Plumbing Detention Basin Weir Length Calculator
Conditional free sharpRECTANGULARweirL=Q/[(2/3) Cd√2g h^1.5], independent end contraction/submergence external; not triangular notch or generated safe basin outlet. Actual independently matched units, regime, material/equipment and governing references; not a hydraulic code, safe pressure, water pot ability or operational approval.
Description
A free rectangular weir relates flow to crest length and head.
A free rectangular weir relates flow to crest length and head.1
Solving for length requires an independently calibrated coefficient and applicable free-flow conditions. The calculation and input requirements are explained below.
When to use Plumbing Detention Basin Weir Length Calculator
Enter nonnegative specified discharge m³/s and positive calibrated rectangular-weir Cd, gravity m/s² and head meters.
How to use Plumbing Detention Basin Weir Length Calculator and how it works
- Prepare the measurements or independently established model inputs described below, with matching units and observation scope.
- Enter the required fields and run Plumbing Detention Basin Weir Length Calculator.
- Read the result fields using the formula, output units, signs and ordering explained below.
- Correct any rejected inputs and rerun; interpret the result within the stated model and its assumptions.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| callerEngineerSpecifiedWeirDischarge | Caller Engineer Specified Weir Discharge. Use the units and matching context stated in the calculation below. | number | Required; nonnegative; finite; other constraints below |
| callerCalibratedWeirDischargeCoefficient | Caller Calibrated Weir Discharge Coefficient. Use the units and matching context stated in the calculation below. | number | Required; strictly positive; finite; other constraints below |
| callerGravityMetersPerSecondSquared | Caller Gravity Meters Per Second Squared. Use the units and matching context stated in the calculation below. | number | Required; strictly positive; finite; other constraints below |
| actualHeadAboveCrestMeters | Actual Head Above Crest Meters. Use the units and matching context stated in the calculation below. | number | Required; strictly positive; finite; other constraints below |
Enter nonnegative specified discharge m³/s and positive calibrated rectangular-weir Cd, gravity m/s² and head meters. Divide by (2/3)Cd*sqrt(2g)*h^1.5 to return crest length meters. End-contraction and submergence applicability must be established externally.
crestLengthM=Q/((2/3)*Cd*sqrt(2*g)*headM^1.5) Apply the input ordering, units and branch conditions stated above.
| Output field | Meaning | Value type |
|---|---|---|
| result | Object containing the calculated or selected fields below. | object |
| result.value | Numeric result under the formula and output units explained above. | number |
{
"input": {
"callerEngineerSpecifiedWeirDischarge": 1,
"callerCalibratedWeirDischargeCoefficient": 1,
"callerGravityMetersPerSecondSquared": 2,
"actualHeadAboveCrestMeters": 1
},
"output": {
"result": {
"value": 0.75
}
}
}Limitations and assumptions
The calculation uses the supplied observations and model inputs. It does not collect measurements, select a reference population or coefficient, or establish that the model applies to the actual case. The stated branch conditions and output units remain part of the result.
All fields require explicit values. Unexpected fields, wrong types, nonfinite numbers and sparse arrays are rejected. Alignment, bounds and supported-token rules are explained above; extremely large inputs or nonfinite results can also fail. Input errors differ from successful false comparisons, unavailable-domain flags and empty match lists.
Alternative or Complementary methods
Use Plumbing Weir Flow Triangular Calculator for a complementary operation: A sharp triangular weir relates free-discharge flow to head and notch angle.
Use Plumbing Detention Basin Outlet Orifice Size Calculator for a complementary operation: An ideal outlet orifice relates discharge to area, head and coefficient.
References
Similar or alternative tools
- Plumbing Weir Flow Triangular Calculator
A sharp triangular weir relates free-discharge flow to head and notch angle.
- Plumbing Detention Basin Outlet Orifice Size Calculator
An ideal outlet orifice relates discharge to area, head and coefficient.