro-cedures used in individual cases must becoordinated in a material and formal senseand then be brought into harmony witheach other in terms of content. The mate-rial agreement and balancing of inter-ests related to it permit integral treatmentand assessment, even in complex projects.Two different approaches are possible inthe formal respect: Coordination model. Several au-thorities remain responsible in various pro-cedures and harmonize decisions in termsof content. Concentration model. A single au-thority carries out the various procedures.The FOWG coordinates the relevant proce-dures at the federal level.

*Due to the variety of federalist structures,these 2001 guidelines must be restricted tothe collaboration between the federal govern-ment and the cantons.

24

UFA

EGF

OW

G

Legal Standards

Strategy

Action

Procedure

Project Design

Measures

Appendix

*Other interfaces. Flood control measurescan also affect national treaties and other inter-national agreements. There are also interfaceswith other concerns of federal law. Those espe-cially worth mentioning are:

the decree on security precautions forpipeline facilities (in connection with safedistances);

the decree on security of dam facilities (StaV,in connection with risks for riparians).

Other federal standardsBeside the WBG and the ordinance relatedto it (WBV), there is a series of other fed-eral legal standards* that can relate toflood control. They often require specialdecisions or procedures: Federal Law on Land-Use Planning(RPG). Planning of flood control is a stepin establishing a cantonal structure andland-use plan. It has to be coordinatedwith space requirements of other sectorsby weighing interests. In particular, plan-ners must consider the rivers or streamsspace requirements needed for flood con-trol and to guarantee ecological function-ing. Structural measures for flood controlrequire a construction permit. A waiverpermit must be obtained outside construc-tion zones. Engineers must prove that themeasure is bound to the location, and apreponderance of interests must not op-pose it. Federal Law on Water Quality(GSchG). Hydraulic engineering projectsmust not cause water pollution. The imple-mentation of such projects is only condi-tionally possible in water protection areasand groundwater protection zones. Hy-draulic flood control measures need a le-gal permit for water quality control pro-tection, in particular endangered waterprotection areas. The law basically forbidsto cover rivers or streams by structures orto lay them into culverts. Extraction ofsand, gravel and other material requires afederal law permit (it cannot be granted ifthe sediment regime in rivers or streams isadversely affected). The water quality law(like the hydraulic engineering law) re-quires maintenance or restoration of natu-ral rivers.

Federal Law on Fisheries (BGF).Interventions in rivers, their discharge re-gime, or their course as well as in bank andbed areas assume a legal fishery permit (tothe extent that no permit is required inconnection with the water quality law). Federal Law on Protection of Na-ture and Landscape (NHG). Objectslisted as of national importance in the fed-eral inventory of alluvial zones are of spe-cial importance. They are to be maintainedundiminished (thus flood-control mea-sures are only permitted in a restrictedmanner). In all other protection areas, ac-cording to the NHG, unavoidable interven-tions require compensation or restorationmeasures. Ecological compensation is alsoforeseen in intensively used areas (e.g., byrestoring riparian vegetation) and by iden-tifying ecological buffer zones to protectbiotopes. Federal Law on the Forests (WaG).The law enacted a ban on clearing in prin-ciple. Waivers are only granted under strictconditions, especially if the envisionedstructure or facility is confined to the loca-

The Federal Law on Flood Control(Wasserbaugesetz, WBG; SR 721.100) andsupplemental Ordinance on FloodControl (Wasserbauverordnung, WBV; SR721.100.1) occupy center stage amongfederal legal tasks concerning flood con-trol.The federal legal outlook can be summa-rized as follows: Legislative attention fo-cuses primarily on land use which recog-nizes existing natural hazards andmaintains (or creates) the necessary bufferareas. Thus recognized hazards should notbe punctually removed but imbedded in aglobal concept for the entire area.As soon as structural protective measuresbecome necessary, federal law makesqualitative demands that lie in the interestof a varied animal and plant world as wellas river ecology. In each case a minimumspace must be reserved for rivers andstreams. Therefore, maintaining or creatingfloodplains while establishing and ensur-ing floodways also belongs to expedientplanning of measures.

25

http://www.admin.ch/

Already in 1874 the Swiss people through Article 24 of that eras federalconstitution has given the federal government competence for hydraulicengineering and forest police. The related hydraulic police law was approvedon 22 June 1877. At first it applied only to high mountain areas, but from1897 on it affected other areas as well. This law was replaced in anupdated constitutional version by a water resources managementarticle in 1975 (in the revised federal constitutions Article 76 Water).However, the hydraulic police law was only replaced during the 1990s by theFederal Law on Flood Control (Wasserbaugesetz, WBG) and its relatedOrdinance on Flood Control (Wasserbauverordnung, WBV).

tion. Basically, property compensation isto be provided. But this can be waived incase of flood control measures. Nature andlandscape protection measures can also beused for compensation instead of property.The clearing permit does not obviate theneed for a construction permit waiver inregard to land-use planning. Training ofstreams by forestry engineering methodsthat serves to maintain forests is alsoruled by the forest law. Details are derivedfrom the hydraulic engineering law (if thesituation arises, responsibility is to be co-ordinated between forestry managementand hydraulic-engineering). Based on theWaG, the federal government grants sub-sidies in case of any other protective mea-sures that supplement hydraulic engineer-ing (avalanches, rockfalls, erosion zones,landslides not related to river activity). Federal Law on EnvironmentalProtection (USG). The legally regulatedprecaution principle manifests itself in theenvironmental impact study that is to becarried out in case of important hydraulicengineering measures. USG regulationsare also to be observed for noise control,soil pollution, and waste planning. Federal Law on Hunting and Pro-tection of Mammals and Fowl Livingin the Wild (JSG). The federal govern-ment declares reservations for water andmigratory birds of national and interna-tional importance. The opinion of the re-sponsible Federal Office for Environment,Forestry, and Landscape must be obtainedin case of hydraulic engineering plans thatimpact protection areas. Federal Law on Footpaths and Hik-ing Paths (FWG). The cantons are con-cerned with planning footpaths and hiking

networks. They coordinate them with theirother space impact activities including thehydraulic engineering sector. Federal Law on Hydropower Use(WRG). Requires coordination of hydrau-lic engineering measures with concessionrights (and vice versa). In particular, it con-cedes a right to compensation to thehydropower concessionaire if interven-tions in the rivers course affect his previ-ous use of it permanently (presuming ad-aptation of the plant is unreasonable). Onthe other hand, the concession can alsoenvision the concessionaires financialparticipation in maintenance costs andpossible structural protection measures. Federal Law on Agriculture (LwG).The federal government can support sub-sidies for low intensity use of farmland.Moreover, cantons, communities, and hy-draulic engineering associations can com-pensate for measures that serve floodcontrol goals (e.g., inundation zones).Stream restoration (including land acqui-sition) can also be supported in connectionwith rural engineering. Basically, hydraulicand rural engineering projects should becoordinated. Federal Law on Dispossession(EntG). In implementing the law on hy-draulic engineering law, the cantons candispossess the rights in question or trans-fer the right to dispossess to third parties. Federal Law on Financial Aid andCompensation (SuG). This governs thefederal governments guarantee of com-pensation and financial aid. In accord withit, among other features, possible partici-pation of beneficiaries and those liableshould be considered. Before receivingthe contribution guarantee, those granted

subsidies may only begin construction ormake major acquisitions if the subsidizingauthority gives its approval. Federal Law on Use of a Special-Purpose Mineral Oil Tax (MinVG). Thefederal government uses a portion of themineral oil tax revenue earmarked forhighway traffic for structures protectingagainst natural hazards along highwaysand particularly flood control measures. Minimum requirements for linking eco-logical compensation zones are set out inthe Ordinance on Ecological Quality(QV).

26

Fran

k; K

eyst

one

Framework Conditions

Protection objectives are to be examined (and adapted,if necessary) within a interest-weighing procedure

concerning their economic and ecological proportionality.

Strategy

Action

Procedure

Project Design

Measures

Appendix

Flood control cannot be planned or real-ized in a manner detached from other de-mands for space. Coordination and agree-ment with other space-impact plans (e.g.,from the sectors of highway design, for-estry management, farming, water qualitycontrol, water use, and river restoration)and other intentions for land use (e.g.,development of building sites) are cogentin any case, and the related fundamentalsshould be considered.Therefore, any flood control project shoulddetermine right from the start if other dis-ciplines are affected. Only in this way willpotential conflicts be recognized on timeand considered properly in planning.

ProportionalityBasically every measure has to fulfill thefollowing conditions in connection withflood-control: On one hand, the measuresenvisioned must achieve the goal desired.On the other, they should be as unobtru-sive and cost as little as possible. More-over, a reasonable ratio should exist be-tween the desired goal and the intrusioninto protected legal goods (e.g., pri-vate property). Therefore, any flood controlmeasure should be examined from theviewpoint of its proportionality: Costs. Flood control projects must beeconomical and expedient. Thus, a balanceis necessary between the cost of theprotective measures and the potentialdamage expected. No claims for compen-sation or financial aid can be justified foruneconomical or inexpedient flood-controlprojects. If such a project involves not onlythe public interest but especially that ofprivileged third parties, the costs are to beapportioned among the participants.

Ecological claims. Proportionality hasalso to be respected in case of claimslodged on behalf of nature and the land-scape. Basically the existing conditionsshould not be worsened but improved asmuch as possible. In case of supplementalclaims, the costs related to the ecologicalbenefit (even if they cannot be deter-mined monetarily) should be factored intothe comparison. Private interests. Often hydraulic en-gineering needs and private interests failto harmonize. Owner positions must bowwhenever a sufficient public interest exists.Therefore, the cantons have the right todispossess property in the interest of floodcontrol. On the other hand, private partiesaffected may present their concernsthrough the procedures envisioned forthem by the cantons and the federal gov-ernment.

27

Federal Subsidies

The crucial assumption for a subsidy issuedby the federal government is expedientplanning of the related flood-controlproject: Agreement and coordination with otherinterests and partners is secured. There is no dual subsidy (e.g., from hy-draulic engineering and forestry manage-ment). The work is in the public interest. Cost participation corresponds to the in-terest situation ascertained. In case of conflicting goals, the verdictsare justified. The project fulfills the requirements ofall federal laws (i.e., regulations on water-way protection, land-use planning, natureand landscape protection, environmentalprotection, etc.)

DocumentationIn case of subsidy applications for struc-tural measures, the natural hazards, possi-ble damage, selected protection objec-tives, and impacts of measures envisionedshould be identified, clarified, and under-standable.Another assumption for a federal subsidyapplication is that the responsible can-tonal authorities have already made a le-gally binding decision on the relatedproject.Federal authorities also require projectdocumentation in order to carry out athorough examination of the project. Thisincludes documentation on technical andcost factors as well as opinions andascertainments of cantonal authorities.

LegitimizationWithin approved loans, the federal govern-ment carries out settlements for: Preparation of basic data for assessinghazards (including concepts, hazard andevent register, or hazard maps). Planning and building flood-controlstructures and flood control facilities (aswell as restoring or replacing them). Clearing channel beds and restoring asufficient flow section after the occurrenceof extreme events. Setting up and operating gauging sta-tions in the interest of flood control. Building up early-warning services. Acquiring land for protective structures. Restoring rivers when stressed by hy-draulic engineering measures. There is nobasis for legal claims. Priority is given toprojects that enhance natural river dynam-ics and serve to network habitats (e.g.,through culvert removal and by creatingenough buffer zones and transition areasbetween land and water).

28

Luft

bild

Sch

wei

z

Regular Procedure

The step-by-step approach within proceduralplanning can identify an optimum solution

for flood control balancing technology,ecology, and economics: maintenance as

well as planning and structural measures of-ten stand in close correlation, since they

exercise a mutual influence on each other.

Appendix: Checklists

Strategy

Action

Procedure

Project Design

Measures

Appendix

The first planning level is the preliminarystudy (in flood control also frequently re-ferred to as the concept). All possibleoptions (i.e., the do nothing approach,too) should be discussed, and the optionworth pursuing should be defined. Impor-tant framework conditions should be con-sidered here, and potential conflict pointsshould be listed.

At the preliminary project planninglevel (often called the general projectin flood control), planning measures forthe elected options are detailed to the ex-tent that (1) a rough cost estimateemerges, (2) major dimensions of poten-tial structural measures are known, and (3)an overview of the hydraulic, economic,and ecological impacts of the related ap-proaches can be provided.

The construction project includes thetechnical report, the project plans, and thecost estimate. It becomes the basis for thebuilding permit procedure, the decision onsubsidies, and the call for tenders. Thosedirectly affected must be able to recognizethe related impacts on each parcel pre-cisely (except for urgent measures afterfloods and sediment disasters).

The implementation project (oftenalso called the detailed project in floodcontrol terminology) presents all calcula-tions, dimensions, construction details,and instructions needed to realize themeasures selected.

The regular procedure for flood-controlmeasures can be divided into foursubsteps.

Step 1: Laying out the projectEach canton usually has a specializedoffice responsible for flood control. Thisoffice has multiple tasks: It is responsible for handling and coor-dinating project applications. It advises local responsible persons oragencies, farming cooperatives, privatelandowners, and third parties on floodcontrol issues and in connection with riverrestoration. It is the direct contact in the flood con-trol sector for the Federal Office for Waterand Geology (FOWG). The procedure canbe simplified considerably if an early in-formation exchange on the flood con-trol project takes place between the can-tonal office and the FOWG. This appliesespecially if important fundamentals (e.g.,design parameters) are to be determined.Yet early agreement by all involved is alsoof great usefulness if other federal inter-ests are involved (e.g., projects in areaswith a claim for protection due to federalinventories).

Step 2: FOWG opinionIn case of important projects and in spe-cial cases (see also page 23), the respon-sible cantonal field office consults with theFOWG which issues a binding opinion. The

FOWG can also express itself here on theamount of a possible federal contribution.

Step 3: Cantonal decisionThe next step is the cantons legally bind-ing decision on the hydraulic engineeringplan and its financing. In case of plans re-quiring an environmental impact study(UVP), cantonal law determines the proce-dure definitively.

Step 4: Subsidy procedureBased on the legally binding decision ofthe cantonal authorities, the cantonaloffice can submit applications for subsi-dies to the FOWG. The FOWG checks theproject documentation and determines theamount of the federal contribution as wellas related conditions. The projects harmo-nization with other federal laws is alsochecked in this connection.

29

Monitoring and maintenance

Plan implementation

Implementation project(detailed project)

Cantonal authorities decision

Preliminary study(concept)

Preliminary project(general project)

Construction projectRelated cantonalopinion reports

Possible environmentalimpact study

Important projector special case?

no

yes

Services of theFederal Office

for Water and Geology(FOWG)

Advising

Harmonizingbasic requirements

Ascertainingkey parameters

Coordinating

Cooperationand information

FOWG opinionInternal opinion:

BUWAL ARE BLWASTRA EFV BAK ENHK

Subsidy decision by FOWG(coordinated with EFV,

possibly linked to conditions)

Subsidy application to FOWG

Procedural flow at the cantonal level Procedural flow at the federal level

30

UFA

EG-F

OW

G; F

rank

; Ke y

ston

e

Accelerated Procedure

After a disastrous event, acanton can request support from

the federal government, e.g., inpreparing event documentation.

Strategy

Action

Procedure

Project Design

Measures

Appendix

If obvious security deficits appear afterfloods and sediment disasters and imme-diate measures have to be taken, an accel-erated procedure can be used to approvesubsidies. To justify such an approach, im-mediate measures are defined as: work immediately after an event, i.e.,clearing channels or restoration of ruinedprotective structures; anticipated measures that reduce exist-ing security deficits as soon as possible.

Checkpoints to be notedThe following should be considered inplanning and implementing immediatemeasures: Priority should be given to measuresthat reduce an existing risk or damage po-tential as quickly and effectively as possi-ble. On the other hand, measures that af-fect security only marginally should behandled in connection with regular pro-cedure (see page 28). Before starting any work, the cantonsspecialized offices should be consulted(and also third parties, if necessary). Coordination with other projects inthe area affected should also be assured. If projects are important, coordinationwith the Federal Office of Water and Geol-ogy (FOWG) is also necessary. This espe-cially applies for plans with important costconsequences or for work in an area thatis protected by federal inventory. If necessary for security reasons, theFOWG can grant a temporary buildingpermit based on subsidy law for urgentwork before definitive funding approval.This allows work to be undertaken imme-diately without having to wait for comple-tion of the subsidy procedure.

Before restoring destroyed protectivestructures, investigation should confirmwhether simple restoration of these struc-tures makes sense. The cause of failureshould be determined as far as possible,and structure security should be enhanced. Basically, space which the river hastaken during the event should be securedas river space. New space restrictionsshould be avoided. Greater flexibility canbe achieved for definitive measures in thismanner. Definitive solutions should be real-ized in case of local problems and clearframework conditions. On the other hand, in case of majorplanning that has to balance the variousinterests, low-cost temporary struc-tures should be built. Hence, time can besaved for expedient project management. Immediate measures and restorationsteps should create no prejudgmentsabout definitive solutions. Special fundamentals apply to alluvialzones (see page 53).

31

Services of theFederal Office

for Water and Geology(FOWG)

Advising

Supportingevent documentation

Engage experts

Organizingaerial photography

Securing financing

Coordinating(with other federal offices

and other cantons)

Information,coordination, and

supportAssessing hazardafter storms

No, notnecessary

Harmonizing at federal level(temporary building permit from

FOWG based on subsidy law)

Subsidy application to FOWG

Implementing emergency measures

Are immediatemeasures

necessary or not?

Decision of cantonal authorities

Harmonizing with thoseaffected and interested

Yes, necessary

Proper procedurefor planning measures

Procedural flow at cantonal level Procedural flow at federal level

Subsidy decision by FOWG(possible conditions)

32

Fran

k (3

); Sc

hub

lin (

1)

Participation

Conflicts in flood control plans areusually the result from differing interests

concerning use in the planning area.

Strategy

Action

Procedure

Project Design

Measures

Appendix

All flood control measures should bebased on an understandable, transparent,and comprehensive weighing of interests.This means that a compromise satisfac-tory for all involved must be found throughcommunication and discussion. It shouldbe noted here that differing concernsshould be rated in terms of the goals for-mulated and considered according to theirimportance.

InformationLandowners and farmers directly affectedby the plan should be informed of theplanning approach in a timely, understand-able, and schedule-related manner.Informing those affected should not occuronly once but in an expedient ongoingmanner at the right moments during theentire planning process.

Forms of participationIf concerns are raised from the public, aspirit of give-and-take should be promoted(to the extent that individual interests arecompatible with the general welfare). Co-ordination of hydraulic engineering plansis also important for both downstreamriparians along rivers and streams (sincethey are directly affected by the projectsimpact) and those upstream (e.g.,hydropower plant operators).The level at which participation begins de-pends on the project in question. Variousforms of involvement are possible. Thegoal of this approach is to realize soundprojects and thus improve acceptance ofmeasures related to them. Public involve-ment also offers the opportunity to useknow-how of local residents and to drawthem into planning at an early date. Possi-

ble forms of involving the public and thoseaffected are varied: Presentations by experts, public gather-ings, or discussion evenings. Local visits or excursions to areas withsimilar situations. Exhibitions and public-informationpostings. Study groups or expert panels in whichvarious interest groups discuss goals andoptional solutions with a moderator. Interdisciplinary monitoring committees,e.g., one established with success alongthe River Thur. Information in local and regional newsmedia.

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Goal: Involving those affected.

Overcoming Conflict

Plannings goal is to work out a projectthat wins consensus and can be realizedwithin a reasonable period. Nonetheless:rivers and streams and their related floodproblems are so closely bound to totallydiffering demands for use that planningflood control measures often leads to con-flict. The reasons are varied. They may liein divergent claims for use. Yet it is alsoconceivable that conflicts arise throughshortcomings of the planning pro-cess. This applies, for example, if doubts,desires, or demands of collaborators andthose affected are not assessed on time ortaken seriously. Differences could thusarise that end up in objections (and thuspostponements).

RecommendationsThere are various recommendations onhow conflicts can be recognized, avoided,and resolved. The most important arenoted here: Before working out a project,involve all affected early and within theframework of an open and comprehensiveinformation policy. Identification with thecorresponding plans and understandingfor the measures needed can be promotedin this way. The following points should beobserved in addition: The legal framework and space re-quirements for natural habitats as wellas procedural flow are expressed clearly atthe beginning of planning. In case this framework cannot be con-sidered, the reasons for it should be pre-sented openly. Broad-based discussion of the draftproject including local visits contributes tomutual understanding and early clarifica-tion of potential points of conflict.

Conflict points that cannot be resolvedimmediately may be neutralized at times,if improved decision-making basesare made available through more detailedexamination. If, despite all efforts, further conflictscannot be overcome, responsible authori-ties at the cantonal level must weigh theinterests involved. A decision by the responsible author-ity follows. It may be appealed, dependingof the law involved. Finally, it is important that decisionsmade are explained and made known toall involved.

Project Design

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The Sequence of Project Design Work

Depth of study dependson project step

Project design work,an iterative ormultistep process:

In order that gaps never completely bridgedbetween the natural framework and societysclaims are not excessive, a change incourse regarding flood control proceduresmay also be necessary: Back away frompure flood control defense; advance to aculture aware of risks is the thrust of thenew motto that should be experienced atall levels i.e., the federal government, thecantons, and municipalities in the future.

Recommended reading

FEDRO/FOT/FOWG/SBB (1998/2002): Safetyof Structures in Water. Recommendation forthe Surveillance and Indications for the Con-struction of New Structures Order of priorities

Problem formulation

Goals

Fundamentals

Study of options

Third-party participation

Weighing interests

Cost effectiveness

Assessing remaining risks

There are no standard recipes for solvingflood-control problems. Yet recommenda-tions can be made based on experiencesfrom the recent past on how flood-controlgoals can be achieved in a timely and cost-effective manner: In any project the necessary should beseparated from the desirable in order tokeep costs within reason. The depth of study should be adaptedto project requirements. The necessary basis for decision-mak-ing must be prepared early. Basic data needed for the project mustbe complete. There are enough examplesto show that a single unclarified issue candelay a project for years (or even cause afailure). Expertise from various disciplines is usu-ally required during a projects stages. It istherefore important that partners as-signed special tasks be selected carefully.Those bidding for project tasks must beable to demonstrate their specialized tech-nical skill, qualitative record, and businessperformance in managing the work envi-sioned. Furthermore, they must be able towork in a team. If the interest-weighing process es-tablished that economic, ecological, oreven technical measures lack proportion-ality, adaptations must occur in the uses

foreseen and also the protection objec-tives selected (see also guiding principles,page 10).

Optimizationby multistep approachOnce the need for action, the problem for-mulation and the necessary fundamentalsare established, the goals to achieve withplanning measures need to be defined. Fortheir part, these goals influence the natureand quality of the basic data required, andthe measures again lead to adaptationsand supplemental steps. Project optimiza-tion through such a multistep approach istherefore an iterative procedure. At-tention should be paid to: Documentation of the originalsituation. This includes documentationon the hazard situation and the state ofthe river or stream, as well as the questionof an extreme floods impact. Estimate of possible damages. Thisstudy provides information on the finan-cial consequences of a certain event. Planning measures. A rule of thumbstates that impact on rivers should be assmall as possible. Another principle callsfor upholding the priorities set by federalLaw (maintenance and land-use planningmeasures have priority over structural pro-tection measures). Important improve-ments for flood control may often beachieved at little cost, and finally compre-hensive weighing of interests leads to bet-ter options. Assessing the residual risks. Clari-fying residual risks belongs to a completeplanning of corrective measures. This canbe done only being aware of uncertaintieslinked to natural events.

Emergency planning and emer-gency organization. Each flood controlproject also includes a catastrophe mana-gement plan oriented towards the currenthazard situation. Maintenance and monitoring. Anessential component of a flood controlproject is also to set up a maintenanceconcept (total security and use plan).

Implementinginto land-use planningThe remaining danger situation after real-izing protective measures should be pre-sented in the form of a hazard map andconsidered in establishing the structureand land-use planning.If the project is rejected, the responsibleflood control authorities must work outthe hazard map corresponding to the origi-nal situation and make sure that it is im-plemented into structure and land-useplanning.

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Conditions in the Catchment

A phenomena map produced by field survey is ameaningful supplement to event documentation. It records

characteristics and indicators observed in the field inmap and text form. It also refers to the status, triggering

mechanics, and impact of potential types of hazards.

Recommended reading

BWW/BUWAL (1995 recommendations):Naturgefahren. Symbolbaukasten zurKartierung der Phnomene [Natural Hazards.Symbol Toolbox for Mapping Phenomena]

PLANAT/BWG/BUWAL (2000 compendium):Vom Gelnde zur Karte der Phnomene[From the Field to the Map of Phenomena]

Strategy

Action

Procedure

Project Design

Measures

Appendix

Processes occurring in rivers or streamswill be determined largely by conditions inthe corresponding catchment. Importantparameters are: topography (surface, form, gradients,readiness of a zone in relation to a certainprocess); structure and distribution of varioustypes of soil; geology; geomorphology (processes that haveshaped the catchments); precipitation conditions; degree of glaciation; forested area (and its condition); discharge regime; channel geometry (longitude profileand cross sections) and channel mor-phology (grain size diameter of bed sub-strata).

Available basic dataAny flood-control project is based on nu-merous pieces of basic information on theriver and its catchment. Part of these datais also available in digital form (e.g.,topographic and topical maps as well asaerial photographs) or is integrated intogeographic information systems (GIS).Various cantons as well as the federal gov-ernment also operate coordinating offices.The following working and planning toolsare of particular importance: Precipitation data. Governmentaland private institutions collect this data.Evaluations of weather radar data are of-ten valuable in assessing and classifyingmajor precipitation events. Discharge data. Governmental andprivate institutions also collect this data;rated and made accessible to the public

(e.g., in the form of the FOWGs Hydro-logisches Jahrbuch der Schweiz [Hydro-logic Yearbook of Switzerland] also on theInternet). Registered events. Those who wantto foresee the future need to look backinto the past. Therefore, experiencesgained from earlier events are of great usein assessing and estimating future events.This assumes a comprehensive and accu-rate documentation of individual events.Besides noting the crucial processes anddegree of damage, event documentationprovides information on areas affected bythe natural hazard involved as well as themeteorological, geological, geomorpho-logic, and hydrological conditions. Basic data concerning geology.Geological conditions influence runoff, thenature of sediment and its yield, as well asthe sediments physical characteristics.Stability calculations related to massmovement cannot be carried out withoutknowing the geological conditions. More-over, when intervening in groundwater,drainage as well as measures near sourcesrequires investigations of the hydrogeo-logical situation. Inventory. The so-called federal inven-tory represents important tools for protect-ing nature and the landscape. It distin-guishes between landscape and biotopeinventories, because they differ in legalimportance. Accepting an object of na-tional importance in a landscape inven-tory in accord with Article 5 NHG mainlycommits federal agencies themselves (aswell as those that fulfil federal tasks orclaim federal funds for their plans). Ex-cepted is the inventory of moor land-scapes, which is based on Article 23b NHG

and is applied directly to property owners.Substantially more authority has beengranted to the federal government since1987 in the sector of biotope protection.The legal basis of the biotope inventory(including a federal inventory of nationallyimportant alluvial zones) is Article 18aNHG. After hearing testimony from thecantons, the Federal Council identifies thebiotope of national importance, deter-mines its status, and sets protection goals. Damage potential. Based on theirdocuments, cantonal building insurancecan provide data on potential damage andobject protection measures.

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Basic data Contact/Sources

Heavy precipitation: Federal Research Institute for Water, Snow, and Landscape (WSL), Birmensdorf Entire Switzerland surveys: SMA MeteoSwiss, Zurich Radar weather assessments: SMA MeteoSwiss, Zurich Local surveys: hydropower plants; private meteo offices

Entire Switzerland surveys: FOWG-LHG, Biel and Berne Local surveys: waterpower plants; cantonal flood control offices; cantonal water management offices

Cantonal land-use planning offices

Cantonal land-use planning offices Municipality administrations

Federal Office for the Environment, Forestry, and the Landscape (BUWAL), Berne Cantonal land-use planning offices

BUWAL, Berne (Forestry Directorate) Cantonal flood control offices

Entire Switzerland documentation: FOWG, Biel; BUWAL, Berne Regional and local surveys: cantonal flood control offices

Cantonal flood control offices Cantonal land-use planning offices Municipality administrations

Cantonal flood control offices Cantonal space planning offices Municipality administrations

Cantonal flood control offices FOWG, Biel

Cantonal structure insurance

Federal inventory (landscape and biotope inventories): BUWAL, Berne Regional and local inventories: cantonal nature protection offices Red lists: BUWAL, Berne; cantonal nature protection offices; environmental associations

Geological maps (however, the National Geology Atlas at a 1:25000 scale is incomplete).

Geological studies that were carried out for other projects. The National Geology Division (FOWG)operates the Swiss Geology Documentation Center (SGD), which also collects unpublished documents.

Additional geological, geotechnical, or hydrogeological studies on reservoirs, check-dams, dams,and interventions into water regime (e.g., lowering groundwater).

Precipitation data

Discharge data

Structure plans

Land-use plans (local)

Landscape developmentconcepts (LEK)

Events register

Protection structuresregister

Hazard index maps

Hazard maps

Project files (old)

Damage potential

Inventory

Basic dataconcerning geology

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Keys

tone

Uncertainties of Basic Data

Calculating return periods is quite tricky, as the example of the Reussin Uri cantone shows. During the mid-1980s this river was designed for

a flood discharge of 600m3/s, and that value was considered as a100-year event (Q 100). Yet a detailed hydrologic study after the 1987flood showed that this design valu