Accepted Papers - 3.pdf - UNESCO

Hazens equations
Sub main: Area = 168 x 0.5 = 84 m 2
d gross = 0.01363 m, = 7200 sec.
Capacity (flow rate)
Q = (0.01363 x 84) / 7200
= 1.59 Õ 10 -4 m 3 /sec or = 572.46 lph
length of lateral - 14 m; Number of lateral - 8
Capacity of each lateral
Q lat = 572.46 / 8 = 71.55 lph
Emitter discharge
=
Gross depth of water × wetted area of
Duration of application
d gross At
q
t
×
= ,
= 2.55 lph
0 . 01363 × 0.
5 × 1.
5 × 0.
4
= ,
2
Daily water requirement :
The daily water requirement of crop grown
under drip irrigation method was estimated by using
the formula.
V = ET × S p × Sr
× Wp , = 10.2 x 0.5 x 1.5 x 0.4
= 3.06 litre per plant
Required discharge for micro sprinkler:
Application depth, Di = 0.50 x Mc x dr, = 0.50 x
0.27 x 0.40, = 5.4 cm
Number of laterals, ln = W/ S = 6/ 1.5, = 4
1,
Discharge of a lateral,
Q
Q × η × η
=
d a
1 ,
S n × ln
= 0.0318 lps
Discharge of a micro sprinkler,
Qs = Q1
× S s / L1
, = (70.318 x 2) / 14
= 0.045 lps
one plant
Estimation of quantity of water
The crop water requirement in drip and micro
sprinkler irrigation treatment was based on the
formula referred by Indian National Committee on
Irrigation and Drainage (INCID) in drip irrigation
in India (Anonymous, 1994) as:
V1 = E p × Kc
× K p × A × N
Net volume of water to be applied,
350
Vn = V1
− Re
× A
Number of operating hours of system (T) during a
week.
T =
Vn × Wp
no.
of dripper/
plant × no.
of plants × dripper discharge
T
Operating hours per application =
N.
m
Where,
V = volume of water applied in (litres), E = mean
1 p
pan evaporation for the week in (mm/day), K = the c
crop factor, K = the pan factor, A = the area to be
p
irrigated in (sq m), N = no. of days in a week, R = e
the effective rainfall in (mm), W = percentage
p
wetting
Nm = No. of application / week , T = No. of operation
hour/week
Water use, Crop yield and Water use efficiency
The seasonal water use of different irrigation
methods was worked out by simple water budgeting
method over the growing season under two modes
of irrigation. This facilitated the comparison of
seasonal water use of all irrigation methods. The
water use efficiency of different irrigation treatments
was worked out in order to evaluate its performances
in terms of per unit of water used. The irrigation
schedule adopted in the surface irrigation was based
on 50% depletion of available soil moisture at the
root zone depth.
RESULTS AND DISCUSSION
Crop Water Requirement for Bitter Gourd
The value of ET peak and crop coefficient for
initial stage, development stage, mid season stage
and late season stage were found to be 7.3, 7.8, 6.5,
4.7 and 0.79, 0.94, 1.18, 1.14 respectively. The ET
values for these four stages were determined as
164.4, 296.7, 220.9 and 119.3 mm respectively. Thus
ET for whole crop period was found to be 801.3
mm and presented in the (Table 2).
Seasonal Water Use
The seasonal water use for the crop was
determined with all the irrigation treatments. The
lowest seasonal water use was found to be 747.5