Description
Multiply nonnegative rainIntensity and area by coefficient in [0, 1] and positive unitFactor for flowContribution.
Flow calculations relate volume, time, cross-section, velocity, and supplied model parameters. A local ratio or contribution does not by itself solve a complete hydraulic system.
Multiply nonnegative rainIntensity and area by coefficient in [0, 1] and positive unitFactor for flowContribution.
When to use this tool
Use Rational Runoff Impervious Area Term when you need one explicit flow component with coherent units and references.
How to use the tool and how it works
- Enter rainIntensity, area, coefficient, unitFactor. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read flowContribution. Use the output convention below.
Multiply nonnegative rainIntensity and area by coefficient in [0, 1] and positive unitFactor for flowContribution.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| rainIntensity | Rain Intensity | Required. Finite number; minimum 0. |
| area | Area on the common unit basis stated above. | Required. Finite number; minimum 0. |
| coefficient | Coefficient | Required. Finite number; minimum 0; maximum 1. |
| unitFactor | Unit Factor | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| flowContribution | Flow Contribution | Required. Finite number. |
{
"input": {
"rainIntensity": 20,
"area": 5,
"coefficient": 0.8,
"unitFactor": 1
},
"output": {
"flowContribution": 80
}
}Limitations and assumptions
- The caller supplies the unit factor and runoff coefficient; this is one rational-formula contribution without storm-duration selection, catchment timing, routing, or flood-design approval.
- 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 surveyed geometry, appropriate calibration, and a complete hydraulic model for operational or design decisions.
References
Similar or alternative tools
- Runoff Coefficient Landuse Weight Term
Return area × coefficient/totalArea.
- Runoff Depth Catchment Volume
Multiply nonnegative runoffMm by areaKm2 and 1000 for grossVolumeM3, then by connectedFraction in [0, 1].