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lum lookup tables

Three lookup files supply numeric parameters that landuse.lum references by name: cntable.lum (SCS curve numbers), cons_practice.lum (USLE P factor and maximum slope length), and ovn_table.lum (overland-flow Manning's n). Each file has the same shape: a title line, a header line, then one record per row. Rows are read with list-directed I/O, so any column after the last typed field is ignored by the solver.

cntable.lum

Curve number table. Each entry holds four SCS-CN values for hydrologic soil groups A, B, C, and D.

Source

Format

  • Line 1: title (skipped).
  • Line 2: header (skipped).
  • One record per curve number entry. Fields are list-directed.
# Field Type Default Description
1 name char(40) blank curve number entry name. Referenced from landuse.lum field cn_lu
2 cn(1) real 30.0 curve number for hydrologic soil group A
3 cn(2) real 55.0 curve number for hydrologic soil group B
4 cn(3) real 70.0 curve number for hydrologic soil group C
5 cn(4) real 77.0 curve number for hydrologic soil group D

Curve numbers are dimensionless and bounded by 0 and 100. SWAT+ Editor writes additional description, treat, and cond_cov columns after cn(4). The reader does not consume them.

Example

Excerpt from refdata/Ames_sub1/cntable.lum:

cntable.lum: written by SWAT+ editor v2.3.3 on 2023-10-25 08:58 for SWAT+ rev.60.5.7
name                      cn_a          cn_b          cn_c          cn_d  description                                                             treat                                     cond_cov
fal_bare              77.00000      86.00000      91.00000      94.00000  Fallow                                                                  Bare_soil                                 ----
rc_strow_g            67.00000      78.00000      85.00000      89.00000  Row_crops                                                               Straight_row                              Good
wood_f                36.00000      60.00000      73.00000      79.00000  Woods                                                                   ----                                      Fair
urban                 98.00000      98.00000      98.00000      98.00000  Paved_parking_lots_roofs_driveways_etc_(excl_right-of-way)              ----                                      ----

cons_practice.lum

Conservation practice table. Supplies the USLE support practice factor (P) and the maximum slope length used for length-slope factor calculations.

Source

Format

  • Line 1: title (skipped).
  • Line 2: header (skipped).
  • One record per practice. Fields are list-directed.
# Field Type Default Units Description
1 name char(40) blank - practice name. Referenced from landuse.lum field cons_prac
2 pfac real 1.0 - USLE support practice factor (P). Dimensionless, 0 to 1
3 sl_len_mx real 1.0 m maximum slope length for the practice

SWAT+ Editor writes a description column after sl_len_mx. The reader does not consume it.

Example

Excerpt from refdata/Ames_sub1/cons_practice.lum:

cons_practice.lum: written by SWAT+ editor v2.3.3 on 2023-10-25 08:58 for SWAT+ rev.60.5.7
name                    usle_p   slp_len_max  description
up_down_slope          1.00000     121.00000  Up_and_down_slope
cross_slope            0.75000     121.00000  Cross_slope_tillage
contour_farming        0.50000     121.00000  Contour_tillage
strip_contour          0.25000     121.00000  Strip_cropping_contour
ter_3-8_sodout         0.50000      76.00000  terraces_3-8%_slopes_sod-outlet

ovn_table.lum

Overland-flow Manning's n table. Supplies a mean, minimum, and maximum n per land use class for sheet-flow routing across the HRU.

Source

Format

  • Line 1: title (skipped).
  • Line 2: header (skipped).
  • One record per class. Fields are list-directed.
# Field Type Default Units Description
1 name char(40) blank - class name. Referenced from landuse.lum field ovn
2 ovn real 0.5 s m^(-1/3) mean Manning's n for overland flow
3 ovn_min real 0.5 s m^(-1/3) minimum Manning's n for overland flow
4 ovn_max real 0.5 s m^(-1/3) maximum Manning's n for overland flow

SWAT+ Editor writes a description column after ovn_max. The reader does not consume it.

Example

Excerpt from refdata/Ames_sub1/ovn_table.lum:

ovn_table.lum: written by SWAT+ editor v2.3.3 on 2023-10-25 08:58 for SWAT+ rev.60.5.7
name                  ovn_mean       ovn_min       ovn_max  description
convtill_nores         0.09000       0.06000       0.12000  Conventional_tillage_no_residue
convtill_res           0.19000       0.16000       0.22000  Conventional_tillage_residue
notill_2-9res          0.30000       0.17000       0.47000  No_till_2-9_t/ha_residue
forest_med             0.60000       0.50000       0.70000  Forest_medimum_good
urban_asphalt          0.01100       0.01100       0.01100  Urban_asphalt
  • landuse.lum. Master land-use management table. Its cn_lu, cons_prac, and ovn columns name rows in these three files.
  • hru-data.hru. Selects a landuse.lum row per HRU, which in turn selects rows in these three tables.