Bruun Rule Shoreline Retreat
Compute signed ideal Bruun profile-translation retreat using supplied active width/closure/berm, assuming conservation and no alongshore exchange; not a site forecast.
Description
Bruun profile translation is an ideal sediment-conserving response to sea-level change.
Bruun profile translation is an ideal sediment-conserving response to sea-level change. Retreat remains signed when sea level falls.
Compute signed ideal Bruun profile-translation retreat using supplied active width/closure/berm, assuming conservation and no alongshore exchange; not a site forecast.
When to use Bruun Rule Shoreline Retreat
Use this tool to compute signed ideal Bruun profile-translation retreat using supplied active width/closure/berm, assuming conservation and no alongshore exchange; not a site forecast.
Gather the water, wave, current or profile observations and any supplied calibration constants. Confirm units and the stated coordinate and pressure conventions.
How to use Bruun Rule Shoreline Retreat and understand its results
- Gather the water, wave, current or profile observations and any supplied calibration constants. Confirm units and the stated coordinate and pressure conventions.
- Enter seaLevelChangeM, activeProfileWidthM, closureDepthM, bermHeightM using the field table and calculation rules, then run the tool.
- Read signedBruunRetreatM. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| seaLevelChangeM | Sea level change m | number | Required |
| activeProfileWidthM | Active profile width m | number | Required |
| closureDepthM | Closure depth m | number | Required |
| bermHeightM | Berm height m | number | Required |
Use positive active width and closure depth and nonnegative berm height. Preserve signed sea-level change and signed retreat in meters.1
retreat = sea-level change × active width/(closure depth + berm height) Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| signedBruunRetreatM | Signed bruun retreat m | number |
{
"input": {
"seaLevelChangeM": 0.5,
"activeProfileWidthM": 100,
"closureDepthM": 10,
"bermHeightM": 2
},
"output": {
"signedBruunRetreatM": 4.166666666666667
}
}Limitations and assumptions
No alongshore exchange or site-specific shoreline forecast is modeled.
Numbers and computed results must be finite; overflow produces an error. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use Closure Depth Hallermeier Formula: Evaluate a caller-coefficient Hallermeier closure-depth screen using the wave height exceeded for the caller selected duration; empirical applicability and wave statistic selection remain external. For a complementary task, use Beach Nourishment Fill Volume: Integrate measured target-minus-existing profile fill on supplied stations and length, then account for retention; target cuts error rather than silently crediting cut volume as nourishment.
References
-
Bruun Rule Shoreline Retreat — tool.io
Similar or alternative tools
- Closure Depth Hallermeier Formula
Evaluate a caller-coefficient Hallermeier closure-depth screen using the wave height exceeded for the caller selected duration; empirical applicability and wave statistic selection remain external.
- Beach Nourishment Fill Volume
Integrate measured target-minus-existing profile fill on supplied stations and length, then account for retention; target cuts error rather than silently crediting cut volume as nourishment.