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day_start

Beginning day of the simulation

SWAT+ is able to begin a simulation at any day of the year. This option can for example be useful, if the user wishes to simulate hydrological years instead of calendar years.

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If day_start = 0, the model will start the simulation on January 1st.

If the simulation begins before the first day of the observed climate data, SWAT+ will use simulated climate data for the time period before the start of the observed climate data.

hydcon

Hydrograph connections

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This output file is used by the SWAT+ developers for debugging connectivity errors and infinite loops. Its usefulness for SWAT+ users is probably very limited. Accordingly, there is no description of this output file included in the section.

SWAT+ Output Files

obj_typ_no

Number of the object to print output for

Soil water contents of the soil layers can be printed for all HRUs in the same file by setting obj_typ_no = 0. For all other outputs, a separate object print record with a unique name has to be defined for each object.

object.prt

This file allows the user to print selected output for individual spatial objects.

The object.prt file is commonly used to:

  • Print daily channel outflow to compare to observed streamflow a stream gage

  • Print daily flow to a file that can be read in as a point source from another SWAT+ simulation

The only timestep output can be printed at using this file is daily. A description of the output files is provided in the section.

Field
Description
Type

Type of hydrograph to print

string

filename

User-defined name of output file

string

id

ID of the object print record

integer

obj_typ

Type of object to print output for

string

obj_typ_no

Number of the object to print output for

integer

SWAT+ Output Files

obj_typ

Type of object to print output for

Output can be printed for the following types of objects:

Object Code
Description
hyd_typ

Reservoir

sdc

Channel

exc

Export Coefficient

dr

Delivery Ratio

out

Outlet

hru

HRU

hlt

HRU-lte

ru

Routing Unit

res

hyd_typ

Type of hydrograph to print

The following hydrographs can be printed:

Hydrograph Code
Description
Object type

Surface runoff

hru, ru

lat

Lateral flow

hru, ru

til

Tiledrain flow

hru, ru

sol_water

Soil moisture

hru

solnut_ly

Soil nutrients (N and P) by layer

hru

solnut_pr

Soil nutrients (N and P) for entire profile

hru

plant

Plant status

hru

cha_fp

Channel and floodplain water balance

hru

tot

Total flow

all

rhg

Percolation

hru, ru

sur

yrc_start

Beginning year of the simulation

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If the simulation begins before the first day of the observed climate data, SWAT+ will use simulated climate data for the time period before the start of the observed climate data.

day_end

Ending day of the simulation

SWAT+ is able to end a simulation at any day of the year. This option can for example be useful, if the user wishes to simulate hydrological years instead of calendar years.

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If day_end = 0, the model will end the simulation on December 31st.

If the simulation begins before the first day of the observed climate data, SWAT+ will use simulated climate data for the time period before the start of the observed climate data.

step

Time step of the simulation

SWAT+ is able to run at the following time steps:

Code
Time Step

0

day

2

12 hours

24

hour

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When using the Green & Ampt method ( in ) for calculating surface runoff, the time step of the precipitation data must match the simulation time step.

96

15 minutes

1440

minute

gampt
codes.bsn

time.sim

This file controls the simulation time period and time step.

Field
Description
Type

Beginning day of the simulation

integer

Beginning year of the simulation

integer

Simulation Settings

There are three files that control the settings for a simulation run:

  • specifies the land area and the total area (including ponds and reservoirs) of the watershed and the counts of all spatial objects in a simulation,

  • controls the simulation time period and time step, and

controls which output files will be printed for a simulation.

An additional, optional file, , allows the user to print selected output for individual spatial objects.

object.cnt
time.sim

Ending day of the simulation

integer

Ending year of the simulation

integer

Time step of the simulation

integer

day_start
yrc_start
day_end
print.prt
object.prt
yrc_end
step

yrc_end

Ending year of the simulation

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If the simulation ends after the last day of the observed climate data, SWAT+ will use simulated climate data for the time period after the end of the observed climate data.

interval

Print interval within the period

This parameter specifies the interval within the specified printing period.

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Example: If interval = 2, output will be printed for every other day.

object.cnt

This file specifies the land area and the total area (including ponds and reservoirs) of the watershed and the counts of all spatial objects in a simulation.

Field
Description
Type

name

Name of the watershed

string

ls_area

Land area of the watershed in ha

real

tot_area

Total area of the watershed in ha

real

obj

Total number of spatial objects in the simulation

integer

hru

Number of HRUs in the simulation

integer

lhru

Number of HRU-ltes in the simulation

integer

rtu

Number of routing units in the simulation

integer

gwfl

Number of gwflow river cells

integer

aqu

Number of aquifers in the simulation

integer

cha

Currently not used

integer

res

Number of reservoirs in the simulation

integer

rec

Number of recalls (point sources/inlets) in the simulation

integer

exco

Number of export coefficients in the simulation

integer

dlr

Number of delivery ratios in the simulation

integer

can

Currently not used

integer

pmp

Currently not used

integer

out

Number of outlets in the simulation

integer

lcha

Number of channels in the simulation

integer

aqu2d

Currently not used

integer

hrd

Currently not used

integer

wro

Currently not used

integer

aa_int_cnt

Number of print intervals for average annual output

If aa_int_cnt = 0, the model will print average annual output for the entire period. If aa_int_cnt > 0, the end years of the print intervals have to be specified by the user by listing them in chronological order in the same line as aa_int_cnt.

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Example: If aa_int_cnt = 3 1955 1965 1975, average annual results will be printed for the time periods ending in 1955, 1965, and 1975.

nyskip

Number of years at the beginning of the simulation to not print output

Some simulations will need a warm-up or equilibration period. The use of a warm-up period becomes more important as the simulation period of interest shortens. For 30-year simulations, a warm-up period is optional. For a simulation covering 5 years or less, a warm-up period is recommended.

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Examples: If nyskip = 2, the model will skip printing the first two years regardless of the starting year. If nyskip = 0, output for all years of the simulation will be printed. If nyskip equals the number of years in the simulation, no output will be printed.

print.prt

This file controls which output files will be printed during the simulation.

The print.prt file is formatted differently than most other SWAT+ input files (see figure below). In line three, there are several variables for controlling the time period to be printed. In line five, the user can specify the number of print intervals for average annual output. In line seven, the user can select to have output files printed in a specific file format (in addition to the default *.txt output files). In line 9, the user can control the printing of outputs for soils and management as well as flow duration curves. In lines 11 to 90, there is a list of outputs for different spatial levels and objects that can be printed at daily, monthly, yearly, and average annual time steps. A description of the output files is provided in the SWAT+ Output Files section.

Format of the print.prt file
Field
Description
Type

Number of years at the beginning of the simulation to not print output

integer

day_start

Julian day to start printing output (for daily printing only)

integer

yrc_start

Calendar year to start printing output

integer

day_end

Julian day to stop printing output (for daily printing only)

integer

yrc_end

Calendar year to stop printing output

integer

Print interval within the period

integer

Number of print intervals for average annual output

integer

csvout

Code for printing output in CSV format (y=yes, n=no)

string

dbout

Code for printing output in DB format (y=yes, n=no)

string

cdfout

Code for printing output in Net-CDF format (y=yes, n=no)

string

crop_yld

Code for printing yearly and average annual crop yields (y=yes, n=no)

string

mgtout

Code for printing management output (y=yes, n=no)

string

Code for printing hydrograph connection output (y=yes, n=no)

string

fdcout

Code for printing flow duration curve output (y=yes, n=no)

string

Objects that output can be printed for at different time steps

string

daily

Code for printing daily output (y=yes, n=no)

string

monthly

Code for printing monthly output (y=yes, n=no)

string

yearly

Code for printing yearly output (y=yes, n=no)

string

avann

Code for printing average annual output (y=yes, n=no)

string

nyskip
interval
aa_int_cnt
hydcon
object

object

Objects that output can be printed for at different time steps

The table below lists the objects that are listed in the first column of this section of the print.prt file. For each of these objects, output can be printed at daily, monthly, yearly, and average annual time steps by entering y (=yes) or n (=no) in the following four columns.

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The user is advised to print only those outputs that are needed for model evaluation or further analysis. Especially daily printing can result in very large output files that may exceed hard drive storage.

Object
Definition

basin_sd_cha

Basin SWAT-DEG channel

basin_psc

Basin point sources

region_wb

Currently not used

region_nb

Currently not used

region_ls

Currently not used

region_pw

Currently not used

region_aqu

Currently not used

region_res

Currently not used

region_sd_cha

Currently not used

region_psc

Currently not used

water_allo

Water allocation

lsunit_wb

Landscape unit water balance

lsunit_nb

Landscape unit nutrient balance

lsunit_ls

Landscape unit losses

lsunit_pw

Landscape unit plant and weather

hru_wb

HRU water balance

hru_nb

HRU nutrient balance

hru_ls

HRU losses

hru_pw

HRU plant and weather

hru-lte_wb

HRU-lte water balance

hru-lte_nb

Not used (no nutrient processes simulated for HRU-lte objects)

hru-lte_ls

HRU-lte losses

hru-lte_pw

HRU-lte plant and weather

channel

Currently not used

channel_sd

SWAT-DEG channel output

aquifer

Aquifer output

reservoir

Reservoir output

recall

Point source output

hyd

Incoming and outgoing hydrographs

ru

Routing unit output

pest

Pesticide output for all objects and basin

basin_salt

hru_salt

ru_salt

aqu_salt

channel_salt

res_salt

wetland_salt

basin_cs

hru_cs

ru_cs

aqu_cs

channel_cs

res_cs

wetland_cs

basin_wb

Basin water balance

basin_nb

Basin nutrient balance

basin_ls

Basin losses

basin_pw

Basin plant and weather

basin_aqu

Basin aquifer

basin_res

Basin reservoir

basin_cha

Currently not used