Upstream Accumulation
Each cell receives its own contribution plus contributions routed from upstream cells.
A(i)=1+Σj∈upstream(i)A(j)
Best used when: deriving drainage concentration, stream thresholds or catchment structure.
Flow Accumulation
Count or accumulate upstream contributing cells according to the flow-direction network.
HydrologyEnd-User DocumentationTheory + Formula + Parameters1. What This Feature Does
Count or accumulate upstream contributing cells according to the flow-direction network.
Cloud workflow: choose data → configure the scientific method → run → review the resulting layer/report. No programming is required.
2. Recommended Workflow
Prepare a valid flow-direction raster (usually from a sink-filled DEM).
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Accumulate upstream contributions.
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Interpret large values as concentrated drainage paths.
3. Theory, Methods & Equations
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 | — |
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.