Constructed wetlands in Finland - Berninger, Koskiaho and Tattari

WP6
WP5
CONSTRUCTED WETLANDS IN FINLAND
Results of Baltic Compass case study
and National Round Table
Kati Berninger, Jari Koskiaho & Sirkka Tattari
Regional Wetland/Flood control Dialogue Workshop
Kristianstad 24.-25. September 2012

Baltic Compass work on
wetlands in Finland
• Focus on constructed wetlands in agricultural
environments
• Case study to
– Describe the current knowledge on the functioning of wetlands
largely based on automatic monitoring data from existing
wetlands
– Describe the Finnish wetland support system and its historical
development
– Analyze the enabling factors and barriers related to the current
wetland support
– Give recommendations for the new programming period
• National Round Table Workshop on April 18 th 2012
discussing
– new ways of promoting the construction of wetlands
– the potential of collective action
• Wetland excursion on September 6th 2012

Why construct wetlands?
• In Finland many natural wetlands have been dried
during the last few centuries
– Competing land uses do not allow the formation of new
natural wetlands
• Constructed wetlands returning some of the lost
capacity to retain floods, erosion and nutrients
• Wetlands are also important for their biodiversity,
recreational and hunting values

Finnish wetlands
• Most of the constructed
wetlands are small, about
1 ha. A few large wetlands
• Automatic water quality
measurements of
inflowing and outflowing
water in some areas

The nutrient retention capacity of a
wetland is good when:
The water stays a long time even during
flooding periods
The size of the wetland compared to the
catchment area above it – dimensioning
High nutrient concentrations in the
incoming water
Hydraulic efficiency – utilizing the whole
wetland area efficiently
Removing top soil before construction–
removes also dissolved phosphorus

Turbidity (FTU)
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Example of an “ideal” wetland
4000
Inflow
3000
Outflow
2000
1000
0
Time

Flow and retention in the Hovi wetland based on
sensor data in 2007–2011* and on water sampling in
1999–2000**
Period
Inflow
(mm)
TSS ret.
(kg/ha)
NO3 ret.
(kg/ha)
TP ret.
(kg/ha)
2007–2008 417 30 300 (70%) 133 (67%) 45 (67%)
2008–2009 287 15 200 (57%) 38 (54%) 22 (53%)
2009–2010 570 16 200 (71%) 251 (84%) 23 (71%)
2010–2011 160 6 300 (92%) 67 (79%) 10 (91%)
Mean 2007–2011 358 17 000 (68%) 122 (75%) 25 (66%)
1999–2000 341 24 300 (68%) 220 (35%) 24 (62%)
*Unpublished
**Koskiaho, J., Ekholm, P., Räty, M., Riihimäki, J. & Puustinen, M. 2003.
Retaining agricultural nutrients in constructed wetlands - experiences
under boreal conditions. Ecological Engineering 20(1): 89-103.

Finnish wetland support
• The support is mainly based on water
protection efficiency
– Eligibility criteria:
• Fields cover > 20 % of the catchment area
• Size of wetland ≥ 0.5 % of upstream catchment
• At least 0.3 ha of size
• Target: 1626 new wetlands by nonproductive
investment support
– Positive decisions during 2008-2011 165
= 10 % of the target

The role of projects
• Wetland promotion, advise and wetland planning
– TEHO project
– Järki project
• Also funding and support during the whole process
– Return of Rural Wetlands Life+ project
– WWF wetland project
– Vesijärvi Foundation
– Have built all together 59 wetlands
• Made possible the construction of wetlands not
eligible for wetland support
• Drafted regional wetland plans

Constructing wetlands in drainage projects
• A great potential for wetland construction in connection
with drainage cooperation
– Several landowners involved
• Broadening thinking to cover all measures slowing down
the water flow
– levelling of ditch banks, construction of flooding terraces or
meandering
• Good drainage reduces nutrient leaching from fields by
increasing productivity
• Drainage projects
with environmental
measures as
examples of winwin
situations

Supporting wetlands through land consolidation
• Land consolidation projects aim at getting larger parcels
easier to cultivate
– The state may offer alternative land parcels
• Projects may also take potential wetland locations into
account
• Land consolidation could solve several problems related to
wetlands:
– landowners not interested in cooperation could get a land parcel
outside the wetland area
– wetland areas could follow the landowner’s borders
– if the water covers productive fields, they could be compensated by
an equal parcel elsewhere

Lessons learned I
• Support should be organized so that farmers don’t have
to take financial or other risks during the wetland project
• Wetland support is needed for both water protection and
biodiversity reasons. The target areas may differ.
• A special support for collaborative projects involving
several landowners needed
• Farmers need help during the whole wetland
construction process from planning to finding and
supervising contractors.

Lessons learned II
• The best results have been reached in wetland projects
managed by NGOs/special funds who work directly with
farmers
• Higher support level for watersheds/projects with a
particularly good potential to reduce nutrient load
– may be seen as a way to implement outcome-based support
• We need to learn more about managing wetlands

More info
• Report of the Baltic Compass project:
Berninger, K., Koskiaho, J. & Tattari, S. 2012. Constructed wetlands
in Finnish agricultural environments: Balancing between effective
water protection and multi-functionality. 29 p.
Thank you!
sirkka.tattari@ymparisto.fi, kati_berninger@yahoo.ca