Water Management of grasslands in Europe and the economic interface

Transcription

1 Enhancing economic viability of grasslands by green farming in Europe, International Workshop, Plosti, Latvia, May, 2015 Water Management of grasslands in Europe and the economic interface Examples from The Netherlands, Germany and Czech Republic Henk Ritzema & Jakub Stibinger

2 Definitions for grasslands Permanent grasslands 1. Agriculturally-improved permanent grasslands 2. Semi-natural grasslands 2.1 Pastures, including rangelands, rough grazing, wood pastures, etc Sole use Common land 2.2 Traditional hay meadows 3. Permanent grasslands no longer used for production Huyge et at,

3 Examples of water management Controlled drainage of grasslands: 1) the Netherlands: intensive agriculture 2) the Netherlands: recreation 3) Germany: extensive agriculture and nature 4) Czech Republic: reducing peak runoff rates 3

4 The Netherlands Area: 34,000 km 2 Elevation: 50% below sea level Agriculture: 60% Urban area: 15% Surface water: 15% Woods / nature: 10% Population: 16.8 million (470 per km 2) 65% of the Netherlands would be flooded in absence of dikes Cattle Pigs Poultry 3.7 million 10 million 80 million

5 Thus pumping is needed for drainage Traditional: windmills Now: pumping stations

6 The Netherlands: need for drainage Drainage requirements: Winter/early spring: excess rainfall drainage to enable land preparation in early spring. Summer: rainfall deficit only drainage after heavy rainstorms and sometimes supplementary irrigation Oosterbaan, 2005

7 New paradigm: three step approach in drainage Ritzema and Stuyt, 2015

8 Controlled drainage: Reduction of peak discharge Drain discharges in Pilot Area Rilland Precipitation controlled gravity Field research : Reduction in peak discharge rate: 5-28% Depending on soil & hydrological conditions Kselik and Stuyt, 2013

9 Nitrogen disposal in drainage discharge Results Rusthoeve Pilot Area ( ): 75% of the N-gifts is used by the crop 10-15% de-nitrification 10-15% disposed via drainage water Stuyt et al 2013

10 Nature: Rewetting grassland on peat Woestenburg,

11 Water management scenarios for rewetting Existing water management Scenario I: 1 unit Scenario II: 2 units 2 units & subsurface drainage Woestenburg,

12 Example Bussloo: recreation Challenge: Constant water level Fluctuation in level > 1 m

13 Germany: rewetting Lake Dümmer Confluence of Hunte and Dümmer 13

14 Germany: rewetting Lake Dümmer Drainage peat mineralisation decline of meadow birds Shrinkage of peat layer 14

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16 Polder approach: independent WM units Cut-off drain to divert runoff from intensive agricultural areas 16

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18 Czech Republic: reducing peak runoff rates Lubenec June 2013 small city on the Vltava River close to Prague

19 Concept of drainage retention capacity (DREC) One of many reasons of floods and waterlogging, besides other things, is very low infiltration ability and especially unsatisfactory drainage capacity of grassland surface layers in mountain landscape during period with precipitations (snow melting, heavy rains) Of course, good infiltration and drainage conditions of grassland surface layers in mountain landscape can t definitely eliminate floods and runoff, but can mitigate its negative impacts very strongly. Drainage Retention Capacity (DREC) of Grassland Surface Layers for Mitigation of Negative Impacts of Runoff

20 Creation of gravity water retention capacity in grassland profile corresponds to the social-economy cost of alternative measure water reservoir in a value of 15 EU / m 3 By Šišák L., Šach F., Švihla V., Pulkrab K., Černohous V., 2010: Methodology of Assessment of Social-Economic Functions in Nature (in Czech), ISBN , Publisher: CULS Prague. DREC = 71,5 mm, Horní Maxov meadow R (mm/day) By DREC is possible to obtain (approximately) values from 36mm to 93 mm, representative value can be 65 mm, which corresponds with 650 m 3 /ha. Corresponding cost of alternative measure water reservoir is about 650 m 3 /ha x 15 EU = 9750 EU/ha. Drainage system with DREC can be around 2000 EU /ha L (m) presented numbers and data would be served as base for economical assessment of water management in grassland areas in Czech Republic.

21 Runoff from grassland versus cereal farm land in connection with extreme runoff From a few hectares of flat area of wheat (after drought period) was measured extreme 50-years runoff 0.44 m 3 /sec (verified by hydrological models KINFIL, WBCM type). In a case of land-use change (grassland substitution) is approximately valid: Q( grass) Q( cereals ) C( grass) C( cereals ) v( grass) * v( cereals ) 0.31 * Q( grass) Q( cereals)* * m3/ sec Q(grass) = 0.23 m 3 /s Q(cereals) = 0.44 m 3 /s.presented numbers show that grassland in the case demonstrated above (in Czech Republic conditions) can significantly decrease the runoff peak and by this way mitigate negative impacts of hydrological extremes.

22 Examples of water management Controlled drainage of grasslands: 1) the Netherlands: intensive agriculture 2) the Netherlands: recreation 3) Germany: extensive agriculture and nature 4) Czech Republic: reducing peak runoff rates Benefits for the farmer: (1) more flexibility/workability (2) less fertilizers Benefits for the water manager: (1) reduction of peak runoff rates (2) less pollution 22

23 Water Management of grasslands in Europe and the economic interface Thanks Jakub & Henk 23