Osu_1hru walkthrough

Osu_1hru is the smallest SWAT+ project that exercises every input group. One HRU, ten hectares, near Osu, Korea. The land use is rice140_lum (a 140-day rice rotation). The folder is at swatplus/refdata/Osu_1hru.

Use this dataset when you want to see every input file in file.cio populated, but only one HRU to track.

Prerequisites¶

A working SWAT+ executable. See Install.
A local copy of refdata/Osu_1hru.

file.cio: every group used¶

Unlike Ames_sub1, this project populates almost every slot. Open Osu_1hru/file.cio:

simulation        time.sim          print.prt         null              object.cnt
basin             codes.bsn         parameters.bsn
climate           weather-sta.cli   weather-wgn.cli   null              pcp.cli           tmp.cli           slr.cli           null              wnd.cli
connect           hru.con           null              rout_unit.con     null              aquifer.con       null              null              null      recall.con              null              null              null              chandeg.con
channel           initial.cha       null              null              null              nutrients.cha     channel-lte.cha   hyd-sed-lte.cha
reservoir         initial.res       null              null              sediment.res      nutrients.res     weir.res          wetland.wet       hydrology.wet
routing_unit      rout_unit.def     rout_unit.ele     rout_unit.rtu
hru               hru-data.hru
aquifer           initial.aqu       aquifer.aqu
hydrology         hydrology.hyd     topography.hyd    field.fld

The project has channels, aquifers, routing units, reservoirs, recall, and a wetland. Most of those tables are populated with template entries from the SWAT+ Editor; the single HRU in hru.con is what actually runs.

Reference: file.cio.

time.sim and print.prt¶

time.sim:

day_start  yrc_start   day_end   yrc_end      step
       1      2010       365      2023         0

January 1 2010 through December 31 2023, daily.

print.prt has nyskip = 3, so the first three years are discarded. The objects table sets basin_wb to yearly and avann. Every other object is avann only.

References: time.sim, print.prt.

codes.bsn¶

pet  event  crack  rtu_wq  sed_det  rte_cha  deg_cha  wq_cha  nostress  cn  c_fact  carbon  lapse  uhyd  sed_cha  tiledrain  wtable  soil_p  gampt  atmo_dep  stor_max  i_fpwet
  1      0      0       1        0        0        0       1         0   0       0       0      0     1        0          0       0       0      0          a        0        0

Settings worth noting:

pet = 1: Penman-Monteith PET. Needed because the climate has solar radiation, humidity, and wind.
rtu_wq = 1: routing-unit water quality on.
wq_cha = 1: in-stream water quality on.
carbon = 0: legacy static mineralization (no C-FARM, no Century).
gampt = 0: curve-number infiltration.

Reference: codes.bsn.

climate¶

Five climate files for the Imsil station:

Imsilpcp.pcp: daily precipitation.
Imsiltmp.tmp: daily max and min temperature.
Imsilsol.slr: daily solar radiation.
Imsilwind.wnd: daily wind speed.

(Relative humidity is generated from the weather generator.) The index files pcp.cli, tmp.cli, slr.cli, wnd.cli each list one filename, and weather-sta.cli binds those four index files to the station s35610n127290e.

References: *.cli, *.pcp, *.tmp.

hru.con: a single HRU¶

id  name     gis_id  area  lat       lon         elev    hru  wst              cst  ovfl  rule  out_tot
 1  hru0001       1    10  35.65311  127.36763   350.97   1   s35610n127290e   0    0     0     0

Area is 10 ha. hru = 1 and wst = "s35610n127290e" bind this row to HRU 1 and to the weather station. out_tot = 0 means no downstream routing object: the run produces HRU-scale outputs only.

Reference: *.con.

hru-data.hru¶

The single HRU points at:

id  name      topo          hydro      soil        lu_mgt        soil_plant_init  surf_stor   snow     field
 1  hru0001   topohru0001   hyd0001    PadHOEGOG   rice140_lum   soilplant1       paddy0001   snow001  null

soil = PadHOEGOG: a paddy soil. See soils.sol.
lu_mgt = rice140_lum: maps in landuse.lum to plant community rice140_comm and management schedule rice140_rot.
surf_stor = paddy0001: surface-storage record for ponded water. This is what makes it a paddy.

Reference: hru-data.hru.

landuse.lum and management.sch¶

landuse.lum row for rice140_lum binds the HRU to:

plnt_com = rice140_comm (plant community in plant.ini).
mgt = rice140_rot (management schedule in management.sch).
cn2 = rc_strow_g (curve-number table entry in cntable.lum).
cons_prac = cross_slope.
ov_mann = convtill_res.

management.sch then describes the 140-day rice rotation: paddy-fill, transplant, fertilize, harvest, drain.

Reference: landuse.lum.

aquifer.aqu and aquifer.con¶

aquifer.aqu defines twenty shallow aquifer records (aqu011 through aqu102) plus one deep aquifer (aqu_deep010). They share identical parameters. The single HRU links to one of them through aquifer.con so the percolation has somewhere to go.

Reference: *.aqu.

channel-lte.cha and hyd-sed-lte.cha¶

A template channel table is present so the file structure validates, but with out_tot = 0 on the HRU, no flow reaches a channel and the channel outputs will be zero.

Reference: *.cha.

Run the model¶

cd path/to/Osu_1hru
./swatplus-<version>-linux-x86_64

The run takes a few seconds because there is only one HRU. Watch the console for Original Simulation lines.

Read the outputs¶

simulation.out¶

The last line should be Execution successfully completed.

diagnostics.out¶

Every line is a missing reference. Expect a long list because the Editor wrote many template channel and aquifer rows whose companion property records do not all exist. The HRU run itself is unaffected.

Reference: Checker and diagnostics.

checker.out¶

A single row for PadHOEGOG. Confirm zmx, sumfc, sumul, hydgrp are reasonable for a paddy.

basin_wb_aa.txt and basin_wb_yr.txt¶

Annual and average-annual water balance for the basin. Because there is one HRU, basin equals HRU. Compare basin_wb_yr.txt (per-year values) to basin_wb_aa.txt (the average over years 4 through 14, since nyskip = 3).

hru_wb_aa.txt¶

The water-balance row for HRU 1. Look at irr (irrigation depth, large for a paddy), surq_gen (surface runoff), et, perc.

Plant outputs¶

crop_yld_aa.txt reports rice yields by HRU and crop. hru_pw_aa.txt carries plant biomass and water-stress days.

What to change next¶

Switch to Hargreaves PET (pet = 2 in codes.bsn). The model will stop reading the solar, humidity, and wind files.
Turn on daily output for basin_wb to inspect the paddy fill and drain pattern through the season.
Change the simulation period in time.sim to a single year for a fast iteration loop.

See the cookbook for these edits.