Calculator Inputs
Formula Used
The calculator converts a net irrigation requirement into gross irrigation depth by accounting for application losses and optional leaching.
- Gross depth (mm) = (Net depth / Efficiency) x (1 + Leaching)
- Efficiency = application efficiency fraction (percent / 100)
- Leaching = leaching allowance fraction (percent / 100)
- Volume (m3) = Gross depth (mm) / 1000 x Area (m2)
- Run time (h) = Volume (m3) / Flow (m3/s) / 3600
Soil moisture method
When using soil moisture deficit, net depth is estimated from volumetric deficit and root depth: Net depth (mm) = (FC - MC) x Root depth (m) x 1000 x Depletion.
How to Use
- Select a method: direct net depth or soil moisture deficit.
- Enter application efficiency and an optional leaching allowance.
- If needed, add area to compute total applied volume.
- If you know flow rate, get an estimated pumping run time.
- Press calculate to display results above the form.
Example Data Table
| Net depth (mm) | Efficiency (%) | Leaching (%) | Area (ha) | Flow (L/s) | Gross depth (mm) | Volume (m3) | Run time (h) |
|---|---|---|---|---|---|---|---|
| 45 | 70 | 10 | 1 | 25 | 70.71 | 707.14 | 7.86 |
| 30 | 80 | 0 | 0.5 | 18 | 37.50 | 187.50 | 2.89 |
Professional Guide: Gross Irrigation Depth in Construction Projects
Irrigation planning on construction sites often involves temporary landscaping, dust control, hydroseeding, and post-completion green areas. The amount of water that plants or soil actually need is the net irrigation depth. On site, however, not every liter reaches the root zone. Wind drift, evaporation, runoff, and distribution non-uniformity create losses. The gross irrigation depth accounts for these losses so crews can schedule pumping, tanker trips, and valve run times with confidence.
Why efficiency matters
Application efficiency reflects how effectively the selected method delivers water to the target zone. Sprinklers on open areas may have moderate efficiency due to wind and overspray, while drip systems tend to be higher when installed correctly. By dividing net depth by efficiency, the calculator scales water delivery to match real site performance, supporting accurate procurement and fuel or energy budgeting.
Leaching allowance and salinity control
Some projects require a leaching allowance to flush salts below the root zone, especially when water quality is marginal or soil salinity is a known issue. Adding a leaching percentage increases gross depth so the net requirement is still met after the extra flushing volume is applied.
From depth to volume and run time
Depth is useful for agronomic targets, but construction teams usually manage water as volume and time. When you enter an irrigated area, the calculator converts gross depth to applied volume. If a pump or supply line flow rate is provided, it also estimates run time. This helps coordinate shifts, avoid overwatering, and reduce waterlogging near structures or newly placed compaction layers.
Example data and interpretation
Suppose the net requirement is 45 mm, efficiency is 70%, and leaching is 10%. Gross depth becomes about 70.71 mm. For an area of 1 hectare, that is roughly 707.14 m3 of water. With a flow of 25 L/s, estimated run time is about 7.86 hours. Use these outputs to set valve windows, plan tanker refills, and document water use for compliance or project reporting.
Field use tips
- Measure efficiency from field tests when possible, not assumptions.
- Apply lower allowable depletion for shallow-rooted turf or newly planted areas.
- Re-check inputs after nozzle changes, pressure adjustments, or layout revisions.
- Keep records of depth, volume, and time for auditing and troubleshooting.
FAQs
1) What is the difference between net and gross irrigation depth?
Net depth is the water needed in the root zone. Gross depth is the applied water required to deliver that net amount after accounting for losses from evaporation, drift, runoff, and non-uniform distribution.
2) How do I choose an application efficiency value?
Use field performance data if available. Otherwise, select a conservative value based on method and conditions. Windy, open sites often need lower efficiency than sheltered areas or well-designed drip layouts.
3) When should I add a leaching allowance?
Add leaching when salinity management is required due to soil or water quality. If salinity is not a concern, set leaching to zero to avoid unnecessary over-application and potential drainage issues.
4) Can the calculator estimate total water volume for my project area?
Yes. Enter the irrigated area and the calculator converts gross depth into applied volume. This is useful for planning tank deliveries, pump sizing checks, and daily water budgeting.
5) How accurate is the run time estimate?
Run time depends on the accuracy of your flow rate and distribution conditions. Use measured flow at the outlet when possible, and treat results as planning guidance rather than a calibrated control schedule.
6) What does the soil moisture method calculate?
It estimates net depth from the soil moisture deficit between field capacity and current moisture, scaled by root depth and allowable depletion. It is helpful when you monitor soil moisture on site.
7) Which units should I use for area and flow?
Use the units you track on site. The calculator accepts square meters, hectares, or acres for area, and L/s or m3/h for flow. It converts internally for consistent volume and time outputs.