1.
Hydrology
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Hydrology is the scientific study of the movement, distribution, and quality of water on Earth and other planets, including the water cycle, water resources and environmental watershed sustainability. A practitioner of hydrology is a hydrologist, working within the fields of earth or environmental science, physical geography, geology or civil, Hydrology subdivides into surface water hydrology, groundwater hydrology, and marine hydrology. Domains of hydrology include hydrometeorology, surface hydrology, hydrogeology, drainage-basin management and water quality, oceanography and meteorology are not included because water is only one of many important aspects within those fields. Hydrological research can inform environmental engineering, policy and planning, the term hydrology comes from Greek, ὕδωρ, hýdōr, water, and λόγος, lógos, study. Chemical hydrology is the study of the characteristics of water. Ecohydrology is the study of interactions between organisms and the hydrologic cycle, hydrogeology is the study of the presence and movement of groundwater. Hydroinformatics is the adaptation of technology to hydrology and water resources applications. Hydrometeorology is the study of the transfer of water and energy between land and water surfaces and the lower atmosphere. Isotope hydrology is the study of the signatures of water. Surface hydrology is the study of processes that operate at or near Earths surface. Drainage basin management covers water-storage, in the form of reservoirs, water quality includes the chemistry of water in rivers and lakes, both of pollutants and natural solutes. Determining the water balance of a region, mitigating and predicting flood, landslide and drought risk. Real-time flood forecasting and flood warning, designing irrigation schemes and managing agricultural productivity. Part of the module in catastrophe modeling. Designing dams for water supply or hydroelectric power generation, designing sewers and urban drainage system. Analyzing the impacts of antecedent moisture on sanitary sewer systems, predicting geomorphologic changes, such as erosion or sedimentation. Assessing the impacts of natural and anthropogenic environmental change on water resources, assessing contaminant transport risk and establishing environmental policy guidelines. Hydrology has been a subject of investigation and engineering for millennia, for example, about 4000 BC the Nile was dammed to improve agricultural productivity of previously barren lands
2.
Volumetric flow rate
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In physics and engineering, in particular fluid dynamics and hydrometry, the volumetric flow rate, is the volume of fluid which passes per unit time, usually represented by the symbol Q. In US customary units and imperial units, volumetric flow rate is expressed as ft3/s or gallons per minute. Volumetric flow rate should not be confused with volumetric flux, as defined by Darcys law and represented by the symbol q, with units of m3/, the integration of a flux over an area gives the volumetric flow rate. Since this is only the derivative of volume, a scalar quantity. Volumetric flow rate can also be defined by, Q = v ⋅ A where, v = flow velocity A = cross-sectional vector area/surface The above equation is true for flat. In general, including curved surfaces, the equation becomes a surface integral, the area required to calculate the volumetric flow rate is real or imaginary, flat or curved, either as a cross-sectional area or a surface. The vector area is a combination of the magnitude of the area through which the volume passes through, A, the reason for the dot product is as follows. The only volume flowing through the cross-section is the amount normal to the area and this amount is, Q = v A cos θ where θ is the angle between the unit normal n̂ and the velocity vector v of the substance elements. The amount passing through the cross-section is reduced by the factor cos θ, as θ increases less volume passes through. Substance which passes tangential to the area, that is perpendicular to the unit normal, when the mass flow rate is known, and the density can be assumed constant, this is an easy way to get Q. Q = m ˙ ρ Where, ṁ = mass flow rate, in internal combustion engines, the time area integral is considered over the range of valve opening. This has to be factored by the width of the valve throat, the answer is usually related to the cylinders swept volume. Air to cloth ratio Discharge Flow measurement Flowmeter Orifice plate Poiseuilles law Stokes flow Units of flow
3.
Water
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Water is a transparent and nearly colorless chemical substance that is the main constituent of Earths streams, lakes, and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen, Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure, but it often refers also to its solid state or its gaseous state. It also occurs in nature as snow, glaciers, ice packs and icebergs, clouds, fog, dew, aquifers, Water covers 71% of the Earths surface. It is vital for all forms of life. Only 2. 5% of this water is freshwater, and 98. 8% of that water is in ice and groundwater. Less than 0. 3% of all freshwater is in rivers, lakes, and the atmosphere, a greater quantity of water is found in the earths interior. Water on Earth moves continually through the cycle of evaporation and transpiration, condensation, precipitation. Evaporation and transpiration contribute to the precipitation over land, large amounts of water are also chemically combined or adsorbed in hydrated minerals. Safe drinking water is essential to humans and other even though it provides no calories or organic nutrients. There is a correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in developing regions of the world. Water plays an important role in the world economy, approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, rivers, lakes, large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a variety of chemical substances, as such it is widely used in industrial processes. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, Water is a liquid at the temperatures and pressures that are most adequate for life. Specifically, at atmospheric pressure of 1 bar, water is a liquid between the temperatures of 273.15 K and 373.15 K
4.
Inflow (hydrology)
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In hydrology, the inflow of a body of water is the source of the water in the body of water. It can also refer to the volume of incoming water in unit time. All bodies of water have multiple inflows, but often, one inflow may predominate, however, in many cases, no single inflow will predominate and there will be multiple primary inflows. For a lake, the inflow may be a river or stream that flows into the lake. Inflow may also be, strictly speaking, not flows, but rather precipitation, inflow can also be used to refer to groundwater recharge. The dictionary definition of inflow at Wiktionary
5.
Hydrologists
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Hydrology is the scientific study of the movement, distribution, and quality of water on Earth and other planets, including the water cycle, water resources and environmental watershed sustainability. A practitioner of hydrology is a hydrologist, working within the fields of earth or environmental science, physical geography, geology or civil, Hydrology subdivides into surface water hydrology, groundwater hydrology, and marine hydrology. Domains of hydrology include hydrometeorology, surface hydrology, hydrogeology, drainage-basin management and water quality, oceanography and meteorology are not included because water is only one of many important aspects within those fields. Hydrological research can inform environmental engineering, policy and planning, the term hydrology comes from Greek, ὕδωρ, hýdōr, water, and λόγος, lógos, study. Chemical hydrology is the study of the characteristics of water. Ecohydrology is the study of interactions between organisms and the hydrologic cycle, hydrogeology is the study of the presence and movement of groundwater. Hydroinformatics is the adaptation of technology to hydrology and water resources applications. Hydrometeorology is the study of the transfer of water and energy between land and water surfaces and the lower atmosphere. Isotope hydrology is the study of the signatures of water. Surface hydrology is the study of processes that operate at or near Earths surface. Drainage basin management covers water-storage, in the form of reservoirs, water quality includes the chemistry of water in rivers and lakes, both of pollutants and natural solutes. Determining the water balance of a region, mitigating and predicting flood, landslide and drought risk. Real-time flood forecasting and flood warning, designing irrigation schemes and managing agricultural productivity. Part of the module in catastrophe modeling. Designing dams for water supply or hydroelectric power generation, designing sewers and urban drainage system. Analyzing the impacts of antecedent moisture on sanitary sewer systems, predicting geomorphologic changes, such as erosion or sedimentation. Assessing the impacts of natural and anthropogenic environmental change on water resources, assessing contaminant transport risk and establishing environmental policy guidelines. Hydrology has been a subject of investigation and engineering for millennia, for example, about 4000 BC the Nile was dammed to improve agricultural productivity of previously barren lands
6.
Units of measurement
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A unit of measurement is a definite magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same quantity. Any other value of quantity can be expressed as a simple multiple of the unit of measurement. For example, length is a physical quantity, the metre is a unit of length that represents a definite predetermined length. When we say 10 metres, we actually mean 10 times the definite predetermined length called metre, the definition, agreement, and practical use of units of measurement have played a crucial role in human endeavour from early ages up to this day. Different systems of units used to be very common, now there is a global standard, the International System of Units, the modern form of the metric system. In trade, weights and measures is often a subject of regulation, to ensure fairness. The International Bureau of Weights and Measures is tasked with ensuring worldwide uniformity of measurements, metrology is the science for developing nationally and internationally accepted units of weights and measures. In physics and metrology, units are standards for measurement of quantities that need clear definitions to be useful. Reproducibility of experimental results is central to the scientific method, a standard system of units facilitates this. Scientific systems of units are a refinement of the concept of weights, science, medicine, and engineering often use larger and smaller units of measurement than those used in everyday life and indicate them more precisely. The judicious selection of the units of measurement can aid researchers in problem solving, in the social sciences, there are no standard units of measurement and the theory and practice of measurement is studied in psychometrics and the theory of conjoint measurement. A unit of measurement is a quantity of a physical property. Units of measurement were among the earliest tools invented by humans, primitive societies needed rudimentary measures for many tasks, constructing dwellings of an appropriate size and shape, fashioning clothing, or bartering food or raw materials. Weights and measures are mentioned in the Bible and it is a commandment to be honest and have fair measures. As of the 21st Century, multiple unit systems are used all over the world such as the United States Customary System, the British Customary System, however, the United States is the only industrialized country that has not yet completely converted to the Metric System. The systematic effort to develop an acceptable system of units dates back to 1790 when the French National Assembly charged the French Academy of Sciences to come up such a unit system. After this treaty was signed, a General Conference of Weights, the CGPM produced the current SI system which was adopted in 1954 at the 10th conference of weights and measures. Currently, the United States is a society which uses both the SI system and the US Customary system
7.
Rhine
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The largest city on the river Rhine is Cologne, Germany, with a population of more than 1,050,000 people. It is the second-longest river in Central and Western Europe, at about 1,230 km, with an average discharge of about 2,900 m3/s. The Rhine and the Danube formed most of the inland frontier of the Roman Empire and, since those days. The many castles and fortifications along the Rhine testify to its importance as a waterway in the Holy Roman Empire, in the modern era, it has become a symbol of German nationalism. The variant of the name of the Rhine in modern languages are all derived from the Gaulish name Rēnos, spanish is with French in adopting the Germanic vocalism Rin-, while Italian, Occitan and Portuguese retain the Latin Ren-. The Gaulish name Rēnos belongs to a class of river names built from the PIE root *rei- to move, flow, run, the grammatical gender of the Celtic name is masculine, and the name remains masculine in German, Dutch and French. The Old English river name was variously inflected as masculine or feminine, the length of the Rhine is conventionally measured in Rhine-kilometers, a scale introduced in 1939 which runs from the Old Rhine Bridge at Constance to Hoek van Holland. The river length is shortened from the rivers natural course due to a number of canalisation projects completed in the 19th and 20th century. The total length of the Rhine, to the inclusion of Lake Constance and its course is conventionally divided as follows, The Rhine carries its name without distinctive accessories only from the confluence of the Vorderrhein and Hinterrhein near Tamins-Reichenau. Above this point is the catchment of the headwaters of the Rhine. It belongs almost exclusively to the Swiss Canton of Graubünden, ranging from Gotthard Massif in the west via one valley lying in Ticino, traditionally, Lake Toma near the Oberalp Pass in the Gotthard region is seen as the source of the Vorderrhein and the Rhine as a whole. The Hinterrhein rises in the Rheinwald valley below Mount Rheinwaldhorn, the Vorderrhein, or Anterior Rhine, springs from Lai da Tuma, near the Oberalp Pass and passes the impressive Ruinaulta formed by the largest visible rock slide in the alps, the Flims Rockslide. A multiday trekking route is signposted along the young Rhine called Senda Sursilvana, the Hinterrhein/Rein Posteriur, or Posterior Rhine, starts from the Paradies Glacier, near the Rheinwaldhorn. One of its tributaries, the Reno di Lei, drains the Valle di Lei on politically Italian territory, after three main valleys separated by the two gorges, Roflaschlucht and Viamala, it reaches Reichenau. The Vorderrhein arises from numerous source streams in the upper Surselva, one source is Lai da Tuma with the Rein da Tuma, which is usually indicated as source of the Rhine, flowing through it. Into it flow tributaries from the south, some longer, some equal in length, such as the Reno di Medel, the Rein da Maighels, and the Rein da Curnera. The Cadlimo Valley in the Canton of Ticino is drained by the Reno di Medel, all streams in the source area are partially, sometimes completely, captured and sent to storage reservoirs for the local hydro-electric power plants. In its lower course the Vorderrhein flows through a gorge named Ruinaulta through the Flims Rockslide, the whole stretch of the Vorderrhein to the Rhine confluence near Reichenau-Tamins is accompanied by a long-distance hiking trail called Senda Sursilvana
8.
Continuity equation
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A continuity equation in physics is an equation that describes the transport of some quantity. It is particularly simple and powerful when applied to a conserved quantity, continuity equations are a stronger, local form of conservation laws. For example, a version of the law of conservation of energy states that energy can neither be created nor destroyed—i. e. The total amount of energy is fixed and this statement does not immediately rule out the possibility that energy could disappear from a field in Canada while simultaneously appearing in a room in Indonesia. A stronger statement is that energy is conserved, Energy can neither be created nor destroyed. A continuity equation is the way to express this kind of statement. For example, the continuity equation for electric charge states that the amount of charge at any point can only change by the amount of electric current flowing into or out of that point. In an everyday example, there is a continuity equation for the number of people alive, it has a term to account for people being born. Any continuity equation can be expressed in a form, which applies to any finite region. Continuity equations underlie more specific transport equations such as the equation, Boltzmann transport equation. Before we can write down the continuity equation, we must first define flux, the continuity equation is useful when there is some quantity q which can flow or move, such as mass, energy, electric charge, momentum, number of molecules, etc. Let ρ be the density of this property, i. e. the amount of q per unit volume. The way that this quantity q is flowing is described by its flux, the flux of q is a vector field, which we denote as j. Here are some examples and properties of flux, The dimension of flux is amount of q flowing per unit time, outside the pipe, where there is no water, the flux is zero. In a well-known example, the flux of electric charge is the current density. In a simple example, V could be a building, and q could be the number of people in the building, the surface S would consist of the walls, doors, roof, and foundation of the building. Terms that generate or remove q are referred to as a sources and this general equation may be used to derive any continuity equation, ranging from as simple as the volume continuity equation to as complicated as the Navier–Stokes equations. This equation also generalizes the advection equation, mathematically it is an automatic consequence of Maxwells equations, although charge conservation is more fundamental than Maxwells equations
9.
Area
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Area is the quantity that expresses the extent of a two-dimensional figure or shape, or planar lamina, in the plane. Surface area is its analog on the surface of a three-dimensional object. It is the analog of the length of a curve or the volume of a solid. The area of a shape can be measured by comparing the shape to squares of a fixed size, in the International System of Units, the standard unit of area is the square metre, which is the area of a square whose sides are one metre long. A shape with an area of three square metres would have the area as three such squares. In mathematics, the square is defined to have area one. There are several formulas for the areas of simple shapes such as triangles, rectangles. Using these formulas, the area of any polygon can be found by dividing the polygon into triangles, for shapes with curved boundary, calculus is usually required to compute the area. Indeed, the problem of determining the area of plane figures was a motivation for the historical development of calculus. For a solid such as a sphere, cone, or cylinder. Formulas for the areas of simple shapes were computed by the ancient Greeks. Area plays an important role in modern mathematics, in addition to its obvious importance in geometry and calculus, area is related to the definition of determinants in linear algebra, and is a basic property of surfaces in differential geometry. In analysis, the area of a subset of the plane is defined using Lebesgue measure, in general, area in higher mathematics is seen as a special case of volume for two-dimensional regions. Area can be defined through the use of axioms, defining it as a function of a collection of certain plane figures to the set of real numbers and it can be proved that such a function exists. An approach to defining what is meant by area is through axioms, area can be defined as a function from a collection M of special kind of plane figures to the set of real numbers which satisfies the following properties, For all S in M, a ≥0. If S and T are in M then so are S ∪ T and S ∩ T, if S and T are in M with S ⊆ T then T − S is in M and a = a − a. If a set S is in M and S is congruent to T then T is also in M, every rectangle R is in M. If the rectangle has length h and breadth k then a = hk, let Q be a set enclosed between two step regions S and T
10.
Drainage basin
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A drainage basin or catchment area is any area of land where precipitation collects and drains off into a common outlet, such as into a river, bay, or other body of water. Drainage basins connect into other drainage basins at elevations in a hierarchical pattern, with smaller sub-drainage basins. Other terms used to describe drainage basins are catchment, catchment basin, drainage area, river basin and water basin. In closed drainage basins the water converges to a point inside the basin, known as a sink, which may be a permanent lake. The drainage basin acts as a funnel by collecting all the water within the covered by the basin. Each drainage basin is separated topographically from adjacent basins by a perimeter, drainage basins are similar but not identical to hydrologic units, which are drainage areas delineated so as to nest into a multi-level hierarchical drainage system. Hydrologic units are defined to allow multiple inlets, outlets, or sinks, in a strict sense, all drainage basins are hydrologic units but not all hydrologic units are drainage basins. Drainage basins of the oceans and seas of the world. Grey areas are endorheic basins that do not drain to the oceans, the following is a list of the major ocean basins, About 48. 7% of the worlds land drains to the Atlantic Ocean. The two major mediterranean seas of the world also flow to the Atlantic, The Caribbean Sea and Gulf of Mexico basin includes most of the U. S. The Mediterranean Sea basin includes much of North Africa, east-central Africa, Southern, Central, and Eastern Europe, Turkey, and the areas of Israel, Lebanon. Just over 13% of the land in the world drains to the Pacific Ocean, the Indian Oceans drainage basin also comprises about 13% of Earths land. It drains the eastern coast of Africa, the coasts of the Red Sea and the Persian Gulf, the Indian subcontinent, Burma, antarctica comprises approximately eight percent of the Earths land. The five largest river basins, from largest to smallest, are the basins of the Amazon, the Río de la Plata, the Congo, the Nile, and the Mississippi. The three rivers that drain the most water, from most to least, are the Amazon, Ganga, endorheic drainage basins are inland basins that do not drain to an ocean. Around 18% of all land drains to endorheic lakes or seas or sinks, the largest of these consists of much of the interior of Asia, which drains into the Caspian Sea, the Aral Sea, and numerous smaller lakes. Some of these, such as the Great Basin, are not single drainage basins but collections of separate, in endorheic bodies of standing water where evaporation is the primary means of water loss, the water is typically more saline than the oceans. An extreme example of this is the Dead Sea, drainage basins have been historically important for determining territorial boundaries, particularly in regions where trade by water has been important
11.
Drainage area
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A drainage basin or catchment area is any area of land where precipitation collects and drains off into a common outlet, such as into a river, bay, or other body of water. Drainage basins connect into other drainage basins at elevations in a hierarchical pattern, with smaller sub-drainage basins. Other terms used to describe drainage basins are catchment, catchment basin, drainage area, river basin and water basin. In closed drainage basins the water converges to a point inside the basin, known as a sink, which may be a permanent lake. The drainage basin acts as a funnel by collecting all the water within the covered by the basin. Each drainage basin is separated topographically from adjacent basins by a perimeter, drainage basins are similar but not identical to hydrologic units, which are drainage areas delineated so as to nest into a multi-level hierarchical drainage system. Hydrologic units are defined to allow multiple inlets, outlets, or sinks, in a strict sense, all drainage basins are hydrologic units but not all hydrologic units are drainage basins. Drainage basins of the oceans and seas of the world. Grey areas are endorheic basins that do not drain to the oceans, the following is a list of the major ocean basins, About 48. 7% of the worlds land drains to the Atlantic Ocean. The two major mediterranean seas of the world also flow to the Atlantic, The Caribbean Sea and Gulf of Mexico basin includes most of the U. S. The Mediterranean Sea basin includes much of North Africa, east-central Africa, Southern, Central, and Eastern Europe, Turkey, and the areas of Israel, Lebanon. Just over 13% of the land in the world drains to the Pacific Ocean, the Indian Oceans drainage basin also comprises about 13% of Earths land. It drains the eastern coast of Africa, the coasts of the Red Sea and the Persian Gulf, the Indian subcontinent, Burma, antarctica comprises approximately eight percent of the Earths land. The five largest river basins, from largest to smallest, are the basins of the Amazon, the Río de la Plata, the Congo, the Nile, and the Mississippi. The three rivers that drain the most water, from most to least, are the Amazon, Ganga, endorheic drainage basins are inland basins that do not drain to an ocean. Around 18% of all land drains to endorheic lakes or seas or sinks, the largest of these consists of much of the interior of Asia, which drains into the Caspian Sea, the Aral Sea, and numerous smaller lakes. Some of these, such as the Great Basin, are not single drainage basins but collections of separate, in endorheic bodies of standing water where evaporation is the primary means of water loss, the water is typically more saline than the oceans. An extreme example of this is the Dead Sea, drainage basins have been historically important for determining territorial boundaries, particularly in regions where trade by water has been important
12.
Recession
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In economics, a recession is a business cycle contraction which results in a general slowdown in economic activity. Macroeconomic indicators such as GDP, investment spending, capacity utilization, household income, business profits, and inflation fall, while bankruptcies, in the United Kingdom, it is defined as a negative economic growth for two consecutive quarters. Recessions generally occur when there is a drop in spending. This may be triggered by events, such as a financial crisis, an external trade shock. Governments usually respond to recessions by adopting expansionary macroeconomic policies, such as increasing money supply, in a 1979 New York Times article, economic statistician Julius Shiskin suggested several rules of thumb for defining a recession, one of which was two down consecutive quarters of GDP. In time, the rules of thumb were forgotten. Some economists prefer a definition of a 1. 5-2 percentage points rise in unemployment within 12 months, in the United States, the Business Cycle Dating Committee of the National Bureau of Economic Research is generally seen as the authority for dating US recessions. Almost universally, academics, economists, policy makers, and businesses defer to the determination by the NBER for the dating of a recessions onset. In the United Kingdom, recessions are generally defined as two consecutive quarters of economic growth, as measured by the seasonal adjusted quarter-on-quarter figures for real GDP. The exact same recession definition applies for all states of the European Union. These summary measures reflect underlying drivers such as employment levels and skills, household savings rates, corporate investment decisions, interest rates, demographics, when these relationships become imbalanced, recession can develop within the country or create pressure for recession in another country. Policy responses are often designed to drive the economy back towards this ideal state of balance, a severe or prolonged recession is referred to as an economic depression, although some argue that their causes and cures can be different. As an informal shorthand, economists refer to different recession shapes. The type and shape of recessions are distinctive, japan’s 1993–94 recession was U-shaped and its 8-out-of-9 quarters of contraction in 1997–99 can be described as L-shaped. Korea, Hong Kong and South-east Asia experienced U-shaped recessions in 1997–98, recessions have psychological and confidence aspects. For example, if companies expect economic activity to slow, they may reduce employment levels, such expectations can create a self-reinforcing downward cycle, bringing about or worsening a recession. Consumer confidence is one used to evaluate economic sentiment. The term animal spirits has been used to describe the factors underlying economic activity
13.
Unit hydrograph
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A hydrograph is a graph showing the rate of flow versus time past a specific point in a river, or other channel or conduit carrying flow. The rate of flow is typically expressed in meters or cubic feet per second. It can also refer to a showing the volume of water reaching a particular outfall. Graphs are commonly used in the design of sewerage, more specifically, the discharge is measured at a specific point in a river and is typically time variant. The end of stormflow and the return to groundwater-derived flow is taken as the point of inflection of the recession limb. The recession limb represents the withdrawal of water from the built up in the basin during the earlier phases of the hydrograph. k. a. However, the process of separating “baseflow” from “direct runoff” is an inexact science, in part this is because these two concepts are not, themselves, entirely distinct and unrelated. Therefore, separation of a purely “baseflow component” in a hydrograph is a somewhat arbitrary exercise, nevertheless, various graphical and empirical techniques have been developed to perform these hydrograph separations. A unit hydrograph is the hypothetical unit response of a watershed to an input of rainfall. It can be defined as the runoff hydrograph resulting from one unit of effective rainfall occurring uniformly over that watershed at a uniform rate over a unit period of time. As a UH is applicable only to the direct component of a hydrograph. A UH is specific to a watershed, and specific to a particular length of time corresponding to the duration of the effective rainfall. That is, the UH is specified as being the 1-hour, 6-hour, or 24-hour UH, thus, for a given watershed, there can be many unit hydrographs, each one corresponding to a different duration of effective rainfall. The UH technique provides a practical and relatively easy-to-apply tool for quantifying the effect of a unit of rainfall on the runoff from a particular drainage basin. UH theory assumes that a watersheds runoff response is linear and time-invariant, in the real world, none of these assumptions are strictly true. Nevertheless, application of UH methods typically yields an approximation of the flood response of natural watersheds. This allows for a straightforward calculation of the hydrograph response to any arbitrary rain event. An instantaneous unit hydrograph is a refinement of the concept, for an IUH
14.
Rating curve
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Numerous measurements of stream discharge are made over a range of stream stages. The rating curve is plotted as discharge on x-axis versus stage on y-axis. The development of a rating curve involves two steps, in the first step the relationship between stage and discharge is established by measuring the stage and corresponding discharge in the river. And in the part, stage of river is measured. Stage is measured by reading a gauge installed in the river, if the stage-discharge relationship does not change with time, it is called permanent control. If the relationship does change, it is called shifting control, shifting control is usually due to erosion or deposition of sediment at the stage measurement site. Bedrock-bottomed parts of rivers or concrete/metal weirs or structures are often, though not always, the constant a can be measured when a stream is flowing under section control as the surveyed gauge height of the lowest point of the section control feature. When a stream is flowing under channel control conditions, the parameter a does not have a physical analogue and must be estimated by following standard methods given in literature. The parameter β is typically in the range of 2.0 to 3.0 when a stream is flowing under section control, a stream will typically transition from section control at lower gauge heights to channel control at higher gauge heights. The transition from section control to channel control can often be inferred by a change in the slope of a curve when plotted on log-log graph paper
15.
Sediment transport
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Sediment transport is the movement of solid particles, typically due to a combination of gravity acting on the sediment, and/or the movement of the fluid in which the sediment is entrained. Sediment transport due to fluid motion occurs in rivers, oceans, lakes, seas, Transport is also caused by glaciers as they flow, and on terrestrial surfaces under the influence of wind. Sediment transport due only to gravity can occur on sloping surfaces in general, including hillslopes, scarps, cliffs, sediment transport is important in the fields of sedimentary geology, geomorphology, civil engineering and environmental engineering. Aeolian or eolian is the term for sediment transport by wind and this process results in the formation of ripples and sand dunes. Typically, the size of the sediment is fine sand and smaller, because air is a fluid with low density and viscosity. Bedforms are generated by aeolian sediment transport in the terrestrial near-surface environment, ripples and dunes form as a natural self-organizing response to sediment transport. Aeolian sediment transport is common on beaches and in the regions of the world, because it is in these environments that vegetation does not prevent the presence. Wind-blown very fine-grained dust is capable of entering the upper atmosphere, dust from the Sahara deposits on the Canary Islands and islands in the Caribbean, and dust from the Gobi desert has deposited on the western United States. This sediment is important to the budget and ecology of several islands. Deposits of fine-grained wind-blown glacial sediment are called loess, in geology, physical geography, and sediment transport, fluvial processes relate to flowing water in natural systems. This encompasses rivers, streams, periglacial flows, flash floods, sediment moved by water can be larger than sediment moved by air because water has both a higher density and viscosity. In typical rivers the largest carried sediment is of sand and gravel size, coastal sediment transport takes place in near-shore environments due to the motions of waves and currents. At the mouths of rivers, coastal sediment and fluvial sediment transport processes mesh to create river deltas, coastal sediment transport results in the formation of characteristic coastal landforms such as beaches, barrier islands, and capes. As glaciers move over their beds, they entrain and move material of all sizes, glaciers can carry the largest sediment, and areas of glacial deposition often contain a large number of glacial erratics, many of which are several metres in diameter. Glaciers also pulverize rock into glacial flour, which is so fine that it is carried away by winds to create loess deposits thousands of kilometres afield. Sediment entrained in glaciers often moves approximately along the glacial flowlines, in hillslope sediment transport, a variety of processes move regolith downslope. For this reason, the tops of hills generally have a parabolic concave-up profile, as hillslopes steepen, however, they become more prone to episodic landslides and other mass wasting events. Large masses of material are moved in debris flows, hyperconcentrated mixtures of mud, clasts that range up to boulder-size, debris flows move as granular flows down steep mountain valleys and washes
16.
Sediment
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For sediment in beverages, see dregs. For example, sand and silt can be carried in suspension in water and on reaching the sea be deposited by sedimentation. Sediments are most often transported by water, but also wind, beach sands and river channel deposits are examples of fluvial transport and deposition, though sediment also often settles out of slow-moving or standing water in lakes and oceans. Desert sand dunes and loess are examples of transport and deposition. Glacial moraine deposits and till are ice-transported sediments, sediment can be classified based on its grain size and/or its composition. Sediment size is measured on a log base 2 scale, called the Phi scale, composition of sediment can be measured in terms of, parent rock lithology mineral composition chemical make-up. This leads to an ambiguity in which clay can be used as both a size-range and a composition, sediment is transported based on the strength of the flow that carries it and its own size, volume, density, and shape. Stronger flows will increase the lift and drag on the particle, causing it to rise, rivers and streams carry sediment in their flows. This sediment can be in a variety of locations within the flow and these relationships are shown in the following table for the Rouse number, which is a ratio of sediment fall velocity to upwards velocity. If the upwards velocity is less than the settling velocity, but still high enough for the sediment to move, it will move along the bed as bed load by rolling, sliding. If the upwards velocity is higher than the velocity, the sediment will be transported high in the flow as wash load. As there are generally a range of different particle sizes in the flow, sediment motion can create self-organized structures such as ripples, dunes, antidunes on the river or stream bed. These bedforms are often preserved in rocks and can be used to estimate the direction. Overland flow can erode soil particles and transport them downslope, the erosion associated with overland flow may occur through different methods depending on meteorological and flow conditions. If the initial impact of rain droplets dislodges soil, the phenomenon is called rainsplash erosion, if overland flow is directly responsible for sediment entrainment but does not form gullies, it is called sheet erosion. If the flow and the substrate permit channelization, gullies may form, glaciers carry a wide range of sediment sizes, and deposit it in moraines. The overall balance between sediment in transport and sediment being deposited on the bed is given by the Exner equation and this expression states that the rate of increase in bed elevation due to deposition is proportional to the amount of sediment that falls out of the flow. This can be localized, and simply due to obstacles, examples are scour holes behind boulders, where flow accelerates
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Stream gauge
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A stream gauge, streamgage or gauging station is a location used by hydrologists or environmental scientists to monitor and test terrestrial bodies of water. Hydrometric measurements of water surface elevation and/or volumetric discharge are generally taken and observations of biota. The location of gauging stations are found on topographical maps. Some gauging stations are automated and may include telemetry capability transmitted to a central data logging facility. Automated direct measurement of streamflow discharge is difficult at present, in place of the direct measurement of streamflow discharge, one or more surrogate measurements can be used to produce discharge values. In the majority of cases, a measurement is used as the surrogate. Low gradient streams are influenced by variable downstream channel conditions. For these streams, a stream gauge would be installed. This value would be used along with the measurement to more accurately determine the streamflow discharge. These sensors are mounted in the stream and measure velocity at a particular location in the stream. In those instances where only a stage measurement is used as the surrogate, a rating curve is the functional relation between stage and discharge. Once the rating curve is established, it can be used in conjunction with measurements to determine the volumetric streamflow discharge. This record then serves as an assessment of the volume of water passes by the stream gauge and is useful for many tasks associated with hydrology. In those instances where a velocity measurement is used as a surrogate. This analysis uses a velocity sensor, often either magnetic or acoustic, once again, discrete measurements of streamflow discharge are made by the technician or hydrologist at a variety of stages. For each discrete determination of streamflow discharge, the velocity of the cross section is determined by dividing streamflow discharge by the cross-sectional area. A rating curve, similar to that used for stage-discharge determinations, is constructed using the mean velocity, an additional rating curve is constructed that relates stage of the stream to cross-sectional area. The streamflow discharge is computed as the estimate of the cross section area, electromagnetic gauges Discharge measurements of a stream or canal without an established stream gage can be made using a current meter or Acoustic Doppler current profiler
18.
Luna Leopold
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Luna Bergere Leopold was a leading U. S. geomorphologist and hydrologist, and son of Aldo Leopold. Leopold suggested that a new philosophy of management is needed, one based on geologic, geographic, and climatic factors as well as traditional economic, social. He argued that the management of water resources cannot be successful as long as it is perceived from an economic and political standpoint. From 1937 to 1940, Leopold worked as an engineer for the U. S, soil Conservation Service in New Mexico. In 1940, he enlisted and was a part of the U. S. Army Weather Service and he was in the Army until 1946 and he rose from the rank of Private to Captain. From 1946 to 1950, Leopold served as the Chief Meteorologist of the Pineapple Research Institute, in 1950, he joined the U. S. Geological Survey. He worked for the USGS until 1972 serving as Hydraulic Engineer, Chief Hydrologist, in 1972, Leopold joined the faculty of the University of California, Berkeley as a professor in the Department of Geology and Geophysics and Department of Landscape Architecture. He retired in 1986 and continued as a Professor Emeritus until his death in 2006,1980 - Honorary Doctorate from the University of Wisconsin 1981 - Honorary Doctorate from the University of St. Andrews, Scotland 1991 - Awarded the National Medal of Science. Leopold, Aldo and Leopold, Luna B, water, Life Science Library, Time Life Education. Wolman, M. Gordon, and Miller, John P. Fluvial Processes in Geomorphology, harvard University Press, New Ed edition. The San Francisco Chronicle, 3/3/2006 New York Times, 3/20/2006 The Virtual Luna Leopold Project Association of Engineering Societies website
19.
United States Department of Agriculture
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Approximately 80% of USDAs $140 billion budget goes to the Food and Nutrition Service program. The largest component of the FNS budget is the Supplemental Nutrition Assistance Program, after the resignation of Thomas Vilsack on January 13,2017 and the departure of President Barack Obama from office on January 20,2017, the acting Secretary of Agriculture is Michael Young. Activities in this include the Supplemental Nutrition Assistance Program, which provides healthy food to over 40 million low-income. The USDA also is concerned with assisting farmers and food producers with the sale of crops and it plays a role in overseas aid programs by providing surplus foods to developing countries. This aid can go through USAID, foreign governments, international bodies such as World Food Program, the Agricultural Act of 1949, section 416 and Agricultural Trade Development and Assistance Act of 1954, also known as Food for Peace, provides the legal basis of such actions. The USDA is a partner of the World Cocoa Foundation, early in its history, the economy of the United States was largely agrarian. Officials in the government had long sought new and improved varieties of seeds, plants. In 1837 Henry Leavitt Ellsworth, a Yale-educated attorney interested in improving agriculture, became Commissioner of Patents and he began collecting and distributing new varieties of seeds and plants through members of the Congress and agricultural societies. In 1839, Congress established the Agricultural Division within the Patent Office and allotted $1,000 for the collection of agricultural statistics, Ellsworth was called the Father of the Department of Agriculture. In 1849, the Patent Office was transferred to the newly created Department of the Interior, in the ensuing years, agitation for a separate bureau of agriculture within the department or a separate department devoted to agriculture kept recurring. Lincoln called it the peoples department, in the 1880s, varied advocacy groups were lobbying for Cabinet representation. Business interests sought a Department of Commerce and Industry, and farmers tried to raise the Department of Agriculture to Cabinet rank, finally, on February 9,1889, President Grover Cleveland signed a bill into law elevating the Department of Agriculture to Cabinet level. In 1887, the Hatch Act provided for the funding of agricultural experiment stations in each state. The Smith-Lever Act of 1914 then funded cooperative extension services in each state to teach agriculture, home economics, with these and similar provisions, the USDA reached out to every county of every state. During the Great Depression, farming remained a way of life for millions of Americans. The Department of Agricultures Bureau of Home Economics, established in 1923, published shopping advice and recipes to stretch family budgets and make food go farther. USDA helped ensure that continued to be produced and distributed to those who needed it, assisted with loans for small landowners. The Department of Agriculture was authorized a budget for Fiscal Year 2015 of $139.7 billion, the Washington Post reports that he said There are days when I have literally nothing to do, he recalled thinking as he weighed his decision to quit
20.
Hydropower
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Hydropower or water power is power derived from the energy of falling water or fast running water, which may be harnessed for useful purposes. A trompe, which compressed air from falling water, is sometimes used to power other machinery at a distance. In the late 19th century, hydropower became a source for generating electricity, cragside in Northumberland was the first house powered by hydroelectricity in 1878 and the first commercial hydroelectric power plant was built at Niagara Falls in 1879. In 1881, street lamps in the city of Niagara Falls were powered by hydropower, since the early 20th century, the term has been used almost exclusively in conjunction with the modern development of hydroelectric power. In China and the rest of the Far East, hydraulically operated pot wheel pumps raised water into crop or irrigation canals, the power of a wave of water released from a tank was used for extraction of metal ores in a method known as hushing. The method was first used at the Dolaucothi Gold Mines in Wales from 75 AD onwards, hushing was also widely used in Britain in the Medieval and later periods to extract lead and tin ores. It later evolved into hydraulic mining when used during the California Gold Rush and these include an endless belt with jugs attached, a cow-powered shadoof, and a reciprocating device with hinged valves. In 1753, French engineer Bernard Forest de Bélidor published Architecture Hydraulique which described vertical-, the growing demand for the Industrial Revolution would drive development as well. At the beginning of the Industrial Revolution in Britain, water was the source of power for new inventions such as Richard Arkwrights water frame. In the 1830s, at the peak in US canal-building, hydropower provided the energy to transport barge traffic up. Technological advances had moved the water wheel into an enclosed turbine or water motor. Francis, while working as engineer of Lowells Locks and Canals company. He applied scientific principles and testing methods to the problem of turbine design and his mathematical and graphical calculation methods allowed confident design of high efficiency turbines to exactly match a sites specific flow conditions. The Francis reaction turbine is still in use today. Hydraulic power networks used pipes to carrying pressurized water and transmit power from the source to end users. The power source was normally a head of water, which could also be assisted by a pump and these were extensive in Victorian cities in the United Kingdom. A hydraulic power network was developed in Geneva, Switzerland. The world-famous Jet dEau was originally designed as the relief valve for the network
21.
Hydroelectricity
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Hydroelectricity is electricity produced from hydropower. In 2015 hydropower generated 16. 6% of the total electricity and 70% of all renewable electricity. Hydropower is produced in 150 countries, with the Asia-Pacific region generating 33 percent of global hydropower in 2013, China is the largest hydroelectricity producer, with 920 TWh of production in 2013, representing 16.9 percent of domestic electricity use. The cost of hydroelectricity is relatively low, making it a source of renewable electricity. The hydro station consumes no water, unlike coal or gas plants, the average cost of electricity from a hydro station larger than 10 megawatts is 3 to 5 U. S. cents per kilowatt-hour. With a dam and reservoir it is also a source of electricity since the amount produced by the station can be changed up or down very quickly to adapt to changing energy demands. Once a hydroelectric complex is constructed, the project produces no direct waste, Hydropower has been used since ancient times to grind flour and perform other tasks. In the mid-1770s, French engineer Bernard Forest de Bélidor published Architecture Hydraulique which described vertical-, by the late 19th century, the electrical generator was developed and could now be coupled with hydraulics. The growing demand for the Industrial Revolution would drive development as well, in 1878 the worlds first hydroelectric power scheme was developed at Cragside in Northumberland, England by William George Armstrong. It was used to power an arc lamp in his art gallery. The old Schoelkopf Power Station No.1 near Niagara Falls in the U. S. side began to produce electricity in 1881. The first Edison hydroelectric power station, the Vulcan Street Plant, began operating September 30,1882, in Appleton, Wisconsin, by 1886 there were 45 hydroelectric power stations in the U. S. and Canada. By 1889 there were 200 in the U. S. alone, at the beginning of the 20th century, many small hydroelectric power stations were being constructed by commercial companies in mountains near metropolitan areas. Grenoble, France held the International Exhibition of Hydropower and Tourism with over one million visitors, by 1920 as 40% of the power produced in the United States was hydroelectric, the Federal Power Act was enacted into law. The Act created the Federal Power Commission to regulate hydroelectric power stations on federal land, as the power stations became larger, their associated dams developed additional purposes to include flood control, irrigation and navigation. Federal funding became necessary for development and federally owned corporations, such as the Tennessee Valley Authority. Hydroelectric power stations continued to become larger throughout the 20th century, Hydropower was referred to as white coal for its power and plenty. Hoover Dams initial 1,345 MW power station was the worlds largest hydroelectric station in 1936
22.
Dam
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A dam is a barrier that impounds water or underground streams. Reservoirs created by not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aquaculture. Hydropower is often used in conjunction with dams to generate electricity, a dam can also be used to collect water or for storage of water which can be evenly distributed between locations. Dams generally serve the purpose of retaining water, while other structures such as floodgates or levees 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, the first known appearance of dam occurs in 1165. However, there is one village, Obdam, that is mentioned in 1120. The word seems to be related to the Greek word taphos, so the word should be understood as dike from dug out earth. The names of more than 40 places from the Middle Dutch era such as Amsterdam and Rotterdam, early dam building took place in Mesopotamia and the Middle East. Dams were used to control the level, for Mesopotamias weather affected the Tigris. The earliest known dam is the Jawa Dam in Jordan,100 kilometres northeast of the capital Amman and this gravity dam featured an originally 9-metre-high and 1 m-wide stone wall, supported by a 50 m-wide earth rampart. The structure is dated to 3000 BC, the Ancient Egyptian Sadd-el-Kafara Dam at Wadi Al-Garawi, located about 25 km south of Cairo, was 102 m long at its base and 87 m wide. The structure was built around 2800 or 2600 BC as a dam for flood control. During the Twelfth Dynasty in the 19th century BC, the Pharaohs Senosert III, Amenemhat III, 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 km2 and is today as Berkat Qaroun. One of the wonders of the ancient world was the Great Dam of Marib in Yemen. Repairs were carried out during various periods, most important around 750 BC and these extensive works were not actually finalized until 325 AD and allowed the irrigation of 25,000 acres. By the mid-late 3rd century BC, an intricate water-management system within Dholavira in modern-day India was built, the system included 16 reservoirs, dams and various channels for collecting water and storing it. Eflatun Pınar is a Hittite dam and spring temple near Konya and it is thought to be from the time of the Hittite empire between the 15th and 13th century BC
23.
List of conventional hydroelectric power stations
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This article lists hydroelectric power stations that generate power using the conventional dammed method. This list includes stations that are larger than 1,000 MW in maximum net capacity. Those power stations that are smaller than 1,000 MW, or those that are only at a stage may be found in regional lists. As of 2016, the largest hydroelectric station is the Three Gorges Dam in China. After passing on 7 December 2007 the 14,000 MW mark of the Itaipu Dam, the dam is 181 m high,2,335 m long and 115 m in width. Power is generated by 32 turbines rated at 700 MW, construction of this dam commenced in 1994, and was completed in 2012, nearly two decades after it started. The next four largest dams after the Three Gorges Dam are the Itaipu Dam, Xiluodu Dam, Guri Dam, all five dams are the largest power-generating bodies respectively, before the Kashiwazaki-Kariwa Nuclear Power Plant at 8,212 MW, the largest non-renewable energy-generating facility in the world. The currently planned Grand Inga Dam would be twice the size of the Three Gorges Dam at 39,000 MW
24.
Pumped-storage hydroelectricity
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Pumped-storage hydroelectricity, or pumped hydroelectric energy storage, is a type of hydroelectric energy storage used by electric power systems for load balancing. The method stores energy in the form of potential energy of water. Low-cost surplus off-peak electric power is used to run the pumps. During periods of electrical demand, the stored water is released through turbines to produce electric power. Pumped-storage hydroelectricity allows energy from intermittent sources and other renewables, or excess electricity from continuous base-load sources to be saved for periods of higher demand. The reservoirs used with pumped storage are quite small compared to conventional hydroelectric dams of similar power capacity. The round-trip energy efficiency of PSH varies between 70%–80%, with sources claiming up to 87%. The main disadvantage of PHS is the specialist nature of the site required, at times of low electrical demand, excess generation capacity is used to pump water into the upper reservoir. When there is demand, water is released back into the lower reservoir through a turbine. Reversible turbine/generator assemblies act as a pump and turbine generator unit. Taking into account evaporation losses from the water surface and conversion losses. The relatively low density of pumped storage systems requires either large flows and/or large differences in height between reservoirs. The only way to store a significant amount of energy is by having a body of water located relatively near, but as high above as possible. In some places this occurs naturally, in one or both bodies of water were man-made. Projects in which both reservoirs are artificial and in which no natural inflows are involved with either reservoir are referred to as closed loop systems, hence pumped storage systems are crucial when coordinating large groups of heterogeneous generators. However, capital costs for pumped-storage plants are relatively high, along with energy management, pumped storage systems help control electrical network frequency and provide reserve generation. Thermal plants are less able to respond to sudden changes in electrical demand, potentially causing frequency. Pumped storage plants, like other plants, can respond to load changes within seconds
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Small hydro
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Small hydro is the development of hydroelectric power on a scale suitable for local community and industry, or to contribute to distributed generation in a regional electricity grid. The definition of a small hydro project varies, but a capacity of 1 to 20 megawatts is common. In contrast many hydroelectric projects are of size, such as the generating plant at the Three Gorges Dam at 22,500 megawatts or the vast multiple projects of the Tennessee Valley Authority. Small hydro projects may be built in isolated areas that would be uneconomic to serve from an electricity grid. The use of the small hydro varies considerably around the world. While a minimum limit is not usually set, the US National Hydropower Association specifies a limit of 5 MW. The small hydro description may be stretched up to 50 MW in the United States, Canada, Small hydro can be further subdivided into mini hydro, usually defined as 100 to 1,000 kilowatts, and micro hydro which is 5 to 100 kW. Micro hydro is usually the application of hydroelectric power sized for smaller communities, the smallest installations are pico hydro, below 5 kW. According to a report by REN21, during 2008 small hydro installations grew by 28% over year 2005 to raise the total world small hydro capacity to 85 gigawatts, over 70% of this was in China, followed by Japan, the United States and India. China planned to electrify a further 10,000 villages between 2005 and 2010 under their China Village Electrification Program, including investments in small hydro. By 2010, China had 45,000 small hydro installations, especially in rural areas, in the mountains and rain forests of British Columbia, Canada there are a great many sites suitable for hydro development. However environmental concerns towards large reservoirs after the 1980s halted new dam construction, the solution to coping with increased demand was to offer contracts to independent power producers, who have built 100 run of the river projects under 50MW. Power production without reservoirs varies dramatically, but older conventional dams retain or release water to average out production though the year, in 2014 these independent producers generated 18,000 GWh from 4,500 MW of capacity. Hydroelectric power is the generation of power from the movement of water. A hydroelectric facility requires a flow of water and a reasonable height for the water to fall. In a typical installation, water is fed from a reservoir through a pipe into a turbine, the water flowing through the turbine causes a electrical generator to rotate, converting the motion into electrical energy. Small hydro may developed by constructing new facilities or through re-development of existing dams whose primary purpose is flood control, either of these cost saving advantages can make the return on investment for a small hydro site well worth the use of existing sites. Many companies offer standardized turbine generator packages in the size range of 200 kW to 10 MW
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Micro hydro
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Micro hydro is a type of hydroelectric power that typically produces from 5 kW to 100 kW of electricity using the natural flow of water. Installations below 5 kW are called pico hydro and these installations can provide power to an isolated home or small community, or are sometimes connected to electric power networks, particularly where net metering is offered. There are many of these installations around the world, particularly in developing nations as they can provide a source of energy without the purchase of fuel. Micro hydro systems complement solar PV power systems because in areas, water flow. Micro hydro is frequently accomplished with a wheel for high head. The installation is often just a small dammed pool, at the top of a waterfall, construction details of a microhydro plant are site-specific. Sometimes an existing mill-pond or other artificial reservoir is available and can be adapted for power production, in general, microhydro systems are made up of a number of components. The most important include the intake where water is diverted from the stream, river. An intake structure such as a box is required to screen out floating debris and fish. In temperate climates this structure must resist ice as well, the intake may have a gate to allow the system to be dewatered for inspection and maintenance. The intake then tunnels water through a pipeline to the building containing a turbine. In mountainous areas, access to the route of the penstock may provide considerable challenges, if the water source and turbine are far apart, the construction of the penstock may be the largest part of the costs of construction. At the turbine, a valve is installed to regulate the flow. The turbine converts the flow and pressure of the water to mechanical energy, usually microhydro installations do not have a dam and reservoir, like large hydroelectric plants have, relying on a minimal flow of water to be available year-round. Microhydro systems are set up in areas capable of producing up to 100 kilowatts of electricity. This can be enough to power a home or small business facility and this production range is calculated in terms of head and flow. The higher each of these are, the power available. Hydraulic head is the measurement of water falling in a pipe expressed as a function of the vertical distance the water falls
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Pico hydro
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Pico hydro is a term used for hydroelectric power generation of under 5 kW. It is useful in small, remote communities that only a small amount of electricity – for example. Even smaller turbines of 200–300 W may power a home in a developing country with a drop of only one meter. The DIY-community has used abandoned water mills to mount a waterwheel and this approach has also been popularised in the TV-series Its Not Easy Being Green. These are usually smaller turbines of ~5 kW or less, through the internet, the community is now able to obtain plans to construct DIY-water turbines, and there is a growing trend toward building them for domestic requirements. The DIY-hydroelectric plants are now being used both in developed countries and in developing countries, to power residences and small businesses, two examples of pico hydro power can be found in the towns of Kithamba and Thimba in the Central Province of Kenya. These produce 1.1 kW and 2.2 kW, local residents were trained to maintain the hydro schemes. The pico hydro sites in Kenya won Ashden Awards for Sustainable Energy, sam Redfield of the Appropriate Infrastructure Development Group has developed a pico-hydro generator made from common PVC pipe and a modified Toyota alternator housed in a five gallon bucket. The generator was developed to power to communities without access to the electricity grid in developing countries. Envisioned as a source to charge cell phones, provide lighting and charge batteries. The Toyota alternator used in the generator is converted to a permanent magnet alternator allowing it to power at low RPMs. The Five Gallon Bucket Hydroelectric Generator was the subject of a group at the 2008 International Development Design Summit at the Massachusetts Institute of Technology. During the Summer of 2013 an energy project in Abra Malaga, a website has been put together as a forum for ideas and further iterations of the generator that includes a build manual. Common centrifugal water pumps, can be operated in reverse to act as turbines, while these machines rarely have optimum hydraulic characteristics when operated as turbines, their availability and low cost makes them attractive. If the power will be used more than 30 meters from the generator, many small systems use automotive alternators producing 12 VDC, and possibly charging a battery. For example, a 12 V system that produces 1 kW of power has a flow of 80 A, the cost to run two strands of wire 1000 is $2400. To avoid such a large wire cost a higher voltage and lower amperage is required, if a 240 VAC alternator is used instead the flow is only 4 A over 1000 of 18 gauge wire costing $180. The cost of wire resulted in North America using 120/240 VAC after DC voltage lost the War of Currents in the late 1800s, small hydro 1 to 20 MW Micro hydro 5 to 100 kW Hydro power Renewable Energy Sustainable energy Grid-tied electrical system What is Pico Hydro
28.
Francis turbine
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The Francis turbine is a type of water turbine that was developed by James B. Francis in Lowell, Massachusetts. It is a reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today and they operate in a water head from 40 to 600 m and are primarily used for electrical power production. The electric generators that most often use this type of turbine have an output that generally ranges just a few kilowatts up to 800 MW. Penstock diameters are between 3 and 33 ft, the speed range of the turbine is from 75 to 1000 rpm. A wicket gate around the outside of the turbines rotating runner controls the rate of flow through the turbine for different power production rates. Francis turbines are almost always mounted with the vertical to isolate water from the generator. This also facilitates installation and maintenance, water wheels of different types have been used historically for more than 1,000 years to power mills of all types, but they were relatively inefficient. Nineteenth-century efficiency improvements of water turbines allowed them to nearly all water wheel applications. After electric generators were developed in the late 1800s turbines were a source of generator power where potential hydro-power sources existed. In 1826 Benoit Fourneyron developed a high efficiency outward-flow water turbine, water was directed tangentially through the turbine runner, causing it to spin. Jean-Victor Poncelet designed a turbine in about 1820 that used the same principles. Howd obtained a US patent in 1838 for a similar design and he applied scientific principles and testing methods to produce a very efficient turbine design. More importantly, his mathematical and graphical calculation methods improved turbine design and his analytical methods allowed confident design of high efficiency turbines to precisely match a sites water flow and pressure. A Francis turbine consists of the main parts, Spiral casing. Throughout its length, it has openings at regular intervals to allow the working fluid to impinge on the blades of the runner. These openings convert the energy of the fluid into momentum energy just before the fluid impinges on the blades. Guide or stay vanes, The primary function of the guide or stay vanes is to convert the energy of the fluid into the momentum energy
29.
Kaplan turbine
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The Kaplan turbine is a propeller-type water turbine which has adjustable blades. The Kaplan turbine was an evolution of the Francis turbine and its invention allowed efficient power production in low-head applications that was not possible with Francis turbines. The head ranges from 10–70 metres and the output from 5 to 200 MW, runner diameters are between 2 and 11 metres. Turbines rotate at a constant rate, which varies from facility to facility and that rate ranges from as low as 69.2 rpm to 429 rpm. Kaplan turbines are now used throughout world in high-flow, low-head power production. Viktor Kaplan living in Brno, Czech Republic, obtained his first patent for an adjustable blade propeller turbine in 1912, but the development of a commercially successful machine would take another decade. Kaplan struggled with problems, and in 1922 abandoned his research for health reasons. In 1919 Kaplan installed a demonstration unit at Poděbrady, Czechoslovakia, in 1922 Voith introduced an 1100 HP Kaplan turbine for use mainly on rivers. In 1924 an 8 MW unit went on line at Lilla Edet and this marked the commercial success and widespread acceptance of Kaplan turbines. The Kaplan turbine is an outward flow turbine, which means that the working fluid changes pressure as it moves through the turbine. Power is recovered from both the head and from the kinetic energy of the flowing water. The design combines features of radial and axial turbines, the inlet is a scroll-shaped tube that wraps around the turbines wicket gate. Water is directed tangentially through the gate and spirals on to a propeller shaped runner. The outlet is a specially shaped tube that helps decelerate the water and recover kinetic energy. The turbine does not need to be at the lowest point of water flow as long as the tube remains full of water. A higher turbine location, however, increases the suction that is imparted on the blades by the draft tube. The resulting pressure drop may lead to cavitation, variable geometry of the wicket gate and turbine blades allow efficient operation for a range of flow conditions. Kaplan turbine efficiencies are typically over 90%, but may be lower in very low head applications, current areas of research include CFD driven efficiency improvements and new designs that raise survival rates of fish passing through
30.
Tyson turbine
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The Tyson Turbine is a hydropower system that extracts power from the flow of water. This design doesnt need a casement, as it is inserted directly into flowing water and it consists of a propeller mounted below a raft, driving a power system, typically a generator, on top of the raft by belt or gear. The turbine is towed into the middle of a river or stream, where the flow is the fastest and it requires no local engineering, and can easily be moved to other locations. The Tyson Turbine is a common way to reuse energy
31.
Gorlov helical turbine
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The Gorlov helical turbine is a water turbine evolved from the Darrieus turbine design by altering it to have helical blades/foils. It was patented in a series of patents from September 19,1995 to July 3,2001, GHT was invented by Professor Alexander M. Gorlov of Northeastern University. GHT, turby and quietrevolution solved pulsatory torque issues by using the helical twist of the blades, the term foil is used to describe the shape of the blade cross-section at a given point, with no distinction for the type of fluid. In this way, the sum of the lift and drag forces on each blade do not change abruptly with rotation angle, the turbine generates a smoother torque curve, so there is much less vibration and noise than in the Darrieus design. It also minimizes peak stresses in the structure and materials, in testing environments the GHT has been observed to have up to 35% efficiency in energy capture reported by several groups. Among the other vertical-axis turbine systems, the Davis Hydro turbine, the EnCurrent turbine, overall, these technologies represent the current norm of tidal current development. The main difference between the Gorlov helical turbine and conventional turbines is the orientation of the axis in relation to current flow, fluid flows, such as wind, will naturally change direction, however they will still remain parallel to the ground. So in all vertical-axis turbines, the flow remains perpendicular to the axis, regardless of the direction. This is one of the advantages of vertical-axis turbines. If the direction of the flow is fixed, then the Gorlov turbine axis could be vertical or horizontal. The GHT operates under a lift-based concept, the foil sections on the GHT are symmetrical, both top-to-bottom and also from the leading-to-trailing edge. The GHT can actually spin equally well in either direction, a GHT is proposed for low-head micro hydro installations, when construction of a dam is undesirable. The GHT is an example of damless hydro technology, the technology may potentially offer cost and environmental benefits over dam-based micro-hydro systems. Some advantages of damless hydro are that it eliminates the potential for failure of a dam, in general, a major ecological issue with hydropower installations is their actual and perceived risk to aquatic life. It is claimed that a GHT spins slowly enough that fish can see it soon enough to swim around it, from preliminary tests in 2001, it was claimed that if a fish swims between the slowly moving turbine blades, the fish will not be harmed. Also it would be difficult for a fish to become lodged or stuck in the turbine, a fish also would not be tumbled around in a vortex, because the GHT does not create a lot of turbulence, so small objects would be harmlessly swept through with the current. In this example the direction of the flow is to the left. The combined effect of two flow components, yields the net total Apparent flow velocity as shown in the next figure
32.
Pelton wheel
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The Pelton wheel is an impulse type water turbine. It was invented by Lester Allan Pelton in the 1870s, the Pelton wheel extracts energy from the impulse of moving water, as opposed to waters dead weight like the traditional overshot water wheel. Many variations of impulse turbines existed prior to Peltons design, water leaving those wheels typically still had high speed, carrying away much of the dynamic energy brought to the wheels. As the water jet impinges upon the contoured bucket-blades, the direction of velocity is changed to follow the contours of the bucket. Water impulse energy exerts torque on the system, spinning the wheel. In the process, the jets momentum is transferred to the wheel. Thus, impulse energy does work on the turbine, for maximum power and efficiency, the wheel and turbine system is designed such that the water jet velocity is twice the velocity of the rotating buckets. Typically two buckets are mounted side-by-side on the wheel, which permits splitting the water jet into two equal streams and this balances the side-load forces on the wheel and helps to ensure smooth, efficient transfer of momentum of the fluid jet of water to the turbine wheel. Because water and most liquids are incompressible, almost all of the available energy is extracted in the first stage of the hydraulic turbine. Therefore, Pelton wheels have only one stage, unlike gas turbines that operate with compressible fluid. It is used for generating electricity, Pelton wheels are the preferred turbine for hydro-power, when the available water source has relatively high hydraulic head at low flow rates, where the Pelton wheel geometry is most suitable. Pelton wheels are made in all sizes, there exist multi-ton Pelton wheels mounted on vertical oil pad bearings in hydroelectric plants. The largest units can be over 400 megawatts, the smallest Pelton wheels are only a few inches across, and can be used to tap power from mountain streams having flows of a few gallons per minute. Some of these systems use household plumbing fixtures for water delivery and these small units are recommended for use with 30 metres or more of head, in order to generate significant power levels. Depending on water flow and design, Pelton wheels operate best with heads from 15–1,800 metres, the specific speed η s parameter is independent of a particular turbines size. Compared to other designs, the relatively low specific speed of the Pelton wheel. Thus it is most suitable to being fed by a source with a low ratio of flow to pressure. The specific speed is the criterion for matching a specific hydro-electric site with the optimal turbine type
33.
Turgo turbine
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The Turgo turbine is an impulse water turbine designed for medium head applications. Operational Turgo Turbines achieve efficiencies of about 87%, in factory and lab tests Turgo Turbines perform with efficiencies of up to 90%. It works with net heads between 15 and 300 m, developed in 1919 by Gilkes as a modification of the Pelton wheel, the Turgo has some advantages over Francis and Pelton designs for certain applications. First, the runner is less expensive to make than a Pelton wheel, second, it doesnt need an airtight housing like the Francis. Third, it has higher speed and can handle a greater flow than the same diameter Pelton wheel, leading to reduced generator. Turgos operate in a range where the Francis and Pelton overlap. While many large Turgo installations exist, they are popular for small hydro where low cost is very important. Like all turbines with nozzles, blockage by debris must be prevented for effective operation, the Turgo turbine is an impulse type turbine, water does not change pressure as it moves through the turbine blades. The waters potential energy is converted to energy with a nozzle. The high speed jet is then directed on the turbine blades which deflect. The resulting impulse spins the turbine runner, imparting energy to the turbine shaft, water exits with very little energy. Turgo runners are extremely efficient A Turgo runner looks like a Pelton runner split in half, for the same power, the Turgo runner is one half the diameter of the Pelton runner, and so twice the specific speed. The Turgo can handle a greater flow than the Pelton because exiting water doesnt interfere with adjacent buckets. The specific speed of Turgo runners is between the Francis and Pelton, single or multiple nozzles can be used. Increasing the number of jets increases the speed of the runner by the square root of the number of jets. Water turbine Hydroelectric power Turgo turbine math, Czech
34.
Cross-flow turbine
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A cross-flow turbine, Bánki-Michell turbine, or Ossberger turbine is a water turbine developed by the Australian Anthony Michell, the Hungarian Donát Bánki and the German Fritz Ossberger. Michell obtained patents for his design in 1903, and the manufacturing company Weymouth made it for many years. Ossbergers first patent was granted in 1933, and he manufactured this turbine as a standard product, today, the company founded by Ossberger is the leading manufacturer of this type of turbine. Unlike most water turbines, which have axial or radial flows, in a cross-flow turbine the water passes through the turbine transversely, as with a water wheel, the water is admitted at the turbines edge. After passing to the inside of the runner, it leaves on the opposite side, passing through the runner twice provides additional efficiency. When the water leaves the runner, it also helps clean it of small debris, the cross-flow turbine is a low-speed machine that is well suited for locations with a low head but high flow. Although the illustration shows one nozzle for simplicity, most practical cross-flow turbines have two, arranged so that the water flows do not interfere, cross-flow turbines are often constructed as two turbines of different capacity that share the same shaft. The turbine wheels are the diameter, but different lengths to handle different volumes at the same pressure. The subdivided wheels are built with volumes in ratios of 1,2. The subdivided regulating unit, the guide vane system in the upstream section, provides flexible operation, with 33,66 or 100% output. Low operating costs are obtained with the relatively simple construction. The turbine consists of a water wheel or runner with a horizontal shaft, composed of numerous blades. The blades edges are sharpened to reduce resistance to the flow of water, a blade is made in a part-circular cross-section. The ends of the blades are welded to disks to form a cage like a cage and are sometimes called squirrel cage turbines, instead of the bars. The water flows first from the outside of the turbine to its inside, the regulating unit, shaped like a vane or tongue, varies the cross-section of the flow. The water jet is directed towards the cylindrical runner by nozzle, the water enters the runner at an angle of about 45/120 degrees, transmitting some of the waters kinetic energy to the active cylindrical blades. The regulating device controls the flow based on the power needed, the ratio is that of the water is admitted to 0-100%×30/4 blades. Water admission to the two nozzles is throttled by two shaped guide vanes and these divide and direct the flow so that the water enters the runner smoothly for any width of opening
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Water wheel
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A water wheel is a machine for converting the energy of flowing or falling water into useful forms of power, often in a watermill. A water wheel consists of a wheel, with a number of blades or buckets arranged on the outside rim forming the driving surface. Most commonly, the wheel is mounted vertically on a horizontal axle, vertical wheels can transmit power either through the axle or via a ring gear and typically drive belts or gears, horizontal wheels usually directly drive their load. Water wheels were still in use well into the 20th century. Uses included milling flour in gristmills, grinding wood into pulp for papermaking, hammering wrought iron, machining, some water wheels are fed by water from a mill pond, which is formed when a flowing stream is dammed. A channel for the water flowing to or from a wheel is called a mill race. The race bringing water from the pond to the water wheel is a headrace. In the mid to late 18th century John Smeatons scientific investigation of the water led to significant increases in efficiency supplying much needed power for the Industrial Revolution. Water wheels began being displaced by the smaller, less expensive and more efficient turbine, developed by Benoît Fourneyron, turbines are capable of handling high heads, or elevations, that exceed the capability of practical-sized waterwheels. The main difficulty of water wheels is their dependence on flowing water, modern hydroelectric dams can be viewed as the descendants of the water wheel, as they too take advantage of the movement of water downhill. The two main functions of water wheels were historically water-lifting for irrigation purposes and as a power source, when used for water-lifting power can be supplied by either human or animal force or by the water current itself. Water wheels come in two designs, either a vertical or a horizontal axle. The latter type can be subdivided, depending on where the hits the wheel. Engineers of the Hellenistic era Mediterranean region are credited with the development of the water wheel, Mediterranean engineers of the Hellenistic and Roman periods were also the first to use it for both irrigation and as a power source. The technological breakthrough occurred in the advanced and scientifically minded Hellenistic period between the 3rd and 1st centuries BCE. This is seen as an evolution of the paddle-driven water-lifting wheels that had appeared in ancient Egypt by the 4th century BCE. According to John Peter Oleson, both the wheel and the hydraulic Noria appeared in Egypt by the 4th century BCE. This is supported by finds at Faiyum, where the oldest archeological evidence of a water-wheel has been found
