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Types of Irrigation. Dr. Salve P. N. M.A.,SET, Ph.D . Maharaja Jivajiro Shinde Mahavidyalya Shrigonda Dist : Ahmednagar. Defining the Need for Irrigation.
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Types of Irrigation Dr. Salve P. N. M.A.,SET, Ph.D. Maharaja JivajiroShindeMahavidyalyaShrigonda Dist : Ahmednagar
Defining the Need for Irrigation • The purpose of irrigation is to supply adequate amount of water when rainfall is not sufficient or timely to meet the crops’ water needs. Since the 1980s, one of Dole’s priorities has been to develop a more scientific approach to better schedule the irrigation of bananas and to apply water only when and where necessary as a way to compensate for water deficiencies in the soil. • In order to assess the need for irrigation, several factors must be considered: 1. Weather conditions such as rain, humidity, evaporation 2. Weather forecasts 3. Crop capacity for water absorption 4. Water available in the soil 5. “Allowable” water deficit for issues such as crop resistance
Introduction:Irrigation refers to the process of supply of water through artificial means such as pipes, ditches, sprinklers, etc. • The irrigation system helps the farmers to have less dependency on rain-water for the purpose of agriculture. The necessity and importance of irrigation is highlighted below in points: • 1. Variety of Climate:Indian climate and weather conditions experiences a varied range of climate. There is extreme heat at some places, while the climate remains extremely cold at other places. While there is excessive rainfall at some places, other places experience extreme dryness. So, irrigation is needed in India. • 2. Irregular and uncertain monsoon:India is a land of monsoon. But monsoon is irregular and erratic in nature. Sometimes it comes easily and brings heavy rainfall, but sometimes it come late and brings inadequate rainfall. Further, there is irregularity in the distribution of rainfall throughout the year. The irrigation system helps the farmers to have less dependency on rain-water. During the months of inadequate rainfall, the crops are supplied water through irrigation systems
3. Agriculture based economy:Indian economy is based on agriculture. A large portion of Indian population depends on agriculture. Without irrigation agriculture is not possible in dry areas or during the months of inadequate rainfall. Naturally, for the agricultural activities across diverse regions, there is a need for proper irrigation system. • 4. Winter crop:India is a vast country with fertile plain lands suitable for Rabi as well Kharif crops. But there is no rainfall during winter months in several places. Without irrigation production of Rabi crops along with other crops is not possible. Rabi crops are grown during the long dry spell of winter season. This is possible mainly due to advanced irrigation facilities. • 5. High breed seeds:At present because of high-breed seeds, crops can be produced at any seasons. But the production of crops is totally depending on water. The introduction of advanced irrigation system have enabled the farmers to produce crops even on during dry season. • 6. Soil Character:In many places, the soils have less water-retaining capacities. • 7. Jute and Paddy:Irrigation is needed for growing some thirsty plants like jute and paddy. • Conclusion: Hence, irrigation is of utmost importance for a agriculture based country like India. To feed a population of over one billion people, there is a need for production of crops round the year. But for this purpose, irrigation water is needed. So for the production of food crops and cash crops, irrigation is a must
Important of Irrigation • The need and importance of Irrigation in India are described in the following points: • 1. The rainfall anomalies of various types bring about crop failure especially in the rainfall deficient areas or drought prone areas. These are mainly located in parts of north-west of India, Gujarat, and the Deccan Plateau etc. Crop failure leads to famine condition unless adequate protective measures are not provided in terms of irrigation.Normally, inadequacy of rainfall in those rainfall deficient areas or drought prone areas (below 1000 mm annual average) has to be made good by irrigation. • 2. Incidentally, the greater degree of variability and uncertainty has further augmented the element of risk in agricultural enterprise even in wet areas of India. Irrigation can be used to tide over the risk. • 3. Perennial irrigation can be used to produce additional crops in the dry months (cold and hot weather season).
What is the importance of Irrigation? • 1. Irrigation maintains moisture in the soil. Moisture is necessary for the germination of seeds. Seeds do not grow in dry soil. That is why irrigation is done before tilling. • 2. Irrigation is essential for the growth of the roots of the crop plants. Roots of the plants do not grow well in dry soil. • 3. Irrigation is necessary for the absorption of mineral nutrients by the plants from the soil. Thus, irrigation is essential for the general growth of the plants. • 4. Water supplies two essential elements hydrogen and oxygen to the crop.
1. IRRIGATION METHODS AND DESIGNS 1 IRRIGATION METHODS • a) Surface Irrigation: Just flooding water. About 90% of the irrigated areas in the world are by this method. • b) Sprinkler Irrigation: Applying water under pressure. About 5 % of the irrigated areas are by this method. • c) Drip or Trickle Irrigation: Applying water slowly to the soil ideally at the same rate with crop consumption. • d) Sub-Surface Irrigation: Flooding water underground and allowing it to come up by capillarity to crop roots. 2. SURFACE IRRIGATION • Water is applied to the field in either the controlled or uncontrolled manner. Controlled: Water is applied from the head ditch and guided by corrugations, furrows, borders, or ridges. Uncontrolled: Wild flooding. Surface irrigation is entirely practised where water is abundant. The low initial cost of development is later offset by high labour cost of applying water. There are deep percolation, runoff and drainage problems
Design of Sprinkler Irrigation System • Objectives and Procedures • Provide Sufficient Flow Capacity to meet the Irrigation Demand • Ensure that the Least Irrigated Plant receives adequate Water Ensure Uniform Distribution of Water. DRIP OR TRICKLE IRRIGATION Introduction: In this irrigation system: i) Water is applied directly to the crop ie. entire field is not wetted. ii) Water is conserved (iii) Weeds are controlled because only the places getting water can grow weeds. (iv) There is a low pressure system. (v) There is a slow rate of water application somewhat matching the consumptive use. Application rate can be as low as 1 - 12 l/hr. (vi) There is reduced evaporation, only potential transpiration is considered. vii) There is no need for a drainage system.
Components of a Drip Irrigation System Control Head Wetting Pattern Unit Mainline Or Manifold Emitter Lateral Layout of The Trickle Irrigation System Sub – Surface Irrigation System Applied in places where natural soil and topographic condition favor water application to the soil under the surface, a practice called sub-surface irrigation. These conditions include: • a) Impervious layer at 15 cm depth or more • b) Pervious soil underlying • c) Uniform topographic condition • d) Moderate slopes.
Components of a Sprinkler Irrigation System SPRINKLER IRRIGATION Introduction: The sprinkler system is ideal in areas where water is scarce. A Sprinkler system conveys water through pipes and applies it with a minimum amount of losses. Water is applied in form of sprays sometimes simulating natural rainfall. The difference is that this rainfall can be controlled in duration and intensity. If well planned, designed and operated, it can be used in sloping land to reduce erosion where other systems are not possible.
BENEFITS OF IRRIGATION • Irrigation increases crop yields.- The 17% of land that is irrigated is producing 40% of the global food • The value of production of irrigated cropland is about $625/ha/year ($95/ha/year for rain-fed cropland and $17.50/ha/year for rangelands). • Irrigation affects total factor productivity (TFP) beyond the input value of the water(evanson,pray,Rosegrant)., • Irrigation allows improve timing and spatial distribution of water. It allows double cropping, it enables supply stabilization. It enable production of vegetables and fruits. • Increases consumer well being& employment & farm income(net income increase per family in Africa was $150 - $1000) • The high productivity of agriculture slowed expansion of deforestation.
Productivity of irrigation • 1% increase in irrigation increase productivity by .12-.25%. • But these are marginal effects • There is a significant heterogeneity within fields-35% of yield variance is within field • There is a significant fixed effect of water. • Irrigation may double or even triple yields,it increase water availability and controls when and where water is available. . The high yields of irrigations may reflect climatic effects-desert areas have higher sun energy and degree days that with irrigation leads to higher yields Modern irrigation and pumping modify ranking and values of land- irrigation technologies is water quality augmenting.
Types of Irrigation • Definition Irrigation may be defined as the process of supplying water by artificial means to agricultural fields for crop production. If water available to the plants from rainfall is not sufficient, it is supplemented by irrigation water. In order to achieve this objective, an irrigation system is required to be developed that involves planning, design, construction, operation and maintenance of various irrigation works: • Source: River, Reservoirs • Control structure: Barrages, Head Regulators • Distribution system: Irrigation Canals
Types of Irrigation Surface Irrigation Sprinkler Irrigation Drip Irrigation • Surface Irrigation - Surface irrigation is defined as the group of application techniques where water is applied and distributed over the soil surface by gravity. It is by far the most common form of irrigation throughout the world • Types of Surface Irrigation Basin Irrigation Border Irrigation Furrow Irrigation • Basin Irrigation - Basin irrigation is the most common form of surface irrigation, particularly in regions with layouts of small fields. If a field is level in all directions, is encompassed by a dyke to prevent runoff, and provides an undirected flow of water onto the field, it is herein called a basin. A basin is typically square in shape but exists in all sorts of irregular and rectangular configurations • Crops for Basin Irrigation - Paddy rice grows best when its roots are submerged in water and so basin irrigation is the best method to use for this crop. Not suited to crops which cannot stand in wet or waterlogged conditions for periods longer than 24 hours (e.g. potatoes, beet and carrots, etc.)
Suitable Land Slopes for Basin Irrigation The flatter the land surface, the easier it is to construct basins. On flat land only minor levelling may be required to obtain level basins. • Suitable Soil for Basin Irrigation Loamy soils are preferred for basin irrigation so that waterlogging (permanent saturation of the soil) can be avoided (which can occur on clayey soils). Coarse sands are not recommended for basin irrigation as, due to the high infiltration rate, percolation losses can be high. • Irrigation water is led directly from the field channel into the basin through bund breaks. In the following figure "Basin a" is irrigated first, then "Basin b" is irrigated and so on. This method can be used for most crop types and is suitable for most soils.
Border irrigation can be viewed as an extension of basin irrigation to sloping, long rectangular or contoured field shapes, with free draining conditions at the lower end. • Above figure illustrates a typical border configuration in which a field is divided into sloping borders. Water is applied to individual borders from small hand-dug checks from the field head ditch. When the water is shut off, it recedes from the upper end to the lower end.
Furrow irrigation • Furrow irrigation avoids flooding the entire field surface by channeling the flow along the primary direction of the field using ‘furrows,’ ‘creases,’ or ‘corrugations’. Water infiltrates through the wetted perimeter and spreads vertically and horizontally to refill the soil reservoir.
Irrigation techniquesSprinkler irrigation: System layout Sprinkler irrigation is a method of applying irrigation water which is similar to natural rainfall. Water is distributed through a system of pipes usually by pumping. It is then sprayed into the air through sprinklers so that it breaks up into small water drops which fall to the ground.
Irrigation techniquesSprinkler irrigation Sprinkler Spray pattern
Hand move laterals Variation in pressure Hop along system Solid set system
Drip irrigation is sometimes called trickle irrigation and involves dripping water onto the soil at very low rates (2-20 litres/hour) from a system of small diameter plastic pipes fitted with outlets called emitters or drippers. Water is applied close to plants so that only part of the soil in which the roots grow is wetted, unlike surface and sprinkler irrigation, which involves wetting the whole soil profile. Suitable for high value row crops. • The suitability of the various irrigation methods, i.e. surface, sprinkler or drip irrigation, depends mainly on the following factors: natural conditions type of crop type of technology previous experience with irrigation required labour inputs costs and benefits. • Natural Conditions Soil type: Sandy soils have a low water storage capacity and a high infiltration rate. They therefore need frequent but small irrigation applications. Under these circumstances, sprinkler or drip irrigation are more suitable than surface irrigation. On loamy or clay soils all three irrigation methods can be used, but surface irrigation is more commonly found.
Sprinkler irrigation: Linear move system Sprinkler irrigation: Mobile raingun
Drip irrigation irrigation: Root zone
Irrigation techniques - Micro irrigation: Emitters Micro sprinklers
Wells and tube-wells: • 38% of irrigation land uses wells and tube wells in India. By this method, wells are dug to reach the underground water level. Then the water is lifted up to the surface to be used for farming. If the underground water level is near the surface, the wells can be shallow. After the wells and tube wells are constructed the water is lifted by two methods: • Common method is the Persian Wheel: Normally animals like cattle drag a rope to the surface at the end of which a bucket of water is lifted from the well to the surface. By the Persian wheel method, a wheel with many buckets around the circumference is pulled by a rope by an animal in such a manner that buckets of water rise from the well to the surface one by one. • The other method of lifting water to the surface used today is by electric pumps or diesel pumps. In a short time large amounts of water can be lifted usually from deep wells or tube wells. • This type of irrigation is common in the plains of North India – Punjab, U.P., Bihar, West Bengal and Assam. Some wells are also seen in Gujarat, Maharashtra, Tamil Nadu etc.
Well:Tube Well: • Tube Well:Tube Well: A tube well is a type of water well in which a long 100–200 millimetres stainless steel tube or pipe is bored into an underground aquifer. The lower end is fitted with a strainer, and a pump at the top lifts water for irrigation.
Wells and Tube Wells Irrigation in India • A well is a hole dug in the ground to obtain the subsoil water. An ordinary well is about 3-5 metres deep but deeper wells up-to 15 metres are also dug. • This method of irrigation has been used in India from time immemorial. Various methods are used to lift the ground water from the well for irrigation, drinking, bathing and for other purposes. Some of the widely used methods are the persian wheel, reht, charas or mot, and dhinghly (lever). • Well irrigation is popular in areas where sufficient sweet ground water is available. These areas include a large part of the Great Northern Plain, the deltaic regions of the Mahanadi, the Godavari, the Krishna and the Cauvery, parts of the Narmada and the Tapi valleys and the weathered layers of the Deccan Trap and crystalline rocks and the sedimentary zones of the Peninsula. • However, the greater part of the Penisnular India is not suitable for well irrigation due to rocky structure, uneven surface and lack of underground water. Large dry tracts of Rajasthan, the adjoining parts of Punjab, Haryana, and Gujarat and some parts of Uttar Pradesh have brackish ground water which is not fit for irrigation and human consumption and hence unsuitable for well irrigation.
A tube well is a deeper well (generally over 15 metres deep) from which water is lifted with the help of a pumping set operated by an electric motor or a diesel engine. Obviously, a tube well cannot be constructed everywhere and requires some geographical conditions favouring its installation. The main factors are: • (i) There should be sufficient quantity of ground water because a tube well can generally irrigate 2 hectares per day against 0.2 hectares per day irrigated by an ordinary well. • (ii) The water level should be nearly 15 metres. If the water table is more than 50 metres deep the cost of pumping out water from the tube well becomes uneconomic. • (iii) There should be regular supply of cheap electricity or diesel so that water from the tube well can be taken out at the hour of need. • (iv) The soil in the immediate neighborhood of the tube-well should be fertile so that there is demand for irrigation and the cost involved in the construction and operation of the tube well can be recovered by the increased farm production.
The first tube well of India was sunk in Uttar Pradesh in 1930. Till 1951 India had just 2,500 tube wells. The central and the state governments are helping the farmers by distributing pumping sets, granting loans and giving subsidies. The number of electrical pump sets/tube wells increased from 2 lakh in 1960 to over 4 million in 1995-96 while the dieselized pump sets increased from 2 3 lakh to about 3 million during the same period. • In several areas, the ‘persian wheel’ earlier used for lifting water has been replaced by tube wells. Tamil Nadu with 11 lakh tube wells has the largest number in the country followed by Maharashtra (9 lakh), Andhra Pradesh (6.7 lakh), Uttar Pradesh (5.3 lakh), Madhya Pradesh (4.6 lakh), Karnataka (4.4 lakh), Punjab (3.9 lakh) and Haryana (3.5 lakh) Thus more than three-fourths of India’s tube wells are functioning in Tamil Nadu, Maharashtra, Andhra Pradesh, Uttar Pradesh, Madhya Pradesh, Karanataka and Punjab.
Well Irrigation: Advantages • 1. Whenever necessity is felt, in any tract locally, well may be sunk to start open well irrigation. Much consideration need not be given to any of the other factors which are given proper weightage while introducing canal irrigation. • 2. There is no need of constructing many and expensive hydraulic structures. The cost of well irrigation project is therefore much less. • 3. When the water is withdrawn from the subsoil formation by means of wells the waters table obviously lowers and water-logging of the land is prevented. • 4. The water is used more economically as cultivator has to put in labour for lifting water. • 5. The water can be used at any time depending upon the choice of cultivator and water needs of crops. • 6. As the water is assured for whole of the year, provided groundwater conditions are favourable, two to three corps can be grown on the same field in one year. • 7. Maintenance cost of a well is less. Also as the well is situated usually in the middle of the field water losses in transit are less. • 8. By constructing number of wells in any tract intensive irrigation of some valuable crops can be done. • 9. In well irrigation duty realized is higher. • 10. Well water irrigates the un-commanded patches of the culturable land in the canal irrigated tract. Thus it assists the canal irrigation. • 11. Well water is cooler in summer season and warmer in winter season. This water when applied to the crops, tries to neutralize the bad effects of the hot or cold season.
Well Irrigation: Disadvantages • 1. To make the water available for irrigation purposes it is necessary to lift it from underground. For lifting the water power is required. Thus the well irrigation is much dependent on the availability of power or trouble free working of the machinery which is very rare thing. • 2. Sometimes cost of well water is so high that the returns obtained from it are not justifiable. • 3. Availability of water from the wells depends on groundwater storage. The discharge from well is low and area commanded is less. • 4. The water in well is static and therefore it is free of suspended silt. Water carrying silt together with some useful suspended salts is very beneficial to the crops. Well water thus lacks in this respect.
Merits of Well and Tube Well Irrigation: • 1. Well is simplest and cheapest source of irrigation and the poor Indian farmer can easily afford it. • 2 Well is an independent source of irrigation and can be used as and when the necessity arises. Canal irrigation, on the other hand, is controlled by other agencies and cannot be used at will. • 3. Excessive irrigation by canal leads to the problem of rah which is not the case with well irrigation. • 4. There is a limit to the extent of canal irrigation beyond the tail end of the canal while a well can be dug at any convenient place. • 5 Several chemicals such as nitrate, chloride, sulphate, etc. are generally found mixed in well water. They add to the fertility of soil when they reach the agricultural field along with well water. • 6. The farmer has to pay regularly for canal irrigation which is not the case with well irrigation.
Demerits of Well and Tube Well Irrigation: • 1. Only limited area can be irrigated. Normally, a well can irrigate 1 to 8 hectares of land. • 2. The well may dry up and may be rendered useless for irrigation if excessive water is taken out • 3. In the event of a drought, the ground water level falls and enough water is not available in the well when it is needed the most. • 4. Tube wells can draw a lot of groundwater from its neighboring areas and make the ground dry and unfit for agriculture. • 5. Well and tube well irrigation is not possible in areas of brackish groundwater.
Irrigation from tanks, ponds and lakes: • 15% of irrigation is provided from tanks, ponds, and lakes. In the plateau of South India impervious rocks do not allow rainwater to penetrate underground. As the relief is undulating rainwater can be easily stored in low-lying area. From such reservoirs of water in tanks, ponds and lakes, water can be used for irrigation by pumping. The main drawback of this method is the loss of water in summer due to high temperatures which does not provide irrigation when required most i.e. dry season. • This type of irrigation is seen in Andhra Pradesh, Karnataka and Tamil Nadu mainly. Such irrigation is also seen in West Bengal, Orissa, Assam, Bihar etc.
Methods of Irrigation in India • There are four methods of irrigation viz. Irrigation using buckets and water cans – this useful for small gardens and is out of our purview, Surface irrigation, Sprinkler Irrigation and Drip Irrigation • Surface irrigation • This refers to application of water by gravity flow to the surface of the field. This can be of three types depending on if the entire field is flooded (basin irrigation) or the water is fed into small channels (furrows) or strips of land (borders). The three types include Basin, Furrow and Border Irrigation. • Basins are flat areas of land, surrounded by low bunds. The bunds prevent the water from flowing to the adjacent fields. • Basin irrigation is commonly used for rice grown on flat lands or in terraces on hillsides. Trees can also be grown in basins, where one tree is usually located in the middle of a small basin. • In general, the basin method is suitable for crops that are unaffected by standing in water for long periods such as 12-24 hours.
Furrow Irrigation • Furrows are small channels, which carry water down the land slope between the crop rows. Water infiltrates into the soil as it moves along the slope. The crop is usually grown on the ridges between the furrows. • This method is suitable for all row crops and for crops that are affected in water for long periods such as 12-24 hours
Border Irrigation • Borders are long, sloping strips of land separated by bunds. They are sometimes called border strips. • Irrigation water can be fed to the border in several ways: opening up the channel bank, using small outlets or gates or by means of siphons or spiles. A sheet of water flows down the slope of the border, guided by the bunds on either side.
Sprinkler Irrigation • It involves applying irrigation water which is similar to natural rainfall. Water is distributed through a system of pipes usually by pumping. It is then sprayed into the air through sprinklers so that it breaks up into small water drops which fall to the ground. • The pump supply system, sprinklers and operating conditions must be designed to enable a uniform application of water. • Sprinkler irrigation is suited for most row, field and tree crops and water can be sprayed over or under the crop canopy. • However, large sprinklers are not recommended for irrigation of delicate crops such as lettuce because the large water drops produced by the sprinklers may damage the crop.
Drip Irrigation • With drip irrigation, water is conveyed under pressure through a pipe system to the fields, where it drips slowly onto the soil through emitters or drippers which are located close to the plants. Only the immediate root zone of each plant is wetted. Therefore this can be a very efficient method of irrigation. Drip and Sprinkler Irrigation involves irrigating crops at the root zone as per the crop requirement. It greatly enhances water use efficiency and can also be used for fertilizer application. Drip irrigation is sometimes called trickle irrigation.
Rainguns: Rainguns are high performance impact sprinklers designed for a variety of uses and applications where relatively high flows and extended radius of throw are desired. Rainguns are available with operating pressure of 2.0 to 7.5 kg/cm2 and flows of 3 to 30lps usually with nozzle diameters ranging from 10 to 30 mm and with a wetting radius of 27 to 60 metre.
