Agriculture & Forestry
Agricultural Drainage Tile Spacing & Depth (Hooghoudt Equation)
Calculate agricultural drainage tile spacing & depth (hooghoudt equation) using the stated engineering or scientific relationship and adjustable field inputs.
Preparing your result…
What this calculator does
Calculates Agricultural Drainage Tile Spacing & Depth (Hooghoudt Equation) using the formula verified against the cited source.
What your result means
An estimate from the inputs you enter, within the scope stated below — not advice.
Formula
S² = (8·Kb·d·h + 4·Ka·h²) ÷ q
The step-by-step working for your own numbers appears with the result above and in the PDF report.
Frequently asked questions
Symbols and assumptions
- Inputs
- The values entered in the fields above
- • Steady-state Hooghoudt spacing S=sqrt[(8Kb×d×h+4Ka×h²)/q]. Ka/Kb are hydraulic conductivity above/below drains; h is midpoint water-table height above drain; d is equivalent depth; q is recharge/drainage flux.
Sources and review
Reviewed 2026-10-18 · Next review 2027-04-18
- • FAO Irrigation and Drainage Paper62 Annex 17. Use one length/time system: e.g.K and q m/day, d/h m, yielding spacing m. Equivalent d is not simply geometric depth to barrier and depends on drain geometry/spacing; supply a properly calculated d or solve iteratively. Formula sizes spacing at chosen conditions, not drain depth or all hydraulic details.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Quick reference
| Scenario | Conductivity above drains Ka (m/day) | Conductivity below drains Kb (m/day) | Equivalent depth to barrier d (m) | Drain spacing |
|---|---|---|---|---|
| Worked example | 0.5 | 1 | 1.5 | 30.4725 m |
| Half the amounts | 0.25 | 0.5 | 0.75 | 14.2522 m |
| Double the amounts | 1 | 2 | 3 | 60.9449 m |
Need the full picture? Get the detailed PDF report with charts, tables, formulas and working steps.
Reviewed 2026-10-18 · Next review 2027-04-18
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