Edit basin data

What is it?

This interface is for modifying general watershed attributes related to runoff, water quality and management. For detailed description of the parameters, please refer to SWAT Theoretical Documentation and SWAT Input/Output Documentation.

How to use it:

Click on the tabs at the top of the interface to load relevant input parameters.
Select appropriate values for the each parameter described below.

Water balance

SFTMP: Snowfall temperature (°C)
SMTMP: Snow melt base temperature (°C)
SMFMX: Melt factor for snow on June 21 (mm H₂O/°C-day)
SMFMN: Melt factor for snow on December 21 (mm H₂O/°C-day)
TIMP: Snow pack temperature lag factor.
SNOCOVMX: Minimum snow water content that corresponds to 100% snow cover, SNO₁₀₀,(mm H₂O).
SNO50COV: Fraction of snow volume represented by SNOCOVMX that corresponds to 50% snow cover.
PET method: Potential evapotranspiration (PET) method.
PET File: Potential evapotranspiration file, to read, if PET method is 'Read-in PET'. Select a file to upload.
ESCO: Soil evaporation compenstaion factor.
EPCO: plant uptake compensation factor.
EVLAI: Leaf area index at which no evaporation occurs from water surface.
FFCB: Initial soil water storage expressed as a fraction of field capacity water content.

Water balance

Rainfall-runoff method: Select appropriate method.
ICN: Daily curve number calculation method.
CNCOEF: Plant evapotranspiration curve number coefficient.
CN_FROZ: Parameter for frozen soil adjustment on infiltration/runoff.
Crack flow: Crack flow code.
SURLAG: Surface runoff lag time (days).
ISED_DET: Method governing calculation of daily maximum half-hour rainfall value.
ADJ_PKR: Peak rate adjustment factor for sediment routing in the subbasin (tributary channels).
TB_ADJ: Adjustment factor for subdaily unit hydrograph basetime.
PRF: Peak rate adjustment factor for sediment routing in the main channel.
SPCON: Linear parameter for calculating the maximum amount of sediment that can be reentrained during channel sediment routing.
SPEXP: Exponent parameter for calculating sediment reentrained in channel sediment routing.

Reaches

Channel routing method: Select appropriate method.
MSK_CO1: Calibration coefficient used to control impact of the storage time constant (Km) for normal flow for Muskingum method.
MSK_CO2 : Calibration coefficient used to control impact of the storage time constant (Km) for low flow for Muskingum method.
MSK_X: Weighting factor controlling relative importance of inflow rate and outflow rate in determining water storage in reach segment for Muskingum method.
Channel degradation: Select whether to model channel degradation.
Stream water quality: Select whether to model stream water quality.
TRNSRCH: Fraction of transmission losses from main channel that enter deep aquifer.
EVRCH: Reach evaporation adjustment factor.
Routing pesticide: Need to add pesticide to enable this option.
Algae/CBOD/dissolved oxygen simulation: Select wheter to simulate these parameters.

Nutrient and water quality

RCN: Concentration of nitrogen in rainfall (mg N/l).
CMN: Rate factor for humus mineralization of active organic nitrogen.
CDN: Denitrification exponential rate coefficient.
SDNCO: Denitrification threshold water content.
N_UPDIS: Nitrogen uptake distribution parameter.
P_UPDIS: Phosphorus uptake distribution parameter.
NPERCO: Nitrogen percolation coefficient.
PPERCO: Phosphorus percolation coefficient.
PHOSKD: Phosphorus soil partitioning coefficient.
PSP: Phosphorus sorption coefficient.
RSDCO: Residue decomposition coefficient.
PERCOP: Pesticide percolation coefficient.
IATMODEP: Atmospheric deposition file. 0 = average annual inputs 1 = monthly inputs.
RAMMO_SUB: Atmospheric deposition of ammonium (mg/l).
RCN_SUB: Atmospheric deposition of nitrate (mg/l).
DRYDEP_NH4: Atmospheric dry deposition of ammonium (kg/ha/yr).
DRYDEP_NO3: Atmospheric dry deposition of nitrates (kg/ha/yr).

Bacteria

WDPQ: Die-off factor for persistent bacteria in soil solution (1/day).
WGPQ: Growth factor for persistent bacteria in soil solution (1/day).
WDLPQ: Die-off factor for less persistent bacteria in soil solution (1/day).
WGLPQ: Growth factor for less persistent bacteria in soil solution (1/day).
WDPS: Die-off factor for persistent bacteria adsorbed to soil particles (1/day).
WGPS: Growth factor for persistent bacteria adsorbed to soil particles (1/day).
WDLPS: Die-off factor for less persistent bacteria adsorbed to soil particles (1/day).
WGLPS: Growth factor for less persistent bacteria adsorbed to soil particles (1/day).
BACTKDQ: Bacteria partition coefficient.
THBACT: Temperature adjustment factor for bacteria die-off/growth.
WOF_P: Wash-off fraction for persistent bacteria on foliage.
WOF_LP: Wash-off fraction for less persistent bacteria on foliage.
WDPF: Persistent bacteria die-off factor on foliage at 20°C (1/day).
WGPF: Persistent bacteria growth factor on foliage at 20°C (1/day).
WDLPF: Less persistent bacteria die-off factor on foliage at 20°C (1/day).
WGLPF: Less persistent bacteria growth factor on foliage at 20°C (1/day).
BACT_SWF: Fraction of manure applied to land areas that has active colony forming units.
BACTMX: Bacteria percolation coefficient (10 m3/Mg).
BACTMINLP: Minimum daily bacteria loss for less persistent bacteria (# cfu/m2).
BACTMINP: Minimum daily bacteria loss for persistent bacteria (# cfu/m2).
WDLPRCH: Die-off factor for less persistent bacteria in streams (moving water) at 20°C (1/day).
WDPRCH: Die-off factor for persistent bacteria in streams (moving water) at 20°C (1/day).
WDLPRES: Die-off factor for less persistent bacteria in water bodies (still water) at 20°C (1/day).
WDPRES: Die-off factor for persistent bacteria in water bodies (still water) at 20°C (1/day).

Tile drains

ITDRN: Tile drainage equations flag. 1: Simulate tile flow using DRAINMOD subroutine (wt_shall), 2: Simulate tile flow using origtile subroutine (wt_shall,d).
IWTDN: Water table depth algorithms flag. 1: simulate wt_shall using subroutine new water table depth routine, 0: simulate wt_shall using subroutine original water table depth routine.
DDRAIN_BSN: Depth to the sub-surface drain (mm).
TDRAIN_BSN: Time to drain soil to field capacity (hours).
GDRAIN_BSN: Drain tile lag time (hours).
RE_BSN: Effective radius of drains (mm).
SDRAIN_BSN: Distance between two drain tubes or tiles (mm).
DRAIN_CO_BSN: Daily drainage coefficient (mm/day).
PC_BSN: Pump capacity (mm/hr).
LATKSATF_BSN:Multiplication factor to determine lateral ksat from SWAT ksat input value for HRU.

Additional parameters

DORM_HR: Time threshold used to define dormancy (hours).
SMXCO : Adjustment factor for maximum curve number S factor.
FIXCO : Nitrogen fixation coefficient.
NFIXMX : Maximum daily-n fixation (kg/ha).
ANION_EXCL_BSN : Fraction of porosity from which anions are excluded.
CH_ONCO_BSN : Channel organic nitrogen concentration in basin (ppm).
CH_OPCO_BSN : Channel organic phosphorus concentration in basin (ppm).
HLIFE_NGW_BSN : Half-life of nitrogen in groundwater (days).
RCN_SUB_BSN : Concentration of nitrate in precipitation (ppm).
BC1_BSN : Rate constant for biological oxidation of NH3 (1/day).
BC2_BSN : Rate constant for biological oxidation NO2 to NO3 (1/day).
BC3_BSN : Rate constant for hydrolosis of organic nitrogen to ammonia (1/day).
BC4_BSN : Rate constant for decay of organic phosphorus to dissolved phosphorus (1/day).
DECR_MIN: Minimum daily residue decay.
ICFAC : C-factor calculation method.
RSD_COVCO : Residue cover factor for computing fraction of cover.
VCRIT : Critical velocity.
CSWAT : Code for new carbon routines.
RES_STLR_CO : Reservoir sediment settling coefficient.
BFLO_DIST: Baseflow distribution factor during the day for subdaily runs. 1:profile of baseflow in a day follows rainfall pattern, 0:baseflow evenly distributed to each time step during a day.
IUH : Unit hydrograph (UH) method. 1=triangular UH, 2=gamma function UH.
UHALPHA : alpha coefficient for gamma function unit hydrograph. Required if iuh=2 is selected.
IABSTR: Initial abstraction on impervious cover (mm).
SOL_P_MODEL: if = 1, use new soil P model.
R2ADJ_BSN: basinwide retention parm adjustment factor.
SSTMAXD_BSN: basinwide retention parm adjustment factor.
ISMAX: max depressional storage code.
CO2_X2: Quadratic coefficient for incrementinig future CO2 concentrations using a quadratic equation.
CO2_X: Linear coefficient for incrementing future CO2 concentrations using a quadratic equation.
SFSEDMEAN: Mean sediment concentration coming out of sand filter.
SFSEDSTDEV: Standard deviation of sediment concentration coming out of sand filter.

Urban BMPs

Select Urban land classes that DO NOT contribute runoff to BMPs.
URHD: Residential-High Density.
URMD: Residential-Medium Density.
URML: Residential-Med/Low Density.
URLD: Residential-Low Density.
UCOM: Commercial.
UIDU: Industrial.
UTRN: Transportation.
UINS: Institutional.
URBN: Residential.

Sub-daily erosion

EROS_SPL: The splash erosion coefficient ranges 0.9 - 3.1.
RILL_MULT: Multiplier to USLE_K for soil susceptible to rill erosion, ranges 0.5 - 2.0.
EROS_EXPO: An exponent in the overland flow erosion equation, ranges 1.5 - 3.0.
SUBD_CHSED: Instream sediment model, 0=Bagnold model, 1=Brownlie model, 2=Yang model.
C_FACTOR: Scaling parameter for Cover and management factor in ANSWERS erosion model.
CH_D50: Median particle diameter of channel bed (mm).
SIG_G: Geometric standard deviation of particle sizes.

After making the changes, click 'Save Edits' and close the interface.
Don't forget to click 'Save Edits' butoon on the 'mgnSWAT Edit SWAT Data' interface.