the Value of Floodplains along the River Elbe

Transcrição

“Climate Change and Nature Conservation in Europe
- an ecological, policy and economic perspective”
25 - 27 June 2013, Bonn, Germany
Riparian Ecosystems and Climate Change: the
Value of Floodplains along the River Elbe
Alexandra Dehnhardt,
Malte Grossmann, Volkmar Hartje
Mathias Scholz
Dietmar Mehl
TU Berlin, Environmental and Land Economics
Helmholtz Centre for Environmental Research, UFZ
biota, Institut für ökologische Forschung und Planung
“Climate Change and Nature Conservation in Europe - an ecological, policy and economic perspective” - June 2013, Bonn
Outline
1. Introduction
•
Ecosystem services of natural floodplains
•
Riparian ecosystems and climate change
•
Economic value of floodplains
2. Case studies
•
Ecosystem functions and services of floodplains in Germany
•
Economic value of floodplain restoration along the German river Elbe
3. Concluding remarks
Alexandra Dehnhardt
Environmental and Land Economics
Introduction
•
Riparian ecosystems provide a wide range of services with value for human society
 Attractive landscapes for recreation (cultural services)
 Hot-spots for biodiversity (supporting services)
 Water quality improvement and flood control (regulating services)
•
Functions and services are only provided by intact, near-natural ecosystems
 Intensive land use and settlement
 Straightening and embankment
 About 70-90 % of the original floodplain area is disconnected ; only 10 % of the
remaining floodplains are in a natural condition (Status report of floodplains 2009)
 increasing flood risk and a number of ecosystem services affected
•
Former and topical extreme flood events
 German Environment Minister calls for rethink in flood protection: “…give rivers more
room to buffer their floodwaters, if necessary through … relocation of dikes.”
 Political change to an integrated flood risk management considering the benefits
provided by ecosystems
Alexandra Dehnhardt
Climate change and riparian restoration
Impacts (-)
Climate Change
Riparian
Ecosystems
Adaptation
actions
Mitigation
actions
Floodplain restoration
adaptive capacity (+)
Regulating services
Flood protection
Climate regulation
Benefits from reduced flood risk
Benefits from reduced greenhouse gas emissions
Nutrient retention
Biodiversity and habitat
Recreation and aesthetics
Benefits from increased water quality,
recreational value and nature conservation
Economic
perspective:
considering the
value of multiple
ESS in policy-making
Ecosystem functions and services of floodplains in Germany - Case study I
•
Quantification and assessment of ecosystem functions and services of large rivers
in Germany
 Flood retention
 Nutrient retention
 Carbon stocks and carbon sinks
 Habitat function (biodiversity)
•
Funded by the German Federal Agency for Nature Protection (BfN)
•
Study area and data
 Nationwide inventory of loss and status of German floodplains
 15,000 km2 along 79 rivers (former and active floodplains and rivers)
Source: Scholz, M., Mehl, D., Schulz-Zunkel, C., Kasperidus, H.D., Born, W. & K. Henle
(2012): Ökosystemfunktionen von Flussauen - Analyse und Bewertung von
Hochwasserretention, Nährstoffrückhalt, Kohlenstoffvorrat, Treibhausgasemissionen
Institut für ökologische Forschung und Planung GmbH
und Habitatfunktion. Naturschutz und Biologische Vielfalt 124, Bonn.
biota
biota
Results: flood retention and carbon storage
•
Flood retention
 Hydro morphological structure and flooding characteristics not available nationwide;
high degree of uncertainty in terms of potential damage
 Qualitative assessment of the loss of
flood retention potential
14%
9%
21%
•
Carbon storage and
greenhouse gas emissions
very low
low
29%
distinct
high
 Significant potential for carbon storage and
sequestration of greenhouse gas emissions
in floodplain soils
27%
very high
 Peatlands as an important source of greenhouse gases due to intensive land use
 Calculated carbon stock of active floodplains: 158 mill t: 70% in organic soils of
peatlands, 26% in mineral alluvial soils, 4% in terrestrial soils
 15.4 mill t total storage in alluvial forests in active floodplains
 Land use change ( riparian forests) will have a significant effect for
climate change mitigation
biota
Institut für ökologische Forschung und Planung GmbH
biota
Economic value of restored floodplains along the German Elbe - Case study II
•
Assessing the economic effects of two alternative strategies within an integrated
floodplain management
 Large scale floodplain restoration (‘room for the river’) due to dike relocation  dike
strengthening + controlled polder is regarded in a cost-benefit analytical framework
River stretch
Number of
Polder area
Relocation
Option  Description
Applying an ecosystem service
approach
to
estimate
the
economic
value
the
(Elbe km)
sites
(ha)
areaof
(ha)
multiple benefits: flood water retention (hydrological service), nutrient retention
117-536
60
0
34,659
(biochemical service), biodiversity (ecological service)
DR I
Dike relocation large
DR II
Dike relocation small
•
PI
P II•
120,5-536
33
0
117-427
31
25,576
180
5
3,248
0
180
5
3,248
0
Funded by the German Federal Agency for Nature Protection (BfN)
Controlled polder large
Controlled
Study
area polder small
9,432
P (e) II
Polder with ecological
flooding
P+DR
Multifunctional
117-418
17
4,143
3,402
P(e)+DR
Multifunctional,
ecological flooding
117-418
17
4,143
3,402
Source: Grossmann, M., Hartje, V. & J. Meyerhoff (2010): Ökonomische
Bewertung naturverträglicher Hochwasservorsorge an der Elbe, Naturschutz und
Biologische Vielfalt 89, Bonn.
Benefits of flood risk reduction
•
Assessing the avoided average annual flood damage
 Estimating the flood risk (probability of a (extreme) flood event combined with the
associated expected damage)
 Comparing the benefits (with and without measures) in terms of the difference
between average annual damage
1. Estimating downstream effects of planned and unintended retention on peak
water level on a large scale: 1D-hydraulic routing model, inundation model for
dike breaches / dike overtopping
2. Estimating damages: macro-scale approach; assessing the resulting flood damage
as a function of inundation depth and land use classes
Source: de Kok, J.L. & M. Grossmann (2010): Large-Scale assessment of flood risk
and the effects of mitigation measures along the Elbe River, Natural Hazards
(52), 143-166.
Avoided average annual flood damages
Programme
DR L
DR S
PL
P S / P (e) S
P+DR / P (e) +DR
Restored floodplain area
Total area
Controlled polder
ha
%
34,659
0
9,432
0
25,576
100
3,248
100
7,545
55
Avoided average
annual damage
€ ha-1
165
68
1,015
4,120
1,825
Source: de Kok, J.L. & M. Grossmann (2010): Large-Scale assessment of flood risk
and the effects of mitigation measures along the Elbe River, Natural Hazards
(52), 143-166.
Distribution of costs and benefits of polders along the river trajectory
Only upstream polder
(small scale)
Large scale polder
Results of the cost-benefit analysis (Net present value)
Focus on flood
risk reduction
Positive net
present value
only for
alternatives with
controlled polder
Results of the cost-benefit analysis (Net present value)
Considering the
benefit estimates
of multiple
ecosystem
services
Positive net
present value for
all alternatives
Results of the cost-benefit analysis: distribution along the river Elbe
Only dike relocation
(large)
Only dike relocation
(small)
NPV: net present value (3%)
PC: project costs
SC: saved maintenance costs
FD: avoided flood damage
BD: willingness-to-pay for biodiversity
NR: benefits of nutrient retention
Concluding remarks
•
Large-scale strategies of floodplain restoration contribute to
 Climate change adaptation and mitigation
 Flood risk management (rather than focussing only on protection) to meet the
demands of the EU Flood Directive
 Nature protection to meet the demands of the FFH Directive
 Achieving the water quality objectives of the EU Water Framework Directive
 Exploring possible synergies between different policy goals  integrated management
•
Multidimensional perspective necessary
 Floodplain restoration might not be not economically advantageous looking from only a
flood risk or water management perspective:
costs of restoration high, benefits with regard to a single target comparatively low
 Dike relocations as an integrated strategy to nature conservation and flood protection
are economically advantageous: benefits outweigh the costs
 Economic valuation and cost-benefit analysis suitable to include secondary benefits
•
To improve integration of ecosystem services into (climate change) policy-making,
still more attention is needed for the quantification of the effects
as well as for the benefit estimates
Alexandra Dehnhardt
Thank you for your attention.
Alexandra Dehnhardt
[email protected]
Nationwide inventory of loss and status of German floodplains
Auenzustandsklassen
Veränderung:
sehr gering
gering
deutlich
stark
Status of active floodplains
sehr stark
nicht bewertet
Source:
www.bfn.de/0324_auenz
ustandsbericht.html

the Value of Floodplains along the River Elbe

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