DESIGN AND DEVELOPMENT OF MICRO IRRIGATION MODEL

FOR TEA PLANTATION IN CENTRAL DOOARS OF WEST BENGAL,

INDIA THROUGH SOFTWARE SIMULATION AND ANALYSIS

MANTU DAS1, SUBHASISH DAS2*, ASIS MAZUMDAR3 1Junior Research Fellow, School of Water Resources Engineering, Jadavpur University,

Kolkata, India 2Assitant Professor, School of Water Resources Engineering, Jadavpur University, Kolkata,

India 3Professor and Director, School of Water Resources Engineering, Jadavpur University,

Kolkata, India

* Corresponding to: Dr. Subhasish Das, School of Water Resources Engineering, Jadavpur University,

188, Raja S.C. Mallick Road, Kolkata 700032, West Bengal, India Phone: +9133-24146979. E-mail: subhasishju@gmail.com

ABSTRACT

This paper will assist in evaluating the crop water requirement, irrigation scheduling and hydraulic design of drip irrigation system for tea plantation through software applications in Central Dooars of West Bengal, India. It also focuses on developing a micro irrigational system model for Tea plantation which determines the best system suited to the plot keeping the main objectives of optimizing the water uses and energy efficient through sustainable agricultural production. The studies describe specifically the design techniques of drip irrigation pipeline network comprising of emitters, laterals and pipes using pipe network simulating software where suitable pipe diameter can be selected and energy cost reduced. The study shows techniques on proper pump selection for the irrigation system. Later the analytical study will be conducted after measuring the experimental data in the field between two systems: one is drip irrigation system and the other is sprinkler irrigation system on the same experimental conditions. The irrigation efficiency of both the systems will be collected eventually for the irrigation season. Water soluble fertilizers for tea will also be supplied through the systems. The model will check the best energy efficient system over unit area under such conditions. The proposed model shall be the economically checked, looking from capital as well as operation and maintenance costs in addition to meet the planning and design requirements mentioned above. The work involves reviewing the ongoing projects i.e. mainly sprinkler irrigation systems, review of the resources used and available around the project area (both existing and proposed), study of the water managements and their sustainability. KEY WORDS: tea; drip irrigation; sprinkler irrigation; pipeline; pump

INTRODUCTION

To develop a micro irrigational system model for Tea plantation which determines the best system suited to the plot keeping the main objectives of optimizing the water and energy uses through sustainable agricultural production. At the present scenario rotating-head sprinkler is the most commonly used irrigation system for tea gardens which consists of a head with one

or two nozzles, rotated slowly by the action of water passing through it. It irrigates roughly a circular patch of land around the sprinkler which requires wide range of pressure and discharge at its rotating head. This paper covers mainly the design of drip irrigation system and minimizing the pressure head in the network and explains how detailed hydraulic design in software can save energy and later the model implemented on field. It also describes how software can be instrumental in evaluating the crop water requirement by utilizing real climatic data or data available from authorized agencies. Drip irrigation is perceived to be an efficient irrigation system because water is applied to a small surface area and targeted for transpiration. However, a saturated or nearly saturated soil surface generally exists beneath each emitter. In arid dry land farming, reductions in evaporative losses can significantly increase water use efficiency (Soussa, 2010). Drip irrigation has been used to eliminate surface ponding by excessive flooding. The drip irrigation technique slowly applies a small amount of water to the plant's root zone (Capra and Scicolone, 1998). Water is supplied frequently, often daily, to maintain favorable soil moisture condition and prevent moisture-stress in the plant with proper use of water resources (Solomon, 1988). Conventional irrigation methods like overhead sprinklers and flood-type feeding systems usually wet the lower leaves and stem of the plants. The entire soil surface is saturated and often stays wet long after irrigation is completed. Flood-type method consume a large amount of water, but the area between crop rows remains dry and receives moisture only from the incidental rainfall (Ayars et. al., 1999). Drip (trickle) irrigation offers the potential for precise water management and divorces irrigation from the engineering and cultural constraints that complicate furrow and sprinkler irrigation. It also provides the ideal vehicle to deliver nutrients in a timely and efficient manner. However, to achieve high water and nutrient use efficiency while maximizing crop productivity intensive management is required (Kessler, 2006). Central to that management is appropriate irrigation scheduling, both in terms of timing and volume applied. The objectives of drip irrigation system are: - to maintain optimum moisture level for optimization of crop yield; to design a suitable type of irrigation system for crop; to design a manageable system and friendly with farmers; to satisfy and fulfill the requirement of crops and farmers, to minimize the initial cost, annual and power; to design a system which is easy to operate and maintain (Hanson, 2004). There are two basic approaches to scheduling drip irrigation: soil-moisture-based scheduling and a water-budget-based approach that estimates crop evapo-transpiration. There are limitations to both methods, but when used together they are a reliable way to determine both quantity and timing of drip irrigation (Hanson and May, 2006). The amount of water evaporated from the soil surface and lost through transpiration of the crop is collectively called evapo-transpiration (ET). With drip irrigation, evaporation from the soil is minimized, particularly in plastic mulch production systems, leaving crop transpiration as the main component of water loss (Allen et al., 1998). This discussion focuses on design of tea plantation micro irrigation in one of the tea estates in Central Dooars, West Bengal. We know maximum response of irrigation is generally obtained in the best sections of existing mature tea areas. For this it will be also essential to identify and remove other limiting factors. The best results are expected to come from irrigating unpruned or early light skiffed teas. In general, depending upon rainfall received in October irrigation should commence from November and continue till March/April. The first application in November can be a little

more than the estimated field irrigation requirement followed by five more applications, each at an interval of three weeks (Annual report, 2012). Uniformity, efficiency and adequacy of irrigation were calculated and the scheduling of irrigation water was reviewed. Operators were interviewed to highlight the main benefits and problems of the system. Investment and recurrent costs of drip and overhead sprinkler systems were quantified and compared. Root development was assessed qualitatively using excavation pits. Scheduling drip irrigation using tensiometers offered potential water savings of 26% in comparison to a water balance schedule, but these are not currently realized. Gross marginal income was very sensitive to tea price and yield. The higher costs under drip, compared to overhead sprinklers, were mainly for purchase and installation and fertilizer. The costs of labor for applying water and fertilizer were reduced by nearly 50%. The main threats to drip system performance are discussed. Future research efforts should aim at establishing the yield response of tea to water and fertilizer under drip irrigation (Möller and Weatherhead, 2007). This historical perspective and the vestige of belief in the tea industries that sprinkler irrigation system is better than drip irrigation because of its low cost would be better off if optimization of water, energy, labor cost and high yield all together is realized can bring a change of this attitude. But a change is all that is needed and the change is needed now. However, the later research will start with lateral experiments on two systems fed on the same plot – one with sprinkler irrigation set and other with developed drip irrigation model. The various irrigation efficiencies of both the systems will be collected eventually. Water soluble fertilizers for tea will also be supplied through the systems. This study shows how the design is performed in software and a method is described in properly designed irrigation system. It has been revealed that 60% losses or even more occurred in the pipelines and valves so understanding of some basic hydraulics which is an important factor (Das et al., 2008). The overall frictional head losses that can cause pressure transiency and create stress on the pipeline system. Hydraulic simulating software like WaterGEMS can also be a tool in research for irrigation pipeline distribution to improve our understanding. MATERIAL AND METHODS

Site Description

The study is carried out in Chuapara Tea Estate in the Section No. – 16 at the Top Division considering a unit area suitable with water source which is at Dooars, West Bengal. It is located at N26°44′445′′ and E89°27′004′′ at 166 m mean seal level (MSL) as viewed in Fig. 1. This paper specifically describes the design procedure and hydraulic parameters analysis for the drip irrigation system. It is often found in case of drip irrigation system design, evaluation of hydraulic parameters at each emitter is manually not feasible and so designers sometimes still have to rely on specific discharge rates (SDR) curves and many a times on assumptions. The maximum length of run for laterals is also important factor for the designer to decide the last emitting point which provides the same discharge as the first which depends on the minimum rated pressure of the emitter. The specific objectives are to design an irrigation model in tea garden for small area by analysis the design hydraulic aspects and eventually developed on field to check the model in running conditions. The layout map for the whole proposed site is studied and the study area focused on design techniques is selected

as shown in (Fig. 1). A comprehensive survey is done on site and the water sources location is identified and a total survey is done with GPS (Global Positioning System) receiver to get exact measurement of elevation, latitude, longitude, length or any other required data. In-house work starts with determination of crop water requirement using the nearby climatic data of station Jalpaiguri from CLIMAT 2.0 for CROPWAT 8.0 software developed by the Food and Agriculture Organization (FAO). The software calculates the exact crop water requirement and specifically the irrigation scheduling for a large area in tea plantation irrigation scheduling being a major problem for portable sprinkler irrigation system while this can be done with the developed model. Survey Details

Physical measurement of land i.e. length, width, shape, north direction; demarcation of roads, pathways, water sources, structure, electrical poles, permanent landmarks; measurement of slope if slope is more than 1% then contour survey is must with instruments like dump level, tilting level, theodolite, total station; marking of existing pipeline, if any. The elevations at many are known as per our GPS (Global Positioning System) survey, it is a network of satellites that continuously transmit coded information, which makes it possible to precisely identify locations on earth by measuring distance from the satellites (Garmin, 2000). GPS now has been widely used by surveyors, commercial fishermen, recreational and so on to keep track of their current locations, find their way to a specified location and know what direction to take to get to the intended destination, here as it is flat topography so all elevations of points are found to 166 m as shown in Table 1. After all, there is no payment or charged acquired to utilize the technology. In the study we try to integrate the GPS mapping with Windows and the GPSr (GPS receiver) itself. Traditionally, paper-based map survey has been the only navigation tool and collection of required data. As far as we are concern, they are many drawbacks of using paper map. People find it difficult to locate themselves in the paper-based map available because they are not really familiar with the specified place as well as the landmarks around them. Fig. 2 shows the site location for model set-up. Crop Details

All the data related to the type of crop variety, spacing row to row and plant to plant, number of rows, total number of plants, method of planting, age of plant, canopy, duration and rotation of crops in different seasons for a few years have been taken from the field survey and official staffs of the estate. Climate Data

As climatic data such as temperature, relative humidity, minimum and maximum temperature and relative humidity, wind speed and direction, solar radiation (day light), evaporation rate or evapotranspiration rate, rainfall, maximum intensity of rain in a day, cloudy days are very important for calculating potential evapotranspiration and eventually the crop water requirement for tea. We have referred the nearby station data of Jalpaiguri from CLIMAT 2.0 and analyzed in CROPWAT 8.0 as shown in Fig. 3. The effective rainfall (Peff) is calculated by USDA soil conservation service method, FAO by CROPWAT 8.0.

(125 0.2 3 ) 250, mm125 3

125 2500.1 , mm3 3

eff

eff

P PP for P

P P for P

− =

= +

(1)

where effP = effective rainfall (mm)

P = average monthly rainfall (mm) CROP WATER REQUIREMENT USING CROPWAT 8.0 CROPWAT is a decision support system developed by FAO having main functions as –

• To calculate: reference evapotranspiration, crop water requirements, crop irrigation requirements.

• To develop: irrigation schedules under various management conditions, scheme water supply.

The water balance method is used for calculation of irrigation schedules in CROPWAT, which means that the incoming and outgoing water flows from the soil profile are monitored. The input data and output calculated is shown in Fig. 4. The reference evapotranspiration (ETo) is calculated by using Penman-Monteith method, 1948 by the software from the climatic data of Jalpaiguri.

2

02

9000.408 ( ) ( )273

(1 0.34 )

n s aR G u e eTET

u

− + −+=

+ +

(2) where

0ET = reference evapotranspiration (mm/day)

nR = net radiation at the crop surface (MJ/m2day) G = soil heat flux density (MJ/m2day) T = mean daily air temperature at 2 m height (oC)

2u = wind speed at 2 m height (m/s)

se = saturation vapour pressure (kPa)

ae = actual vapour pressure (kPa) Δ= slope vapour pressure curve (kPa/oC) γ = psychometric constant (kPa/oC) Water Source Details

The work involves reviewing the ongoing projects i.e. mainly sprinkler irrigation systems, review of the resources used and available, study of the water managements (both existing and proposed), identifying and analyzing of the present water source which is ground water. Analyzing the water quality and reviewing whether that is causing environmental pollution if any, suggesting improvements of the quality of water and any filtration required before

irrigation so that the drip systems can run efficiently. Type of water source – open well, bore well, canal, lake or check dam; size, depth of water, volume, lowest water level in summer; yield of water source in case of bore well; water availability and duration; location, distance, elevation of water source; use of gravity water whether possible; storage facility. Collection Of Soil Sample From Field

The amount of water retained after drainage of saturated soil is called field capacity (FC) moisture. At field capacity a loam or clay soil retains moisture at about 0.33 (atm) atmospheric pressure, whereas in sandy soil it may be as low as 0.1 atm. At permanent wilting point (PWP), the soil moisture tension reaches about 15 atm. FC moisture and PWP moisture are influenced by soil texture. Finer the texture higher is FC and PWP moisture content in soil. The range of moisture between field capacity and wilting point is available to plant roots. Fifty percent of this available moisture is considered as readily available moisture for working of irrigation schedule (Annual report, 2012). It helps to decide the numbers of drippers and its discharges; helps to work out the irrigation schedule and interval; helps to work out the micro nutrient dosage, cropping pattern, variety, spacing can be determined; in case of saline soil – soil reclamation measures can be decided; proper treatment can be given to polluted soils. Collection Of Water Sample From The Source

It helps to verify the suitability of water for drip irrigation; to select proper filters for the drip irrigation system; to check the possibility of clogging of the system; to recommend the acid and chlorine treatment to avoid the clogging and decide the frequency of the treatments; to recommend the adequate pre-treatment to make water suitable for irrigation of crop; to work out the exact fertilizer dosages in case of water source fertilizer. Here we found clean and clear water which is suitable for drip irrigation. Pump Details, Power Availability And Working Houses

Details of the pump if existing – type, make, horse power (HP), discharge and head, kilowatt (KW) rating, revolution per minute (RPM), suction and delivery size; availability of power - electrical, diesel; working hours. We utilize the existing pump house for running the sprinklers for irrigation. We are here taking an outlet from the existing high HP pump as by-pass coupled with pressure gauge and flow meter to provide the calculated flow and head. Design Of The System

Selection of components of the drip irrigation system to suit the water requirement of the crops and the local field conditions is called as design of the drip irrigation system. We have selected eight (8) lph drippers of two numbers for each plant in our set-up model for the selected section and analyzed the pipeline design for minimum head loss and optimum pipe diameter. The irrigating system comprises of filter and fertigation unit, mainline, sub-mains and valves, laterals and drippers. The design approach starts from the tail end to the head end and from dripper selection to pump selection. The total design is being done in hydraulic modeling software.

Guiding Principles For Selection Of Drip Irrigation System Compound

System component parameter – guiding principles in addition to cost effectiveness; emitter discharge – soil type, crop water requirement, low risk of clogging, easy maintenance, long life; lateral pipe sizes and length – extent of field and desired uniformity of water distribution; filter type – hydro cyclone, screen filters for sand yielding bore wells not yielding sand; mainline and sub main pipe sizes – velocity of flow not exceeding 1.5 m/s; fertigation equipment – fertilizer tank of capacity depending upon the crops. The selected area divided into four numbers of sections as per the arrangements of drippers of varied discharged viz. Plot-1, Plot-2, Plot-3 and Plot-4 highlighted in Fig. 5. This is deliberately done to divide the whole irrigation with four different emitting discharges to optimize water requirement and minimize the head loss at single point and also in keeping the view of techno economical aspects while the water source remains the same. For the design purpose, plots are so divided such that Plot-1 and Plot-2 are online drip system while Plot-3 and Plot-4 are inline drip system, in the later stage of research the results out of the four will reveal the best option to be adopted in terms of optimization of water resources, maximum yield, minimum pressure and cost effective while each component will be studied separately, so here we are focusing on Plot-1 sectioning with valve (V-1) as shown in Fig. 6 (a-b). When hydraulic calculation on any water orifice systems like fire fighting, sprinklers, drippers misting sprayers in such situations we use the k-factor formula. It allows discharge estimation for any emitter type on which a k-factor is associated. However we must check the value from the manufacturer’s value that is acceptable. The below formula shows basic calculation flow from nozzle: = 0.5q kp (3) where q = flow in litre per hour (lph) k = nozzle discharge coefficient or k-factor for head in lph/bar p = pressure in bar

This formula can be rewritten to give us:

0.5

2

qkp

and

qpk

=

=

(4)

The drawing of network is so designed as shown in Fig. 5 is to be simulated in WaterGEMS software such that the last emitter point of the farthest lateral should get minimum pressure (p) equals to or greater than 1.0 kg/cm2 (10 m) to deliver rated discharge and can be analyzed in our hydraulic model by changing the pipe diameter to meet all the hydraulic parameters.

Pipes

Pipes are so linked to feed water in the network from one-point to another. Software assumes itself that pipes are full flow at all times. Flow directions shown after running system which are actually the flow from end at higher potential of pump to lower potential. The frictional head loss of flowing water with the inner side-walls of pipe, generally calculated using any of three formulas:

1. Hazen-Williams (HW) formula 2. Darcy-Weisbach (DW) formula 3. Chezy-Manning (CM) formula

The HW head loss formula in pipeline is commonly used. We have also used this one. The equation given below shows how to find out head loss between two nodes that is the start and end junction of any pipe considered. B

lH Aq= (5) where

lH = head loss (length), A = resistance coefficient q = flow rate (volume per unit time), B = flow exponent. Table 2 lists the expression for resistance coefficient and also the values of the flow exponent in the formula where “C” is HW roughness coefficient is, d is pipe diameter (m), L is pipe length (m). Minor Losses

Losses that occurred because of water turbulence caused in all pipe fittings like bends, tees, etc. The computation of all losses depending on layout of network and accuracy is achieved. This head loss is the result of product of this coefficient and velocity head of the pipe, i.e.

2

lvH K2g

=

(6)

where

lH = minor head loss K = minor loss coefficient v = flow velocity (m/s) g = acceleration due to gravity (m/s2). The pipeline is drafted in AutoCAD by taking care where there is road crossing, avoiding much road crossing and maximum mainlines are drawn from pumping point and pipe distribution network drawn has been modeled into the software WaterGEMS as shown in Fig. 7(a-b). Here the symbols P-, J- indicate pipe, junction associated with their individual numbers. In our layout the hydraulic modeling has been worked out in following process for pipeline network: The tank (T-1) say for the source having some head initially which will

serve the purpose of pump is drawn first then the connecting links as pipes, valves, laterals and emitting points are drawn later to join water source, all are drawn from the toolbar beside software’s drawing window. Designating the junctions as presented in Fig. 8 from J-1 to J-22 as laterals of 16mm diameter and J-24 to J-59 as the emitting points for each plant which comprises of two drippers resulting to 16 lph placed at the plant stem. For Running The Design In The Software Few Assumptions Are Made

The fluid considered here is apparently clean clear water and homogeneous in nature. Elasticity of fluid and pipeline material follows linear pattern. Flow is one dimensional and incompressible. The software uses average velocity. The elevations at many are known as per our GPS survey and found to be flat. Excluding Software Few More Assumptions That Are Taken

All new pipes are having same roughness coefficient “C” as 150. All pipe materials are Polyvinyl chloride (PVC). Average temperature is assumed at 20° C for software simulation. Pump input data is rated data without having the pump curves. Water quality simulation is not in our present scope of study. Data Entry For Lateral And Dripper

The technical data of lateral is labeled by J-1 to J-22 and dripper as discharge element from J-24 to J-59 in software. As all the 22 laterals used here are same type so the specifications are same so the farthest lateral is analyzed considering that if the farthest is optimized then the near ones will receive sufficient pressure at its discharging point. Discharge of each lateral is 0.166 (L/s) which and discharge of each emitting point is 0.004 (L/s) operates at 100.0 (kPa) or 1.0 (kg/cm2).

RESULTS AND DISCUSSION

Irrigation Scheme

Calculated irrigation requirement of tea for the year on daily, monthly and flow rate per area basis has been presented in Table 3. Values of precipitation deficient for tea indicates the net irrigation requirement for the months where value 0.0 found in the months of May to September indicates that effective rainfall is much higher and there is no need of irrigation for the tea. Calculated 100% irrigation area indicates the area of our concerned model area. This calculation is made on the data arrived for the station Jalpaiguri which is shown in Fig. 9(a-b). Simulations And Analysis Of Irrigation Network In The Software

All data that are put in software are required for simulating and then analyzed for finding out pipelines network drawn for each section are correct or need some changes as pipe diameter and pressure classes in the drawing are pre-selected. The head losses, pressures, system curves and other profiles are studied to ensure that whatever design we proposed is accurate or it requires some modifications or safety measures. The material of pipe considered is as (Polyvinyl Chloride) PVC which HW co-efficient “CH” is 150 as taken for every study. The input values like elevation, discharge and typical operating pressures at which they will

operate along with all pipe details are feed in software. Same inputs are required for the intermediate junctions. Selections of pipes and length (as per drawing), diameter, roughness coefficients are also entered. Once the inputs are entered in software, the network is first validated where a notification comes confirming no error is found, we then run the design. The flow directions in the network indicate the flow of water which enables to start simulating the pipe sizes as shown in Fig. 8. Then outputs such as pressure, frictional head loss, velocity, and flow from all pipes checked and analyzed as shown in Table 4. The network is simulated to get the optimum design. All the technical required data is fed in all the flex sheets of WaterGEMS and the PVC pipe suitable diameter of 75 mm, 63 mm of pressure Class III and 16mm linear low density polyethylene (LLDPE) as per required flow; keeping the decreasing sizes of pipeline with the decreasing flow in pipeline. The Table 5 showing generated data in software after the program is RUN. Calculated values of velocity in Table 4 are within the desired limit with a maximum of 1.1 m/s to minimum of 0.02 m/s. In Table 6 the final scenario can be observed after simulation and it is found that J-54 to J-59 the minimum pressure is 10.0 m which is desired and this result in determining the head of the system that is the driving force by gravity from T-1 which is the water source is shown in Table 6. Development Of The Model On Field As Per The Design

As per the design and drawing the model is developed on field by taking on by-pass outlet from an existing pump delivery instead of T-1 as shown in Fig. 10 and pressure gauge and flow meter being set to the design parameters (Flow = 3.796 L/s and Head = 11.2 m) and checked the discharge rate at the laterals after execution as shown in Fig. 11(a-b). The tank height (T-1) which is used as the total head as generated includes operating pressure plus the head losses, it is the pressure head at which drippers provide fixed discharge is adjusted in the delivery by-pass through gate valves and also the required flow is supplied in order to utilized the existing pump. The losses are not excluding suction head and also the delivery head of pump. Similarly all the four plots are studied, in similar fashion flex tables and individual hydraulic parameters are obtained. Initially we compare all the drippers discharge rate at the starting as well as the end points with our selected developed model and we found it functioning at satisfactorily level and thus claim the justification of this paper. Fig. 12 shows the developed set-up running successfully on the site which we designed with the software. We have design the system as per our survey, designed in a software and installed accordingly at site which validates our design is satisfactory and optimized.

CONCLUSIONS

Introducing drip irrigation in a tea estate traditionally irrigated by overhead sprinklers poses opportunities and challenges. Irrigation water optimizing, irrigation uniformities and efficiencies in this study on later stages will be encouraging and they significantly exceed those of present over head sprinkler system. The optimal supply of water and fertilizer directly to the root zone year around is believed to contribute to increased yield under drip irrigation, an assumption that will be verified experimentally in this study. Economics are a major driver for or against a system choice. On the background of the currently low tea price at the world market, profitability of tea production can only be achieved by high yields and

by control of costs. Hence, efforts to improve gross margins should address those recurrent cost items (fertilizer, electricity). Overall, the conversion of 1 acre at Chuapara Tea Estate to drip is technically set-up. Recurrent training of committed system operators and the incorporation of external expert advice will contribute substantially to the good results. Attempt to harmonize operation schedules of new drip schemes with field pruning cycles, i.e. blocks in the same operation should be pruned at the same time. This enables a modified water and fertilizer regime following pruning. Future scope of study will be yield response curves of tea to water and fertilizer under drip irrigation which are currently unknown, and should be determined experimentally. A better understanding of optimal fertilizer rates and seasonal fertilizer distribution under drip would have significant economic impact for the tea industry in the Dooars, Assam, and Darjeeling of India. On a technology-transfer scale, the viability of small-scale (low pressure, low cost) drip irrigation systems for smallholder tea growers in India should be examined. The engineering and agronomic aspects of this study should be complemented by a comprehensive economic and socio-cultural analysis. The secrets in successful designing depends on identification, selection of suitable components, placement of drippers at right position eventually keeping the knowledge of all its technical specifications, its efficiency and finally economic decision at the beginning of the designing process. The design is done successfully considering conditions of the site as per drawing. From selecting dripper to the pressure gauge and flow meter, it is done with accuracy. Since the study is designed and simulated totally with software so there are less chances of error by simulating in WaterGEMS software. The study is implemented and desired output is achieved in terms of setting up of the model. Thus it justifies the design and development of micro irrigation system through software simulation plays a better in understanding all the hydraulic aspects of the model after execution on field. Thus we can conclude in any micro-irrigation system that software application can play a big role in designing for accuracy and perfection. The problems or the hurdles found if done manually without software use lie in calculations and simulations for so many sections comprising pipes network, maximum length of run of laterals with different types can create chances of error on human calculations. Designing with software in such systems also reduced the time. This study is done with best possible accuracy, all data that are available and it has shown a path for any other design in micro irrigation system.

ACKNOWLEDGEMENTS

The study is supported by Department of Science and Technology, Govt. of India under DST-INSPIRE Fellowship and School of Water Resources Engineering, Jadavpur University, Kolkata. The authors heartily thank Mcleod Russel India Ltd for their esteemed support of the research study. The authors wish to acknowledge the assistance Chuapara Tea Estate and all the staffs for data access, transportation of materials, on field assistance as well as fruitful discussions on agronomic and technical issues of this project

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LIST OF FIGURES:

Fig. 1. Site location

Fig. 2. Selected area and water source at site

Fig. 3. Rainfall data of Jalpaiguri from FAO

Fig. 4. Climatic data of Jalpaiguri acquired from FAO

Fig. 5. Proposed drip irrigation drawing with four sections

Fig. 6(a). Plot-1 section containing 8 lph drippers

Fig. 6(b). Plot-1 section controlling by valve (V-1)

Fig. 7(a). Showing piping layout and dripper position in WaterGEMS software

Fig. 7(b). Showing tank (T-1) in the software

Fig. 8. Showing laterals position (J-1 to J-22) and drippers points (J-24 to J-59)

Fig. 9(a) Calculated ETo for Jalpaiguri

Fig. 9 (b). Calculated crop water requirement

ETo mm/dayMin Temp °CMax Temp °CSun hoursRad MJ/m²/day

Month121110987654321

30

28

26

24

22

20

18

16

14

12

10

8

6

4

2

0

ETc mm/decIrr. Req. mm/dec

Month121110987654321

50.048.046.044.042.040.038.036.034.032.030.028.026.024.022.020.018.016.014.012.010.08.06.04.02.00.0

Fig. 10. Shows the by-pass assembly from existing pump instead of T-1 calibrated to supply Flow =

3.796 L/s and Head = 11.2 m)

Fig. 11(a). Showing developed model laterals on field as considered in the software as junctions J-1 to

J-9

Fig. 11(b). Showing emitting points as considered in the software as junctions J-24 to J-27

Fig. 12. Discharging desired amount as per design consideration

LIST OF TABLES: Table 1. GPS survey details at Chuapara Tea Estate GPS Waypoints Latitude & Longitude GPS

Waypoints Latitude & Longitude

569 (Water Source)

N26 44.460; E89 27.018 579 N26 44.440; E89 27.002

570 N26 44.460; E89 27.018 580 N26 44.436; E89 26.998 571 N26 44.460; E89 27.018 581 N26 44.433; E89 26.997 572 N26 44.461; E89 27.016 582 N26 44.430; E89 26.997 573 N26 44.460; E89 27.012 583 N26 44.429; E89 26.999 574 N26 44.452; E89 27.010 584 N26 44.451; E89 27.015 575 N26 44.451; E89 27.010 585 N26 44.445; E89 27.020 576 N26 44.451; E89 27.009 586 N26 44.436; E89 27.026 577 N26 44.445; E89 27.004 587 N26 44.433; E89 27.028 578 N26 44.445; E89 27.004 588 N26 44.432; E89 27.027

Table 2. Pipe head loss formulas for full flow (for head loss in m and flow rate in L/s) Formula Resistance Coefficient (A) Flow Exponent (B)

Hazen-Williams ( ) 1.852 4.871469.855 C d L− − 1.852

Table 3. Calculated water supply scheme for tea from CROPWAT 8.0

E To station: JALPAIGURI

Cropping pattern: Tea Crop

Rain station: JALPAIGURI

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Precipitation deficit

1. Tea 44.1 52.9 75.8 38.4 0.0 0.0 0.0 0.0 0.0 8.1 63.1 53.6 Net scheme irr. req.

in mm/day 1.4 1.9 2.4 1.3 0.0 0.0 0.0 0.0 0.0 0.3 2.1 1.7 in mm/month 44.1 52.9 75.8 38.4 0.0 0.0 0.0 0.0 0.0 8.1 63.1 53.6 in l/s/h 0.16 0.22 0.28 0.15 0.0 0.0 0.00 0.00 0.00 0.03 0.24 0.20 Irrigated area 100 100 100 100 0.0 0.0 0.0 0.0 0.0 100 100 100

(% of total area)

Irr. req. for actual area

0.16 0.22 0.28 0.15 0.00 0.0 0.00 0.00 0.00 0.03 0.24 0.20

(l/s/h)

Table 4. Calculated and simulated hydraulic details of the irrigation model from software

Label Length (m)

Start Node

Stop Node

Diameter

(mm)

Flow (L/s)

Velocity (m/s)

Headloss

Gradient (m/m)

Headloss (m)

Hydraulic Grade

(Start) (m)

Hydraulic Grade

(Stop) (m)

Pressure Loss (m)

P-1 50 T-1 J-1 75 3.796 0.86 0.01 0.494 177.20 176.71 0.493 P-2 1 J-1 J-2 63 3.63 1.16 0.021 0.021 176.71 176.69 0.021 P-3 1 J-2 J-3 63 3.464 1.11 0.019 0.019 176.69 176.67 0.019 P-4 1 J-3 J-4 63 3.298 1.06 0.018 0.018 176.67 176.65 0.018 P-5 1 J-4 J-5 63 3.132 1.00 0.016 0.016 176.65 176.63 0.016 P-6 1 J-5 J-6 63 2.966 0.95 0.015 0.015 176.63 176.62 0.015 P-7 1 J-6 J-7 63 2.800 0.90 0.013 0.013 176.62 176.6 0.013 P-8 1 J-7 J-8 63 2.634 0.84 0.012 0.012 176.60 176.59 0.012 P-9 1 J-8 J-9 63 2.468 0.79 0.01 0.010 176.59 176.58 0.010

P-10 1 J-9 J-10 63 2.302 0.74 0.009 0.009 176.58 176.57 0.009 P-11 1 J-10 J-11 63 2.136 0.69 0.008 0.008 176.57 176.56 0.008 P-12 1 J-11 J-12 63 1.970 0.63 0.007 0.007 176.56 176.56 0.007 P-13 1 J-12 J-13 63 1.804 0.58 0.006 0.006 176.56 176.55 0.006 P-14 1 J-13 J-14 63 1.638 0.53 0.005 0.005 176.55 176.55 0.005 P-15 1 J-14 J-15 63 1.472 0.47 0.004 0.004 176.55 176.54 0.004 P-16 1 J-15 J-16 63 1.306 0.42 0.003 0.003 176.54 176.54 0.003 P-17 1 J-16 J-17 63 1.140 0.37 0.002 0.002 176.54 176.54 0.002 P-18 1 J-17 J-18 63 0.974 0.31 0.002 0.002 176.54 176.54 0.002 P-19 1 J-18 J-19 63 0.808 0.26 0.001 0.001 176.54 176.53 0.001 P-20 1 J-19 J-20 63 0.642 0.21 0.001 0.001 176.53 176.53 0.001 P-21 1 J-20 J-21 63 0.476 0.15 0.000 0.000 176.53 176.53 0.000 P-22 1 J-21 J-22 63 0.310 0.1 0.000 0.000 176.53 176.53 0.000 P-24 0.83 J-22 J-24 16 0.144 0.72 0.043 0.035 176.53 176.50 0.035 P-25 0.83 J-24 J-25 16 0.140 0.7 0.041 0.034 176.50 176.46 0.034 P-26 0.83 J-25 J-26 16 0.136 0.68 0.038 0.032 176.46 176.43 0.032 P-27 0.83 J-26 J-27 16 0.132 0.66 0.036 0.030 176.43 176.40 0.030 P-28 0.83 J-27 J-28 16 0.128 0.64 0.034 0.029 176.40 176.37 0.028 P-29 0.83 J-28 J-29 16 0.124 0.62 0.032 0.027 176.37 176.35 0.027 P-30 0.83 J-29 J-30 16 0.12 0.6 0.031 0.025 176.35 176.32 0.025 P-31 0.83 J-30 J-31 16 0.116 0.58 0.029 0.024 176.32 176.30 0.024 P-32 0.83 J-31 J-32 16 0.112 0.56 0.027 0.022 176.30 176.27 0.022 P-33 0.83 J-32 J-33 16 0.108 0.54 0.025 0.021 176.27 176.25 0.021 P-34 0.83 J-33 J-34 16 0.104 0.52 0.023 0.019 176.25 176.23 0.019 P-35 0.83 J-34 J-35 16 0.100 0.50 0.022 0.018 176.23 176.22 0.018 P-36 0.83 J-35 J-36 16 0.096 0.48 0.020 0.017 176.22 176.20 0.017 P-37 0.83 J-36 J-37 16 0.092 0.46 0.019 0.015 176.20 176.18 0.015 P-38 0.83 J-37 J-38 16 0.088 0.44 0.017 0.014 176.18 176.17 0.014 P-39 0.83 J-38 J-39 16 0.084 0.42 0.016 0.013 176.17 176.16 0.013 P-40 0.83 J-39 J-40 16 0.08 0.40 0.014 0.012 176.16 176.14 0.012 P-41 0.83 J-40 J-41 16 0.076 0.38 0.013 0.011 176.14 176.13 0.011 P-42 0.83 J-41 J-42 16 0.072 0.36 0.012 0.010 176.13 176.12 0.010 P-43 0.83 J-42 J-43 16 0.068 0.34 0.011 0.009 176.12 176.12 0.009 P-44 0.83 J-43 J-44 16 0.064 0.32 0.010 0.008 176.12 176.11 0.008 P-45 0.83 J-44 J-45 16 0.060 0.30 0.008 0.007 176.11 176.10 0.007

Table 5. Output of pressure head at all lateral starting points and dripper points of the developed irrigation model from software Label Elevation

(m) Demand

(L/s) Hydraulic Grade (m)

Pressure (m)

Label Elevation (m)

Demand (L/s)

Hydraulic Grade (m)

Pressure (m)

J-1 166 0.166 176.71 10.7 J-31 166 0.004 176.30 10.3 J-2 166 0.166 176.69 10.7 J-32 166 0.004 176.27 10.3 J-3 166 0.166 176.67 10.6 J-33 166 0.004 176.25 10.2 J-4 166 0.166 176.65 10.6 J-34 166 0.004 176.23 10.2 J-5 166 0.166 176.63 10.6 J-35 166 0.004 176.22 10.2 J-6 166 0.166 176.62 10.6 J-36 166 0.004 176.20 10.2 J-7 166 0.166 176.60 10.6 J-37 166 0.004 176.18 10.2 J-8 166 0.166 176.59 10.6 J-38 166 0.004 176.17 10.1 J-9 166 0.166 176.58 10.6 J-39 166 0.004 176.16 10.1 J-10 166 0.166 176.57 10.6 J-40 166 0.004 176.14 10.1 J-11 166 0.166 176.56 10.5 J-41 166 0.004 176.13 10.1 J-12 166 0.166 176.56 10.5 J-42 166 0.004 176.12 10.1 J-13 166 0.166 176.55 10.5 J-43 166 0.004 176.12 10.1 J-14 166 0.166 176.55 10.5 J-44 166 0.004 176.11 10.1 J-15 166 0.166 176.54 10.5 J-45 166 0.004 176.10 10.1 J-16 166 0.166 176.54 10.5 J-46 166 0.004 176.09 10.1 J-17 166 0.166 176.54 10.5 J-47 166 0.004 176.09 10.1 J-18 166 0.166 176.54 10.5 J-48 166 0.004 176.08 10.1 J-19 166 0.166 176.53 10.5 J-49 166 0.004 176.08 10.1 J-20 166 0.166 176.53 10.5 J-50 166 0.004 176.08 10.1 J-21 166 0.166 176.53 10.5 J-51 166 0.004 176.07 10.1 J-22 166 0.166 176.53 10.5 J-52 166 0.004 176.07 10.1 J-24 166 0.004 176.50 10.5 J-53 166 0.004 176.07 10.1 J-25 166 0.004 176.46 10.4 J-54 166 0.004 176.07 10.0 J-26 166 0.004 176.43 10.4 J-55 166 0.004 176.07 10.0 J-27 166 0.004 176.40 10.4 J-56 166 0.004 176.07 10.0 J-28 166 0.004 176.37 10.4 J-57 166 0.004 176.07 10.0 J-29 166 0.004 176.35 10.3 J-58 166 0.004 176.07 10.0 J-30 166 0.004 176.32 10.3 J-59 166 0.004 176.07 10.0

P-46 0.83 J-45 J-46 16 0.056 0.28 0.007 0.006 176.10 176.09 0.006 P-47 0.83 J-46 J-47 16 0.052 0.26 0.006 0.005 176.09 176.09 0.005 P-48 0.83 J-47 J-48 16 0.048 0.24 0.006 0.005 176.09 176.08 0.005 P-49 0.83 J-48 J-49 16 0.044 0.22 0.005 0.004 176.08 176.08 0.004 P-50 0.83 J-49 J-50 16 0.040 0.20 0.004 0.003 176.08 176.08 0.003 P-51 0.83 J-50 J-51 16 0.036 0.18 0.003 0.003 176.08 176.07 0.003 P-52 0.83 J-51 J-52 16 0.032 0.16 0.003 0.002 176.07 176.07 0.002 P-53 0.83 J-52 J-53 16 0.028 0.14 0.002 0.002 176.07 176.07 0.002 P-54 0.83 J-53 J-54 16 0.024 0.12 0.002 0.001 176.07 176.07 0.001 P-55 0.83 J-54 J-55 16 0.02 0.1 0.001 0.001 176.07 176.07 0.001 P-56 0.83 J-55 J-56 16 0.016 0.08 0.001 0.001 176.07 176.07 0.001 P-57 0.83 J-56 J-57 16 0.012 0.06 0.000 0.000 176.07 176.07 0.000 P-58 0.83 J-57 J-58 16 0.008 0.04 0.000 0.000 176.07 176.07 0.000 P-59 0.83 J-58 J-59 16 0.004 0.02 0.000 0.000 176.07 176.07 0.000

Table 6. Tank (T-1) details from software ID Label Elevation

(Base) (m) Elevation

(Minimum) (m)

Elevation (Initial)

(m)

Elevation (Maximum)

(m)

Diameter (m)

Flow (Out net) (L/s)

Hydraulic Grade (m)

28 T-1 175 176 177.2 183 3.05 3.796 177.2