Table 4.
Parameters involved in the calibration with their range before and after calibration. The values in the bracket represent the average of calibrated values. For each parameter the related SWAT input file, the method of calibration (M = manual; SA = semi-automatic calibration using SUFI-2), and type of data used for calibration are reported.
| Module | Process | Parameter and input file | Definition | Unit | Range | Calibrated Range (average value) | Data used in calibration | Calibration method |
|---|---|---|---|---|---|---|---|---|
| Crop yields | Plant growth | HVSTI.crop | Crop harvest index for optimal growing conditions | NA | 0.02–2 | 0.04–2.5 (0.68) | EUROSTAT (2013) | M |
| Plant growth | T_OPT.crop | Optimal temperature for plant growth | oC | 12.5–30 | 12.5–30 (22.6) | EUROSTAT (2013) | M | |
| Plant growth | T_BASE.crop | Minimum/base temperature for plant growth | oC | 0–12 | 0 | EUROSTAT (2013) | M | |
| Water | Baseflow | ALPHA_BF.gw | Baseflow alpha factor | d | 0–1 | 0.26–0.98 (0.73) | Monthly streamflow | SA |
| Surface runoff | CN2.mgt1 | SCS runoff curve number for moisture condition II | NA | − 15–+15 e | − 15–+15 (10) | Daily surface runoff | SA | |
| Surface runoff | CH_N1.sub | Manning's value for tributary channel | NA | 0.025 - 0.30 | 0.01–0.14 (0.096) | Daily surface runoff | SA | |
| Tile drainage flow | DDRAIN.mgt1a | Depth to subsurface tile | mm | 0–2000 | 300–900 (687) | Monthly streamflow | SA | |
| Tile drainage flow | DEP_IMP.hrua | Depth to impervious layer | mm | 0–6000 | 1050–6000 (3100) | Monthly streamflow | SA | |
| Lateral flow | EPCO.hru | Plant evaporation compensation factor | NA | 0.01–1 | 0.01–0.94 (0.44) | Daily lateral flow | SA | |
| Lateral flow | ESCO.hru | Soil evaporation compensation factor | NA | 0.01–1 | 0.03–0.99 (0.57) | Daily lateral flow | SA | |
| Tile drainage flow | GDRAIN.mgt1a | Drainage lag time | hr | 0–100 | 1–40 (20) | Monthly streamflow | SA | |
| Baseflow | GW_DELAY.gw | Groundwater delay | d | 0–500 | 0.75–498 (41) | Monthly streamflow | SA | |
| Baseflow | GWQMN.gw | Threshold depth of water in the shallow aquifer required for return flow to occur | mm | 0–1000 | 5.5–991 (618) | Monthly streamflow | SA | |
| Baseflow | GW_REVAP.gw | Groundwater ‘revap’ coefficient | NA | 0.02–2 | 0.02–0.19 (0.06) | Monthly streamflow | SA | |
| Snow proecess | PLAPS.sub | Precipitation laps rate | mm/km | 0–100 | 0.97–64.7 (24) | Monthly streamflow | SA | |
| Baseflow | RCHRG_DP.gw | Groundwater recharge to deep aquifer | fr | 0–1 | 0.005–0.93 (0.09) | Monthly streamflow | SA | |
| Baseflow | REVAPMN.gw | Threshold depth of water in the shallow aquifer for revap to occur | mm | 0–500 | 0.25–443 (196) | Monthly streamflow | SA | |
| Snow melt | SFTMP.sno | Snowfall temperature | oC | − 5–+5 | − 1.57–1.11 (− 0.84) | Monthly streamflow | SA | |
| Snow melt | SMFMN.sno | Melt rate for snow on Dec 21 | mm H2O °C− 1 d− 1 | 0–10 | 0.09–9.66 (5.10) | Daily streamflow | SA | |
| Snow melt | SMFMX.sno | Melt rate for snow on Jun 21 | mm H2O °C− 1 d− 1 | 0–10 | 0.01–9.97 (4.36) | Daily streamflow | SA | |
| Snow melt | SMTMP.sno | Snowmelt base temperature | oC | − 5–+5 | − 0.17–2.53 (0.60) | Monthly streamflow | SA | |
| Lateral flow/Infiltration | SOL_AWC.sol | Available water capacity of the soil layer | fr | − 25–+25 | − 25–+25 (10) | Daily lateral flow | SA | |
| Lateral flow/Infiltration | SOL_K.sol | Saturated hydraulic conductivity | mm h− 1 | − 25–+25 | − 25–+25 (16) | Daily lateral flow | SA | |
| Snow melt | TIMP.sno | Snow pack temperature lag factor | 0.01–1 | 0.01–0.55 (0.18) | Monthly streamflow | SA | ||
| Snow melt | TLAPS.sub | Temperature laps rate | °C/km | − 10–0 | − 9.82 to − 1.83 (− 5.37) | Monthly streamflow | SA | |
| Tile drainage flow | RE.hru/.sdr | Effective radius of drains | mm | 5d–100 | 5–100 (52) | Monthly streamflow | SA | |
| Tile drainage flow | SDRAIN.hru/.sdr | Distance between two drain or tile tubes | mm | 7600–30,000 | 5060–27,700 (16020) | Monthly streamflow | SA | |
| Tile drainage flow | DDRAIN_CO.hru/.sdr | Drainage coefficient | mm/day | 10–51 | 6–50 (24) | Monthly streamflow | SA | |
| Tile drainage flow | LATKSATF.hru/.sdr | Multiplication factor to determine lateral ksat from SWAT ksat input value | NA | 0.01–4 | 0.09–3.4 (1.22) | Monthly streamflow | SA | |
| Nutrients | Denitrification | CDN.bsn | Denitrification exponential rate coefficient | NA | 0–3 | 2.5 | Velthof et al. (2009) | M/SA |
| Mineralization | CMN.bsn | Rate factor for humus mineralization of active organic nitrogen | NA | 0.0001–0.0003 | 0.000145 | Monthly concentration | M/SA | |
| Transport of nitrogen with sediment | ERORGN.hru | Organic nitrogen enrichment ratio | NA | 0–5 | 0.05–4.5 (0.7) | Monthly concentration | M/SA | |
| Shallow aquifer nitrates | HLIFE_NGW.gw | Half-life of nitrate–nitrogen in the shallow aquifer | day− 1 | 0–200 | 0–200 (116) | Monthly concentration | M/SA | |
| Nitrogen percolation | NPERCO.bsn | Nitrogen percolation coefficient | NA | 0–1 | 0.5 | Monthly concentration | M/SA | |
| Nitrogen settling rate | NSETLR1.lwq = NSETLR2.lwqb | Nitrogen settling rate | m/year | 1 - 150c | 5.5–150 (30) | Monthly concentration | M/SA | |
| Nitrogen uptake | N_UPDIS.bsn | Nitrogen uptake distribution parameter | NA | 1–31 | 28 | Monthly concentration | M/SA | |
| Residue | RSDCO.bsn | Residue decomposition coefficient | NA | 0.02–1 | 0.02 | Monthly concentration | M/SA | |
| Denitrification | SDNCO.bsn | Denitrification threshold water content | NA | 0–1 | 1 | Velthof et al. (2009) | M/SA | |
| Transport of phosphorus with sediment | ERORGP.hru | Organic phosphorus enrichment ratio | NA | 0–5 | 0–0.25 (0.1) | Monthly concentration | M/SA | |
| Phosphorus settling rate | PSETLR1.lwq = PSETLR2.lwqb | Phosphorus settling rate | m/year | 1–150c | 9.5–150 (57) | Monthly concentration | M/SA |
a
Only in tile drained HRUs
b
The nitrogen and phosphorus settling rate didn't change during the year.
c
The range of settling rate of nutrients in reservoirs was set larger that the default accordingly with Panuska and Robertson (1999).
d
The lower limit of the RE was set to 5 mm to investigate all the possible range of values
e
CN2 was set to 30 in the HRUs with tile drain systems