Description
Calculate gravity-head margin between a water source and an outlet.
Garden-resource planning uses supplied geometry, material stocks, visit counts and accounting boundaries. Water elevation difference gives nominal head before losses, while a screened reject fraction uses the screened total. Local arithmetic does not establish plant compatibility, suitable animal care, drainage performance or a safe structural design.
Calculate gravity-head margin between a water source and an outlet.
When to use this tool
Use Roof Garden Gravity Head Margin when you already have sourceWaterElevation, outletElevation, suppliedRequiredHead and need to calculate gravity-head margin between a water source and an outlet.
How to use the tool and how it works
- Enter sourceWaterElevation, outletElevation, suppliedRequiredHead. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read availableHead, headMargin. Use the output convention below.
Require suppliedRequiredHead>=0; available=source elevation-outlet elevation and margin=available-required.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| sourceWaterElevation | Source Water Elevation | Required. Finite number. |
| outletElevation | Outlet Elevation | Required. Finite number. |
| suppliedRequiredHead | Supplied Required Head | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| availableHead | Source water elevation-outlet elevation, before hydraulic losses. | Required. Finite number. |
| headMargin | Head Margin | Required. Finite number. |
{
"input": {
"sourceWaterElevation": 8,
"outletElevation": 3,
"suppliedRequiredHead": 2
},
"output": {
"availableHead": 5,
"headMargin": 3
}
}Limitations and assumptions
- Elevations need one datum; no pressure loss, flow, contamination, structural support or safe roof installation is calculated.
- 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
Measure actual site geometry and reconcile resource stocks, transfers and observation periods. For water delivery, account for the complete hydraulic path and losses; nominal head and local garden margins remain preliminary bookkeeping or geometry.
References
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