1. Assignment
Course No:Agron.504
Principles and Practices of Water Management
• SUBMITTED TO:-
• Dr. D. M. Patel,
• Associate Professor & Head,
• Department ofAgronomy,
• C.P. College ofAgriculture,
S.D.A.U, Sardarkrushinagar.
• SUBMITTED BY:-
• PATEL SHANIKKUMAR ,
• 1st sem. MSc. (Agronomy),
• C.P. College of Agriculture,
S.D.A.U, Sardarkrushinagar.
2. • Different irrigation efficiency
1. Water conveyance efficiency
• It may defined as the percentage ratio of the water delivered to the field or
farm to the amount of water diverted from the sources.
• Ec = Wf *100
• Wd
•
• Where,
• Ec = water conveyance efficiency
• Wf =Amount of water received to the field or farm through field supply
channel or farm or
distribution system
Wd =Amount of water diverted from the sources
•
•
3. Water conveyance efficiency related to the conveyance sources such as canal network , farm
channels from sources such as reservoir , rivers and dams to field or farm for crop use.
In conveyance efficiency seepage losses are due to the nature and porosity of the soil , depth ,
turgidity, and temperature of water , age, and shape of the canal section the ground water level.
Lining is an effective way to control seepage losses. Pre-fabricated channel section are the best and
cheapest considering the number of years they serve efficiency.
Example:-
• Calculate conveyance efficiency given the following data: Water @2600l/min is being
turned into an unlined canal from the reservoir . There were 100 furrows irrigated. The inflow rate
into 25 furrows was 18l/min and 75 furrows 28l/min.
• In
• 1 furrow inflow rate =18l/min
• 25 furrow inflow rate =25*18
• =450l/min
4. • For 75 furrow = 75*28
• =2100l/min
• Total inflow rate = 450+2100
• =2550l/min
• Conveyance efficiency = Quantity of water received at the field * 100
• Quantity of water released at source
•
•
•
=2550*100
2600
Ec =98.07%
•
2. Water application efficiency
water application efficiency defined as the percentage ratio of the amount of water
stored in the crop root zone to the amount of water delivered to the field. The volume of water
actually delivered at the field.
5. • Ea = Ws*100
• Wf
• Where,
•
•
Ea = water application efficiency
Ws = irrigation water stored in the root zone of farm soil
• Wf = irrigation water delivered to the farm(at field supply
channel)
6. Example:-
• Calculate the field water application efficiency when a stream of 95l/s received at the farm gate after
being diverted from a canal delivered 72l/s to the field during irrigation to wheat crop for 8 h. 350 & 158 cum
of water respectively were lost by run off and deep percolation.
• Water lost during irrigation= runoff loss+ deep percolation
• =350+158
• =508m2
• =508*1000
• =5,08,000 lit (1cum= 1000lit)
• Water delivered to the field=72 l/s for 8h
• = 72*8*60*60
• =20,73,600 lit
• Water stored in the root zone = water delivered – losses
• = 20,73,600 -5,08,000
• =15,65,600 lit
7. Now,
Water application efficiency (Ea)= water stored in the root zone*100
water delivered to the field
=15,65,600*100
20,73,600
Ea =75.50%
3. Water storage efficiency
Water storage efficiency refers to the percentage ratio of the amount of water stored in
the effective root zone soil to the amount of water needed to make up the soil water depleted in crop root
zone prior to irrigation.
Es = Ws*100
Wn
Where,
Es = water storage efficiency , per cent
Ws=Amount of water actually stored in the crop root zone during irrigation
Wn=To the amount of water to needed to meet the soil water depleted in crop root zone prior to
irrigation
8. Example:-
Calculate the storage efficiency of an irrigation given the following: when (the desired depth of
irrigation fills the soil to field capacity ,the term storage efficiency is used as an index of adequacy of
irrigation).
Average depth of infiltration = 3.50cm
Average pre-irrigation water content of the field = 20% by volume
Root zone of crop = 60 cm depth
Field capacity of the soil = 30% by volume
Amount of water to fill the root zone to field capacity = 60(30-20)/100
=60(10)/100
=6 cm
Storage efficiency = Ws*100
Wn
= 3.50*100
6
Es = 58.33%
9. 4. Consumptive use efficiency
It defined as the ratio of consumptive water used by the crop irrigation
farm or project and the irrigation water stored in the root zone of the soil on the
farm or project area.
After irrigation water is stored in the soil , it may not be available for
use by the crop because water may evaporate from the ground surface or
continuously move downward beyond root zone as it may happen in wide
furrow spacing. The loss of water by deep penetration and by surface
evaporation following irrigation is evaluated from the following expression:
Cu = Moisture content after irrigation – Moisture content before
irrigation * B.D * Depth
100
Cu = consumptive use efficiency
B.D = bulk density
10. Example :-
Soil moisture content in sample drawn from different depths in a wheat field two days after
irrigation at the CRI stage and just before next irrigation at the late tillering stage are given in following
table . Workout the total and daily Cu of the crop for the interval (22 days).
Cu = Moisture content after irrigation – Moisture content before irrigation * B.D *
Depth
100
11. For 10 – 15 cm depth of soil = (32.2 -16.2 ) *1.4*15
100
= 3.36 cm
For 15 – 30 cm depth of soil =(33.5 -17.5 )*1.42*15
100
=3.41 cm
For 30 – 45 cm depth of soil = (32.6 – 22.6 )*1.42*15
100
= 2.13 cm
For 45 – 60 cm depth of soil = (32.8 – 32.8 )*1.44*15
100
= 0 cm
Total = 8.90 cm
In 22 days 8.90 cm has been consumed.
So, the loss per day is = 8.90/22
=0.40 cm /day
12. 5. Water distribution efficiency
• Water distribution efficiency measure the extent to which water is
uniformly distributed and stored in the effective root zone in soil along with
irrigation run.
•
•
Ed = ( 1- d )*100
D
• Where,
•
•
Ed = water distribution efficiency
d =Average numerical deviation in depth of water stored in root zone soil
along the irrigation run from
the
D= average depth of water stored during irrigation along the water run
•
•
13. Example:-
A stream of 135 lit/sec was diverted from a canal & 100lit/sec was
delivered to field.An area of 1.6 ha was irrigated in 8 hr. The effective depth
of root zone 18 m. The runoff loss in the field was 432 cum. The depth of
water penetration varied linearly from 1.8 m at the head end of the field to 1.2
m at the tail end. Determine the water application efficiency & water
distribution efficiency.
Water delivered to the plot = 100*60*60*8
= 2880000 lit1000
= 2880 cum
Water stored in the root zone = 2880-432
= 2448 cum
1)Water application efficiency Ea = Ws / Wf*100
=2448*100
2880
=85%
14. 2 )Water distribution efficiency Ed = 100 (1-d/D)
D = 1.8 + 1.2
2
=1.5 m
Numerical deviation for depth of penetration
At upper end = 1.8 - 1.5 = 0.3
At lower end = 1.5 – 1.2 =0.3
Average numerical deviation = 0.3 +0.3/2 =0.3
Ed = 100(1 - 0.3)
1.5
=80%
