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94-512: The Dukan Dam was built between 1954 and 1959 as a multi-purpose dam to provide water storage, irrigation and hydroelectricity . The design for the dam was carried out by the British engineering company Binnie & Partners (with Partner and third generation Binnie engineer Geoffrey Binnie the key engineer). Additional structural analysis was done for Binnie by his friends at Imperial College, Professor Pippard and Letitia Chitty , who "developed

188-461: A is the secondary compression index t is the length of time after consolidation considered t 95 is the length of time for achieving 95% consolidation Coefficient of compressibility a v = Δ e Δ σ ′ {\displaystyle a_{v}={\frac {\Delta e}{\Delta \sigma _{'}}}} . The compressibility of saturated specimens of clay minerals increases in

282-540: A ball drive, gear drive, or impact mechanism. Rotors can be designed to rotate in a full or partial circle. Guns are similar to rotors, except that they generally operate at very high pressures of 275 to 900 kPa (40 to 130 psi) and flows of 3 to 76 L/s (50 to 1200 US gal/min), usually with nozzle diameters in the range of 10 to 50 mm (0.5 to 1.9 in). Guns are used not only for irrigation, but also for industrial applications such as dust suppression and logging . Sprinklers can also be mounted on moving platforms connected to

376-419: A circular or semi-circular pattern. Traveling Sprinklers: These move along the hose path on their own, watering as they go, ideal for covering long, narrow spaces. Each type offers different advantages based on garden size and shape, water pressure, and specific watering needs. Subirrigation has been used for many years in field crops in areas with high water tables . It is a method of artificially raising

470-589: A clock or timer. Most automatic systems employ electric solenoid valves . Each zone has one or more of these valves that are wired to the controller. When the controller sends power to the valve, the valve opens, allowing water to flow to the sprinklers in that zone. There are two main types of sprinklers used in lawn irrigation, pop-up spray heads and rotors. Spray heads have a fixed spray pattern, while rotors have one or more streams that rotate. Spray heads are used to cover smaller areas, while rotors are used for larger areas. Golf course rotors are sometimes so large that

564-426: A computerized set of valves . In sprinkler or overhead irrigation, water is piped to one or more central locations within the field and distributed by overhead high-pressure sprinklers or guns. A system using sprinklers, sprays, or guns mounted overhead on permanently installed risers is often referred to as a solid-set irrigation system. Higher pressure sprinklers that rotate are called rotors and are driven by

658-494: A direct financial cost to the farmer. Irrigation often requires pumping energy (either electricity or fossil fuel) to deliver water to the field or supply the correct operating pressure. Hence increased efficiency will reduce both the water cost and energy cost per unit of agricultural production. A reduction of water use on one field may mean that the farmer is able to irrigate a larger area of land, increasing total agricultural production. Low efficiency usually means that excess water

752-416: A flood (spate), water is diverted to normally dry river beds (wadis) using a network of dams, gates and channels and spread over large areas. The moisture stored in the soil will be used thereafter to grow crops. Spate irrigation areas are in particular located in semi-arid or arid, mountainous regions. Micro-irrigation , sometimes called localized irrigation , low volume irrigation , or trickle irrigation

846-409: A higher profit than potatoes. The land is flood irrigated twice a day to simulate tidal flooding; the water is pumped from the sea using wind power. Additional benefits are soil remediation and carbon sequestration . Until the 1960s, there were fewer than half the number of people on the planet as of 2024. People were not as wealthy as today, consumed fewer calories and ate less meat , so less water

940-417: A key aspect of agriculture for over 5,000 years and has been developed by many cultures around the world. Irrigation helps to grow crops, maintain landscapes, and revegetate disturbed soils in dry areas and during times of below-average rainfall. In addition to these uses, irrigation is also employed to protect crops from frost , suppress weed growth in grain fields, and prevent soil consolidation . It

1034-520: A logarithmic relationship is assumed between the volume of the soil sample and the effective stress carried by the soil particles. The constant of proportionality (change in void ratio per order of magnitude change in effective stress) is known as the compression index, given the symbol λ {\displaystyle \lambda } when calculated in natural logarithm and C C {\displaystyle C_{C}} when calculated in base-10 logarithm. This can be expressed in

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1128-424: A rectangular or square pattern. They are good for covering large, flat areas evenly. Impact (or Pulsating) Sprinklers: These create a rotating, pulsating spray, which can cover a circular or semi-circular area. They are useful for watering large lawns. Stationary Sprinklers: These have a fixed spray pattern and are best for smaller areas or gardens. Rotary Sprinklers: These use spinning arms to distribute water in

1222-708: A result of irrigation and the subsequent effects on natural and social conditions in river basins and downstream of an irrigation scheme . The effects stem from the altered hydrological conditions caused by the installation and operation of the irrigation scheme. Amongst some of these problems is depletion of underground aquifers through overdrafting . Soil can be over-irrigated due to poor distribution uniformity or management wastes water, chemicals, and may lead to water pollution . Over-irrigation can cause deep drainage from rising water tables that can lead to problems of irrigation salinity requiring watertable control by some form of subsurface land drainage . In 2000,

1316-424: A single sprinkler is combined with a valve and called a 'valve in head'. When used in a turf area, the sprinklers are installed with the top of the head flush with the ground surface. When the system is pressurized, the head will pop up out of the ground and water the desired area until the valve closes and shuts off that zone. Once there is no more pressure in the lateral line, the sprinkler head will retract back into

1410-468: A stress analysis technique using relaxation methods and a rubber model to verify the design form." Prior to the flooding of Lake Dukan, the area was subjected to archaeological research to investigate as many archaeological sites as possible. An archaeological survey in the Ranya Plain documented some 40 archaeological sites with evidence for occupation ranging from the sixth millennium BCE up to

1504-399: Is supplementary to rainfall as happens in many parts of the world, or whether it is ' full irrigation' whereby crops rarely depend on any contribution from rainfall. Full irrigation is less common and only happens in arid landscapes experiencing very low rainfall or when crops are grown in semi-arid areas outside of any rainy seasons. Surface irrigation, also known as gravity irrigation, is

1598-409: Is 95% Where T 95 =1.129 T 50 =0.197 The theoretical formulation above assumes that time-dependent volume change of a soil unit only depends on changes in effective stress due to the gradual restoration of steady-state pore water pressure. This is the case for most types of sand and clay with low amounts of organic material. However, in soils with a high amount of organic material such as peat ,

1692-480: Is a form of sprinkler irrigation utilising several segments of pipe (usually galvanized steel or aluminium) joined and supported by trusses , mounted on wheeled towers with sprinklers positioned along its length. The system moves in a circular pattern and is fed with water from the pivot point at the center of the arc. These systems are found and used in all parts of the world and allow irrigation of all types of terrain. Newer systems have drop sprinkler heads as shown in

1786-503: Is a system where water is distributed under low pressure through a piped network, in a pre-determined pattern, and applied as a small discharge to each plant or adjacent to it. Traditional drip irrigation use individual emitters, subsurface drip irrigation (SDI), micro-spray or micro-sprinklers, and mini-bubbler irrigation all belong to this category of irrigation methods. Drip irrigation, also known as microirrigation or trickle irrigation, functions as its name suggests. In this system, water

1880-415: Is also the means of delivery of fertilizer. The process is known as fertigation . Deep percolation, where water moves below the root zone, can occur if a drip system is operated for too long or if the delivery rate is too high. Drip irrigation methods range from very high-tech and computerized to low-tech and labor-intensive. Lower water pressures are usually needed than for most other types of systems, with

1974-502: Is also used to cool livestock , reduce dust , dispose of sewage , and support mining operations. Drainage , which involves the removal of surface and sub-surface water from a given location, is often studied in conjunction with irrigation. There are several methods of irrigation that differ in how water is supplied to plants. Surface irrigation , also known as gravity irrigation, is the oldest form of irrigation and has been in use for thousands of years. In sprinkler irrigation , water

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2068-422: Is common in many parts of the world as rainfed agriculture , or it can be full irrigation, where crops rarely rely on any contribution from rainfall. Full irrigation is less common and only occurs in arid landscapes with very low rainfall or when crops are grown in semi-arid areas outside of rainy seasons. The environmental effects of irrigation relate to the changes in quantity and quality of soil and water as

2162-422: Is considered to be "overconsolidated". This is the case for soils that have previously had glaciers on them or that have been affected by land subsidence . The highest stress that it has been subjected to is termed the " preconsolidation stress ". The "over-consolidation ratio" (OCR) is defined as the highest stress experienced divided by the current stress. A soil that is currently experiencing its highest stress

2256-422: Is delivered at or near the root zone of plants, one drop at a time. This method can be the most water-efficient method of irrigation, if managed properly; evaporation and runoff are minimized. The field water efficiency of drip irrigation is typically in the range of 80 to 90% when managed correctly. In modern agriculture, drip irrigation is often combined with plastic mulch , further reducing evaporation, and

2350-457: Is dependent upon farmers having sufficient access to water. However, water scarcity is already a critical constraint to farming in many parts of the world. There are several methods of irrigation. They vary in how the water is supplied to the plants. The goal is to apply the water to the plants as uniformly as possible, so that each plant has the amount of water it needs, neither too much nor too little. Irrigation can also be understood whether it

2444-577: Is divided over a spillway tunnel with three radial gates having a combined maximum discharge of 2,440 cubic metres (86,000 cu ft) per second, and an emergency bell mouth spillway with a capacity of 1,860 cubic metres (66,000 cu ft) per second. Two irrigation outlets with a combined discharge of 220 cubic metres (7,800 cu ft) per second have not been operated over the last ten years. The powerhouse of five Francis units at 80 MW each releases between 110 and 550 cubic metres (3,900 and 19,400 cu ft) per second. Lake Dukan,

2538-571: Is especially true in saturated clays because their hydraulic conductivity is extremely low, and this causes the water to take an exceptionally long time to drain out of the soil. While drainage is occurring, the pore water pressure is greater than normal because it is carrying part of the applied stress (as opposed to the soil particles). T v = c v ∗ t ( H d r ) 2   {\displaystyle T_{v}={\frac {c_{v}*t}{(H_{dr})^{2}}}\ } Where T v

2632-462: Is known as "intrinsic consolidation". The process of consolidation is often explained with an idealized system composed of a spring , a container with a hole in its cover, and water. In this system, the spring represents the compressibility or the structure of the soil itself, and the water which fills the container represents the pore water in the soil. The time for consolidation to occur can be predicted. Sometimes consolidation can take years. This

2726-424: Is less expensive to install than a center pivot, but much more labor-intensive to operate – it does not travel automatically across the field: it applies water in a stationary strip, must be drained, and then rolled to a new strip. Most systems use 100 or 130 mm (4 or 5 inch) diameter aluminum pipe. The pipe doubles both as water transport and as an axle for rotating all the wheels. A drive system (often found near

2820-475: Is lost through seepage or runoff, both of which can result in loss of crop nutrients or pesticides with potential adverse impacts on the surrounding environment. Soil consolidation Soil consolidation refers to the mechanical process by which soil changes volume gradually in response to a change in pressure . This happens because soil is a three-phase material, comprising soil grains and pore fluid, usually groundwater . When soil saturated with water

2914-421: Is often no alternative for farmers but to use water polluted with urban waste directly to water their crops. There can be significant health hazards related to using untreated wastewater in agriculture. Municipal wastewater can contain a mixture of chemical and biological pollutants. In low-income countries, there are often high levels of pathogens from excreta. In emerging nations , where industrial development

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3008-443: Is often the irrigation choice for developing nations, for low value crops and for large fields. Where water levels from the irrigation source permit, the levels are controlled by dikes ( levees ), usually plugged by soil. This is often seen in terraced rice fields (rice paddies), where the method is used to flood or control the level of water in each distinct field. In some cases, the water is pumped, or lifted by human or animal power to

3102-422: Is outpacing environmental regulation, there are increasing risks from inorganic and organic chemicals. The World Health Organization developed guidelines for safe use of wastewater in 2006, advocating a ‘multiple-barrier' approach wastewater use, for example by encouraging farmers to adopt various risk-reducing behaviors. These include ceasing irrigation a few days before harvesting to allow pathogens to die off in

3196-537: Is piped to one or more central locations within the field and distributed by overhead high-pressure water devices. Micro-irrigation is a system that distributes water under low pressure through a piped network and applies it as a small discharge to each plant. Micro-irrigation uses less pressure and water flow than sprinkler irrigation. Drip irrigation delivers water directly to the root zone of plants. Subirrigation has been used in field crops in areas with high water tables for many years. It involves artificially raising

3290-586: Is practiced in the vineyards at Lanzarote using stones to condense water. Fog collectors are also made of canvas or foil sheets. Using condensate from air conditioning units as a water source is also becoming more popular in large urban areas. As of November 2019 a Glasgow-based startup has helped a farmer in Scotland to establish edible saltmarsh crops irrigated with sea water. An acre of previously marginal land has been put under cultivation to grow samphire , sea blite , and sea aster ; these plants yield

3384-423: Is removed from a consolidated soil, the soil will rebound, regaining some of the volume it had lost in the consolidation process. If the stress is reapplied, the soil will consolidate again along a recompression curve, defined by the recompression index. The gradient of the swelling and recompression lines on a plot of void ratio against the logarithm of effective stress often idealised to take the same value, known as

3478-401: Is said to be "normally consolidated" and has an OCR of one. A soil could be considered "underconsolidated" or "unconsolidated" immediately after a new load is applied but before the excess pore water pressure has dissipated. Occasionally, soil strata form by natural deposition in rivers and seas may exist in an exceptionally low density that is impossible to achieve in an oedometer; this process

3572-478: Is similar in principle and action to subsurface basin irrigation. Another type of subirrigation is the self-watering container, also known as a sub-irrigated planter . This consists of a planter suspended over a reservoir with some type of wicking material such as a polyester rope. The water is drawn up the wick through capillary action. A similar technique is the wicking bed ; this too uses capillary action. Modern irrigation methods are efficient enough to supply

3666-431: Is subjected to an increase in pressure, the high volumetric stiffness of water compared to the soil matrix means that the water initially absorbs all the change in pressure without changing volume, creating excess pore water pressure . As water diffuses away from regions of high pressure due to seepage , the soil matrix gradually takes up the pressure change and shrinks in volume. The theoretical framework of consolidation

3760-437: Is supplied at one end using a large hose. After sufficient irrigation has been applied to one strip of the field, the hose is removed, the water drained from the system, and the assembly rolled either by hand or with a purpose-built mechanism, so that the sprinklers are moved to a different position across the field. The hose is reconnected. The process is repeated in a pattern until the whole field has been irrigated. This system

3854-476: Is the preconsolidation stress of the soil. This method assumes consolidation occurs in only one-dimension. Laboratory data is used to construct a plot of strain or void ratio versus effective stress where the effective stress axis is on a logarithmic scale . The plot's slope is the compression index or recompression index. The equation for consolidation settlement of a normally consolidated soil can then be determined to be: The soil which had its load removed

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3948-666: Is the time factor. H dr is the average longest drain path during consolidation. t is the time at measurement C v is defined as the coefficient of consolidation found using the log method with C v = T 50 H d r 2 t 50 {\displaystyle C_{v}={\frac {T_{50}H_{dr}^{2}}{t_{50}}}} or the root method with C v = T 95 H d r 2 t 95 {\displaystyle C_{v}={\frac {T_{95}H_{dr}^{2}}{t_{95}}}} t 50 time to 50% deformation (consolidation) and t 95

4042-552: Is therefore closely related to the concept of effective stress , and hydraulic conductivity . The early theoretical modern models were proposed one century ago, according to two different approaches, by Karl Terzaghi and Paul Fillunger . The Terzaghi’s model is currently the most utilized in engineering practice and is based on the diffusion equation . In the narrow sense, "consolidation" refers strictly to this delayed volumetric response to pressure change due to gradual movement of water. Some publications also use "consolidation" in

4136-583: Is used for irrigation in agriculture, the nutrient (nitrogen and phosphorus) content of the treated wastewater has the benefit of acting as a fertilizer . This can make the reuse of excreta contained in sewage attractive. In developing countries , agriculture is increasingly using untreated municipal wastewater for irrigation – often in an unsafe manner. Cities provide lucrative markets for fresh produce, so they are attractive to farmers. However, because agriculture has to compete for increasingly scarce water resources with industry and municipal users, there

4230-556: Is usually not considered as a form of irrigation. Rainwater harvesting is the collection of runoff water from roofs or unused land and the concentration of this. Irrigation with recycled municipal wastewater can also serve to fertilize plants if it contains nutrients, such as nitrogen, phosphorus and potassium. There are benefits of using recycled water for irrigation, including the lower cost compared to some other sources and consistency of supply regardless of season, climatic conditions and associated water restrictions. When reclaimed water

4324-577: The United States , China , and European countries like the United Kingdom , also fund and organize some schemes within other nations. By 2021 the global land area equipped for irrigation reached 352 million ha, an increase of 22% from the 289 million ha of 2000 and more than twice the 1960s land area equipped for irrigation. The vast majority is located in Asia (70%), where irrigation

4418-573: The commercial greenhouse production, usually for potted plants . Water is delivered from below, absorbed by upwards, and the excess collected for recycling. Typically, a solution of water and nutrients floods a container or flows through a trough for a short period of time, 10–20 minutes, and is then pumped back into a holding tank for reuse. Sub-irrigation in greenhouses requires fairly sophisticated, expensive equipment and management. Advantages are water and nutrient conservation, and labor savings through reduced system maintenance and automation . It

4512-424: The "father of soil mechanics ", Karl von Terzaghi , consolidation is "any process which involves a decrease in water content of saturated soil without replacement of water by air". More generally, consolidation refers to the process by which soils change volume in response to a change in pressure , encompassing both compaction and swelling. Consolidation is the process in which reduction in volume takes place by

4606-416: The "swelling index" (given the symbol κ {\displaystyle \kappa } when calculated in natural logarithm and C S {\displaystyle C_{S}} when calculated in base-10 logarithm). C c can be replaced by C r (the recompression index) for use in overconsolidated soils where the final effective stress is less than the preconsolidation stress. When

4700-506: The Dokan Dam are expected to cost over $ 8 million and be complete in late 2012. The Dukan Dam is a multi-purpose concrete arch dam abutted by gravity monoliths. It is 360 metres (1,180 ft) long and 116.5 metres (382 ft) high. At its base it is 32.5 metres (107 ft) wide, tapering off to 6.2 metres (20 ft) at the top. The combined maximum discharge of the dam is 4,300 cubic metres (150,000 cu ft) per second. This

4794-760: The Nile river in Egypt and Sudan; and in the Mississippi-Missouri river basin, the Southern Great Plains, and in parts of California in the United States. Smaller irrigation areas are spread across almost all populated parts of the world. By 2012, the area of irrigated land had increased to an estimated total of 3,242,917 km (801 million acres), which is nearly the size of India. The irrigation of 20% of farming land accounts for

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4888-450: The basis for advanced theoretical studies of particularly complex problems. Due to the different approach to the problem of consolidation by the two scientists, a bitter scientific dispute arose between them, and this unfortunately led to a tragic ending in 1937. After Fillunger’s suicide, his theoretical results were forgotten for decades, whereas the methods proposed by Terzaghi found widespread diffusion among scientists and professionals. In

4982-415: The broad sense, to refer to any process by which soil changes volume due to a change in applied pressure. This broader definition encompasses the overall concept of soil compaction , subsidence , and heave . Some types of soil, mainly those rich in organic matter , show significant creep , whereby the soil changes volume slowly at constant effective stress over a longer time-scale than consolidation due to

5076-469: The center pivot. This type of system is known as LEPA (Low Energy Precision Application). Originally, most center pivots were water-powered. These were replaced by hydraulic systems ( T-L Irrigation ) and electric-motor-driven systems (Reinke, Valley, Zimmatic). Many modern pivots feature GPS devices. A series of pipes, each with a wheel of about 1.5 m diameter permanently affixed to its midpoint, and sprinklers along its length, are coupled together. Water

5170-485: The centre of the wheel line) rotates the clamped-together pipe sections as a single axle, rolling the whole wheel line. Manual adjustment of individual wheel positions may be necessary if the system becomes misaligned. Wheel line systems are limited in the amount of water they can carry, and limited in the height of crops that can be irrigated. One useful feature of a lateral move system is that it consists of sections that can be easily disconnected, adapting to field shape as

5264-428: The coefficient of consolidation ( C v {\displaystyle C_{v}} ) and hydraulic conductivity ( K {\displaystyle K} ). Clays undergo consolidation settlement not only by the action of external loads (surcharge loads) but also under its own weight or weight of soils that exist above the clay. Clays also undergo settlement when dewatered (groundwater pumping) because

5358-711: The components of these irrigation systems are hidden under ground, since aesthetics are important in a landscape. A typical lawn sprinkler system will consist of one or more zones, limited in size by the capacity of the water source. Each zone will cover a designated portion of the landscape. Sections of the landscape will usually be divided by microclimate , type of plant material, and type of irrigation equipment. A landscape irrigation system may also include zones containing drip irrigation, bubblers, or other types of equipment besides sprinklers. Although manual systems are still used, most lawn sprinkler systems may be operated automatically using an irrigation controller , sometimes called

5452-406: The construction of embankments , and tunnel and basement excavation in clay. Geotechnical engineers use oedometers to quantify the effects of consolidation. In an oedometer test, a series of known pressures are applied to a thin disc of soil sample, and the change of sample thickness with time is recorded. This allows the consolidation characteristics of the soil to be quantified in terms of

5546-408: The crop or field requirements. Increasing the application efficiency means that the amount of crop produced per unit of water increases. Improved efficiency may either be achieved by applying less water to an existing field or by using water more wisely thereby achieving higher yields in the same area of land. In some parts of the world, farmers are charged for irrigation water hence over-application has

5640-461: The designation "secondary" distinguishes it from "primary consolidation", which refers to volume change due to dissipation of excess pore water pressure. Creep typically takes place over a longer time-scale than (primary) consolidation, such that even after the restoration of hydrostatic pressure some compression of soil takes place at slow rate. Analytically, the rate of creep is assumed to decay exponentially with time since application of load, giving

5734-535: The diffusion of water. To distinguish between the two mechanisms, "primary consolidation" refers to consolidation due to dissipation of excess water pressure, while "secondary consolidation" refers to the creep process. The effects of consolidation are most conspicuous where a building sits over a layer of soil with low stiffness and low permeability, such as marine clay , leading to large settlement over many years. Types of construction project where consolidation often poses technical risk include land reclamation ,

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5828-419: The effective stress on the clay increases. Coarse-grained soils do not undergo consolidation settlement due to relatively high hydraulic conductivity compared to clays. Instead, Coarse-grained soils undergo the immediate settlement. The first modern theoretical models for soil consolidation were proposed in the 1920s by Terzaghi and Fillunger , according to two substantially different approaches. The former

5922-410: The entire field uniformly with water, so that each plant has the amount of water it needs, neither too much nor too little. Water use efficiency in the field can be determined as follows: Increased irrigation efficiency has a number of positive outcomes for the farmer, the community and the wider environment. Low application efficiency infers that the amount of water applied to the field is in excess of

6016-502: The exception of low-energy center pivot systems and surface irrigation systems, and the system can be designed for uniformity throughout a field or for precise water delivery to individual plants in a landscape containing a mix of plant species. Although it is difficult to regulate pressure on steep slopes, pressure compensating emitters are available, so the field does not have to be level. High-tech solutions involve precisely calibrated emitters located along lines of tubing that extend from

6110-898: The final effective stress is greater than the preconsolidation stress, the two equations must be used in combination to model both the recompression portion and the virgin compression portion of the consolidation processes, as follows, δ c = C r 1 + e 0 H log ⁡ ( σ z c ′ σ z 0 ′ ) + C c 1 + e 0 H log ⁡ ( σ z f ′ σ z c ′ )   {\displaystyle \delta _{c}={\frac {C_{r}}{1+e_{0}}}H\log \left({\frac {\sigma _{zc}'}{\sigma _{z0}'}}\right)+{\frac {C_{c}}{1+e_{0}}}H\log \left({\frac {\sigma _{zf}'}{\sigma _{zc}'}}\right)\ } where σ zc

6204-480: The flooded area, around 1,000–1,200 families, were resettled to the west of the lake. The power station was designed in 1973 by the Russian company Hydroproject and became operational in 1979. In 1990 the dam was used to house a group of 'human shield' hostages. They were held initially at the guest lodge nearby, thereafter in the offices adjacent to the cafeteria inside the dam and later inside prefabricated huts on

6298-630: The following decades Biot fully developed the three-dimensional soil consolidation theory, extending the one-dimensional model previously proposed by Terzaghi to more general hypotheses and introducing the set of basic equations of poroelasticity . Today, the Terzaghis’ one dimensional model is still the most utilized by engineers for its conceptual simplicity and because it is based on experimental data, such as oedometer tests , which are relatively simple, reliable and inexpensive and for which theoretical solutions in closed form are well known. According to

6392-475: The following equation, which is used to estimate the volume change of a soil layer: δ c = C c 1 + e 0 H log ⁡ ( σ z f ′ σ z 0 ′ )   {\displaystyle \delta _{c}={\frac {C_{c}}{1+e_{0}}}H\log \left({\frac {\sigma _{zf}'}{\sigma _{z0}'}}\right)\ } where When stress

6486-399: The formula: S s = H 0 1 + e 0 C a log ⁡ ( t t 95 )   {\displaystyle S_{s}={\frac {H_{0}}{1+e_{0}}}C_{a}\log \left({\frac {t}{t_{95}}}\right)\ } Where H 0 is the height of the consolidating medium e 0 is the initial void ratio C

6580-504: The gradual expulsion or absorption of water under long-term static loads. When stress is applied to a soil, it causes the soil particles to pack together more tightly. When this occurs in a soil that is saturated with water, water will be squeezed out of the soil. The magnitude of consolidation can be predicted by many different methods. In the classical method developed by Terzaghi, soils are tested with an oedometer test to determine their compressibility. In most theoretical formulations,

6674-534: The ground. In flower beds or shrub areas, sprinklers may be mounted on above ground risers or even taller pop-up sprinklers may be used and installed flush as in a lawn area. Hose-end sprinklers are devices attached to the end of a garden hose, used for watering lawns, gardens, or plants. They come in a variety of designs and styles, allowing you to adjust the water flow, pattern, and range for efficient irrigation. Some common types of hose-end sprinklers include: Oscillating Sprinklers: These spray water back and forth in

6768-409: The image that follows. As of 2017 most center pivot systems have drops hanging from a U-shaped pipe attached at the top of the pipe with sprinkler heads that are positioned a few feet (at most) above the crop, thus limiting evaporative losses. Drops can also be used with drag hoses or bubblers that deposit the water directly on the ground between crops. Crops are often planted in a circle to conform to

6862-490: The irrigation results in flooding or near flooding of the cultivated land. Historically, surface irrigation is the most common method of irrigating agricultural land across most parts of the world. The water application efficiency of surface irrigation is typically lower than other forms of irrigation, due in part to the lack of control of applied depths. Surface irrigation involves a significantly lower capital cost and energy requirement than pressurised irrigation systems. Hence it

6956-399: The level of the land. Surface irrigation is even used to water urban gardens in certain areas, for example, in and around Phoenix, Arizona . The irrigated area is surrounded by a berm and the water is delivered according to a schedule set by a local irrigation district . A special form of irrigation using surface water is spate irrigation , also called floodwater harvesting. In case of

7050-441: The line is moved. They are most often used for small, rectilinear, or oddly-shaped fields, hilly or mountainous regions, or in regions where labor is inexpensive. A lawn sprinkler system is permanently installed, as opposed to a hose-end sprinkler, which is portable. Sprinkler systems are installed in residential lawns, in commercial landscapes, for churches and schools, in public parks and cemeteries, and on golf courses . Most of

7144-435: The oldest form of irrigation and has been in use for thousands of years. In surface ( furrow, flood , or level basin ) irrigation systems, water moves across the surface of agricultural lands, in order to wet it and infiltrate into the soil. Water moves by following gravity or the slope of the land. Surface irrigation can be subdivided into furrow, border strip or basin irrigation . It is often called flood irrigation when

7238-608: The order kaolinite <illite<smectite. The compression index Cc, which is defined as the change in void ratio per 10-fold increase in consolidation pressure, is in the range of 0.19 to 0.28 for kaolinite, 0.50 to 1.10 for illite, and 1.0 to 2.6 for montmorillonite, for different ionic forms. The more compressible the clay, the more pronounced the influences of cation type and electrolyte concentration on compressibility. Coefficient of volume compressibility m v = Δ V / V Δ σ ′ =

7332-434: The other hand, Fillunger had a rigorous approach to the above problems and provided rigorous mathematical models that paid particular attention to the methods of local averaging of the involved variables. Fillunger’s model was very abstract and involved variables that were difficult to detect experimentally, and, therefore, it was not applicable to the study of real cases by engineers and/or designers. Nevertheless, this provided

7426-436: The overarching goal of increasing self-sufficiency. Irrigation water can come from groundwater (extracted from springs or by using wells ), from surface water (withdrawn from rivers , lakes or reservoirs ) or from non-conventional sources like treated wastewater , desalinated water , drainage water , or fog collection . While floodwater harvesting belongs to the accepted irrigation methods, rainwater harvesting

7520-414: The phenomenon of creep also occurs, whereby the soil changes volume gradually at constant effective stress. Soil creep is typically caused by viscous behavior of the clay-water system and compression of organic matter. This process of creep is sometimes known as "secondary consolidation" or "secondary compression" because it also involves gradual change of soil volume in response to an application of load;

7614-410: The present. Five of these sites were then excavated: Tell Bazmusian , ed-Dem, Kamarian, Qarashina and Tell Shemshara . The excavations at Tell Bazmusian revealed a temple dating to the second millennium BCE. At Tell Shemshara, an early-sixth millennium BCE village was excavated, as well as an early-second millennium BCE palace with a small archive of clay tablets . The inhabitants of some 50 villages in

7708-567: The production of 40% of food production. The scale of irrigation increased dramatically over the 20th century. In 1800, 8 million hectares globally were irrigated, in 1950, 94 million hectares, and in 1990, 235 million hectares. By 1990, 30% of the global food production came from irrigated land. Irrigation techniques across the globe includes canals redirecting surface water, groundwater pumping, and diverting water from dams. National governments lead most irrigation schemes within their borders, but private investors and other nations, especially

7802-475: The regions saw increases in the area equipped for irrigation, with Africa growing the fastest (+29%), followed by Asia (+25%), Oceania (+24%), the Americas (+19%) and Europe (+2%). Irrigation enables the production of more crops, especially commodity crops in areas which otherwise could not support them. Countries frequently invested in irrigation to increase wheat , rice , or cotton production, often with

7896-520: The reservoir created by the Dukan Dam, has a surface area of 270 square kilometres (100 sq mi). Its anticipated capacity is 6.8 cubic kilometres (1.6 cu mi) with a maximum of 8.3 cubic kilometres (2.0 cu mi). Irrigation Irrigation (also referred to as watering of plants ) is the practice of applying controlled amounts of water to land to help grow crops , landscape plants , and lawns . Irrigation has been

7990-400: The sprinkler arrives back at the reel the system shuts off. This type of system is known to most people as a "waterreel" traveling irrigation sprinkler and they are used extensively for dust suppression, irrigation, and land application of waste water. Other travelers use a flat rubber hose that is dragged along behind while the sprinkler platform is pulled by a cable. Center pivot irrigation

8084-493: The sunlight; applying water carefully so it does not contaminate leaves likely to be eaten raw; cleaning vegetables with disinfectant; or allowing fecal sludge used in farming to dry before being used as a human manure. Irrigation water can also come from non-conventional sources like treated wastewater , desalinated water , drainage water , or fog collection . In countries where humid air sweeps through at night, water can be obtained by condensation onto cold surfaces. This

8178-571: The top of the dam. The intention was to deter coalition air strikes in the upcoming 1991 Gulf war. They were released in December 1990 and returned home. Due to lack of maintenance and repairs, the power station has underperformed and is now, after 30 years of service, due for replacement. In 2007, the World Bank began a US$ 40 million project to repair the Dokan and Darbandikhan Dams . Repairs to

8272-812: The total fertile land was 2,788,000 km (689 million acres) and it was equipped with irrigation infrastructure worldwide. About 68% of this area is in Asia, 17% in the Americas, 9% in Europe, 5% in Africa and 1% in Oceania. The largest contiguous areas of high irrigation density are found in Northern and Eastern India and Pakistan along the Ganges and Indus rivers; in the Hai He, Huang He and Yangtze basins in China; along

8366-405: The water source by a hose. Automatically moving wheeled systems known as traveling sprinklers may irrigate areas such as small farms, sports fields, parks, pastures, and cemeteries unattended. Most of these use a length of polyethylene tubing wound on a steel drum. As the tubing is wound on the drum powered by the irrigation water or a small gas engine, the sprinkler is pulled across the field. When

8460-414: The water table to allow the soil to be moistened from below the plants' root zone. Often those systems are located on permanent grasslands in lowlands or river valleys and combined with drainage infrastructure. A system of pumping stations, canals, weirs and gates allows it to increase or decrease the water level in a network of ditches and thereby control the water table. Subirrigation is also used in

8554-404: The water table to moisten the soil below the root zone of plants. Irrigation water can come from groundwater (extracted from springs or by using wells ), from surface water (withdrawn from rivers , lakes or reservoirs ) or from non-conventional sources like treated wastewater , desalinated water , drainage water , or fog collection . Irrigation can be supplementary to rainfall , which

8648-413: Was a key component of the green revolution; the Americas account for 16% and Europe for 8% of the world total. India (76 million ha) and China (75 million ha) have the largest equipped area for irrigation, far ahead of the United States o fAmerica (27 million ha). China and India also have the largest net gains in equipped area between 2000 and 2020 (+21 million ha for China and +15 million ha for India). All

8742-450: Was based on diffusion equations in eulerian notation , whereas the latter considered the local Newton’s law for both liquid and solid phases, in which main variables, such as partial pressure, porosity, local velocity etc., were involved by means of the mixture theory . Terzaghi had an engineering approach to the problem of soil consolidation and provided simplified models that are still widely used in engineering practice today, whereas, on

8836-666: Was needed to produce their food. They required a third of the volume of water humans presently take from rivers. Today, the competition for water resources is much more intense, because there are now more than seven billion people on the planet, increasing the likelihood of overconsumption of food produced by water-thirsty animal agriculture and intensive farming practices. This creates increasing competition for water from industry , urbanisation and biofuel crops . Farmers will have to strive to increase productivity to meet growing demands for food , while industry and cities find ways to use water more efficiently. Successful agriculture

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