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120-574: The dam , designed by the British Royal Engineers under the direction of Lt. Colonel John By, was built by crews working for contractor John Redpath . It was built by hand, with the assistance of a few draft animals. When completed in late 1831, the Jones Falls dam was the highest dam in North America , a major accomplishment of early 19th century engineering. The dam was built at the head of

240-401: A balancing compression stress in the downstream face, providing additional economy. For this type of dam, it is essential to have an impervious foundation with high bearing strength. Permeable foundations have a greater likelihood of generating uplift pressures under the dam. Uplift pressures are hydrostatic pressures caused by the water pressure of the reservoir pushing up against the bottom of

360-540: 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

480-485: A bedrock canyon, located part way up the rapids, a location that allowed the arch shape of the stonework of the dam to lock into the bedrock of the canyon walls. The dam has three main components: 1) the keywork, the dressed (shaped) stones that form the backing of the dam, 2) an impermeable layer placed in front of the keywork and 3) the dam apron that protects the front of the dam. The stones, large blocks of Potsdam sandstone, were quarried 9 km (5.6 mi) away, in

600-419: 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

720-589: 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

840-426: 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

960-533: A dam as "jurisdictional" or "non-jurisdictional" varies by location. In the United States, each state defines what constitutes a non-jurisdictional dam. In the state of Colorado a non-jurisdictional dam is defined as a dam creating a reservoir with a capacity of 100 acre-feet or less and a surface area of 20 acres or less and with a height measured as defined in Rules 4.2.5.1. and 4.2.19 of 10 feet or less. In contrast,

1080-495: A dam that directed waterflow. It was finished in 251 BC. A large earthen dam, made by Sunshu Ao , the prime minister of Chu (state) , flooded a valley in modern-day northern Anhui Province that created an enormous irrigation reservoir (100 km (62 mi) in circumference), a reservoir that is still present today. Roman dam construction was characterized by "the Romans' ability to plan and organize engineering construction on

1200-494: 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

1320-485: A distinct vertical curvature to it as well lending it the vague appearance of a concave lens as viewed from downstream. The multiple-arch dam consists of a number of single-arch dams with concrete buttresses as the supporting abutments, as for example the Daniel-Johnson Dam , Québec, Canada. The multiple-arch dam does not require as many buttresses as the hollow gravity type but requires a good rock foundation because

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1440-416: 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

1560-471: A grand scale." Roman planners introduced the then-novel concept of large reservoir dams which could secure a permanent water supply for urban settlements over the dry season. Their pioneering use of water-proof hydraulic mortar and particularly Roman concrete allowed for much larger dam structures than previously built, such as the Lake Homs Dam , possibly the largest water barrier to that date, and

1680-409: 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

1800-505: A minor tributary of the Nieuwe Maas . The central square of Amsterdam, covering the original site of the 800-year-old dam, still carries the name Dam Square . The Romans were the first to build arch dams , where the reaction forces from the abutment stabilizes the structure from the external hydrostatic pressure , but it was only in the 19th century that the engineering skills and construction materials available were capable of building

1920-503: A navigation depth of water into the upper sill of the top lock at Jones Falls and also into the lower sill of Davis Lock, at the head of Sand Lake , which was raised by 2.4 m (8 ft) due to the dam at Jones Falls. Typical of most of the Rideau Canal locks, those locks were built "in the dry" - above the pre-existing water level. It was the completion of the dam that created a navigation depth of flooding into those locks. The dam

2040-505: A notable increase in interest in SHPs. Couto and Olden (2018) conducted a global study and found 82,891 small hydropower plants (SHPs) operating or under construction. Technical definitions of SHPs, such as their maximum generation capacity, dam height, reservoir area, etc., vary by country. A dam is non-jurisdictional when its size (usually "small") excludes it from being subject to certain legal regulations. The technical criteria for categorising

2160-627: A profession based on a rigorously applied scientific theoretical framework. This new emphasis was centered around the engineering faculties of universities in France and in the United Kingdom. William John Macquorn Rankine at the University of Glasgow pioneered the theoretical understanding of dam structures in his 1857 paper On the Stability of Loose Earth . Rankine theory provided a good understanding of

2280-475: A quarry located just outside of present day Elgin. In 1827, a road was built from the quarry to Jones Falls, in order to haul the stones to be used for the dam and the locks. Rough cut stones from the quarry were hauled to the site where the Master mason would direct his masons to do the finishing work. The stones were lifted into place using metal tongs (very large timber tongs) attached to a block and tackle hung from

2400-424: 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

2520-708: 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,

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2640-561: A settling pond, and a 1,000 m (3,300 ft) canal to a distribution tank. These works were not finished until 325 AD when the dam permitted the irrigation of 25,000 acres (100 km ). Eflatun Pınar is a Hittite dam and spring temple near Konya , Turkey. It is thought to date from the Hittite empire between the 15th and 13th centuries BC. The Kallanai is constructed of unhewn stone, over 300 m (980 ft) long, 4.5 m (15 ft) high and 20 m (66 ft) wide, across

2760-424: 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

2880-711: 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 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

3000-415: A tripod. The dimples in the stones for those tongs can still be seen in the original stones today. The stonework for the dam is about 8.2 m (27 ft) thick at the base of the dam, tapering to 3.7 m (12 ft) at the top. The stonework is 17.3 m (57 ft) high from its bedrock foundation. An earthen berm on the top of the dam adds about another 1.2 m (3 ft) in height, making

3120-408: A whole dam itself, that dam also would be held in place by gravity, i.e., there is no tension in the upstream face of the dam holding the top of the dam down. The designer does this because it is usually more practical to make a dam of material essentially just piled up than to make the material stick together against vertical tension. The shape that prevents tension in the upstream face also eliminates

3240-399: 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

3360-480: 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

3480-503: 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

3600-441: Is also employed to protect crops from frost , suppress weed growth in grain fields, and prevent soil consolidation . It 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

3720-415: 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

Jones Falls Dam - Misplaced Pages Continue

3840-485: Is approximately 350 feet (107 m) long (the length of the arch at the top), 60 feet (18 m) high and 27 feet (8 m) thick at the base. The base (canyon wall to canyon wall) is 100 feet (30 m) long. The Jones Falls Great Arch Dam is also known as the Whispering Dam since the shape of the stone face of the dam allows sound to travel along the face. Someone speaking in normal conversation tone at one end of

3960-422: 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

4080-422: 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

4200-424: Is dependent on the strength of the side wall abutments, hence not only should the arch be well seated on the side walls but also the character of the rock should be carefully inspected. Two types of single-arch dams are in use, namely the constant-angle and the constant-radius dam. The constant-radius type employs the same face radius at all elevations of the dam, which means that as the channel grows narrower towards

4320-457: 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

4440-424: 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

4560-421: 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

4680-443: 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

4800-480: Is often used in conjunction with dams to generate electricity. A dam can also be used to collect or store water which can be evenly distributed between locations. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees (also known as dikes ) are used to manage or prevent water flow into specific land regions. The word dam can be traced back to Middle English , and before that, from Middle Dutch , as seen in

4920-422: 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

Jones Falls Dam - Misplaced Pages Continue

5040-581: 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

5160-478: 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

5280-471: Is sloped the distribution is more complicated. The normal component of the weight of the arch ring may be taken by the arch action, while the normal hydrostatic pressure will be distributed as described above. For this type of dam, firm reliable supports at the abutments (either buttress or canyon side wall) are more important. The most desirable place for an arch dam is a narrow canyon with steep side walls composed of sound rock. The safety of an arch dam

5400-437: 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

5520-419: 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 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

5640-399: Is the more widely used of the two, though the hollow dam is frequently more economical to construct. Grand Coulee Dam is a solid gravity dam and Braddock Locks & Dam is a hollow gravity dam. A gravity dam can be combined with an arch dam into an arch-gravity dam for areas with massive amounts of water flow but less material available for a pure gravity dam. The inward compression of

5760-576: Is the thinnest arch dam in the world and one of the oldest arch dams in Asia. It was constructed some 700 years ago in Tabas county , South Khorasan Province , Iran . It stands 60 meters tall, and in crest is a one meter width. Some historians believe the dam was built by Shāh Abbās I, whereas others believe that he repaired it. In the Netherlands , a low-lying country, dams were often built to block rivers to regulate

5880-583: 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

6000-556: 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

6120-634: The Fayum Depression to the Nile in Middle Egypt. Two dams called Ha-Uar running east–west were built to retain water during the annual flood and then release it to surrounding lands. The lake called Mer-wer or Lake Moeris covered 1,700 km (660 sq mi) and is known today as Birket Qarun. By the mid-late third millennium BC, an intricate water-management system in Dholavira in modern-day India

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6240-561: The Harbaqa Dam , both in Roman Syria . The highest Roman dam was the Subiaco Dam near Rome ; its record height of 50 m (160 ft) remained unsurpassed until its accidental destruction in 1305. Roman engineers made routine use of ancient standard designs like embankment dams and masonry gravity dams. Apart from that, they displayed a high degree of inventiveness, introducing most of

6360-613: The National Inventory of Dams (NID). 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 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

6480-512: 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

6600-645: The University of Oxford published a study of the cost of large dams – based on the largest existing dataset – documenting significant cost overruns for a majority of dams and questioning whether benefits typically offset costs for such dams. Dams can be formed by human agency, natural causes, or even by the intervention of wildlife such as beavers . Man-made dams are typically classified according to their size (height), intended purpose or structure. Based on structure and material used, dams are classified as easily created without materials, arch-gravity dams , embankment dams or masonry dams , with several subtypes. In

6720-573: 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

6840-535: The British began construction in 1898. The project was designed by Sir William Willcocks and involved several eminent engineers of the time, including Sir Benjamin Baker and Sir John Aird , whose firm, John Aird & Co. , was the main contractor. Capital and financing were furnished by Ernest Cassel . When initially constructed between 1899 and 1902, nothing of its scale had ever before been attempted; on completion, it

6960-509: The Colorado River is a constant-angle arch dam. A similar type is the double-curvature or thin-shell dam. Wildhorse Dam near Mountain City, Nevada , in the United States is an example of the type. This method of construction minimizes the amount of concrete necessary for construction but transmits large loads to the foundation and abutments. The appearance is similar to a single-arch dam but with

7080-655: The Colorado River. By 1997, there were an estimated 800,000 dams worldwide, with some 40,000 of them over 15 meters high. Early dam building took place in Mesopotamia and the Middle East . Dams were used to control water levels, for Mesopotamia's weather affected the Tigris and Euphrates Rivers. The earliest known dam is the Jawa Dam in Jordan , 100 kilometres (62 mi) northeast of

7200-684: The Middle Ages, dams were built in the Netherlands to regulate water levels and prevent sea intrusion. In the 19th century, large-scale arch dams were constructed around the British Empire, marking advances in dam engineering techniques. The era of large dams began with the construction of the Aswan Low Dam in Egypt in 1902. The Hoover Dam, a massive concrete arch-gravity dam, was built between 1931 and 1936 on

7320-623: 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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7440-489: The United States alone, there are approximately 2,000,000 or more "small" dams that are not included in the Army Corps of Engineers National Inventory of dams . Records of small dams are kept by state regulatory agencies and therefore information about small dams is dispersed and uneven in geographic coverage. Countries worldwide consider small hydropower plants (SHPs) important for their energy strategies, and there has been

7560-516: The World Commission on Dams also includes in the "large" category, dams which are between 5 and 15 m (16 and 49 ft) high with a reservoir capacity of more than 3 million cubic metres (2,400  acre⋅ft ). Hydropower dams can be classified as either "high-head" (greater than 30 m in height) or "low-head" (less than 30 m in height). As of 2021 , ICOLD's World Register of Dams contains 58,700 large dam records. The tallest dam in

7680-403: The arch dam, stability is obtained by a combination of arch and gravity action. If the upstream face is vertical the entire weight of the dam must be carried to the foundation by gravity, while the distribution of the normal hydrostatic pressure between vertical cantilever and arch action will depend upon the stiffness of the dam in a vertical and horizontal direction. When the upstream face

7800-651: The back of the dam through a large pipe to drive a water wheel and watermill . In the 10th century, Al-Muqaddasi described several dams in Persia. He reported that one in Ahwaz was more than 910 m (3,000 ft) long, and that it had many water-wheels raising the water into aqueducts through which it flowed into reservoirs of the city. Another one, the Band-i-Amir Dam, provided irrigation for 300 villages. Shāh Abbās Arch (Persian: طاق شاه عباس), also known as Kurit Dam ,

7920-487: The bottom of the dam the central angle subtended by the face of the dam becomes smaller. Jones Falls Dam , in Canada, is a constant radius dam. In a constant-angle dam, also known as a variable radius dam, this subtended angle is kept constant and the variation in distance between the abutments at various levels is taken care of by varying the radii. Constant-radius dams are much less common than constant-angle dams. Parker Dam on

8040-402: The buttress loads are heavy. In a gravity dam, the force that holds the dam in place against the push from the water is Earth's gravity pulling down on the mass of the dam. The water presses laterally (downstream) on the dam, tending to overturn the dam by rotating about its toe (a point at the bottom downstream side of the dam). The dam's weight counteracts that force, tending to rotate the dam

8160-497: The capital Amman . This gravity dam featured an originally 9-metre-high (30 ft) and 1 m-wide (3.3 ft) stone wall, supported by a 50 m-wide (160 ft) earthen rampart. The structure is dated to 3000 BC. However, the oldest continuously operational dam is Lake Homs Dam , built in Syria between 1319-1304 BC. The Ancient Egyptian Sadd-el-Kafara Dam at Wadi Al-Garawi, about 25 km (16 mi) south of Cairo ,

8280-469: 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

8400-485: 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

8520-626: The city. The masonry arch dam wall was designed by Lieutenant Percy Simpson who was influenced by the advances in dam engineering techniques made by the Royal Engineers in India . The dam cost £17,000 and was completed in 1856 as the first engineered dam built in Australia, and the second arch dam in the world built to mathematical specifications. The first such dam was opened two years earlier in France . It

8640-711: 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

8760-592: The construction of the Rideau Canal in Canada near modern-day Ottawa and built a series of curved masonry dams as part of the waterway system. In particular, the Jones Falls Dam , built by John Redpath , was completed in 1832 as the largest dam in North America and an engineering marvel. In order to keep the water in control during construction, two sluices , artificial channels for conducting water, were kept open in

8880-408: 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

9000-469: The dam by the water reduces the lateral (horizontal) force acting on the dam. Thus, the gravitational force required by the dam is lessened, i.e., the dam does not need to be so massive. This enables thinner dams and saves resources. A barrage dam is a special kind of dam that consists of a line of large gates that can be opened or closed to control the amount of water passing the dam. The gates are set between flanking piers which are responsible for supporting

9120-666: The dam can be heard by someone standing at the other end. This, (and some other smaller dams on the Rideau Canal) may be the only vertically coursed stone arch dams in the world. 44°32′56″N 76°14′15″W  /  44.54889°N 76.23750°W  / 44.54889; -76.23750 Dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation , human consumption , industrial use , aquaculture , and navigability . Hydropower

9240-533: The dam was submitted by a consortium called Six Companies, Inc. Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and the lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned over the dam to the federal government on 1 March 1936, more than two years ahead of schedule. By 1997, there were an estimated 800,000 dams worldwide, some 40,000 of them over 15 m (49 ft) high. In 2014, scholars from

9360-605: The dam. If large enough uplift pressures are generated there is a risk of destabilizing the concrete gravity dam. On a suitable site, a gravity dam can prove to be a better alternative to other types of dams. When built on a solid foundation, the gravity dam probably represents the best-developed example of dam building. Since the fear of flood is a strong motivator in many regions, gravity dams are built in some instances where an arch dam would have been more economical. Gravity dams are classified as "solid" or "hollow" and are generally made of either concrete or masonry. The solid form

9480-407: The dam. The first was near the base of the dam on its east side. A second sluice was put in on the west side of the dam, about 20 ft (6.1 m) above the base. To make the switch from the lower to upper sluice, the outlet of Sand Lake was blocked off. Hunts Creek near the city of Parramatta , Australia , was dammed in the 1850s, to cater to the demand for water from the growing population of

9600-450: The dams' potential range and magnitude of environmental disturbances. The International Commission on Large Dams (ICOLD) defines a "large dam" as "A dam with a height of 15 m (49 ft) or greater from lowest foundation to crest or a dam between 5 m (16 ft) metres and 15 metres impounding more than 3 million cubic metres (2,400  acre⋅ft )". "Major dams" are over 150 m (490 ft) in height. The Report of

9720-410: 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

9840-502: 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

9960-549: The first large-scale arch dams. Three pioneering arch dams were built around the British Empire in the early 19th century. Henry Russel of the Royal Engineers oversaw the construction of the Mir Alam dam in 1804 to supply water to the city of Hyderabad (it is still in use today). It had a height of 12 m (39 ft) and consisted of 21 arches of variable span. In the 1820s and 30s, Lieutenant-Colonel John By supervised

10080-710: The first was the Roman-built dam bridge in Dezful , which could raise water 50 cubits (c. 23 m) to supply the town. Also diversion dams were known. Milling dams were introduced which the Muslim engineers called the Pul-i-Bulaiti . The first was built at Shustar on the River Karun , Iran, and many of these were later built in other parts of the Islamic world . Water was conducted from

10200-534: The force of water. A fixed-crest dam is a concrete barrier across a river. Fixed-crest dams are designed to maintain depth in the channel for navigation. They pose risks to boaters who may travel over them, as they are hard to spot from the water and create induced currents that are difficult to escape. There is variability, both worldwide and within individual countries, such as in the United States, in how dams of different sizes are categorized. Dam size influences construction, repair, and removal costs and affects

10320-534: 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

10440-409: 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

10560-490: 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

10680-399: 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

10800-441: 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

10920-625: The main stream of the Kaveri River in Tamil Nadu , South India . The basic structure dates to the 2nd century AD and is considered one of the oldest water diversion or water regulating structures still in use. The purpose of the dam was to divert the waters of the Kaveri across the fertile delta region for irrigation via canals. Du Jiang Yan is the oldest surviving irrigation system in China that included

11040-617: The names of many old cities, such as Amsterdam and Rotterdam . Ancient dams were built in Mesopotamia and the Middle East for water control. The earliest known dam is the Jawa Dam in Jordan , dating to 3,000 BC. Egyptians also built dams, such as Sadd-el-Kafara Dam for flood control. In modern-day India, Dholavira had an intricate water-management system with 16 reservoirs and dams. The Great Dam of Marib in Yemen, built between 1750 and 1700 BC,

11160-435: 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

11280-668: The other basic dam designs which had been unknown until then. These include arch-gravity dams , arch dams , buttress dams and multiple arch buttress dams , all of which were known and employed by the 2nd century AD (see List of Roman dams ). Roman workforces also were the first to build dam bridges, such as the Bridge of Valerian in Iran. In Iran , bridge dams such as the Band-e Kaisar were used to provide hydropower through water wheels , which often powered water-raising mechanisms. One of

11400-429: The other way about its toe. The designer ensures that the dam is heavy enough that the dam's weight wins that contest. In engineering terms, that is true whenever the resultant of the forces of gravity acting on the dam and water pressure on the dam acts in a line that passes upstream of the toe of the dam. The designer tries to shape the dam so if one were to consider the part of the dam above any particular height to be

11520-436: 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

11640-589: The principles behind dam design. In France, J. Augustin Tortene de Sazilly explained the mechanics of vertically faced masonry gravity dams, and Zola's dam was the first to be built on the basis of these principles. The era of large dams was initiated with the construction of the Aswan Low Dam in Egypt in 1902, a gravity masonry buttress dam on the Nile River . Following their 1882 invasion and occupation of Egypt ,

11760-567: 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

11880-470: 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

12000-400: 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

12120-487: The state of New Mexico defines a jurisdictional dam as 25 feet or greater in height and storing more than 15 acre-feet or a dam that stores 50 acre-feet or greater and is six feet or more in height (section 72-5-32 NMSA), suggesting that dams that do not meet these requirements are non-jurisdictional. Most US dams, 2.41 million of a total of 2.5 million dams, are not under the jurisdiction of any public agency (i.e., they are non-jurisdictional), nor are they listed on

12240-493: 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

12360-734: 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

12480-475: The total height, from base of foundation to top, about 18.3 m (60 ft). The backing face of the dam is set back on about a 1:10 incline In front of the stones is a 1.5 m (5 ft) thick impermeable layer made up of grouted broken stone, which is small angular stone set in hydraulic cement. Normally clay puddle would have been used to form this impermeable layer, but clay of suitable quality ran out early during construction, and grouted broken stone

12600-406: The water level and to prevent the sea from entering the marshlands. Such dams often marked the beginning of a town or city because it was easy to cross the river at such a place, and often influenced Dutch place names. The present Dutch capital, Amsterdam (old name Amstelredam ), started with a dam on the river Amstel in the late 12th century, and Rotterdam began with a dam on the river Rotte ,

12720-634: The water load, and are often used to control and stabilize water flow for irrigation systems. An example of this type of dam is the now-decommissioned Red Bluff Diversion Dam on the Sacramento River near Red Bluff, California . Barrages that are built at the mouths of rivers or lagoons to prevent tidal incursions or use the tidal flow for tidal power are known as tidal barrages . Embankment dams are made of compacted earth, and are of two main types: rock-fill and earth-fill. Like concrete gravity dams, embankment dams rely on their weight to hold back

12840-405: 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

12960-414: 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

13080-577: The world is the 305 m-high (1,001 ft) Jinping-I Dam in China . As with large dams, small dams have multiple uses, such as, but not limited to, hydropower production, flood protection, and water storage. Small dams can be particularly useful on farms to capture runoff for later use, for example, during the dry season. Small scale dams have the potential to generate benefits without displacing people as well, and small, decentralised hydroelectric dams can aid rural development in developing countries. In

13200-532: Was 102 m (335 ft) long at its base and 87 m (285 ft) wide. The structure was built around 2800 or 2600 BC as a diversion dam for flood control, but was destroyed by heavy rain during construction or shortly afterwards. During the Twelfth Dynasty in the 19th century BC, the Pharaohs Senosert III, Amenemhat III , and Amenemhat IV dug a canal 16 km (9.9 mi) long linking

13320-413: 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

13440-430: Was about 6 m (20 ft) above the base on the west side of the dam. A coffer dam located near the head of rapids was used to block off the rapids until each sluiceway could be sealed up. A deep waste water weir, its channel blasted through a bedrock ridge to the south of the dam, allowed the top of the dam to be completed. When completed, the dam raised the water in its location by 13.7 m (45 ft), putting

13560-705: Was an engineering wonder, and Eflatun Pinar, a Hittite dam and spring temple in Turkey, dates to the 15th and 13th centuries BC. The Kallanai Dam in South India, built in the 2nd century AD, is one of the oldest water regulating structures still in use. Roman engineers built dams with advanced techniques and materials, such as hydraulic mortar and Roman concrete, which allowed for larger structures. They introduced reservoir dams, arch-gravity dams, arch dams, buttress dams, and multiple arch buttress dams. In Iran, bridge dams were used for hydropower and water-raising mechanisms. During

13680-551: Was built. The system included 16 reservoirs, dams and various channels for collecting water and storing it. One of the engineering wonders of the ancient world was the Great Dam of Marib in Yemen . Initiated sometime between 1750 and 1700 BC, it was made of packed earth – triangular in cross-section, 580 m (1,900 ft) in length and originally 4 m (13 ft) high – running between two groups of rocks on either side, to which it

13800-483: Was linked by substantial stonework. Repairs were carried out during various periods, most importantly around 750 BC, and 250 years later the dam height was increased to 7 m (23 ft). After the end of the Kingdom of Saba , the dam fell under the control of the Ḥimyarites (c. 115 BC) who undertook further improvements, creating a structure 14 m (46 ft) high, with five spillways, two masonry-reinforced sluices,

13920-666: 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

14040-404: Was possibly the world's first concrete arch dam. Designed by Henry Charles Stanley in 1880 with an overflow spillway and a special water outlet, it was eventually heightened to 10 m (33 ft). In the latter half of the nineteenth century, significant advances in the scientific theory of masonry dam design were made. This transformed dam design from an art based on empirical methodology to

14160-461: Was the first French arch dam of the industrial era , and it was built by François Zola in the municipality of Aix-en-Provence to improve the supply of water after the 1832 cholera outbreak devastated the area. After royal approval was granted in 1844, the dam was constructed over the following decade. Its construction was carried out on the basis of the mathematical results of scientific stress analysis. The 75-miles dam near Warwick , Australia,

14280-658: Was the largest masonry dam in the world. The Hoover Dam is a massive concrete arch-gravity dam , constructed in the Black Canyon of the Colorado River , on the border between the US states of Arizona and Nevada between 1931 and 1936 during the Great Depression . In 1928, Congress authorized the project to build a dam that would control floods, provide irrigation water and produce hydroelectric power . The winning bid to build

14400-415: Was used as a substitute. The apron for the dam extends out about 50 m (160 ft). It was created by hauling rubbish (earth) material using horse drawn carts from a location just to the west of the dam. The dam was built with the aid of sluiceways in the dam to allow the river to flow through the dam during construction. The first sluiceway was near the base of the dam on the east side. The second

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