This document summarizes the methodology used to determine the water requirements of rice crops in Venkatapuram village. It provides background on rice cultivation and methods for calculating irrigation water needs. Key details include: the project area is Venkatapuram village in Andhra Pradesh; rainfall and climate data were collected for the area; the consumptive use of rice was calculated as 143.98 cm using the Blaney-Criddle method; the total water required for rice over the growing season is estimated to be 896,833.60 cubic meters with a required discharge of 0.06 cubic meters/second; and evapotranspiration was calculated as 1155.79 mm/season for rice using the Penman method.

1. Determination of water requirement
of Rice crop in Venkatapuram village

2. CONTENT OF PRESENTATION
 INTRODUCTION
 REVIEW OF LITERATURE
 PROJECT AREA & METHODOLOGY
 RESULT AND CONCLUSION

3. INTRODUCTION
 Introduction on rice crop : Rice is the seed of the grass species Oryza
sativa (Asian rice) or Oryza glaberrima (African rice). India is the third largest
contry to produce rice in the world. Rice is the basic need in human life.
 Irrigation Water requirement : The primary objective of irrigation is
to provide plants with sufficient water to obtain optimum yields and a high
quality harvested product. The required timing and amount of applied water is
determined by the prevailing climatic conditions, the crop and its stage of
growth, soil properties (such as water holding capacity) and the extent of root
development. Water within the crop root zone is the source of water for crop
evapotranspiration. Thus, it is important to consider the field water balance to
determine the irrigation water requirements.

4. REVIEW OF LITERATURE
 PREPARATION OF LAND : Land preparation starts with removal of
shrubs and stumps from rice fields. The land is then ploughed using hand hoes
such as jembe/panga, oxen or tractors. Power and equipment are required
for tillage in different soil types are varied. It is essential to plough when land
is dry to reduce weeds. However in difficult soils such as virgin lands there
may be need to wet the field before ploughing. It is generally recommended
that two ploughs and one harrow or rotovation are sufficient for soil
disturbance long before planting to establish.

5.  DEPTH AND TIME OF IRRIGATION :The depth and time of
irrigation is given by the expression below.
y =
Fc .d. γs
γw
Let, y = depth of water available in root zone
d = depth of root zone in meters
Fc = field capacity of soil expressed as a ratio
γs = Density or unit weight of soil
γw = Density or unit weight of water
Time of irrigation is given by the expression below.
T=
2.778A ×dw
q
Let, A = area of land
q = discharge of water
dw = available moisture depth

6.  CROP AND CROP SEASON IN INDIA :In India, the northern and
north eastern regions have two distinct cropping seasons. The first coinciding
mostly with the South western monsoon is called kharif. Which spans mostly
from July to October. The other, called Rabi, spans generally over October to
March. The summer season crops are planted sometime between April and
June. In southern part of India, there is no such distinct season, but each
region has its own classification of seasons.
 DUTY, DELTA & BASE PERIOD :
1. Delta: Delta is the total depth of water required-by a crop during the entire
period Of crop in the field, and is denoted by a symbolΔ .
2. Base Period: It is the time in days counted from the period of first watering
for a crop before sowing the crop (known as pre sowing irrigation) and the
last watering before harvesting the crop.
3. Duty: Duty is defined as the area irrigated by a unit discharge during the Base
period of crop or in other words Duty may be defined as the area irrigated by
an average discharge of 1 cumec for a specified number of days.

7.  RELATIONSHIP BETWEEN DUTY AND DELTA :
Let D = Duty in hectares/cumec,
∆= Total depth of water (in meters), and
B = Base period in days
If we take a field of area D hectares; water supplied to the field corresponding to
the water depth ∆ meters will be
=∆ x D hectares meters = D x ∆ x 104 cubic meters . . . (1)
(b) Again for the same field of D hectares, one cumec of water is required to
flow during the entire base period. Hence, water supplied to this field
= 1 x (B x 24 x 60 x 60) m3 . . . (2)
Equating Equation (1) And (2) we get,
D×∆×104 = B×24×60×60
∆=
8.64 B
D

8.  CONSUMPTIVE USE OF WATER :Consumptive use for a particular
crop may be defined as the total amount of water used by the plant in
transpiration (building of plant tissues, etc.) and evaporation from
adjacent soils or from plant leaves, in any specified time. The values of
consumptive use (Cu) may be different for different crops, and may be
different for the same crop at different times and places.
 Blaney-Criddle method :
Cu=
k.p
40
[I.8t + 32]
Cu= Monthly consumptive use in cm.
k = Crop factor
t = Mean monthly temperature in °C.
p = Monthly per cent of annual day light hours that occur during the period.
If,
𝑝
40
[I.8t + 32] is represented by f, we get
Cu= k. f

9. Table3: Monthly daytime percentage hours (p)
Table2: Monthly crop coefficient factor k (for use in Blaney-Criddle method)

10.  Penman method :
The penman formula is a semi-empirical equation combining mass transfer (Ea) and
energy budget (H) methods. The formula was developed by Penman in 1948 and is
still widely used for calculating the potential evaporation using synoptic
meteorological data.
According to Penman the potential evaporation Eo (in mm/day) can be calculated
as:
Et =
A.H+ α Ea
A+α
Also,
Ea = 0.002187(160 + u2) (es – ea)
Table4: saturated vapour pressure of water

11. Table5: mean monthly solar radiation incident on earth outer space
Table6: maximum possible hours of bright sunshine in hours

12.  ASSESSMENT OF IRRIGATION WATER :The different type of
Assessment of irrigation water are described below
1. Assessment on area basis: A rate arrived at in this method is called a crop rate.
In a mostly all the canal irrigated tracts are assessed for irrigation charges under
this system. In this system charges are levied on the area which is actually
irrigated. The rate of payment of charges is not some for all states.
2. Volumetric assessment: In this method charges are levied on actual volume of
water supplied to the cultivators. This is ideal system under which cultivators has
incentive for using water economically. However this method has no practical
value induce up till now.
3. Assessment on seasonal basis: In this water charging are mainly based on crop
season. The rate depend on the type of crop grown in the season in that
particular tract.
4. Composite rate: Sometimes land revenue and irrigation revenue are combined.
It is then called a composite rate. This method of assessment is not very
commonly used but still it is in practice in some states of India.

13. PROJECT AREA & METHODOLOGY
 LOCATION OF PROJECT AREA :Venkatapuram is a Village in
Renigunta Mandal in Chittoor District of Andhra Pradesh State, India. It
belongs to Rayalaseema region. It is located 79 KM towards North from
District headquarters Chittoor. 7 KM from Renigunta. And the Longitude,
Latitude values are (79.4967, 13.6629)
 MAP OF PROJECT AREA :

14.  RAINFALL DATA OF AREA:
YEAR 1997 1998 1999 2000 2001 2002 2003 2004 2005
JANUARY 12.2 10.4 6.2 0 0 0 0 0 0
FEBRUARY 22.2 12.4 7.8 1.0 0 0 0 0 0
MARCH 45.9 38.6 35.2 27.2 5.8 2.4 .8 0 0
APRIL 152.2 117.8 72.6 40.4 32.5 27.6 26.4 20.8 19.2
MAY 195 181.9 180 103.7 82.2 75.8 75.6 74.2 50
JUNE 378.8 189.6 180.8 157 101.4 99.2 88.2 87 78.8
JULY 399.5 250 2112 179.7 164.6 163.2 139.4 134.5 123.2
AUGUST 343 250.5 227.4 178.9 169.3 154.7 146.8 138.6 137.8
SEPTEMBER 306.4 270.9 230.1 209.0 198.4 183.6 180.8 143 137.2
OCTOBER 339.6 289.6 288.2 280 272.6 215 198.4 184 176.2
NOVEMBER 360 267.8 238.9 237 220.4 176.8 175.8 173.5 146
DECEMBER 188 176.4 152 122.4 75.2 69.4 65.2 62 48.4

15. 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
16.6 11.6 10.6 1.8 .6 0 0 0 0 0 0 0
47.8 28 24 21.4 17.6 17.4 17.2 9.6 8.4 7.2 1.6 0
69.5 66 64 63 63 53.3 52.8 49.2 34.9 34 30.8 19.2
118 99.6 93.8 93.6 92 81.9 75.4 71.1 43 42 30.2 25
136 128.4 120.7 110.8 95.9 90.8 78.2 77.4 76.3 73.8 47 37.2
133.6 133.2 132 131 126.1 122.8 122.2 103.7 86.6 47.5 47 37.2
149.4 144.6 137.3 132.2 112 108 107.8 93.6 80.9 79.3 75.2 66.6
136.2 120.4 119.6 82.5 71.4 71.4 65.2 53.5 53.2 53.2 48.8 38.4
43.8 43.3 38.6 33.6 29.8 12 11 9.2 2.4 0 0 0

16.  RELATIVE HUMIDITY AND WIND SPEED DATA :

17.  DATA COLLECTED :

18.  ESTIMATION :
 Field irrigation requirement (FIR)/ consumptive use (cu) : Data
collected for rice crop
MONTH MONTHLY
TEMPERATURE
0c
MONTHLY % OF DAY
TIME HOURS OF THE
YEAR
USEFULL
RANFALL (CM)
July 32.778 12.76 6.8
August 31 12.55 16.8
September 30 12.2 37.45
October 29 11.833 46.08
November 27 11.5 19.41
f=
𝑝
40
[I.8t + 32]
MONTH T0c P% F
July 32.778 12.76 29.03
August 31 12.55 27.55
September 30 12.2 26.23
October 29 11.833 24.91
November 27 11.5 23.17
∑𝑓 = 130.89

19. Cu= k×∑f = 1.1×130.89 = 143.98 cm
Re = 6.8+16.8+37.45+46.08+19.41 = 126.54 cm
CIR = CU – Re = 143.98-126.54 = 17.44 cm
NIR=CIR (since no water is used for deep percolation)
FIR =
NIR
ŋa
=
17.44
0.7
= 24.91 cm
 AMOUNT OF WATER REQUIRED : The amount of water required for irrigation
of rice crop in venkatapuram village is
Volume = Area × delta = 1.3×68.9872 = 89.68 hectare-m = 896833.60 m3
Discharge = area/duty = 68.9872/1216.25 = 0.06 m3/s
Crop Base period, B
(days)
Delta,∆
(m)
Duty
D=
8.64 B
∆
Area
(hectare)
Volume
(m3)
Discharge
(m3/s)
Rice 183 1.3 1216.25 68.9872 896833.60 0.06

20.  EVAPOTRANSPIRATION : Evapotranspiration is calculated by penman
method. estimation for rice crop in 2017 is done below
Et =
A.H+ α Ea
A+α
July August September October November Average
54% 60% 67% 72% 80% 67%
Table for Relative Humidity (RH) in 2017
July August September October November Average
8.1 mph 6.9 mph 5.1 mph 4.5 mph 5.6 mph 6.04 mph
Table for wind speed (u) in 2017
α = 0.49 mmhg/0c
A = 1.85 (from table 3)
es =31.81 mmhg (from table 3)
Now,
ea = es × RH = 31.81 ×
67
100
= 21.31 mmhg
u2= u (
2
Z
)1/7 = u = 6.04 mph = 233.29 km/day
Ea = 0.002187(160 + u2) (es – ea)
Ea = 0.002187 (160+233.29) (31.81-21.31) = 9.03 mm/day

21. We know, RA= 14.1, Ø=13.6288, r=0.2, n=12.17, 𝜎=2.01×10-9 mm/day, T= 273+29.96=
302.96 k
H= RA (1-r) (0.29cosØ + 0.55n/N) – α (Tα) 4 (0.56-0.092√ea) (0.10+0.9n/N)
H= 14.1 (1-0.2) (0.29cos13.6288+0.55
12.17
12.1
) -2.01×10-9(302.96)4 (0.56-0.092√21.31)
(0.10+0.9
12.17
12.1
) = 7.04 mmhg/day
Et =
1.85×7.04+0.49×9.03
1.85+0.49
= 7.46 mm of water per month = 1155.79 mm of water/season
 DEPTH AND TIME OF IRRIGATION :
Depth of Water stored =
Fc .d .γd
γw
=
0.27×15×0.9
9.81
= 0.37 m
Available moisture depth (dw) =
d .γd
γw
(Fc − wc) =
0.9×15
9.81
(0.27 − 0.13) = 0.19 m
Depth of Irrigation =
d .γd
γw
(Fc − w) =
0.9×15
9.81
(0.27 − 0.14) = 0.18 m
Time to Irrigate Field:
t=
2.778 A ×dw
q
=
2.778×68.9872×0.19
0.06
= 606.88 hours = 25.29 days

22.  ASSESSMENT OF IRRIGATION :
Assessment of irrigation water is the revenue that should be paid to the
government by using water from irrigation canals. In venkatapuram village
assessment on area basis is followed that means at the end of the crop period a
demand statement for each farmer are prepared. For failure of crops for reasons
beyond the control of the irrigator or for shortage of water supply, remission may
be given to the farmer.

23. RESULT AND CONCLUSION
Water requirement of Crop is the most important factor governing the loss in crop
production in India. It had been so long that, most of farmer in our country is not
provide with proper irrigation water supply. They mostly depend on Rainfall water, due
to increase in global warming and other adverse effect on environment, rate of Rainfall
is in decreasing rate so that Farmers are in great problem.
Based on the experiment and the data estimated for the irrigation field of
venkatapuram village, Andhra Pradesh in 2017, following conclusion are made.
1. The Field Irrigation Requirement (FIR) of Rice crop for whole crop season is 24.91
cm.
2. The consumptive use of water for rice crop is 143.98 cm.
3. The total volume of water required for irrigating field is 896833.60 m3.
4. The evapotranspiration (Et) is 7.45 mm of water per month and 1155.79 mm of
water per season of rice crop.
5. Depth of water stored in root Zone (d) is 0.37 m.
6. The available moisture depth (dw) is 0.19 m.
7. The depth of irrigation water is 0.18 m.
8. Time to irrigate field is 25.29 days.
9. Assessment on area basis or crop rate basis is followed by the farmer of the
venkatapuram village.

24. It should be concluded that all the data obtained is calculated. We can see that
farmer of this village is largely depended on irrigation water. The soil is clay loam
so that the production of rice crop in this area is very good. But other crops like
maize, tobacco etc. production is not suitable.
 FUTURE SCOPE :In future, the production of rice in this area will be
high because new irrigation structure had been constructed in the locality.
And youth of this village are quite focused to continue there ancestor farming
occupation.

25. THANK YOU
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