Free Online Canal Seepage Loss and Conveyance Efficiency Calculator

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Canal Seepage Loss & Conveyance Efficiency — Inflow-Outflow Method

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Notes

Method

The inflow-outflow method estimates seepage by measuring flow at the head and tail of a canal reach: Q_loss = Q_in − Q_out. Conveyance efficiency E_c = Q_out / Q_in. Annual volume assumes continuous full-flow operation; actual loss is lower for seasonal or part-flow canals.

Efficiency Ratings

Typical unlined earthen canals: E_c = 60–80%. Well-maintained earthen canals: 75–85%. Concrete-lined canals: 90–98%. Seepage losses above 30% of inflow often justify a lining investment. (USBR, FAO)

Lining Payback

Enter water value and lining cost in any consistent currency. Lining area = reach length × wetted perimeter — the wetted perimeter of the canal cross-section at the measured flow depth (bottom width plus both wetted slopes). Annual value recovered assumes the lined canal achieves the target E_c continuously. Actual payback will be longer for seasonal canals or if the lining does not reach the target efficiency.

Reference

USBR Water Measurement Manual, 3rd ed. (2001). FAO Irrigation and Drainage Paper 57 (1999).