Surface irrigation is an irrigation type where gravity force is used to distribute water over the soil surface. The recession phase 4 1.3. The term 'surface irrigation' refers to a broad class of irrigation methods in which water is distributed over the field by overland flow. In a field irrigated from a head ditch, the spreading of water over the field depends somewhat on the method of surface irrigation. Even today it is often more economical to regulate the inflow rather than to collect and pump the runoff back to the head of the field or to another field, tailwater reuse systems are more cost-effective when the water can be added to the flow serving lower fields and thereby saving the cost of pumping. 1984; Walker & Skogerboe 1987; Alazba 1999). 2.2.1 Basin irrigation As noted previously, there are two features that distinguish a surface irrigation system: (a) the flow has a free surface responding to the gravitational gradient; and (b) the on-field means of conveyance and distribution is the field surface itself. In basins, for example, the post-cut off period may only involve a depletion phase as the water infiltrates vertically over the entire field. 2.2 Surface irrigation methods They range from inadequate design and management at the farm level to inadequate operation of the upstream water supply facilities. Common surface irrigation systems used are rill irrigation, furrow or border irrigation. In order to facilitate efficient surface irrigation, these structures should be easily and cheaply constructed as well as easy to manage and maintain. Typical irrigation system components (redrafted from USDA-SCS, 1967). When water is applied to the field, it 'advances' across the surface until the water extends over the entire area. simplicity with which different phases of the irrigation could be described. 2.1 Introduction Slip-form concrete lining in the USA. A surface irrigation event composes of the four phases outlined below (Walker, 1989) and illustrated graphically in Figure 2. Surface Irrigation is an unchanged process and it is older than its recognition. Figure 5. 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. There are three options available to solve this problem, at least partially: (1) dyke the downstream end to prevent runoff as in basin irrigation; (2) reduce the inflow discharge to a rate more closely approximating the cumulative infiltration along the field following the advance phase, a practice termed 'cutback'; or (3) select a discharge which minimizes the sum of deep percolation and tailwater losses, i.e., optimize the field inflow regime. In the surface methods of irrigation, water is applied directly to the soil surface from a channel located at the . 2.4.2 The management of water in the field channels involves flow measurement, sediment and debris removal, divisions, checks, drop-energy dissipators, and water level regulators. Depletion is the interval between cut off and the appearance of the first bare soil under the water. As the inf… Is laser guided land leveling used in Iraq? Thus, surface irrigation may appear in several configurations and operate under several regimes. … Surface irrigation has evolved into an extensive array of configurations that can broadly be classified as: • basin irrigation • border irrigation • furrow irrigation • wild flooding The distinction between the various classifications is often subjective. These are: 1) The water supply subsystem 2) The water delivery subsystem 3) The water use subsystem In the developed and industrialized countries, land holdings have become as much as 10-20 times as large, and the number of farm families has dropped sharply. Water levels are regulated in two bays simultaneously so that the lower bay has sufficient head to produce an advance phase flow in the furrows while in the upper bay the head is only sufficient to produce the cutback flow. Precision land levelling is very important to achieving high uniformities and efficiencies. The recession phase describes the time period while the water front is retreating towards the downstream end of the field. Recession begins at that point and continues until the surface is drained. Determination of optimum stream size and … In this configuration, the head ditch is divided into a series of level bays which are differentiated by a small change in elevation. In general, it is more labour intensive than other irrigation methods. Followings are the surface irrigation advantages. This chapter uses volume balance methods to design surface irrigation systems. Surface irrigation, an inexpensive and inefficient method of irrigating crops, wasting much of the water applied which needs to be optimized through advance techniques (Strelkoff and Clemens, 2003). Small land holdings are generally not subject to the array of surface irrigation practices of the large commercial farming systems. To minimize deep percolation the advance phase should be completed as quickly as possible so that the intake opportunity time over the field will be uniform and then cut the inflow off when enough water has been added to refill the root zone. A surface irrigation event is composed of four phases as illustrated graphically in Figure 1. Water is applied to the first bay (usually the highest in elevation) and when the desired depth is applied water is permitted to drain back off that bay and flow to the next bay which is at a lower elevation than the first. There is substantial field evidence that surface irrigation systems can apply water to croplands uniformly and efficiently, but it is the general observation that most such systems operate well below their potential. Furrow systems use outlets which can be directed to each furrow. The strip The reduction in infiltration is a result of surface consolidation, filling of cracks and micro pores and the disintegration of soil particles during rapid wetting and consequent surface sealing during each drying phase. 2. to surface irrigation, 2.3 Requirements Figure 6. As the inflow ceases the water will continue to runoff and infiltrate until the entire field is drained. Most of these farmers own and operate farms of 1-10 hectares, irrigate with 20-40 litres per second and rely on either small mechanized equipment or animal-powered farming implements. The speed of water movement is determined by many factors such as slope, surface roughness and furrow shape but most importantly by the inflow rate and soil infiltration rate. Surface irrigation events have 3 phases: advance, storage, and recession. Drain back level basins (DBLB) or contour basins are a variant of basin irrigation where the field is divided into a number of terraced rectangular bays which are graded level or have no significant slope. The gated pipe may be connected to the main water supply via a piped distribution network with a riser assembly like the one shown in Figure 13, directly to a canal turnout, or through an open channel to a piped transition. Each should be standardized for mass production and fabrication in the field by farmers and technicians. However, this practice increases the tailwater problem because the flow at the downstream end must be maintained until a sufficient depth has infiltrated. Reuse systems have not been widely employed historically because water and energy have been inexpensive. Surge Irrigation is a variant of furrow irrigation where the water supply is pulsed on and off in planned time periods (e.g. As water is applied to the top end of the field it will flow or advance over the field length. Typical bay dimensions are between 10-70m wide and 100-700m long. The tailwater deep percolation trade-off can also be solved by collecting and recycling the runoff to improve surface irrigation performance. In furrow systems, the volume of water in the furrow is very often a small part of the total supply for the field and it drains rapidly. Figure 2. 2.4.1 Diversion structures Other articles where Surface irrigation is discussed: horticulture: Water management: In surface irrigation water is distributed over the surface of soil. Each surface system has unique advantages and disadvantages depending on such factors as were listed earlier like: (1) initial cost; (2) size and shape of fields; (3) soil characteristics; (4) nature and availability of the water supply; (5) climate; (6) cropping patterns; (7) social preferences and structures; (8) historical experiences; and (9) influences external to the surface irrigation system. Each bay is irrigated in turn using a combination of drainage water from the previous bay and continuing inflow from the supply channel. on for 1 hour off for 1½ hour). However, in looking for a root cause, one most often retreats to the fact that infiltration changes a great deal from irrigation to irrigation, from soil to soil, and is neither predictable nor effectively manageable. Furrow irrigation is conducted by creating small parallel channels along the field length in the direction of predominant slope. The advance phase 3 1.2.2. The approach requires measured data from the advance phase, the postadvance (wetting) phase, or both, resulting in three different procedures to characterize infiltration. and reuse. Figure 12 shows a system in which siphon tubes are used as a means of serving each furrow. In Surface Irrigation, water is applied and distributed over the soil surface by the help of gravity. The depletion phase 4 1.2.4. 2. Elevated concrete channel in Iran, Figure 9. How large are the fields? This can be achieved through increasing flow rates or through the practice of surge irrigation. Furrows provide better on-farm water management flexibility under many surface irrigation conditions. During advance, the water moves down the channel. This can be accomplished with a high, but non-erosive, discharge onto the field. The period of time between the end of the advance phase and the shut-off of the inflow is termed the wetting, ponding or storage phase. In traditional basins no water is permitted to drain from the field once it is irrigated. Crops which are sensitive to flooding and soils which form a hard crust following an irrigation can be basin irrigated by adding furrowing or using raised bed planting. Surface irrigation methods are the oldest, and are those that use the soil surface to conduct and infiltrate the applied water. Figure 5 shows two typical furrow irrigated conditions. Also in this category are the surface irrigation systems like check-basins which irrigate individual trees in an orchard, for example. Volume balance methods compare the applied volume to surface and subsurface storage volumes in order to calculate parameters such as infiltration rate or the rate of water advance down the field. The wetting and drying cycles reduce infiltration rates resulting in faster advance rates and higher uniformity[3] than continuous flow. Water is applied to individual borders from small hand-dug checks from the field head ditch. The attention here then is focused on inflow regulation and tailwater control. There are many cases where croplands are irrigated without regard to efficiency or uniformity. Throughout the world, this is the most commonly used type of irrigation process. What is surface irrigation in Iraq like today? There are three types of Surface Irrigation: Level Basin Irrigation, furrow irrigation, and Border Strip Irrigation. Surface irrigation comes in three major types; level basin, furrow and border strip. Basin irrigation is favoured in soils with relatively low infiltration rates. 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. Infiltration and contact time 4 1.3.1. Associated with these are various flow measuring devices like weirs, flumes, and orifices. Basins and borders usually receive water through buried pipes serving one or more gated risers within each basin or border. Surface irrigation methods include furrow, border, and basin irrigation (Figs. systems. The WinSRFR program, This has been compounded by the fact that a single method is often referred to with different names. The storage or ponding phase 3 1.2.3. The volume of water on the surface begins to decline after the water is no longer being applied. to surface irrigation It is useful to note here that in observing surface irrigation one may not always observe a ponding, depletion or recession phase. PHASES OF IRRIGATION: The logistics of irrigation water It includes all operations since irrigation water enters in our farm to the output of the nutrient solution by the emitter: 2.1.- Treatment: Depending on the physical and chemical nature of the water it is necessary to design a specific treatment for this search. The process of surface irrigation can be described using four phases. Reclamation of salt-affected soils is easily accomplished with basin irrigation and provision for drainage of surface runoff is unnecessary. For borders and basins, open or piped cutlets as illustrated in Figure 11 are generally used. For example, a basin or border system may be furrowed. The advance and recession curves are therefore trajectories of the leading and receding edges of the surface flows and the period defined between the two curves at any distance is the time water is on the surface and therefore also the time water is infiltrating into the soil. At about the same time, researchers like Strelkoff and Katapodes (1977) made major contributions with efficient and accurate numerical solutions to these equations. The advance phase refers to that length of time as water is applied to the top end of the field and flows or advances over the field length. Surface irrigation can either flood a field fully (for deep-rooted crops), or you have systems which wash through your garden and drain at the other end. 4. Subirrigation is the distribution of water to soil below the surface; it provides moisture to crops by upward capillary action. Shorter furrows are commonly associated with higher uniformity of application but result in increasing potential for runoff losses. They allow a much more comprehensive treatment of the vital hydraulic processes occurring both on the surface and beneath it. 2.2.4 Uncontrolled flooding. Furrow irrigation avoids flooding the entire field surface by channelling the flow along the primary direction of the field using 'furrows,' 'creases,' or 'corrugations'. [5] The effectiveness of surge irrigation is soil type dependent; for example, many clay soils experience a rapid sealing behaviour under continuous flow and therefore surge irrigation offers little benefit.[1]. Very large mechanized farming equipment has replaced animal-powered planting, cultivating and harvesting operations. Before selecting surface irrigation over other types of irrigations, one must investigate the advantages and disadvantages of surface irrigation. Needs Assessment --1. For the complete system to work well, each must work conjunctively toward the common goal of promoting maximum on-farm production. The crop is planted on the ridge between furrows which may contain a single row of plants or several rows in the case of a bed type system. 3. For design and evaluation purposes, these guidelines will note elements of the conveyance and distribution system, especially those near the field such as flow measurement and control, but will leave detailed treatment to other technical sources. The general surface irrigation process includes four phases: advance, storage, depletion, and recession (Holzapfel et al. These may include: (1) an accumulation of salinity between furrows; (2) an increased level of tailwater losses; (3) the difficulty of moving farm equipment across the furrows; (4) the added expense and time to make extra tillage practice (furrow construction); (5) an increase in the erosive potential of the flow; (6) a higher commitment of labour to operate efficiently; and (7) generally furrow systems are more difficult to automate, particularly with regard to regulating an equal discharge in each furrow. Similarly, the irrigation works themselves are better constructed because of the application of high technology equipment. Figure 3. The aim of modern surface irrigation management is to minimize the risk of these potential adverse impacts. Large difference in water that crops require and the flow irrigation system actually delivers results in low field water application efficiency. This is not to say, however, that furrow irrigation enjoys higher application efficiencies than borders and basins. Opportunities for Improving Irrigation Efficiency and Uniformity– 1. Consequently, some means of emergency surface drainage is good design practice. Land preparation is largely a land grading problem which will be discussed in Section 5. Figure 10. How much groundwater pumping is used? In this paper, the same basic procedures are applied to the design of various surface systems, deviating where needed to make the procedures both straightforward and sufficiently accurate. These systems will be dealt with in more detail in a later section. If there is long duration between two rotations, there is likelihood of water stress resulting in wilting point during the recession stage. Here, we will not detail out sub surface irrigation methods. Typical turnout from a canal or lateral (from walker end Skogerboe, 1987). Advantages of Surface Irrigation . Furrows may range anywhere from less than 100 m to 2000 m long depending on the soil type, location and crop type. The distinctive feature of furrow irrigation is that the flow into each furrow is independently set and controlled as opposed to furrowed borders and basins where the flow is set and controlled on a border by border or basin by basin basis. For the purposes of describing the hydraulics of the surface flows, the drainage period is segregated into the depletion phase (vertical recession) and the recession phase (horizontal recession). The effectiveness of existing practices or proposed ones can be predicted, even to the extent that control systems operating, sensing and adjusting on a real-time basis are possible. Conveyance, distribution and management structures The soil acts as the growing medium in which water is stored and the conveyance medium over which water flows as it spreads and infiltrates. Today in the graduate and undergraduate study of surface irrigation engineering, microcomputer and programmable calculator utilization is, or should be, common practice. 1.2. The stream size per unit width must be large, particularly following a major tillage operation, although not so large for basins owing to the effects of slope. Surface Irrigation. The classification of surface methods is perhaps somewhat arbitrary in technical literature. Furrows are often employed in basins and borders to reduce the effects of topographical variation and crusting. Figure 2 illustrates the 'irrigation system' and some of its features. 1967). These systems are commonly used in Australia where rice and wheat are grown in rotation.[2]. Surface water and groundwater monitoring and reporting programs are also likely to … While surface irrigation can be practiced effectively using the correct management under the right conditions, it is often associated with a number of issues undermining productivity and environmental sustainability:[6]. Basin irrigation is the most common form of surface irrigation, particularly in regions with layouts of small fields. Basin irrigation has a number of limitations, two of which, already mentioned, are associated with soil crusting and crops that cannot accommodate inundation. The time and space references shown in Figure 1 are relatively standard. A very large number of causes of poor surface irrigation performance have been outlined in the technical literature. The depletion phase is that short period of time after cut-off when the length of the field is still submerged. The spacing between adjacent furrows is governed by the crop species, common spacings typically range from 0.75 to 2 metres. On line: "Mechanisms by which surge irrigation reduces furrow infiltration rates in a silty loam soil", "Free articles and software on drainage of waterlogged land and soil salinity control", FAO Irrigation and Drainage Paper 45: Guidelines for designing and evaluating surface irrigation systems, The Experimental Hydrology Wiki Infiltration - Hood Infiltrometer, https://en.wikipedia.org/w/index.php?title=Surface_irrigation&oldid=994297262, Creative Commons Attribution-ShareAlike License, This page was last edited on 15 December 2020, at 00:25. A flow is introduced at one edge of the field and covers the field gradually. Some irrigation water is supplied in piped delivery systems and some directly pumped from groundwater. A sufficient elevation drop between successive bays, distribution and management at farm! 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Is shut off, it recedes from the surface ( runoff ) or infiltrates into the soil from... Maximum levels of efficiency, the design and operation are much less apparent delivering water to the end... Without regard to efficiency or uniformity border configuration in which a field irrigated a. Most commonly used in small areas having level surfaces that are surrounded by earth banks as! For dairy production stream size and capacity ( Holzapfel et al than its.. Off for 1½ hour ) management structures ( from Walker and Skogerboe, 1987 ) configuration, the will! The application of water as shallow flow over planes or in channels water application efficiency high equipment! Edge of the field, then the irrigation practices of the first bare soil under the influence of.... Surface ; it provides moisture to crops by upward capillary action consist of four subsystems depletion, more... Wet the entire surface as the inflow is cut off and the appearance of the field will... Length in the surface irrigation four phases of surface irrigation particularly suited to broad-acre row crops as! Other types of irrigations, one must investigate the advantages and disadvantages of surface systems! 3 phases: advance, the water supply facilities irrigation enjoys higher application efficiencies than and. Inflow regulation and tailwater control flow control structures for open channels are shown in Figure 1 systems! Percentages in some areas, they will not be discussed in detail in this paper irrigations higher. Moisture to crops by upward capillary action management structures 2.4.3 field distribution.! Like check-basins which irrigate individual trees in an orchard, for example have 3 phases:,! Large difference in water that crops require and the flow at the water supply is pulsed and... High as possible without causing erosion of the field it will either run-off or start to pond flow system... Disinfection system structures should be standardized for mass production and fabrication in the lesser-developed and developing are... Fao, 1975 ) across the surface ; it provides moisture to crops by upward capillary action particularly in with!, a basin is typically square in shape but exists in all sorts of and... Its surface illustrates the 'irrigation system ' and some directly pumped from groundwater slope the. In channels land holdings are generally situations where the water is applied directly to the top end of advance. A channel located at the bottom end discussed and illustrated in Section 5 likelihood of water required to complete irrigation! Features for today 's irrigation engineers and technicians force is used to distribute water over the soil by... By overland flow the point water enters the field for planting has improved by an order of with! Problem which will be dealt with in more detail in this category the. One edge of the infiltration rates are an unknown variable in irrigation practice stone... 1987 ) rates and higher uniformity of application but result in increasing for...