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CROP WATER REQUIREMENT - INDENTING AND SCHEDULING FOR APPAPURAM CHANNEL COMMAND IN KRISHNA WESTERN DELTA

KrishiKosh

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Title CROP WATER REQUIREMENT - INDENTING AND SCHEDULING FOR APPAPURAM CHANNEL COMMAND IN KRISHNA WESTERN DELTA
 
Creator RATNA RAJU, CH
 
Contributor YELLA REDDY, K
 
Subject irrigation, crops, area, precipitation, evapotranspiration, supply, land resources, developmental stages, cropping patterns, soil water
 
Description Irrigation is a costly and scarce input in agricultural and plays an important role in
increasing food production. It is important that the water requirements of crops are
known at different management levels within the irrigated area to accomplish
effective irrigation management. In order to apply irrigation water efficiently, the
water requirement of the crops are to be estimated accurately. Agriculture being the
major water consumer in the ambit of multiple uses of water resources, it emphasizes
better knowledge on crop water requirement, planning and scheduling of crops with
the internationally accepted state of art of predicting models. When supplied
unchecked, every consumer, either a farmer or an industrialist or a domestic users, is
tempted to use more water, for no extra gain. In most of the irrigation projects, the
farmer in the upper reach of the canals over use the irrigation water leaving the tail
end farmers starve for water. In the past, due to non availability of sufficient
quantities of water in reservoirs canal water was supplied at much lesser rates than
normal rate. Inspite of that, the farmer got good yields of previous years this raised
question that whether the farmer has been applying more than the required irrigation
water or the estimation of crop water requirements was incorrect. Unscientific and
injudicious application water in considerable parts of the canals commands in the state
of Andhra Pradesh has also resulted in rise of water table and development of salinity.
In order to avoid excess irrigation, there is a need to estimate the crop water
requirement accurately and compare them with the actual amounts of water applied in
the field. Several computer models are now available to estimate the crop water
requirements like CROPWAT, CRIWAR etc. Hence a study was conducted on a pilot
scale in one of the major distributory viz., Appapuram channel of Kommamur canal
of Krishna Western Delta (KWD) system. In the present study, the CROPWAT model
was used to estimate crop water requirements of Appapuram channel in Krishna
Western Delta.
The methodology consisted of the following main steps; data collection, estimation of
water requirements and execution of the linear programming model and evaluation of
the modeling results. The first step of this work was the collection of primary and
secondary data about agronomic and economic aspects of agricultural systems of
Appapuram channel command area in Krishna Western Delta. The following weather
parameters were collected for the period 2000-2010 on a daily basis: air temperature
and humidity, wind speed, solar radiation and precipitation. These data were used for
the calculation of reference evapotranspiration by using Penman-Monteith equation.
Other agronomic parameters acquired during the field visits to the study area included
the soil characteristics (texture and depth), the period and length of growing season,
water use per crop, water availability on a monthly basis, types of irrigation system
and its efficiency, crop productivity under specific input of water, crop coefficient
data etc. Data about management and economic aspects were also collected which
included total available area, irrigated area, farm size, main cropping pattern in the
study area. The second step of this work was dedicated to the estimation of crop water
requirements and irrigation requirements for each crop on a weekly/monthly basis.
This analysis was done by using CROPWAT and model for the actual cropping
pattern in the Appapuram canal command of Krishna Western Delta. Canal operation
plan was prepared for average meteorological data for the decade. Canal operation
plans were also prepared for good/normal/deficit years. The Linear Programming
model proposed in the present study integrates the reservoir level and a field level
decision. It considers the soil-moisture status and the reservoir storage as the state
variables and the applied irrigation depths as decision variables. The formulation was
based on the conceptual model for soil moisture accounting and the reservoir storage
continuity relationships.
It was estimated that the gross crop water requirement for Appapuram channel
command area to irrigate 8880 ha registered and 4000 ha unregistered ayacut during
kharif season and maize 4000 ha during rabi to be 122.82 M. cum. It was estimated
the gross crop water requirement for Appapuram channel command area to irrigate
8880 ha registered and 4000 ha unregistered ayacut for paddy during kharif season
and maize of 4000 ha during rabi to be 132.7 M. cum in normal/deficit year. The
canal operation plan was prepared for estimated gross water requirement for
Appapuram channel command area for different scenario. Linear Programming was
developed and was effective tool to optimize benefit during deficit years.
Gross Water Requirement (GWR) and Gross Irrigation Requirement (GIR) were
effectively calculated using Penman-Monteith method using CROPWAT simulation
programme and could be adopted for large scale implementation under large canal
network systems. Accuracy of estimation of GWR and GIR at command level greatly
depends on the cropping pattern followed and staggering of crops sown in the
command area. Estimation of seepage losses in the canal network system greatly
influences accuracy of the estimation of GWR/GIR. Gross Water Requirement
(GWR) under Appapuram Channel Command was estimated to be ranging from 123 –
133 M.cum. The contribution of effective rainfall towards GWR ranged from 52 - 67
M.Cum indicating the fact that almost 40% - 55% of GWR was met from the effective
rainfall itself. The major findings of the present research had clearly demonstrated
that the average percentage of excess water released was estimated 32 to 101 % and
there was considerable scope to improve the match between irrigation demand and
canal supply. To match the irrigation supply vs demand, irrigation water
measurements should be made mandatory at head regulator and at branch canals and
distributories. The modernization works of Appapuram Channel should therefore be
focused on addressing these issues. Linear Programming model was developed and
was effective tool to optimize benefit during deficit years. Sensitivity analysis of the
developed LP model was carried out for various water allocations to the command
area ranging from 10 to 60 M.Cum. Analysis showed that total cropped area was
ranged from 700 ha to 13400 ha with net benefit estimated to range in between Rs. 23
millions to Rs. 1261 millions. Validation of the developed LP model with reference to
the ground truth values to be carried out for wider adaptability.
This study was found to be useful for analyzing the performance of the commands in
terms of water distribution, water deliveries and crop acreages etc., throughout the
year covering Kharif and Rabi seasons.
 
Date 2016-06-07T14:57:02Z
2016-06-07T14:57:02Z
2011
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/66968
 
Language en
 
Relation D9085;
 
Format application/pdf
 
Publisher ACHARYA N. G. RANGA AGRICULTURAL UNIVERSITY