1.2 Contact details of resource persons and institutions involved in the assessment and documentation of the Technology

1.3 Conditions regarding the use of data documented through WOCAT

The compiler and key resource person(s) accept the conditions regarding the use of data documented through WOCAT:

Yes

1.4 Declaration on sustainability of the described Technology

Is the Technology described here problematic with regard to land degradation, so that it cannot be declared a sustainable land management technology?

No

1.5 Reference to Questionnaire(s) on SLM Approaches (documented using WOCAT)

Regional Environmental program [Norway]

Regulations and financial grants for reduction of pollution and promotion of the cultural landscape.

• Compiler: Kamilla Skaalsveen
• 02/25/2015 midnight

2.1 Short description of the Technology

Definition of the Technology:

A small constructed wetland is a combination of ponds and vegetation filters, designed mainly to remove sediment and nutrients from streams. It is usually located in first and second order streams in agricultural landscapes.

2.2 Detailed description of the Technology

Description:

Purpose/aim: Small constructed wetlands (CWs) are designed to improve water quality in streams and thus downstream water quality as well. The shape of the constructed wetlands can differ and include different components. Generally, they include a deeper sedimentation pond at the inlet (depth 1.5-2 m), followed by one or more shallow vegetated zones (depth 0.5 m). The sedimentation pond decreases the water velocity to allow particles to settle, while the vegetated, shallower zones act as filters for particles passing the sedimentation pond and protect trapped sediments from re-suspension by stabilizing them with their roots.

Small constructed wetlands treating agricultural runoff have been in operation in Norway since the early 1990s. From 1994-2020, more than 1200 CWs have been established across the country, with the aim of reducing sediment, nutrients, pesticides and other pollutants in agricultural runoff.

Establishment/maintenance: Norwegian CW are designed mainly to remove phosphorus and particles (suspended sediment) with main removal mechanism being sedimentation and filtration, and (to a lesser extent) plant uptake. The CWs treating agricultural runoff are usually constructed by expanding the width of natural streams. At the inlet of the CW, the stream water flows into a sedimentation pond. From the sedimentation pond, water passes through a sprinkling zone, and then through one or more vegetated wetland filters. Due to the typical small-scale Norwegian agriculture and the landscape with rough topography, CWs are often quite small (<0.1 % of the catchment area). The size of CWs is one of the crucial factors limiting overall treatment efficiency.

Over the years, the CW will fill up with sediments, and to maintain good treatment efficiency, it is necessary to empty the CWs periodically (Blankenberg et al. 2013 ).

Benefits/impacts: Norwegian studies show that retention of total phosphorus (TP), both particulate P and dissolved P, increase with increasing area of the CW (Braskerud et al. 2005 ). The retention of sediments, nutrients and pesticides in different CWs also varies due to other factors like design principles, soil types in the catchment, hydraulic loads, and locations along the streams (Braskerud and Blankenberg 2005 ; Blankenberg et al. 2007 , 2008 ; Elsaesser et al. 2011 ). Braskerud ( 2001 ) showed that average retention in six CWs in Norway varied from 45% to 74% for soil particles and 21%–44% for TP. For CW in Skuterud catchment Krzeminska et al (2021) showed that average efficiency of removal was 36% of sediment, 19% of phosphorus and 3% of nitrogen .

Natural / human environment: The information presented here is based on the investigations and/or reports from different part of Norway. For the purpose of OPTAIN project, the technology is further presented in the natural and human environment context of the Kråkstad River catchment - a Norwegian Case Study catchment within OPTAIN project.

The Kråkstad River is mainly situated in Ski commune in South-Eastern parts of Norway. The river catchment is a western tributary of the Vannsjø-Hobøl watercourse, also known as the Morsa watercourse. The Kråkstad River catchment area is c.a 51 km², 43% of which is agricultural land, where mostly cereals are produced on heavy clays soils. The main environmental challenge in the area is water quality (incl. high phosphorus pollution) and soil erosion (incl. riverbank erosion and quick-clay landslides).

2.3 Photos of the Technology

2.5 Country/ region/ locations where the Technology has been applied and which are covered by this assessment

Country:

Norway

Region/ State/ Province:

Viken county

Further specification of location:

The Vansø - Hobøl catchment

Specify the spread of the Technology:

• applied at specific points/ concentrated on a small area

Is/are the technology site(s) located in a permanently protected area?

No

Comments:

Here we show only some example locations within the Kråkstad catchment

Map

×

2.6 Date of implementation

If precise year is not known, indicate approximate date:

• 10-50 years ago

2.7 Introduction of the Technology

Specify how the Technology was introduced:

• during experiments/ research

• SMIL (Special Environmental measures in agriculture)

Comments (type of project, etc.):

Constructed wetlands are part of SMIL subsidy system (Special Environmental measures in Agriculture)

3.1 Main purpose(s) of the Technology

• protect a watershed/ downstream areas – in combination with other Technologies
• adapt to climate change/ extremes and its impacts
• mitigate climate change and its impacts

3.2 Current land use type(s) where the Technology is applied

Land use mixed within the same land unit:

No

Cropland

• Annual cropping

Annual cropping - Specify crops:

• cereals - other

• small grains

Number of growing seasons per year:

• 1

Specify:

Longest growing period in days: 135. Longest growing period from month to month: May to mid September

Is intercropping practiced?

No

Is crop rotation practiced?

No

Forest/ woodlands

• Natrual forest

Waterways, waterbodies, wetlands

• Drainage lines, waterways

3.3 Has land use changed due to the implementation of the Technology?

Has land use changed due to the implementation of the Technology?

• No (Continue with question 3.4)

Waterways, waterbodies, wetlands

• Ponds, dams
• Swamps, wetlands

3.4 Water supply

Water supply for the land on which the Technology is applied:

• rainfed

3.5 SLM group to which the Technology belongs

• surface water management (spring, river, lakes, sea)
• wetland protection/ management

3.6 SLM measures comprising the Technology

structural measures

• S5: Dams, pans, ponds

3.7 Main types of land degradation addressed by the Technology

water degradation

• Hp: decline of surface water quality

3.8 Prevention, reduction, or restoration of land degradation

Specify the goal of the Technology with regard to land degradation:

• prevent land degradation
• reduce land degradation

4.1 Technical drawing of the Technology

4.2 General information regarding the calculation of inputs and costs

Specify how costs and inputs were calculated:

• per Technology unit

other/ national currency (specify):

NOK

If relevant, indicate exchange rate from USD to local currency (e.g. 1 USD = 79.9 Brazilian Real): 1 USD =:

8.89

4.3 Establishment activities

4.4 Costs and inputs needed for establishment

If you are unable to break down the costs in the table above, give an estimation of the total costs of establishing the Technology:

87500.0

If land user bore less than 100% of costs, indicate who covered the remaining costs:

The landowners can apply for subsidies to establish and maintenance constructed wetland (70% support of the cost), within SMIL system (Special Environmental measures in Agriculture). Local county authorities are responsible for the administration of these schemes.

Comments:

The information about cost are coming from Blankenber et al (2016):

During a period of 20 years (1994 - 2014) the government has spent in total about 88 million Norwegian crowns (NOK) to subsidize the CWs for agricultural runoff, and total
costs are assumed to be about 150 mill NOK. Costs per CW varies from about 26.000 NOK to 124.000 NOK, and average cost per CW is approximately 87.500 NOK.

4.5 Maintenance/ recurrent activities

4.6 Costs and inputs needed for maintenance/ recurrent activities (per year)

If you are unable to break down the costs in the table above, give an estimation of the total costs of maintaining the Technology:

41000.0

If land user bore less than 100% of costs, indicate who covered the remaining costs:

The landowners can apply for subsidies to establish and maintenance constructed wetland (70 % support of the cost), within SMIL system (Special Environmental measures in Agriculture). Local county authorities are responsible for the administration of these schemes.

Comments:

The information is coming from (Hauge et al 2008):

The cost of maintenance of CWs estimated based n data from 2008 from 16 ponds established or planned in Morsa water region (that includes Kråkstad catchment). The (estimated) costs varied from 5,67 NOK/m2 of water surface area up to 49 NOK/m2 of water surface area

Given number of 41000 NOK is calculated for SKuterud CW (2300 m2 of water surface area).

4.7 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

The most important factor affecting the costs of constructed wetland is the size. Larger constructed wetlands have lower establishment costs per m2 of water surface area. In terms of operating costs for capture ponds - mainly emptying the sedimentation pond - it is assumed that the cost per emptying is more or less independent of the size of the sedimentation pond. This is because a large component in the emptying cost is assumed to be the transport of the machinery and the removal of the excavated mass.

The landowners can apply for subsidies to establish and maintenance constructed wetland (70% support of the cost), within SMIL system (Special Environmental measures in Agriculture). Local county authorities are responsible for the administration of these schemes.

5.1 Climate

5.2 Topography

Indicate if the Technology is specifically applied in:

• not relevant

5.3 Soils

5.4 Water availability and quality

Is water salinity a problem?

No

Is flooding of the area occurring?

Yes

Regularity:

frequently

5.5 Biodiversity

5.6 Characteristics of land users applying the Technology

Indicate other relevant characteristics of the land users:

Population density: < 10 persons/km2
Annual population growth: < 0.5%
10% of the land users are rich and own 10% of the land.
90% of the land users are average wealthy and own 90% of the land.

5.7 Average area of land used by land users applying the Technology

5.8 Land ownership, land use rights, and water use rights

Land ownership:

• individual, titled

Land use rights:

• communal (organized)
• individual

Water use rights:

• open access (unorganized)

5.9 Access to services and infrastructure

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

Ecological impacts

Water cycle/ runoff

Soil

Biodiversity: vegetation, animals

6.2 Off-site impacts the Technology has shown

6.3 Exposure and sensitivity of the Technology to gradual climate change and climate-related extremes/ disasters (as perceived by land users)

Gradual climate change

Gradual climate change

Climate-related extremes (disasters)

Hydrological disasters

6.4 Cost-benefit analysis

How do the benefits compare with the establishment costs (from land users’ perspective)?

How do the benefits compare with the maintenance/ recurrent costs (from land users' perspective)?

6.5 Adoption of the Technology

• 1-10%

Of all those who have adopted the Technology, how many did so spontaneously, i.e. without receiving any material incentives/ payments?

• 0-10%

Comments:

Adaptation of technology is stimulated by subsidies scheme.
Subsidies for the establishment of constructed wetlands are part of the SMIL system (Special Environmental Measures in Agriculture). Both the initial investment for construction and
subsequent maintenance may be paid by subsidies (70% support of the cost). During the period from 1994 to 2012 subsidies for in total 941 sedimentation ponds and constructed wetlands were given in Norway (Greipsland, 2016)

6.6 Adaptation

Has the Technology been modified recently to adapt to changing conditions?

No

6.7 Strengths/ advantages/ opportunities of the Technology

6.8 Weaknesses/ disadvantages/ risks of the Technology and ways of overcoming them

7.1 Methods/ sources of information

7.2 References to available publications

Title, author, year, ISBN:

Hauge A., Blankenberg A-G. B., Hanserud O.H. 2008. Evaluering av fangdammer som miljøtiltak i SMIL. Bioforsk Rapport Vol. 3 Nr. 140 2008.

Available from where? Costs?

https://evalueringsportalen.no/

Title, author, year, ISBN:

Blankenberg A-G.B., Paruch A.M., Paruch L., Deelstra J., Haarstad K. 2016. Nutrients tracking and removal in constructed wetlands treating catchment runoff in Norway. In: Vymazal J. (ed) Natural and Constructed Wetlands. Springer International Publishing Switzerland, pp. 23-40. DOI 10.1007/978-3-319-38927-1_2

Available from where? Costs?

Springer Book

Title, author, year, ISBN:

Krzeminska D., Blankenberg A-G., Bechmann M. Deelstra J. 2021. Effekt av fangdam i et endret klima. NIBIO-rapport;7(101)2021

Available from where? Costs?

NIBIO website

Title, author, year, ISBN:

Greipsland I.2016. Norwegian policy and practices regarding mitigation measures in agriculture.

Available from where? Costs?

NIBIO website

7.3 Links to relevant online information

Title/ description:

Hauge A., Blankenberg A-G. B., Hanserud O.H. 2008. Evaluering av fangdammer som miljøtiltak i SMIL. Bioforsk Rapport Vol. 3 Nr. 140 2008.

URL:

https://evalueringsportalen.no/evaluering/evalueringen-av-fangdammer-som-miljotiltak-i-smil/Rapport%20Evaluering%20av%20fangdammer%20-%20Bioforsk%20Jord%20og%20Milj%C3%B8.pdf/@@inline

Title/ description:

Krzeminska D., Blankenberg A-G., Bechmann M. Deelstra J. 2021. Effekt av fangdam i et endret klima. NIBIO-rapport;7(101)2021

URL:

https://nibio.brage.unit.no/nibio-xmlui/bitstream/handle/11250/2757116/NIBIO_RAPPORT_2021_7_101.pdf?sequence=4&isAllowed=y

Title/ description:

Greipsland I.2016. Norwegian policy and practices regarding mitigation measures in agriculture.

URL:

https://nibio.brage.unit.no/nibio-xmlui/bitstream/handle/11250/2387569/NIBIO_POP_2016_2_21.pdf?sequence=3&isAllowed=y