Theory 088/Food & Agriculture /Irrigation
Irrigation Efficiency Is an Infiltration Match
Efficiency is computed from volume. The loss may happen in the first minutes.
Irrigation efficiency is set by the ratio of application rate to infiltration rate rather than by total water applied, so the same volume delivered faster can lose more to runoff than if delivered slowly.
01The evidence
Efficiency varies widely between systems applying the same volume, and the variation tracks application rate relative to soil intake.
02The tension
Efficiency audits compare volumes applied to volumes stored, which attributes losses to management or evaporation rather than to the rate mismatch.
03The mechanism
Water applied faster than the soil can absorb ponds and runs off. The fraction lost depends on the ratio of application to infiltration, not on the total, so a slow application of the same volume can be nearly lossless.
That makes the ratio the efficiency determinant, and predicts a threshold above which losses rise sharply.
04What this is not
Volume audits compare totals. This compares rates, which explains losses at equal volume.
05Predictions
- P1Efficiency should track the rate ratio.
- P2Slow delivery should cut runoff at equal volume.
- P3A threshold should appear above intake.
06Refutation
Efficiency independent of application rate at equal volume would restore volume audits.
07What it changes
It would change system design and scheduling.