Contributing-Cell Threshold
A cell becomes stream when upstream cell accumulation exceeds a threshold.
Stream(p)=1 if A(p) ≥ Tcells
Best used when: working directly in raster-cell units.
Stream Extraction
Extract a stream network by thresholding flow accumulation, optionally expressing the threshold as contributing-cell count or drainage area.
HydrologyEnd-User DocumentationTheory + Formula + Parameters1. What This Feature Does
Extract a stream network by thresholding flow accumulation, optionally expressing the threshold as contributing-cell count or drainage area.
Cloud workflow: choose data → configure the scientific method → run → review the resulting layer/report. No programming is required.
2. Recommended Workflow
Choose DEM/elevation band.
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Optionally fill sinks.
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Compute flow direction and accumulation.
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Choose threshold unit and value.
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Create the stream raster/network.
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Calibrate the threshold against known hydrography or imagery.
3. Theory, Methods & Equations
Drainage-Area Threshold
Converts accumulation to contributing area using pixel area.
Area(p)=A(p)×Acell
Stream(p)=1 if Area(p) ≥ Tarea
Best used when: a physically interpretable catchment-area threshold is preferred.
4. Input Data
| Input | Type | Requirement | Description |
|---|---|---|---|
| DEM Raster | raster | Required |
5. Parameters Available in the Application
| Parameter | Default | Choices / Range | How to Use It |
|---|---|---|---|
| Elevation Band | — | — | |
| Fill Sinks First | On | — | |
| Threshold Unit | cells | Contributing Cells, Drainage Area (km²) | |
| Stream Threshold | 1000 | 0.0001 to — |
6. Output & Interpretation
The result should be interpreted according to the selected method and the physical meaning of the input data. Preserve source units, coordinate reference information, NoData meaning, acquisition date, and preprocessing level when comparing results.
Scientific interpretation: an algorithm can produce a numerically valid result even when the input data are unsuitable. Always check masks, units, sensor characteristics, spatial resolution and reference data.
7. Best Practices
- Use analysis-ready inputs and remove invalid/cloud/noise artifacts that are not part of the target phenomenon.
- Choose parameters from the physical scale of the data, not only from visual appearance.
- Keep categorical and continuous rasters conceptually separate when selecting interpolation/resampling methods.
- Compare the result with the source image and independent reference information.
- Document the settings used when results will be compared across dates, sensors or study areas.