Office for the Environment

Thurgau
6th International Forum on Waterfront and Watershed Restoration
29 Septemberp2009 (Asian(River Restoration Network))

River Engineering andManagement
D MDr.
M. B
Baumann, SSectionti W
Watert Resources
ROEN TG

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Introduction

2007ª Large and very large supra-regional floods since 1800
2M. Baumann, Section Water Resources OEN TG

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Paradigm
g Shift After 1987
• safety for everyone and everything is not possible• the value of goods at risks has increased enormously• financial resources are limited due to budget constraints
in the public sector• pure defense against hazards is no longer the only issue

certain risks have to be accepted

what might happen / where may it happen ?
3M. Baumann, Section Water Resources OEN TG

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Swiss Flood Policyy

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M. Baumann, Section Water Resources OEN TG

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Hazard Assesmentª Present-dayPt d results
lt off hhazardd assessmentt5
M. Baumann, Section Water Resources OEN TG

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Thurgauu gauHazard Maps
p6
M. Baumann, Section Water Resources OEN TG

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Differentiated Protection Objectives
jª High protection only for high risks

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M. Baumann, Section Water Resources OEN TG

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Swiss Flood Policyyª based on the principle of sustainability
environmental
aspectsprotecting natureand theenvironment
itsocialaspectsprotecting
the public

economic aspects
ecological and economic proportionality
M. Baumann, Section Water Resources OEN TG

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HolisticPlanning

Providing the basics- hazards- land use (existing / planned)- river condition

Definition of goals

Planning the measures- clear priority forsustainable measures- consideration of all typesof measures

Assessment of balance

Implementation ofmeasures

M. Baumann, Section Water Resources OEN TG

Management ofresidual risks9Office for the Environment

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The Flood of Augustg
2005© Canton of Obwalden© Swiss Air Force
M. Baumann, Section Water Resources OEN TG

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The Flood of Augustg2007

11M. Baumann, Section Water Resources OEN TG

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Lessons Learnedª Considerationof the overload caseDDamage

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Design loadLoad• The overload case (the excess of design values) has tobe considered when designing and planning measures• The conceptual design of protective structures mustassure a flexible
fl ibl andd robustb t behaviourb h iiin th
the case off anoverload• Resilience of structures must be gradually and not leadto a sudden increase of damage
M. Baumann, Section Water Resources OEN TG12

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Successful management
gof the overload caseEngelberger Aa River (NW)
flood
corridorsideweirsideweir© Swiss Air Force

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M. Baumann, Section Water Resources OEN TG

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Characteristics of the Thur

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M. Baumann, Section Water Resources OEN TG

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Characteristics of the Thur••

„Wildbach“Thurflooding: 1849,1849 1852 und 1876
with large inundation
HW•

extensive measurements („first correction“)• protection of the population• Reclaim of agricultural areas
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M. Baumann, Section Water Resources OEN TG

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Guiding
gp
principles
pfor Swiss watercourses• Space
pfor the watercourses• Water Quality• Water Quantity
www.bafu.admin.chª From the perspectives of flood
protection and environmental
protection space is the central
li iti ffactor
limitingt
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M. Baumann, Section Water Resources OEN TG

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Thurgauu gauRules for the „„2nd correction“ª sufficient space for the water• to guarantee normal flow
• to guarantee high flow
• to minimize peak flow

ª consider the overload case17
M. Baumann, Section Water Resources OEN TG

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Involvingg Nature When Planning
gPresentFuture18
M. Baumann, Section Water Resources OEN TG

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Thurgauu gauRiver Bed wideninggª Prevention of further degradation
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M. Baumann, Section Water Resources OEN TG

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Thurgauu gauRiver Bed Wideningg2ª Increasing discharge capacit
capacity andlowering the water level20
M. Baumann, Section Water Resources OEN TG

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Overload Case
• Emergency spillway:
into areas with low damage
potential• Structures:to limit the water volume ofthe outflow• Protection measures:for areas with high damage
potential

highdamage
potential
emergency
spillwayprotection
measureslow damage potential

emergency floodway

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M. Baumann, Section Water Resources OEN TG

Office for the Environment

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Overload Case 2

New river bed

Flood retention corridor:
for extreme floods

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M. Baumann, Section Water Resources OEN TG

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The Overlaod Case for the Thurexisting dams

Retention SpaceEmercency Spillwayp
protection
measures

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M. Baumann, Section Water Resources OEN TG

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Thurgauu gauConclusions• A significant need for action exists fromtheh perspective
i off flfloodd protection
i anddenvironmental protection• Watercourses have to be respected asimportant parts of nature and landscape• All functions of watercourses have to beensured
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M. Baumann, Section Water Resources OEN TG

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Thurgauu gauConclusions 2• The problems have to be analyzed
globallyl b ll
• Conflicts should be resolved with aconsequent balance of stakeholders
interests based on a scientific knowledge
interests,ª Sustainable flood protection leads toregenerated watercourses, that areclose to their nat
naturalral conditions
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M. Baumann, Section Water Resources OEN TG

Office for the Environment

Thurgauu gau… because the next event is due to come …
Work together …

... consider„the unthinkable“ ...

... and take all chances …

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M. Baumann, Section Water Resources OEN TG

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ThurgauThank You for
f your attention

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Next slides are for discussion ……

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M. Baumann, Section Water Resources OEN TG

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Guidelines

Flood Control at Rivers
and Streams, 2001

www bafu admin ch
www.bafu.admin.ch
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M. Baumann, Section Water Resources OEN TG

Office for the Environment

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Guidung
gp
principles
pfor Swiss Watercourses... for a sustainable politic
for watercourses

www.bafu.admin.ch
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M. Baumann, Section Water Resources OEN TG

Office for the Environment

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Flooding
g of Augustg
2005 and 2007

ª sufficient space
pfor the water

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M. Baumann, Section Water Resources OEN TG

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It will not work without interdisciplinary
py cooperationp!

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M. Baumann, Section Water Resources OEN TG

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Thurgauu gauHazzard Maps
pmajor hazard

ban zoneno new building zones / no new constructions

moderate hazard

conditional zone

new building
b ildi zones / new constructions
t ti
only
l withith restrictionst i tilow hazard

index zone

information and recommendations for landowners

residual hazard

index zone
emergency planning measuresª ConsequencesC
ffor building
b ildi andd zoningi regulationl ti
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M. Baumann, Section Water Resources OEN TG