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Drainage By Wells
Well drainage means drainage of agricultural lands by wells. Agricultural land is drained by pumped dry wells (vertical drainage) to improve the soils by controlling water table levels and soil salinity. Introduction Subsurface (groundwater) drainage for water table and soil salinity in agricultural land can be done by horizontal and vertical drainage systems. ''Horizontal drainage'' systems are drainage systems using open ditches (trenches) or buried pipe drains. ''Vertical drainage'' systems are drainage systems using pumped wells, either open dug wells or tube wells. Both systems serve the same ''purposes'', namely water table control and soil salinity control . Both systems can facilitate the ''reuse of drainage water'' (e.g. for irrigation), but wells offer more flexibility. Reuse is only feasible if the quality of the groundwater is acceptable and the salinity is low. Design Although one well may be sufficient to solve groundwater and soil salinity problems in a few hect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dry Well
A dry well or soak is a structure formed underground that disposes of unwanted water, such as surface runoff water and stormwater. In this process, the water is infiltrated into the ground, further merging with groundwater in the local area. The way water flows in a dry well is through gravity. A dry well will typically have a chamber structure, or a deep pit covered with gravel. Dry wells may vary from simple to more advanced structures. Design When designing a dry well, there are requirements. Dry wells require optimal conditions prior to installing; they may not be installed where topographic conditions and soil are not at ideal standards. Dry wells should typically be anywhere from 30–100 feet deep, with a width of 3–6 feet at the surface. For safety cautions, the dry wells must be placed at a distance away from property lines, basements, and any foundations. Any plants or other structures should not be placed on top of a dry well in case of maintenance. Furthermore, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquifer
An aquifer is an underground layer of water-bearing material, consisting of permeability (Earth sciences), permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The study of water flow in aquifers and the characterization of aquifers is called ''hydrogeology''. Related concepts include aquitard, a bed (geology), bed of low permeability along an aquifer, and aquiclude (or ''aquifuge''), a solid and impermeable region underlying or overlying an aquifer, the pressure of which could lead to the formation of a confined aquifer. Aquifers can be classified as saturated versus unsaturated; aquifers versus aquitards; confined versus unconfined; isotropic versus anisotropic; porous, karst, or fractured; and transboundary aquifer. Groundwater from aquifers can be sustainably harvested by humans through the use of qanats leading to a well. This groundwater is a major source of fresh water for many regions, althoug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Quality
Water quality refers to the chemical, physical, and biological characteristics of water based on the standards of its usage. It is most frequently used by reference to a set of standards against which compliance, generally achieved through treatment of the water, can be assessed. The most common standards used to monitor and assess water quality convey the health of ecosystems, safety of human contact, extent of water pollution and condition of drinking water. Water quality has a significant impact on water supply and often determines supply options. Impacts on public health Over time, there has been increasing recognition of the importance of drinking water quality and its impact on public health. This has led to increasing protection and management of water quality. Text was copied from this source, which is available under a creativecommons:by/4.0/, Creative Commons Attribution 4.0 International License The understanding of the links between water quality and healt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrology
Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and drainage basin sustainability. A practitioner of hydrology is called a hydrologist. Hydrologists are scientists studying earth science, earth or environmental science, civil engineering, civil or environmental engineering, and physical geography. Using various analytical methods and scientific techniques, they collect and analyze data to help solve water related problems such as Environmentalism, environmental preservation, natural disasters, and Water resource management, water management. Hydrology subdivides into surface water hydrology, groundwater hydrology (hydrogeology), and marine hydrology. Domains of hydrology include hydrometeorology, surface-water hydrology, surface hydrology, hydrogeology, drainage basin, drainage-basin management, and water quality. Oceanography and meteorology are not included beca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Groundwater Model
Groundwater models are computer models of groundwater flow systems, and are used by hydrologists and hydrogeologists. Groundwater models are used to simulate and predict aquifer conditions. Characteristics An unambiguous definition of "groundwater model" is difficult to give, but there are many common characteristics. A groundwater model may be a scale model or an electric model of a groundwater situation or aquifer. Groundwater models are used to represent the natural groundwater flow in the environment. Some groundwater models include (chemical) quality aspects of the groundwater. Such groundwater models try to predict the fate and movement of the chemical in natural, urban or hypothetical scenario. Groundwater models may be used to predict the effects of hydrological changes (like groundwater pumping or irrigation developments) on the behavior of the aquifer and are often named groundwater simulation models. Groundwater models are used in various water management plans for u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anisotropy
Anisotropy () is the structural property of non-uniformity in different directions, as opposed to isotropy. An anisotropic object or pattern has properties that differ according to direction of measurement. For example, many materials exhibit very different physical or mechanical properties when measured along different axes, e.g. absorbance, refractive index, conductivity, and tensile strength. An example of anisotropy is light coming through a polarizer. Another is wood, which is easier to split along its grain than across it because of the directional non-uniformity of the grain (the grain is the same in one direction, not all directions). Fields of interest Computer graphics In the field of computer graphics, an anisotropic surface changes in appearance as it rotates about its geometric normal, as is the case with velvet. Anisotropic filtering (AF) is a method of enhancing the image quality of textures on surfaces that are far away and viewed at a shallow angle. Older ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Program
A computer program is a sequence or set of instructions in a programming language for a computer to Execution (computing), execute. It is one component of software, which also includes software documentation, documentation and other intangible components. A ''computer program'' in its human-readable form is called source code. Source code needs another computer program to Execution (computing), execute because computers can only execute their native machine instructions. Therefore, source code may be Translator (computing), translated to machine instructions using a compiler written for the language. (Assembly language programs are translated using an Assembler (computing), assembler.) The resulting file is called an executable. Alternatively, source code may execute within an interpreter (computing), interpreter written for the language. If the executable is requested for execution, then the operating system Loader (computing), loads it into Random-access memory, memory and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WellHead
A wellhead is the component at the surface of an oil or gas well that provides the structural and pressure-containing interface for the drilling and production equipment. The primary purpose of a wellhead is to provide the suspension point and pressure seals for the casing strings that run from the bottom of the hole sections to the surface pressure control equipment. While drilling the oil well, surface pressure control is provided by a blowout preventer (BOP). If the pressure is not contained during drilling operations by the column of drilling fluid, casings, wellhead, and BOP, a well blowout could occur. When the well has been drilled, it is completed to provide an interface with the reservoir rock and a tubular conduit for the well fluids. The surface pressure control is provided by a Christmas tree, which is installed on top of the wellhead, with isolation valves and choke equipment to control the flow of well fluids during production. Wellheads are typically welded ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquifer Test
In hydrogeology, an aquifer test (or a pumping test) is conducted to evaluate an aquifer by "stimulating" the aquifer through constant pumping, and observing the aquifer's "response" ( drawdown) in observation wells. Aquifer testing is a common tool that hydrogeologists use to characterize a system of aquifers, aquitards and flow system boundaries. A slug test is a variation on the typical aquifer test where an instantaneous change (increase or decrease) is made, and the effects are observed in the same well. This is often used in geotechnical engineering settings to get a quick estimate (minutes instead of days) of the aquifer properties immediately around the well. Aquifer tests are typically interpreted by using an analytical model of aquifer flow (the most fundamental being the Theis solution) to match the data observed in the real world, then assuming that the parameters from the idealized model apply to the real-world aquifer. In more complex cases, a numerical model may ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drainage Equation
A drainage equation is an equation describing the relation between depth and spacing of parallel subsurface drains, depth of the watertable, depth and hydraulic conductivity of the soils. It is used in drainage design. A well known steady-state drainage equation is the Hooghoudt drain spacing equation. Its original publication is in Dutch. The equation was introduced in the USA by van Schilfgaarde. Hooghoudt's equation Hooghoudt's equation can be written as:. :Q L2 = 8 Kb d (Dd - Dw) + 4 Ka (Dd - Dw)2 where: * Q = steady state drainage discharge rate (m/day) * Ka = hydraulic conductivity of the soil above drain level (m/day) * Kb = hydraulic conductivity of the soil below drain level (m/day) * Di = depth of the impermeable layer below drain level (m) * Dd = depth of the drains (m) * Dw = steady state depth of the watertable midway between the drains (m) * L = spacing between the drains (m) * d = equivalent depth, a function of L, (Di-Dd), and r * r = drain radius (m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Numerical Solution
Numerical analysis is the study of algorithms that use numerical approximation (as opposed to symbolic manipulations) for the problems of mathematical analysis (as distinguished from discrete mathematics). It is the study of numerical methods that attempt to find approximate solutions of problems rather than the exact ones. Numerical analysis finds application in all fields of engineering and the physical sciences, and in the 21st century also the life and social sciences like economics, medicine, business and even the arts. Current growth in computing power has enabled the use of more complex numerical analysis, providing detailed and realistic mathematical models in science and engineering. Examples of numerical analysis include: ordinary differential equations as found in celestial mechanics (predicting the motions of planets, stars and galaxies), numerical linear algebra in data analysis, and stochastic differential equations and Markov chains for simulating living cells in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydraulic Conductivity
In science and engineering, hydraulic conductivity (, in SI units of meters per second), is a property of porous materials, soils and Rock (geology), rocks, that describes the ease with which a fluid (usually water) can move through the porosity, pore space, or fracture network. It depends on the intrinsic permeability (, unit: m) of the material, the degree of Water content, saturation, and on the density and viscosity of the fluid. Saturated hydraulic conductivity, , describes water movement through saturated media. By definition, hydraulic conductivity is the ratio of volume flux to Hydraulic head#Hydraulic gradient, hydraulic gradient yielding a quantitative measure of a saturated soil's ability to transmit water when subjected to a hydraulic gradient. Methods of determination There are two broad approaches for determining hydraulic conductivity: *In the ''empirical'' approach the hydraulic conductivity is correlated to soil properties like Porosity, pore-size and particle-s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
