Decision table trigger

[Arantxa Ortiz Elorza]

SWAT+ Issue Report Template

1. Primary Issue Location

• Component: SWAT+Editor
• Area of impact: Model input and application

2. Software Versions

• GIS Interface: QGIS 3.34.6
• SWAT+ Editor: 3.0.4
• SWAT+ Revision: 61.0.1

3. Project Characteristics

• Watershed Details: Ega sub-basin (within the Ebro Basin, Spain), around 1500 km², 1291 HRUs.
• Modeling Aim: Streamflow and sediment yield predictions under climate and land-use change scenarios.

4. Description of Issue

• The Problem: I am trying to implement land-use changes using decision tables. I used as an example the forest-to-corn decision table available in SWAT+ Editor and modified it for each HRU where a land-use change is expected, creating a unique decision table for each HRU. I saved the file as scen_lu.dtl. The problem is that these changes never occur. The lu_change_out.txt file remains empty, as if no change has been triggered.

• Steps to Reproduce: So far, I have tried the following:

  a) Creating scen_lu.dtl and importing it into SWAT+ Editor using the Decision Tables → Scenario Land Use import option, then running the model. SWAT+ Editor reads the file correctly and scen_lu.dtl appears in the TxtInOut folder when the model is run, but lu_change_out.txt does not register any changes.

  b) Since this did not work, I copied and pasted scen_lu.dtl directly into the TxtInOut folder, manually modified file.cio, and ran the model from the command line.

  c) I also added a scen_lu.upd file that links the decision table name to the corresponding land-use change. (However, I don't quite understand what this file makes because I am not connecting it in file.cio or any other file)

  d) I also tried running the model using SWAT+ Toolbox.

  e) In the full scenario, I have 217 different decision tables, one for each land-use change and year. However, I also tested a simplified case using only a single decision table, and lu_change_out.txt was still empty.
  

  f) I also tested a scenario with only one land-use change in 2018, as well as scenarios with changes in multiple years (2018, 2041, 2078, and 2100). The files attached correspond to the 2017–2100 period, but I modified time.sim to run only from 2017 to 2020 so that I would be able to observe the 2018 change. Nevertheless, lu_change_out.txt remained empty.

  g) For all of the above options, I tested different revisions: 61.0.1, 61.0.2, and latest2025.12.12.

What do I need to do to make the decision tables active? Do I need to modify anything else besides file.cio? What do I do to see the changes in lu_change_out.txt?

I will attach the drive link to the TxtInOut folder and inside of it there are the scen_lu.dtl, scen_lu.upd and file.cio files

Thank you.

Arantxa

https://drive.google.com/file/d/1GelqjQTaAHUU6Wp-8ybFQaXexxgs71xW/view?usp=sharing