🌾 SwaNET · Quick Tutorial 10 of 19

Update Land Use During Simulation

Modify land cover types in any HRU mid-simulation using <code>.lup</code> files — essential for modeling scenarios where forest, agriculture, or urban areas change over time.

SwaNET Tutorial 10Prereq: Loaded SwaNET Project5 min read

Key Concepts

WhatChange land use in any HRU during simulation
WhenLand cover changes mid-run (e.g., deforestation in 1985)
RuleNew land use percentages must total exactly 100%
PersistenceChanges remain until end of simulation or next update

○Overview

M4W SwaNET allows users to update land use in any HRU. This is particularly useful when land cover changes during the simulation period. For example, if a model runs from 1980 to 1990 and 50% of forest area in a subbasin is converted to agriculture in 1985, the change can be incorporated through the land use update tool.

After the change is made, the updated land use remains in effect for the rest of the simulation period — or until further updates are applied.

ℹ️

Prerequisite: You need a MAGNET4WATER account and a loaded SwaNET project before using this feature.

1Access the Interface

  1. Click Edit SWAT Databases on the main SwaNET toolbar.
  2. Click the Land use update (.LUP) button.
  3. The landuse update interface loads, showing Year, Month, Day fields and a list of existing land uses in your watershed.

2Update Landuse — Step by Step

  1. Add a land use update — Click Add land use update. The Year, Month, and Day text boxes become active.
  2. Set the date — Enter the year, month, and day the land use change takes effect. The Add new land use button is now enabled.
  3. Select the existing land use — Choose the land use to change from the list on the left. All land uses in the watershed are included.
  4. Add a new land use — Click Add new land use. A new interface lists all available subbasins. Select the replacement land use and click OK.
  5. Review the table — The existing land use, new land use, and percent conversion are displayed. The percent value is the portion of the existing land use being converted.
  6. Add more conversions — Repeat steps d, e, and f to add additional new land uses for the same original land use.
  7. Adjust percentages — The total percentage of all new land uses must add up to 100%. If not all of the original land is being converted, re-enter the original land use as a "new" land use with the remaining percentage.
  8. Choose subbasins — Click Choose subbasins. All subbasins containing the specified land uses are listed on the right. Select the ones to apply changes to (multiple selection allowed).
⚠️

Save your work: Click Save to store the land use change. Then, when you exit the interface, don't forget to click Save Edits on the main Edit SWAT Data interface — otherwise your changes will be lost.

Removing a Land Use Change

To remove a previously created land use change, click the Remove button in the corresponding row of the summary table at the top of the dialog.

3Example: Partial Forest Conversion

Suppose 25% of forested wetland (WETF) is converted to agriculture, 25% to medium-density residential, and 50% remains forested wetland. You would enter three rows:

Land UseNew Land UsePercent
WETFAGRR25%
WETFURMD25%
WETFWETF50%
💡

Key rule: Even though WETF stays WETF for the 50%, you must explicitly include it so the total reaches 100%.

4SWAT Landuse Codes Reference

All SWAT land use codes available in the watershed are shown below. Use these codes when specifying land use conversions.

View all land use codes and descriptions
CodeDescriptionCodeDescription
AGRRAgricultural land — row cropsRNGERange — grasses
BSVGBarren or sparsely vegetatedSAVASavanna
CRDYDryland cropland & pastureSHRBShrubland
CRGRCropland / grassland mosaicSWRNSW US (arid) range
CRIRIrrigated cropland & pastureTUBGBare ground tundra
CRWOCropland / woodland mosaicTUHBHerbaceous tundra
FODBDeciduous broadleaf forestTUMIMixed tundra
FODNDeciduous needleleaf forestTUWOWooded tundra
FOEBEvergreen broadleaf forestUIDUIndustrial
FOENEvergreen needleleaf forestURHDResidential — high density
FOMIMixed forestURLDResidential — low density
FRSDForest — deciduousURMDResidential — medium density
FRSEForest — evergreenWATRWater
FRSTForest — mixedWEHBHerbaceous wetland
GRASGrasslandWETFWetlands — forested
HAYHayWETLWetlands — mixed
MIGSMixed grassland / shrublandWETNWetlands — non-forested
MIXCMixed dryland / irrigated croplandWEWOWooded wetland
RNGBRange — brush

Frequently Asked Questions

Can I apply different land use changes on different dates?
Yes. Click Add land use update for each date and define the conversion independently. All changes are saved in sequence and applied at the appropriate simulation step.
What happens if my percentages don't add up to 100?
The tool requires all percentages to sum to exactly 100%. If you only convert part of a land use, re-enter the original code with the remaining percentage to cover the balance.
Can I undo a land use change after saving?
Yes, click the Remove button next to the entry in the summary table. Be sure to click Save Edits afterward.