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GSSHA
GSSHA (Gridded Surface/Subsurface Hydrologic Analysis) is a two-dimensional, physically based watershed model developed by the Engineer Research and Development Center of the United States Army Corps of Engineers. It simulates surface water and groundwater hydrology, erosion and sediment transport. The GSSHA model is used for hydraulic engineering and research, and is on the Federal Emergency Management Agency (FEMA) list of hydrologic models accepted for use in the national flood insurance program for flood hydrograph estimation. Input is best prepared by the Watershed Modeling System interface, which effectively links the model with geographic information systems (GIS). GSSHA uses a square-grid, constant grid-size representation of watershed topography and characteristics, similar to a digital elevation model representation. Relevant model parameters are assigned to the model grids using index maps. Index maps are often derived from soils, landuse/land cover, vegetation, or ot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WMS (hydrology Software)
WMS (Watershed Modeling System) is a watershed computer simulation and modeling software application from Aquaveo. It was originally created in the early 1990s at the Engineering Computer Graphics Laboratory at Brigham Young University. The software supports a number of hydraulic and hydrologic models that can be used to create drainage basin simulations. Features The Watershed Modeling System (WMS) is a proprietary water modeling software application used to develop watershed computer simulations. The software provides tools to automate various basic and advanced delineations, calculations, and modeling processes. It supports river hydraulic and storm drain models, lumped parameter, regression, 2D hydrologic modeling of watersheds, and can be used to model both water quantity and water quality. , supported models include HEC-1, HEC-RAS, HEC-HMS, TR-20, TR-55, NFF, Rational, MODRAT, HSPF, CE-QUAL-W2, GSSHA, SMPDBK, and other models. History WMS was initially developed b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engineer Research And Development Center
The Engineer Research and Development Center (ERDC) is a US Army Corps of Engineers (USACE) research and laboratory organization. The headquarters is located in Vicksburg, Mississippi, on the site of an antecedent organization, the Waterways Experiment Station. History In October 1999, the Corps of Engineers established a system of laboratories, called the Engineer Research and Development Center (ERDC). The ERDC was a consolidation of seven, pre-existing laboratories: the ''Coastal and Hydraulics, Environmental, Geotechnical and Structures, and Information Technology Laboratories'' in Vicksburg, Mississippi; the ''Construction Engineering Research Laboratory'' in Champaign, Illinois; the Cold Regions Research and Engineering Laboratory in Hanover, New Hampshire; and the ''Topographic Engineering Center'' in Alexandria, Virginia, which became the Army Geospatial Center (AGC) and started reporting directly to the Corps of Engineers as of 2009. As of 2014, ERDC still maintained a ''G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evapotranspiration
Evapotranspiration (ET) is the combined processes by which water moves from the earth’s surface into the atmosphere. It covers both water evaporation (movement of water to the air directly from soil, canopies, and water bodies) and transpiration (movement of water from the soil, through roots and bodies of vegetation, on leaves and then into the air). Evapotranspiration is an important part of the local water cycle and climate, as well as measurement of it plays a key role in agricultural irrigation and water resource management. Definition Evapotranspiration is a combination of evaporation and transpiration, measured in order to better understand crop water requirements, irrigation scheduling, and watershed management. The two key components of evapotranspiration are: * Evaporation: the movement of water directly to the air from sources such as the soil and water bodies. It can be affected by factors including heat, humidity, and wind speed. * Transpiration: the move ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weir
A weir or low head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of lakes, ponds, and reservoirs. There are many weir designs, but commonly water flows freely over the top of the weir crest before cascading down to a lower level. Etymology There is no single definition as to what constitutes a weir and one English dictionary simply defines a weir as a small dam, likely originating from Middle English ''were'', Old English ''wer'', derivative of root of ''werian,'' meaning "to defend, dam". Function Commonly, weirs are used to prevent flooding, measure water discharge, and help render rivers more navigable by boat. In some locations, the terms dam and weir are synonymous, but normally there is a clear distinction made between the structures. Usually, a dam is designed specifically to impound water behind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydraulic Structures
A hydraulic structure is a structure submerged or partially submerged in any body of water, which disrupts the natural flow of water. They can be used to divert, disrupt or completely stop the flow. An example of a hydraulic structure would be a dam, which slows the normal flow rate of the river in order to power turbines. A hydraulic structure can be built in rivers, a sea, or any body of water where there is a need for a change in the natural flow of water.Hydraulic structures United States Army Corps of Engineers Hydraulic structures may also be used to measure the flow of water. When used to measure the flow of water, hydraulic structures are defined as a class of specially shaped, static devices over or through which water is directed in such a way that under fre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Channel Flow
Channel, channels, channeling, etc., may refer to: Geography * Channel (geography), in physical geography, a landform consisting of the outline (banks) of the path of a narrow body of water. Australia * Channel Country, region of outback Australia in Queensland and partly in South Australia, Northern Territory and New South Wales. * Channel Highway, a regional highway in Tasmania, Australia. Europe * Channel Islands, an archipelago in the English Channel, off the French coast of Normandy * Channel Tunnel or Chunnel, a rail tunnel underneath the English Channel * English Channel, called simply "The Channel", the part of the Atlantic Ocean that separates Great Britain from northern France North America * Channel Islands of California, a chain of eight islands located in the Pacific Ocean off the coast of Southern California, United States * Channel Lake, Illinois, a census-designated place in Lake County, Illinois, United States * Channels State Forest, a state forest in Virginia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overland Flow
Surface runoff (also known as overland flow) is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when the soil is saturated by water to its full capacity, and the rain arrives more quickly than the soil can absorb it. Surface runoff often occurs because impervious areas (such as roofs and pavement) do not allow water to soak into the ground. Furthermore, runoff can occur either through natural or man-made processes. Surface runoff is a major component of the water cycle. It is the primary agent of soil erosion by water. The land area producing runoff that drains to a common point is called a drainage basin. Runoff that occurs on the ground surface before reaching a channel can be a nonpoint source of pollution, as it can carry man-made contaminants or natural forms of pollution (such as rotting leaves). Man-made contaminants in runoff incl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richards Equation
The Richards equation represents the movement of water in unsaturated soils, and is attributed to Lorenzo A. Richards who published the equation in 1931. It is a quasilinear partial differential equation; its analytical solution is often limited to specific initial and boundary conditions. Proof of the existence and uniqueness of solution was given only in 1983 by Alt and Luckhaus. The equation is based on Darcy-Buckingham law representing flow in porous media under variably saturated conditions, which is stated as :\vec=-\mathbf(\theta) (\nabla h + \nabla z), where :\vec is the volumetric flux; :\theta is the volumetric water content; :h is the liquid pressure head, which is negative for unsaturated porous media; :\mathbf(h) is the unsaturated hydraulic conductivity; :\nabla z is the geodetic head gradient, which is assumed as \nabla z = \left(\begin 0 \\ 0 \\ 1 \end \right) for three-dimensional problems. Considering the law of mass conservation for an incompressible porous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infiltration (hydrology)
Infiltration is the process by which water on the ground surface enters the soil. It is commonly used in both hydrology and soil sciences. The infiltration capacity is defined as the maximum rate of infiltration. It is most often measured in meters per day but can also be measured in other units of distance over time if necessary. The infiltration capacity decreases as the soil moisture content of soils surface layers increases. If the precipitation rate exceeds the infiltration rate, runoff will usually occur unless there is some physical barrier. Infiltrometers, permeameters and rainfall simulators are all devices that can be used to measure infiltration rates. Infiltration is caused by multiple factors including; gravity, capillary forces, adsorption and osmosis. Many soil characteristics can also play a role in determining the rate at which infiltration occurs. Factors that affect infiltration Precipitation Precipitation can impact infiltration in many ways. The am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Penman–Monteith Equation
The Penman–Monteith equation approximates net evapotranspiration (ET) from meteorological data, as a replacement for direct measurement of evapotranspiration. The equation is widely used, and was derived by the United Nations Food and Agriculture Organization for modeling potential evapotranspiration ET0. Significance Evapotranspiration contributions are very significant in a watershed's water balance, yet are often not emphasized in results because the precision of this component is often weak relative to more directly measured phenomena, e.g. rain and stream flow. In addition to weather uncertainties, the Penman–Monteith equation is sensitive to vegetation specific parameters, e.g. stomatal resistance or conductance. Various forms of crop coefficients (Kc) account for differences between specific vegetation modeled and a ''reference evapotranspiration'' (RET or ET0) standard. Stress coefficients (Ks) account for reductions in ET due to environmental stress (e.g. soil saturat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weather Radar
Weather radar, also called weather surveillance radar (WSR) and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, and estimate its type (rain, snow, hail etc.). Modern weather radars are mostly pulse-Doppler radars, capable of detecting the motion of rain droplets in addition to the intensity of the precipitation. Both types of data can be analyzed to determine the structure of storms and their potential to cause severe weather. During World War II, radar operators discovered that weather was causing echoes on their screen, masking potential enemy targets. Techniques were developed to filter them, but scientists began to study the phenomenon. Soon after the war, surplus radars were used to detect precipitation. Since then, weather radar has evolved on its own and is now used by national weather services, research departments in universities, and in television stations' weather departments. Raw images are routinely used and speciali ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rain Gage
A rain gauge (also known as udometer, pluvia metior, pluviometer, ombrometer, and hyetometer) is an instrument used by meteorologists and hydrologists to gather and measure the amount of liquid precipitation over a predefined area, over a period of time. It is used for determining the depth of precipitation (usually in mm) that occurs over a unit area and thus measuring rainfall amount. History The first known rainfall records were kept by the Ancient Greeks, at around 500 BCE. People living in India began to record rainfall in 400 BCE Ian Strangeways, A History of rain gauges, TerraData, 2010 The readings were correlated against expected growth. In the Arthashastra, used for example in Magadha, precise standards were set as to grain production. Each of the state storehouses were equipped with a rain gauge to classify land for taxation purposes. In 1247, the Song Chinese mathematician and inventor Qin Jiushao invented Tianchi basin rain and snow gauges to reference rain, snowfal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
