Description
Return 2 × velocity/(3 × hydraulicRadius).
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.
Return 2 × velocity/(3 × hydraulicRadius).
When to use this tool
Use Manning Hydraulic Radius Sensitivity when you need one explicit flow component with coherent units and references.
How to use the tool and how it works
- Enter velocity, hydraulicRadius. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read derivative. Use the output convention below.
Require nonnegative velocity and positive hydraulicRadius. Return 2 × velocity/(3 × hydraulicRadius).1
The Manning velocity relation contains hydraulic radius raised to the two-thirds power. Differentiating that relation while holding roughness and energy slope fixed gives the local sensitivity used here; the tool does not fit those parameters.2
| Input field | Meaning and units | Accepted input |
|---|---|---|
| velocity | Velocity | Required. Finite number; minimum 0. |
| hydraulicRadius | Hydraulic Radius | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| derivative | Local velocity sensitivity per length unit of hydraulic radius, holding roughness and energy slope fixed. | Required. Finite number. |
{
"input": {
"velocity": 3,
"hydraulicRadius": 2
},
"output": {
"derivative": 1
}
}Limitations and assumptions
- This is the local Manning-form velocity derivative with respect to hydraulic radius while roughness and energy slope remain fixed; it does not estimate those parameters or a full discharge sensitivity.
- 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
-
Calculation and input contract: hydrology/manning-hydraulic-radius-sensitivity — tool.io
-
EM 1110-2-4000: Sedimentation Investigations of Rivers and Reservoirs — U.S. Army Corps of Engineers
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