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

Name of project which facilitated the documentation/ evaluation of the Technology (if relevant)

Preventing and Remediating degradation of soils in Europe through Land Care (EU-RECARE )

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)

Wageningen Environmental Research (Alterra) - Netherlands

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)

Provincie Holland Zuid - Netherlands

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)

Provincie Utrecht - Netherlands

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)

LTO NOORD - Netherlands

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)

Waterschap Amstel, Gooi en Vecht - Netherlands

1.3 Conditions regarding the use of data documented through WOCAT

When were the data compiled (in the field)?

30/10/2015

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

Yes

2.1 Short description of the Technology

Definition of the Technology:

Submerged drains are drains installed in grassland on peatsoils with the aims to decrease soil subsidence and emission of CO2 and N2O due to the oxidation of peat soil, and to maintain suitable groundwater levels in fields for grassland production and grazing.

2.2 Detailed description of the Technology

Description:

Contrary to usual drains, submerged drains are installed below ditchwater level. Submerged drains diminish the differences between ditch level and groundwater level in the fields by enabling the infiltration from ditch to field and the drainage from field to ditch.
In summer and dry periods the infiltration from ditch to field is much lower than the evapotranspiration of the grass, resulting in a lowering of the groundwater level some decimetres below ditch water level. With submerged drains the groundwater level is lowered less drastically because infiltration from ditch to field is improved. In winter and wet periods, fields are drained
more quickly compared to conventional drainage.

Purpose of the Technology: Submerged drains diminish the differences between ditch level and groundwater level in the fields by enabling the infiltration from ditch to field and the drainage from field to ditch. Under peak rainfall events groundwater levels become less high and remain at high levels for shorter times than in fields without submerged drains.
Due to the increased groundwater level in summer the decomposition of the peat soil is reduced. As a result, the rate of soil subsidence is decreased and also the emission of greenhouse gases and of N and P released to the surface water.

Establishment / maintenance activities and inputs: The installation of submerged drains is done with common drainage installation machines. Submerged drains should be installed between 15 and 25 cm below the ditch water level, and between 45 and 75 cm below the soil surface. The drain pipes should have a diameter of at least 6 cm. The distance between drains is at most 6 m. Drain length is at most 300 m. Submerged drains can be installed in the length or width direction of a field. Drains must be installed level.

Natural / human environment: Submerged drains were designed for peat soils under permanent pasture for dairy farming. More than 70 % of Dutch peat soils are under this land use. Drainage of these peat soils results in subsidence, mainly by decomposition (oxidation) of the peat (partly by shrinkage and consolidation). This is an ongoing process, because every 10 to 15 year ditchwater levels are adapted to the lowered surface in order to enable dairy farming and to prevent the conversion to wetlands. Soil subsidence causes several problems: decreased suitability for grazing and grassland farming, increased flood risk, emission of greenhouse gases, damage to infrastructure (dikes, roads, foundations, sewerage networks) and increased cost of water management.

Submerged drains were tested with a network of practitioners and 10 dairy farmers in the Dutch peat soil area between 2011 and 2013 on an area of 20 ha.

2.3 Photos of the Technology

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

2.6 Date of implementation

If precise year is not known, indicate approximate date:

• less than 10 years ago (recently)

2.7 Introduction of the Technology

Specify how the Technology was introduced:

• during experiments/ research
• through projects/ external interventions

• stimulated by regional authorities

Comments (type of project, etc.):

Since 2003 submerged drains have been applied on several experimental farms in The Netherlands. Implementations over larger areas (i.e. a water management unit, 'peilval' in Dutch) will be done in 2016.

2007: research on soil subsidence in the Western peat area following the large scale groundweter level lowering in the 1960s and 1970s signalled the high rate of soil subsidence (5-12 mm/y) (Van den Akker et al., 2007a)

2008: concerns about soil subsidence in the western peat area from the provincial autorities of Noord-Holland, Utrecht and Zuid-Holland in the policy document 'Voorloper Groene Hart' (2008)

2008-2012: various research projects to test the effectiveness of submerged drains to reduce soil subsidence and to improve conditions for dairy farming, and on the effects for water quality: www.waarheenmethetveen.nl, Hoving et al. (2008), Woestenburg (2009), EU project EUROPEAT, Woestenburg et al. 2009; Jansen et al., 2010; Hendriks and Van den Akker, 2012; Hoving et al. (2008, 2009, 2013)

2011-2012: research on the Peat Area Innovation Centre (VIC) to test effects of submerged drainage in combination with dynamic groundwater level management (Hoving et al., 2013)

2012- testing by research instsiutes of economic viability of submerged drains with regard to water level management and agricultural productivity, on assignment of the province Noord-Holland, waterboard Hollands Noorderkwartier.

2009-2011: various modelling studies assigned by the provinces and water boards of the western peat meadow area on the effects of submerged drains for the demand for inlet and discharge of water and effects on the decomposition of peat and the water quality.

2011: model research on effects of submerged drains on the water demand of the western peat area until 2050 under climate change (Van den Akker et al., 2011)

2010-2013 experimental research in 3 pilots initiated by the province of Utrecht and Zuid-Holland, four water boards and the farmers' organisation LTO Noord. Aim: to test if the application of submerged drains results in larger amounts of water to supply and to discharge from the peat meadow area, and to test if the submerged drains result in a larger load of nutrients to ditches,

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

Comments:

Major land use problems (compiler’s opinion): The major land use problems in the Western Dutch peat soil area is soil subsidence due to the lowering of the groundwater level in the 1960s and 1970s. The soil subsidence amounts to 0-2.5 cm per year. It is mainly caused by the oxidation of peat soil, which releases nutrients to soil and surface water, and CO2 and N2O to the atmosphere. The soil subsidence causes several problems:
- damage to buildings and infrastructure
- increasing costs of water management: high groundwater levels require pumping of water to enable agricultural use, and storage of rainfall excess water during peak rainfall events
- drainage of nature reserves to lowered agricultural land
- water pollution: the lowering of the groundwater level causes upward seepage of nutrient-rich water to polders
- greenhouse gas emissions (2-3% of total CO2 emissions in The Netherlands)
- loss of peat soils (2% per year in the NL)
- increased flood risk (due to combination with sealevel rise)

Major land use problems (land users’ perception): Grassland and arable farming are hampered by high groundwater levels due to a lowered bearing capacity and too wet conditions for crops. Maintaining the groundwater level at a level high enough to prevent the decomposition of peat soil would imply a conversion to wetlands and forest swamps. This is not acceptable to various kinds of land users (nature managers, farmers, users of built-up area). This would also mean the loss of the cultural historic open landscape and habitat for meadow birds, strongly reduced economic possibilities and an increased demand of water from the rivers (view of water managers and governments).

Future (final) land use (after implementation of SLM Technology): Grazing land: Gi: Intensive grazing/ fodder production

If land use has changed due to the implementation of the Technology, indicate land use before implementation of the Technology:

Grazing land: Gi: Intensive grazing/ fodder production

3.3 Further information about land use

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

• rainfed

Specify:

Longest growing period in days: 270Longest growing period from month to month: April-October

Livestock density (if relevant):

> 100 LU /km2

3.4 SLM group to which the Technology belongs

• water diversion and drainage
• ground water management

3.5 Spread of the Technology

Comments:

Total area covered by the SLM Technology is 0.054 m2.

The measure was tested in three pilots in the areas Krimpenerwaard, Keulevaart and Demmerkiksekade. Each pilot covered two fields: one with submerged drains and one without. The area given refers to the pilot in the Krimpenerwaard.

3.6 SLM measures comprising the Technology

Comments:

Main measures: management measures

Specification of other management measures: maintaining high groundwater level

3.7 Main types of land degradation addressed by the Technology

Comments:

Main type of degradation addressed: Cn: fertility decline and reduced organic matter content, Ps: subsidence of organic soils, settling of soil

Secondary types of degradation addressed: Pw: waterlogging, Hg: change in groundwater / aquifer level, Hp: decline of surface water quality

Main causes of degradation: other human induced causes (specify) (lowering of the groundwater level to enable agricultural use of the peat soils results in soil subsidence and detioration of ground- and surface water quality due to capillary rise)

Secondary causes of degradation: change in temperature (higher temperatures under climate change increase the decomposition rate of peat soil; subsidence and CO2 emissions will increase by 75%), change of seasonal rainfall (decrease in summer rainfall (23% in warm and dry CC scenario for NL)), inputs and infrastructure: (roads, markets, distribution of water points, other, …) (maintenance of high water levels in built-up and natural areas increases the difference in groundwater level with agricultural land onb peat soils)

3.8 Prevention, reduction, or restoration of land degradation

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

• reduce land degradation

4.1 Technical drawing of the Technology

4.2 Technical specifications/ explanations of technical drawing

The picture shows a cross section through an agricultural field, bounded by two ditches. A submerged drain (yellow bar in the picture) is installed at 80 cm below the soil surface. It ends in the ditch on the left side at 20 cm below the water level in the ditch. The dotted line indicates the position of the groundwater table in the situation without the submerged drain; the continuous blue line indicates the position in the situation where the submerged drain is installed. The lines show that in summer the groundwater level is raised to nearly the level of the ditch water by the submerged drain, whereas the level would be approximately 30 cm lower without the drain.
In winter, in the situation with the submerged drain, the groundwater level is around 40 cm below the soil surface. This enables the farmer to use the field for grazing or to traffic the field. However, in the situation without the drain, the groundwater level nearly reaches the soil surface in the centre of the field, impeding traffic or grazing on the field.

Technical knowledge required for field staff / advisors: moderate (Estimates of economic benefits due to increased grass production and grazing periods vary between years with meteorological conditions.)

Technical knowledge required for land users: moderate (Specific conditions apply to the dimensions and positioning of submerged drains in the fields. Level position and lebgth are critical.)

Technical knowledge required for companies installing the drains: moderate (Specific conditions apply to the dimensions and positioning of submerged drains in the fields. Level position and lebgth are critical. Soil must have sufficient bearing capacity during installation.)

Technical knowledge required for water board: moderate (submerged drains increase the water supply and discharge from groundwater level management units. Additional pumping effort can be prevented by informed water level management.)

Technical knowledge required for researchers: (the implications of submerged drains on the water management in an entire management unit should be explored using coupled hydraulic and rainfall-runoff models.)

Main technical functions: improvement of topsoil structure (compaction), maintaining soil organic matter

Secondary technical functions: increase of infiltration, increase / maintain water stored in soil, drainage of excess rainfall

Other type of management: Maintaining high groundwater levels.

4.3 General information regarding the calculation of inputs and costs

other/ national currency (specify):

euro

Indicate exchange rate from USD to local currency (if relevant): 1 USD =:

1.09

4.4 Establishment activities

	Activity	Type of measure	Timing
1.	maintenance of drains and outlet in ditch	Structural
2.	installation of submerged drains	Management	in dry periods

4.5 Costs and inputs needed for establishment

	Specify input	Unit	Quantity	Costs per Unit	Total costs per input	% of costs borne by land users
Labour	maintenance of drains and outlet in ditch	ha	1.0	30.14	30.14	100.0
Labour	installation of submerged drains	ha	1.0	1980.0	1980.0	100.0
Total costs for establishment of the Technology					2010.14

Comments:

Lifespan of the drains: 30 years

4.6 Maintenance/ recurrent activities

	Activity	Type of measure	Timing/ frequency
1.	maintenance of submerged drains	Management	several times in lifetime of drains (30 y)

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

	Specify input	Unit	Quantity	Costs per Unit	Total costs per input	% of costs borne by land users
Other	Annual cost incl maintenance	ha	1.0	127.0	127.0	100.0
Total costs for maintenance of the Technology					127.0

Comments:

Machinery/ tools: establishment and installation require specific skills and machinery; hired, not done by the farmer himself

Investment costs of 1500-1800 €/ha are based on submerged drains at 6 m distance. Costs per m of drain establishment based on drains of 6 cm diameter. Costs based on practical experience from farmers. Drains may have a lifetime of 30 years and require little maintenance.

Specific skills and machinery are required for installation and maintenance, hired from a drainage company. The farmer must only ensure that the outlets of the drains in the ditches remain open and undamaged.

4.8 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

We do not have information on specific cost items, only on establishment costs ad between 1500 and 1800 euro/ha, and annual cost of 117 €/ha incl maintenance, assuming a 20-year life time. Establishment costs can also be expressed per m of drain, i.e. 1.10 EURO per m including materials (drain of 6 cm diameter).

Determinate factors include size and geometry of fields; installation in the length direction is cheaper, and results in fewer outlets in the receiving ditch.

5.1 Climate

5.2 Topography

Comments and further specifications on topography:

Altitudinal zone: 0-100 m a.s.l. (Submerged drains are designed for polders in lowland areas on peat soils)
Landforms: Plateau/plains (submerged drains are designed to drain level fields)
Slopes on average: Flat (submerged drains are designed to drain flat terrain, based on hydraulic prressure head differences between field and ditch)

5.3 Soils

If available, attach full soil description or specify the available information, e.g. soil type, soil PH/ acidity, Cation Exchange Capacity, nitrogen, salinity etc.

Soil depth on average: Very deep (if the peat substrate is considered as part of the soil profile, soils are deeper than 120 cm, with peat packages up to 13 m in some parts of the western Dutch peatland area) and shallow (If the top of the C-horizon is considered as the bottom of the soil profile. C-horizons typically start at 15-30 cm below the soil surface)
Soil texture is fine/heavy (for peat soils with a clayey top layer. In peat soils without such a top layer, a soil texture indication is not applicable. Peat soils are defined as having at least 40 cm of peat in the top 80 cm)
Soil fertility is very high (peat soils are able to supply ample nutrients to plants provided that they are well drained)
Topsoil organic matter is high (Organic matter contents in the topsoil are above 20%. Peat soils are defined as having at least 40 cm of peat in the top 80 cm according to the Dutch soil classification system)
Soil drainage/infiltration is poor/none (peat soils inherently have poor drainage due to their low position with reference to the groundwater level in the regional water system. Values of Ksat reported 2.9-5.0 cm/d)
Soil water storage capacity is very high (the soil water storage capacity is very high due to the large pore space (0.70-0.90 m3/m3))

5.4 Water availability and quality

Comments and further specifications on water quality and quantity:

Ground water table: <5m (Average lowest grondwater level in the pilot region is 5-10 cm below the soil surface; average highest level 55-65 cm)
Availability of surface water is good (surface water is amply available due to the low position of the peat soil area compared to the mean sea level, and due to the dense network of ditches and other surface water conveyors and bodies) and excess (surface water levels are under continuous control by the water boards. Therefore flood situations do not occur, but under high-intensity rainfall events fields may submerge)
Water quality (untreated) is for agriculutral use only (Irrigation, surface and groundwater can be used for agriculture without treatment. Nutrient rich water emerging by capillary rise in polders may not be suitable for nature.)
Biodiversity is medium (the grasslands in the western peatsoil area are suitable habtitats for meadow birds)

5.5 Biodiversity

5.6 Characteristics of land users applying the Technology

Indicate other relevant characteristics of the land users:

Difference in the involvement of women and men: Executives of agricultural enterprises in The Netherlands are usually men.
Population density: 200-500 persons/km2
Annual population growth: 1% - 2%
100% of the land users are average wealthy and own 100% of the land.
Off-farm income specification: Dairy farmers in this part of The Netherlands spend 100% of their time on the farm. Sometimes their wives have jobs earning off-farm income.
Market orientation is commercial/market (intensive dairy farming in the NL produces for the market)

5.7 Average area of land owned or leased by land users applying the Technology

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

Land ownership:

• individual, titled

Land use rights:

• individual

Water use rights:

• leased

5.9 Access to services and infrastructure

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

Income and costs

Other socio-economic impacts

Socio-cultural impacts

Ecological impacts

Water cycle/ runoff

Soil

Biodiversity: vegetation, animals

Climate and disaster risk reduction

Other ecological impacts

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

	Season	Type of climatic change/ extreme	How does the Technology cope with it?
annual temperature		increase	well

Climate-related extremes (disasters)

Meteorological disasters

	How does the Technology cope with it?
local rainstorm	well
local windstorm	well

Climatological disasters

	How does the Technology cope with it?
drought	not known

Hydrological disasters

	How does the Technology cope with it?
general (river) flood	well

Other climate-related consequences

Other climate-related consequences

	How does the Technology cope with it?
reduced growing period	well

Comments:

Under extreme rainfall events, submerged drains cannot prevent that the groundwater level rises to above the soil surface. However, the groundwater level will fall more quickly with submerged drainas than without, on average to 10 cm lower levels.

Effects of dry summers have not yet been measured in experiments.

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)?

Comments:

A longer grazing season and the extra yield of fodder are the basis for a viable implementation of submerged drainage for land users. The CBA considers establishment and maintenance costs together: establishment costs of € 1800,-/ha, discounted over 20 years, including maintenance, result in annual cost of € 117,-/ha (6.5% of the investment). Benefits include 500 kg DM/ha extra grass use and 30 extra grazing days. This would yield € 171/ha, resulting in a net saldo of € 54,-. In addition SMD are an investment in sustainable soil management, resulting in an increased economic value of the land in the long term.

6.5 Adoption of the Technology

If available, quantify (no. of households and/ or area covered):

13

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

• 90-100%

Comments:

13 land user families have adopted the Technology without any external material support

Comments on spontaneous adoption: The area under submerged drainage implemented by the 10 dairy farmers from the Community of Practice is 20 ha. The area under SMD in the three pilots described in this questionnaire is roughly an additional 0.05 km2 per farm.

There is a moderate trend towards spontaneous adoption of the Technology

Comments on adoption trend: Due to the growing interest in the peat soil area because of the relevance for climate mitigation and the economic risks of soil subsidence there is growing interest in SMD in combination iwth dynamic groundwater level management to reduce the rate of soil subsidence. Subsidy arrangements are in preparation, which will stimulate adoption of the technology by more dairy farmers.

6.7 Strengths/ advantages/ opportunities of the Technology

Strengths/ advantages/ opportunities in the land user’s view
Submerged drains increase the number of days with a good bearing capacity of grassland, and therefore enable a longer grazing season and less trampling of grass.
Higher effective yield in total.
Short term: slightly cost effective. Long term: good cost effective.

Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view
Submerged drains allow a strong reduction of soil subsidence and GHG emissions (at least 50%, even >50% if combined with higher ditch water levels). How can they be sustained / enhanced? Further implementation by dairy farmers in the peat-meadow area. For this purpose the Community of Practice is recommended, as well as the arrangement of subsidies and the active involvement of regional government and water board. This applies to all mentioned advantages.
The quality of surface water in ditches will slightly improve.
Less problems with difference between subsiding soil surfaces and constant water levels in lakes and high water ditches (along houses).
Less sub-polders with a certain fixed ditch water level, and possibility to create areas with a high surface level (with submerged drains) and a low surface level (without SD).

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

Weaknesses/ disadvantages/ risks in the land user’s view	How can they be overcome?
Grass yield is lower due to reduced mineralization of nitrogen.	Yield could be increased due to better usage of manure (better NUE). On the other hand yield is increased due to increased number of days with a good bearing capacity of grassland, and a longer grazing season and less trampling of grass.

Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view	How can they be overcome?
Submerged drains require more inlet water to polders.	Reduction of inlet requirement is possible by smart water management. This implies water level margins of +/- 10 cm and the use of weather forecasting.
Submerged drains require a bit more pumping to drain water under extreme rain events.

7.2 References to available publications

Title, author, year, ISBN:

Several reports on submerged drainage are available from Alterra, Wageningen UR (in Dutch). The report used for this WOCAT QT is:Effecten van onderwaterdrains in peilvak 9 van polder Groot-Wilnis Vinkeveen : modelstudie naar de effecten van onderwaterdrains op maaivelddaling, waterbeheer, wateroverlast en waterkwaliteit in peilvak 9 Author(s)Hendriks, R.F.A.; Akker, J.J.H. van den; Jansen, P.C.; Massop, H.Th.L. SourceWageningen : Alterra Wageningen UR, 2014 (Alterra-rapport 2480) - p. 124Other literature (in Dutch): Waarheen met het veen. Woestenberg, M. 2009. Uitegeverij Landwerk and Alterra, Wageningen URhttp://www.levenmetwater.nl/static/media/files/Boek_wmhv_def.pdf

Available from where? Costs?

Alterra Reports are available atlibrary.wur.nl