Performance Evaluation of Irrigation Projects - Practices of Irrigation and On-farm Water Management - page 122

where

K ( t ) weightage factor indicating the relative importance of irrigation at the

t th period (say week) of the crop
V ( t )

=

= volume of water delivered to the farm during the t th period

V ∗ ( t ) = target volume of water to be delivered to the farm during the t th period

N = number of time periods for the crop growth

Equity of Water Delivery (EWD)
Equity of water delivery is expressed as

WDP t
WDP h

EWD = (4.16)

where

WDP t = WDP (Water delivery performance) value at the tail of the outlet

WDP h = WDP value at the head of the outlet

Overall Efficiency (OE)

OE = (volume of water needed to maintain the soil moisture above a minimum
level required for crop + nonirrigation deliveries from the distribution

and conveyance system) / (Volume of water diverted into the system

+ inflows from other sources)

(4.17)

Project Application Efficiency

Project application efficiency ( E pa ) is defined (USDA, 1997 ) as the ratio of the aver-
age depth of irrigation water infiltrated and stored in the plant root zone to the
average depth of irrigation water diverted or pumped. That is

(average irri. water diverted or pumped)
(4.18)
It includes the combined efficiencies from conveyance and application. It can be
the overall efficiency of only on-farm facilities.

E pa = (average depth infiltrated) × 100 /

Energy Use Efficiency

It relates to how much energy we need to produce one ton of crop.

E energy use = (crop yield in one hectare land)
× 100 / (energy needed for successful cultivation of one hectare land)

(4.19)