Irrigation Efficiency & From Pump to Root Zone

Irrigation efficiency is the fraction of the water you pump or divert that actually ends up stored in the crop's root zone, available for the plant to use. The rest is lost on the way — to seepage in canals, evaporation in the air, deep percolation below the roots, and uneven spread across the field.

Overall efficiency is the product of the stage efficiencies: Eo = Conveyance × Application × Distribution. For example a system with 90% conveyance, 80% application and 90% distribution has an overall efficiency of 0.90 × 0.80 × 0.90 ≈ 0.65, meaning only about 65% of pumped water reaches the root zone.

Conveyance efficiency measures how much water survives the journey from the source to the field — through canals, channels and pipes. Unlined earthen canals lose a lot to seepage (conveyance can fall below 70%), while lined canals and closed pipes keep conveyance efficiency high (often 90–95%).

Application efficiency is the fraction of water delivered to the field that is actually stored in the root zone, rather than lost to evaporation, runoff or deep percolation. It depends mainly on the method: drip is around 90%, sprinkler around 75% and surface (flood/furrow) often 50–60%.

Distribution efficiency (or uniformity) describes how evenly water is spread across the field. If some parts get plenty while others stay dry, you must over-irrigate the wet areas to satisfy the dry ones, wasting water. Good design, level fields and well-maintained emitters keep distribution high.

It varies widely. A well-managed drip system with piped supply might lose only 15–20% overall. A surface system on unlined canals can lose more than half its water before it ever benefits the crop. This tool shows your net water and water lost so you can see exactly where you stand.

The big levers are lining or piping canals (conveyance), switching to drip or sprinkler (application), levelling fields and maintaining emitters (distribution), and scheduling irrigation to crop demand so you neither under- nor over-apply. Small gains at each stage multiply into a large overall improvement.

Every litre lost is a litre you paid to pump, lift or buy and got nothing for. Low efficiency means higher energy bills, more water drawn from a stressed source, and often waterlogging or salinity from deep percolation. Raising efficiency cuts cost and protects the resource at the same time.

Mostly, but a little deep percolation can be useful for leaching salts in saline soils, and extremely tight efficiency needs good scheduling to avoid crop stress. The aim is high, well-managed efficiency — delivering the crop's needs reliably with minimal waste — not efficiency for its own sake.