Canal Seepage Loss Calculator

Inputs

Calculation method

Pick the approach that matches your data quality.

Canal length (m)

Total wetted reach considered for seepage.

Wetted perimeter (m)

Perimeter in contact with water along the section.

Operating time (hours)

Used for total seepage volume and cost.

Water value (optional, per m³)

Enter 0 if you only need volumes.

Hydraulic conductivity k (m/s)

Typical soils: 1e-9 to 1e-3 m/s.

Head difference Δh (m)

Driving head across lining or embankment.

Flow path thickness d (m)

Approximate seepage path length through soil/lining.

Reset

Note: This tool provides planning-level estimates. For final design, confirm k, head, and boundary conditions with field data and geotechnical inputs.

Scenario	Method	Length (m)	Wetted Perimeter (m)	k (m/s)	Δh (m)	d (m)	Loss Rate (m³/s)	Daily Loss (m³/day)
Unlined reach, sandy silt	Darcy	1000	8.5	1.0×10⁻⁶	1.0	1.5	0.005667	489.60
Lined reach, moderate leakage	Coefficient	1200	7.8	—	—	—	0.001872	161.74
Preliminary audit, measured inflow	Percentage	2000	9.0	—	—	—	0.125000	10800.00

Values are illustrative and should be replaced with project-specific measurements.

Interface area: A = P × L, where P is wetted perimeter and L is canal length.
Darcy method: Q = k × (Δh/d) × A.
Coefficient method: Q = S × A.
Percentage method: Q_loss = Q_in × (p/100).
Daily loss: V_day = Q × 86,400.
Total loss: V_total = Q × (hours × 3,600).

Select a calculation method that matches your available site data.
Enter canal length and wetted perimeter for the reach under review.
Provide method-specific inputs: k, Δh, d, or S, or Qin and percentage.
Set operating hours to estimate total seepage volume over time.
Optionally enter a water value to estimate the monetary impact.
Click Calculate and export results as CSV or PDF.

1) Why seepage loss matters

Seepage is often the largest hidden loss in open conveyance. Even small rates accumulate: a loss of 0.002 m³/s equals 172.8 m³/day, enough to irrigate several hectares depending on crop demand and application efficiency.

2) Choosing a practical method

Use the Darcy option when soil permeability and a representative head gradient can be estimated. Typical hydraulic conductivity ranges from 1×10⁻⁹ m/s (clay) to 1×10⁻⁴ m/s (clean sand), while silts commonly fall near 1×10⁻⁷ to 1×10⁻⁵ m/s. The coefficient method suits lined canals where leakage behaves like an average “area‑based” rate verified from inspections or monitoring for reliable planning outputs.

3) Key inputs that control results

Interface area A = P×L drives the calculation, so measure wetted perimeter carefully at the operating water level. In Darcy seepage, the gradient i = Δh/d is sensitive: doubling the assumed flow path thickness halves the loss rate. For audits, split long canals into reaches with different soils and lining conditions, then sum results. When data is uncertain, test a low, expected, and high input set to bound the outcome.

4) Turning loss into an operational KPI

Report seepage as m³/s per km and as m³/day. This supports benchmarking between projects and seasons. Combine daily loss with operating hours to estimate total volume over a week, month, or rotation. If you enter a water value (currency per m³), the calculator converts volume loss into an estimated financial impact for payback comparisons against lining and rehabilitation costs.

5) Reducing seepage with engineering actions

Common controls include compaction, clay blankets, geomembranes, shotcrete, and concrete lining. Maintenance also matters: joint cracks, animal burrows, and vegetation roots can increase leakage rapidly. Use periodic flow measurements and groundwater observations to update inputs, validate assumptions, and prioritize rehabilitation where the saved volume is highest.

1) What does “wetted perimeter” mean?

It is the length of canal boundary in contact with water at the operating depth. Measure it from the cross‑section using the waterline that represents normal flow conditions.

2) Which method should I choose?

Use Darcy when you can estimate soil permeability and a head gradient. Use the coefficient option for lined reaches with observed leakage behavior. Use percentage when you only have inflow and an audit‑level loss estimate.

3) Why does the calculator use A = P × L?

Seepage is proportional to the contact surface through which water can leak. Multiplying wetted perimeter by length approximates the total interface area along the canal reach.

4) What operating time should I enter?

Enter the number of hours the canal carries water for the period you want to evaluate. For a continuous day, use 24 hours. For rotational supply, enter the actual running hours.

5) How do I estimate the flow path thickness d?

Use lining thickness for lined canals, or an effective seepage path through embankment/foundation for unlined canals. When uncertain, test a reasonable range to see sensitivity.

6) Are results suitable for final design?

This is intended for planning and comparison. Final design should use calibrated parameters from field tests, seepage monitoring, and geotechnical interpretation, including boundary conditions and groundwater levels.

7) How can I reduce seepage losses?

Improve lining integrity, seal joints and cracks, control burrowing animals, remove invasive roots, and compact embankments. Track performance with periodic flow checks and update the inputs to confirm savings.