By Bioforsk SEALINK Team

Transkript

1 By Bioforsk SEALINK Team Csilla Farkas Annelene Pengerud Hans Olav Eggestad Johannes Deelstra Per Stålnacke SEALINK Meeting March, 2009 NIVA CIENS, Oslo, Norway

2 Providing appropriate INCA-N parameter set for agricultural lands in Southern Norway, using the advantage of a well-studied catchment (further used as initial parameter set for arable lands of the Vansjø catchment) Performing scenario analyses to investigat the effect of varioius land use change scenarios on instream water quantity and quality Total area km 2 Low base flow and high flashiness index Subsurface drainage system Productive forest

3 Calibration period: 1 January, December, 1998 To set up the parameters for all the land use types, except the wetland Validation period: 1 January, December, 2007 Setting up wetland parameters Land use types: Forest (31%) Grass (2%) Arable, No Autumn Tillage (18%) Arable, Autumn Tillage (41%) Wetland (0% between ; to be parameterised for the period of ) Urban (8%) Catchment structure No subcatchments, one reach No effluent No abstraction

4 1. Catchment and reach information Catchment area, reach length 2. Data on fertiliser application NO3 fertilisation input files 3. Crop data Multiple growth period input files 4. Soil data From reference soil profiles, belonging to the agricultural area Soils of the forest area were represented by a chosen reference soil profile from an arable land Setting up parameters (soil water deficit maximum; total/available water)

5 1. Driving variables HBV model run output, provided by NVE Soil moisture deficit; effective rainfall; air temperature; precipitation 2. Reference data Discharge measurements (daily data) Nitrate concentration data (composite sampling; approx. every 14 days)

6 1. Flow R 2 and N-S has to be comparable with those, obtained from the HBV runs Peculiarities of a small catchment, with high agricultural impact and productive forest have to be considered Subsurface drainage system effect has to be considered 2. Nitrate concentration Composite sampling and model outputs comparability Efforts to re-calculate the simulated nitrate concentrations

7 1. Parameterisation Available data from the Skuterud catchment and reach Literature review Expert assumptions 2. Calibration procedure Stepwise calibration approach (flow; flow&nitrate) flow flow&nitrate Incorporation of sensitivity analyses results 3. Validation procedure 4. Scenario analyses

8 1. Main hydrological parameters, against which the model appeared to be very sensitive Flow parameters a and b (from the discharge velocity relationship) Base flow index Soil moisture deficit maximum Soil reactive zone time constant Ratio of total to available water in soil

9 Velocity v (m s -1 ) Velocity v (m s -1 ) The relationship: v aq b Manningen: Q s A R s n Q s - Stream discharge (m 3 ) A - Wetted cross section (m 2 ) P - Wetted perimeter (m) R - Hydraulic radius = A/P (m) S - Slope of stream (m/m) n - Roughness parameter, varying between n = y = 1.163x R² = Discharge Q (m 3 ) 1.6 n = Skuterud_real Discharge Q (m 3 )

10 a=1.163; b=0.253 a=0.042; b= sim. - obs.

11 Velocity (v, m s -1 ) 2.0 v = a * Q ^b n(0.025)_real n(0.045)_real n(0.075)_real n(0.025)_calib n(0.045)_calib n(0.075)_calib Discharge (Q, m 3 )

12 Base flow index: 0.19 Soil moisture deficit maximum: forest: 320; grass: 300; no till: 280; till: 250; urban: 100 Ratio of total to available water in soil Soil profile Soil layer Water content at saturation Plant-available water Ratio of total to plant-available water (-) Average ratio Location or land use (SKU 001) (SKU 002) (SKU 003) C2 (Pestrisk) (cm) (v%) (v%) (-) (-) Cereal Cereal Cereal BUT under forest also Direct drilling, farm

13 Parameter name Specific heat capacity due to freeze/thought Maximum temperature difference Degree day factor for snowmelt Thermal conductivity of soil Thermal properties Forest Ref Grass Ref Arable Ref Urban Ref. min max initial min 2 2, 4 2 2, 4 2 2,4 2 2,4 max initial min max initial min min Initial Rankinen et al., 2004a 2. Rankinen et al., 2004b 3. Ranzini et al., Savijoki input file 5. Tamar input file

14 Soil water denitrification rate Nitrogen fixation rate Plant uptake rate nitrate Maximum nitrogen uptake rate Ammonium nitrification rate Ammonium mineralisation rate Ammonium immobilisation rate Plant uptake rate / ammonium Forest Ref. code Grass Ref. code Arable Ref. code Urban m day -1 min , , ,5 0 4 kg ha -1 day -1 max ,3, ,6 initial min ,3 0 1,3 0 1,3 0 2,6 max , ,6 initial m day -1 min kg ha -1 max 0.1(3.5) 5(3) , ,6 initial day -1 min ,6 min 70 4, Initial Ref. code m day -1 min ,5,6 kg ha -1 day -1 max 0.8 5, , initial min ,5,6 max , initial m day -1 min max ,6 initial m day -1 min min 0.12(4.5) 3(6) ,6 Initial Granlund et al., 2004; 2. Manuscript_1; 3. Savijoki input file 4. Wade et tal., 2002; 5. Whitehead et al., 1998; 6. Tamar input file; 7. SOILN_NO

15 starting "0" param. File Skuterud flow a Skuterud flow b Skuterud base flow index Skuterud groundwater residence time Forest soil reactive zone time constant NoAutumT soil reactive zone time constant AutumT soil reactive zone time constant Reach Reach Catchment Catchment Land Use Land Use Land Use R2 R2 K-S_ _Hydr K-S_ _H&N Using calculated a, b as initial; changing base flow flow nitrate Fixed flow parameters "a" and "b" Fixed flow parameters "a" and "b" and fixed base flow index

16 - sim. - obs.

17 Nitrate as nitrogen (mg N / l) results obtained after adjusting INCA-N output to the ideology of composite sampling Measured Simulated

18 Simulated: app. 31 kg N /ha /year for Measured: 39 kg N/ ha /year for

19

20 Improved driving variables from new precipitation data NVE How to parameterise land use parameters further? Differentiation? Presentation from Johannes

21 Thank you for attention!