PATH Cost-Effective Quick Start

How to configure and run a PATH Cost-Effective (PathCE) optimization in WEPPcloud.

What PATH CE Does

PATH Cost-Effective selects the most cost-effective set of post-fire hillslope treatments (mulch presets) that meets user-defined sediment-yield and discharge targets. It uses Omni scenario outputs as the data source and solves a binary linear program to minimize total treatment cost.

Prerequisites

Before running PATH CE you need a completed WEPPcloud run with:

A disturbed-land configuration (fire scenario with SBS map).
The Omni module enabled (PATH CE provisions its own Omni scenarios automatically, but watershed and landuse artifacts must already exist).

Enabling PATH CE

In the WEPPcloud UI, open the Mods dropdown and enable Path CE. This adds the PATH CE configuration panel to your run page.

Configuration Parameters

Parameter	Type	Default	Meaning
`sddc_threshold`	float	0.0	Watershed discharge reduction target.
`sdyd_threshold`	float	0.0	Per-hillslope sediment yield threshold (tons).
`slope_min` / `slope_max`	float	None	Optional slope filter in degrees.
`severity_filter`	list	None	Burn severity filter (e.g. `["High", "Moderate"]`).
`mulch_costs`	dict	presets at 0.0	Unit costs keyed by mulch scenario key ($/ha).

Running from the UI

Open the PATH CE panel on your run page.
Set thresholds, slope range, severity filter, and mulch costs.
Click the run button.
WEPPcloud enqueues an RQ job that provisions Omni scenarios and runs the solver.
Poll the status panel until completion.
Review results: selected hillslopes, total cost, and reduction metrics.

Running from the API

1. Update configuration

POST /runs/{runid}/{config}/api/path_ce/config
Content-Type: application/json

{
  "sddc_threshold": 10.0,
  "sdyd_threshold": 0.5,
  "slope_min": 10,
  "slope_max": 45,
  "severity_filter": ["High", "Moderate"],
  "mulch_costs": {
    "mulch_15_sbs_map": 250,
    "mulch_30_sbs_map": 400,
    "mulch_60_sbs_map": 700
  }
}

2. Launch the RQ job

POST /runs/{runid}/{config}/tasks/path_cost_effective_run

This enqueues the full pipeline: Omni scenario provisioning followed by the solver.

3. Poll status and retrieve results

GET /runs/{runid}/{config}/api/path_ce/status
GET /runs/{runid}/{config}/api/path_ce/results

The results payload includes selected_hillslopes, treatment_hillslopes, total_cost, total_fixed_cost, total_sddc_reduction, final_sddc, and artifact paths.

Output Artifacts

Artifacts are written under <working-directory>/path/:

File	Contents
`analysis_frame.parquet`	Solver-ready merged table with post-fire metrics, treatment reductions, slope, area, and severity.
`hillslope_sdyd.parquet`	Per-hillslope final sediment yield (`wepp_id`, `final_Sdyd`).
`untreatable_hillslopes.parquet`	Hillslopes whose final sediment yield remains above the threshold.

Reading Artifacts

from pathlib import Path
import pandas as pd

wd = Path("/wc1/runs/<runid>/<config>")
analysis = pd.read_parquet(wd / "path" / "analysis_frame.parquet")
sdyd = pd.read_parquet(wd / "path" / "hillslope_sdyd.parquet")

Current Limitations

Treatment options are limited to the mulch presets defined internally; custom treatment catalogs are not yet supported.
The sddc_threshold constraint currently uses NTU-based columns rather than outlet sediment discharge columns.
Burn severity labels are inferred from landuse codes using a default mapping. Non-standard landuse coding may cause unexpected severity filtering behavior.