Water Resource Engineering
Irrigation efficiency = ratio of water consumed by crop to water supplied through irrigation.
Overall efficiency = ηc × ηa (conveyance × application)
Overall efficiency = ηc × ηa (conveyance × application)
Water flow path — where each efficiency applies
1 Water conveyance efficiency (ηc)Standard
River/reservoir से field तक पानी पहुंचाने में कितना % बचा।
Ratio of water delivered to field to water diverted from river/reservoir into canal system.
ηc = Wf / Wr × 100Wf = water delivered to field | Wr = water diverted into canal from river/reservoir
Loss accounted: Seepage from canal, evaporation from canal, absorption by canal banks
2 Water application efficiency (ηa)SSC JE 2014 ★★★
Field में deliver हुए पानी में से कितना root zone में store हुआ।
Ratio of water stored in root zone to water delivered to the field. Also called on-farm efficiency.
ηa = Ws / Wf × 100Ws = water stored in root zone | Wf = water delivered to field
Loss accounted: Surface runoff (Rs) + Deep percolation (Df) below root zone
3 Water use efficiency (ηu)Standard
जो पानी beneficially use हुआ (leaching सहित) उसका ratio delivered water से।
Ratio of water used beneficially (including leaching requirement) to water delivered to field.
ηu = Wu / Wf × 100Wu = water used beneficially (crop use + leaching) | Wf = water delivered to field
Note: Leaching water (to flush salts below root zone) is counted as “beneficial use” — so ηu can be > ηa
4 Water storage efficiency (ηs)Standard
Root zone में जितना पानी store हुआ vs जितना होना चाहिए था (field capacity तक लाने के लिए)।
Ratio of water stored in root zone during irrigation to water needed to fill root zone to field capacity.
ηs = Ws / Wn × 100Ws = water stored in root zone | Wn = Field capacity − Available moisture before irrigation
Ideal ηs = 100% means root zone was filled exactly to field capacity — no under-irrigation.
5 Water distribution efficiency (ηd)Also: uniformity coefficient
Root zone में पानी कितना uniformly distribute हुआ — uniformity coefficient भी कहते हैं।
Evaluates the degree of uniform water distribution throughout the root zone. Also called uniformity coefficient.
ηd = (1 − y/d) × 100d = average depth of water = (d1+d2+…+dn) / n
y = average numerical deviation from mean depth
y = average numerical deviation from mean depth
If all depths equal → y = 0 → ηd = 100% (perfectly uniform). More variation in depth → lower ηd.