MODELING OF SURFACE IRRIGATION SYSTEMS USING ‘SURDEV’ IN COASTAL AREAS OF GUNTUR DISTRICT
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Date
2016
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Acharya N.G. Ranga Agricultural University
Abstract
Water is the most vital input in agriculture and its availability is necessary in
providing stability to food grain production and self-sufficiency. About 80% of total
water resources are being utilized for agriculture. Surface irrigation is widely practiced
throughout the world i.e., more than 95 % of world’s irrigated area is under surface
irrigation (Anonymous, 2003). India has the highest irrigated area with almost one fifth
of the irrigated area in the world. According to statistical year book India 2016,
irrigated land in India is about 64.7 M ha of which 55 M ha is irrigated by surface
methods of irrigation. The irrigated land in Andhra Pradesh is about 4.2 M ha of which
3.68 M ha is under surface methods of irrigation.
All along the coast, Guntur district is predominantly with sandy soils, where
deep percolation losses are more thereby having lot of scope to improve irrigation
efficiency. In the coastal agriculture, small to medium farmers are dominant group
cultivating rice, groundnut and vegetables following check basin and furrow irrigation
systems. Under the aforesaid valid and farmers’ felt research needs, the present post
graduate research work entitled “Modeling of surface irrigation systems using
‘SURDEV’ in coastal areas of Guntur district” is proposed to fulfil the following
major objectives. i) To survey different farmers’ fields for the existing field design of
surface irrigation systems in coastal areas of Guntur district. ii) To estimate the overall
irrigation efficiency of surface irrigation systems using SURDEV model. iii) To model
the design parameters for the improvement of overall irrigation efficiency using
SURDEV.
A total number of 120 coastal farmers’ fields (60 fields under check basin
irrigation system and 60 fields under furrow irrigation system) were surveyed. The
major crops grown in the study area are rice, groundnut, pulses in basins; maize and
vegetables in furrows. The dominant soil type is sandy. In the present study, software
model SURDEV developed by M. Jurriens, was used to determine the existing field
efficiencies and to improve the efficiencies of the irrigation systems. The required data
for inputting into the model was collected from field survey.
With this data from existing basin and furrow irrigation systems were used as
input for BASDEV and FURDEV modules respectively for obtaining the application,
storage, and distribution efficiencies (%), minimum, maximum and average infiltrated
depths (mm), advance and recession times (min), and under-irrigation, over-irrigation
lengths and depths. The performance of surface irrigation system proved to be
unsatisfactory and so suggestions for improvement were evaluated with BASDEV and
FURDEV modules in SURDEV. Also for some fields, cutback and tail water reuse
options in FURDEV were used by giving suitable values of cutback ratio and tail water
reuse ratio to further increase the efficiencies. To know whether the improvement is
statistically significant or not, on theoretical basis, simple statistical analyses were
performed. i) Student ‘t-test’ amongst existing and improved efficiencies ii) standard
error of mean within a particular group of efficiencies and finally iii) correlation matrix
with various input parameters which were changed on hit and miss trials basis were
chosen.
For rice under basin irrigation system, the overall efficiency was increased from
38.14% to 71.55% using BASDEV module in SURDEV. Similarly, for groundnut and
pulses the overall efficiency was increased from 32.48% to 65.15% and 38.49% to
69.15% respectively. For maize under furrow irrigation system, the overall efficiency
was increased from 40.8% to 58.32% using FURDEV module in SURDEV. Similarly,
for cucumber and for watermelon the overall efficiency was increased from 35.63% to
51.84% and 53.68% to 62.83% respectively. With cutback option in FURDEV module
further increase in efficiency was obtained as 9.14% for 20 cucumber fields, 11.85%
for 3 maize fields and 12% for 2 watermelon fields under furrow irrigation system.
Similarly, with tail water reuse further increase in efficiency was found to be 3% for 6
cucumber fields, 4.8% for 6 maize fields and 2.4% for 1 watermelon field.
From the t-test, it was observed that the application and overall efficiencies for
all the crops of study area for basin irrigation system and furrow irrigation system
showed significant variation in the design exercise at 5% level of significance. It was
observed from the standard error calculations that storage efficiency for all crops except
groundnut and distribution, overall efficiencies for maize and watermelon crop showed
less standard error which means that they are more or less following certain governing
pattern and the rest showed standard error equal to and greater than 1 indicating that the
efficiencies varied tremendously.
From the correlation matrix prepared for the various input parameters
(independent variables) and various efficiencies tested in study fields separately for
different soils and different irrigation systems, the correlation has not given any
uniform pattern for any of soils. In some cases, basin width, cut off time and basin
length has shown high correlation and for certain soils like clay loam, sandy loam, loam
and silty clay, the sample sizes were very meagre and hence the statistical results
outcome could not be worked out. If measures are taken to improve at least 10% in the
efficiency by recommending flow rate, cut off time, field dimensions, there will be a
saving of water in the tune of 6.129 BCM because of the fact that as per AP water
vision, the irrigation water consumption is 61.317 BCM at present
Description
D5460
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