Chlorophyll Target Load Back Calculation Tool
Compose inversion of a supplied chlorophyll/P power calibration with a steady Vollenweider-form loading model; excludes internal loads and does not guarantee a management outcome.
Description
A chlorophyll target can be translated into a phosphorus target through a calibrated power relation.
A chlorophyll target can be translated into a phosphorus target through a calibrated power relation. Combining its inverse with a steady loading model produces a candidate external-load target.1
The tool returns impliedTargetPhosphorusMicrogramsPerLiter, modelArealExternalLoadGramsPerM2Year. The computation uses supplied observations and parameters rather than acquiring measurements.
When to use Chlorophyll Target Load Back Calculation Tool
Use this for the following task: Compose inversion of a supplied chlorophyll/P power calibration with a steady Vollenweider-form loading model; excludes internal loads and does not guarantee a management outcome. Prepare observations and calibration parameters on the same unit and reporting basis.
How to use Chlorophyll Target Load Back Calculation Tool and understand its results
- Prepare the measured quantities and supplied model parameters. Match the units and align paired lists before calculating.
- Enter targetChlorophyllMicrogramsPerLiter, chlorophyllPowerCoefficient, chlorophyllPowerExponent, meanDepthM, residenceYears, retentionMultiplier, retentionExponent according to the field table, then run the tool.
- Read impliedTargetPhosphorusMicrogramsPerLiter, modelArealExternalLoadGramsPerM2Year. Use the calculation below to interpret the selected mean or the model’s signs, units and comparison flags.
- Review the supplied assumptions and calibration before comparing or reporting the result.
| Input field | Meaning | Value type and bounds | Requirement |
|---|---|---|---|
| targetChlorophyllMicrogramsPerLiter | Target chlorophyll micrograms per liter | number | Required |
| chlorophyllPowerCoefficient | Chlorophyll power coefficient | number | Required |
| chlorophyllPowerExponent | Chlorophyll power exponent | number | Required |
| meanDepthM | Mean depth m | number | Required |
| residenceYears | Residence years | number | Required |
| retentionMultiplier | Retention multiplier | number | Required |
| retentionExponent | Retention exponent | number | Required |
Supply positive target chlorophyll, power coefficient and exponent, depth and residence time, with nonnegative retention parameters. Invert the chlorophyll relation and then the loading relation.
targetP=(targetChlorophyll/coefficient)^(1/exponent); load g/(m²·year)=(targetP×depth/residence)×(1+retentionMultiplier×residence^retentionExponent)/1000 The symbols and boundary conditions refer to the supplied fields and the implementation described above.
| Output field | Meaning | Value type |
|---|---|---|
| impliedTargetPhosphorusMicrogramsPerLiter | Implied target phosphorus micrograms per liter | number |
| modelArealExternalLoadGramsPerM2Year | Model areal external load grams per m2 year | number |
{
"input": {
"targetChlorophyllMicrogramsPerLiter": 18,
"chlorophyllPowerCoefficient": 2,
"chlorophyllPowerExponent": 2,
"meanDepthM": 5,
"residenceYears": 4,
"retentionMultiplier": 1,
"retentionExponent": 0.5
},
"output": {
"impliedTargetPhosphorusMicrogramsPerLiter": 3,
"modelArealExternalLoadGramsPerM2Year": 0.01125
}
}Limitations and assumptions
Both relations require an applicable site calibration. Internal loading and seasonal behavior are excluded, and the composition does not guarantee a management outcome.
Numerical inputs must be finite. Input-shape and calculation checks do not establish measurement quality or the validity of a supplied calibration.
Alternative or Complementary methods
Choose Chlorophyll Phosphorus Regression Prediction when you need its operation: Fit a log-power chlorophyll/phosphorus relation to caller observations with within-range median prediction; no mutable published regression or uncorrected arithmetic-mean claim. Choose Vollenweider Phosphorus Load Limit for the complementary operation: Invert a caller Vollenweider-form steady retention relation for target areal external phosphorus load; not an authoritative load limit or site-specific ecological guarantee.
Background reference: Water Quality, Hydrology, and Response to Changes in Phosphorus Loading of Nagawicka Lake.
References
-
Water Quality, Hydrology, and Response to Changes in Phosphorus Loading of Nagawicka Lake — U.S. Geological Survey
Similar or alternative tools
- Chlorophyll Phosphorus Regression Prediction
Fit a log-power chlorophyll/phosphorus relation to caller observations with within-range median prediction; no mutable published regression or uncorrected arithmetic-mean claim.
- Vollenweider Phosphorus Load Limit
Invert a caller Vollenweider-form steady retention relation for target areal external phosphorus load; not an authoritative load limit or site-specific ecological guarantee.