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Revegetation

Revegetation lets you replace the default "use observed post-fire cover as-is" assumption with an explicit cover-recovery scenario before running WEPP. It is for users who want to test how different vegetation recovery paths change modeled runoff and erosion after disturbance.

What You Actually See In The UI

When the workflow is enabled, the control appears under WEPP Advanced Options as Revegetation Scenarios. The user-facing controls are:

  • Cover transformation scenario
    • Observed
    • 20-Year Recovery
    • 20-Year Partial Recovery
    • User-Defined Transform
  • Upload cover transform file (.csv) which only appears after User-Defined Transform is selected

These are the labels the user sees. The run is still executed from the normal WEPP controls.

When To Use Each Scenario Option

UI option What it means Best use
Observed Uses the available RAP-derived cover time series without applying a transform; the underlying API value is an empty reveg_scenario Use when you want the project to follow the observed cover record directly
20-Year Recovery Applies the built-in full-recovery style transform curve; the underlying built-in file is 20-yr_Recovery.csv Use when you want a stronger assumed recovery trajectory than the observed record
20-Year Partial Recovery Applies the built-in partial-recovery curve; the underlying built-in file is 20-yr_PartialRecovery.csv Use when you expect slower or incomplete recovery
User-Defined Transform Lets you upload your own transform CSV; the selector uses the user_cover_transform mode until a file is uploaded Use when local expertise, field evidence, or planning assumptions justify a custom recovery curve

What The UI Actions Trigger

There are two separate user actions:

  1. Choosing a built-in scenario The selection is sent with the next WEPP action as reveg_scenario to the WEPP run or prep endpoints such as /rq-engine/api/runs/<runid>/<config>/run-wepp or /rq-engine/api/runs/<runid>/<config>/prep-wepp-watershed.

  2. Uploading a custom CSV The file upload happens immediately when you choose a file. The browser posts it to /rq-engine/api/runs/<runid>/<config>/tasks/upload-cover-transform, which saves the CSV under the run and marks it as the active user-defined transform.

That means picking User-Defined Transform by itself does not change the model. The uploaded file becomes active, and the change takes effect on the next WEPP prep or run. Likewise, simply changing the dropdown to a built-in scenario does not execute anything until the next WEPP prep or run submits that selection.

How The Cover Transform Actually Works

This workflow does not create a new vegetation model. It rescales the post-fire RAP cover trajectory that WEPP preparation uses.

At a practical end-user level:

  • the transform is anchored to the fire-year cover baseline,
  • years before the fire are left alone,
  • years after the fire are scaled by the scenario curve,
  • only the years already available in the run's RAP and climate data are modeled.

Important consequences:

  • choosing a 20-Year ... scenario does not make the project run for 20 years if the climate and RAP inputs are shorter,
  • the transform changes cover assumptions, not soils, topography, or climate,
  • if your custom CSV does not include every burn-class and vegetation-class combination, the missing combinations are left unchanged.

User-Defined Transform Upload Guidance

Use User-Defined Transform only if you can defend the curve you are uploading.

The current upload path expects a .csv file and stores it under the run's revegetation/ folder. The downstream parser expects:

  • the first row to identify burn-severity classes,
  • the second row to identify vegetation labels,
  • later rows to hold year-by-year scale factors.

For end users, the important operational limits are:

  • upload validation is light at upload time,
  • a file can upload successfully and still produce poor or confusing results later if the class names or structure do not match what preparation expects,
  • if the curve ends before the modeled period ends, the last factor is carried forward.

How To Interpret Results

Read revegetation as a scenario-comparison tool, not a source of truth.

In general:

  • earlier or stronger cover recovery usually reduces runoff and sediment,
  • slower or partial recovery usually keeps post-fire response elevated for longer,
  • small differences between scenarios do not necessarily mean the transform failed.

Small differences can happen when:

  • the modeled period is short,
  • cover is not the dominant control in that watershed,
  • the transformed cover does not change the limiting canopy condition enough to change erosion materially.

Core Assumptions And Limits

  • Revegetation does not extend simulation length beyond the available climate and RAP years.
  • It changes post-fire cover assumptions only. It does not directly change weather, soils, burn severity mapping, or treatment effects.
  • The transform is based on burn class and vegetation class, not on a fully dynamic plant-community process model.
  • In WEPP, the resulting cover series acts as a canopy constraint in the growth logic rather than a guarantee that field canopy will exactly match the uploaded percentages every day.
  • If the fire date or disturbance context is wrong, the scenario comparison will also be wrong.

Decision Guidance

Use Observed when your main goal is to honor the available record.

Use 20-Year Recovery or 20-Year Partial Recovery when you need structured planning scenarios and do not have a site-specific curve.

Use User-Defined Transform only when you can explain where the curve came from and why it is more appropriate than the built-in choices.