Description
Measure signed dune migration relative to a supplied baseline coordinate.
Geomorphic measurements distinguish signed coordinates, grain-size scales, profile derivatives and transported-mass or cross-section bases. A supplied datum adjustment or threshold does not detect a landform or establish a process. Plan distance, profile second derivative and slope-normalized curvature are different quantities.
Measure signed dune migration relative to a supplied baseline coordinate.
When to use this tool
Use Dune Migration Signed Baseline Offset when checking the stated local landform, sediment, profile or coordinate convention.
How to use the tool and how it works
- Enter baselinePosition, laterPosition. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read signedGap. Use the output convention below.
Return laterPosition-baselinePosition as a signed gap in one common coordinate unit.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| baselinePosition | Baseline Position | Required. Finite number. |
| laterPosition | Later Position | Required. Finite number. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| signedGap | Signed first/second difference in the direction and units specified above. | Required. Finite number. |
{
"input": {
"baselinePosition": 12,
"laterPosition": 17
},
"output": {
"signedGap": 5
}
}Limitations and assumptions
- Time duration and spatial orientation are not inferred; this does not calculate migration speed or establish an observed dune trend.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use calibrated surveys, mapped geometry and suitable complete sediment/terrain models for trends, process interpretation, uncertainty or hazard assessment.
References
Similar or alternative tools
- Shoreline Signed Transect Offset
Measure a shoreline position's signed offset along a supplied transect.
- Shoreline Tide Stage Reference Offset
Subtract a supplied horizontal tide-stage offset from a shoreline coordinate.