A river mouth is the part of a river where the river debouches into another river, a lake, a reservoir, a sea, or an ocean. The water from a river can enter the receiving body in a variety of different ways; the motion of a river is influenced by the relative density of the river compared to the receiving water, the rotation of the earth, any ambient motion in the receiving water, such as tides or seiches. If the river water has a higher density than the surface of the receiving water, the river water will plunge below the surface; the river water will either form an underflow or an interflow within the lake. However, if the river water is lighter than the receiving water, as is the case when fresh river water flows into the sea, the river water will float along the surface of the receiving water as an overflow. Alongside these advective transports, inflowing water will diffuse. At the mouth of a river, the change in flow condition can cause the river to drop any sediment it is carrying; this sediment deposition can generate a variety of landforms, such as deltas, sand bars and tie channels.
Many places in the United Kingdom take their names from their positions at the mouths of rivers, such as Plymouth and Great Yarmouth. Confluence River delta Estuary Liman
A stream is a body of water with surface water flowing within the bed and banks of a channel. The stream encompasses surface and groundwater fluxes that respond to geological, geomorphological and biotic controls. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long large streams are called rivers. Streams are important as conduits in the water cycle, instruments in groundwater recharge, corridors for fish and wildlife migration; the biological habitat in the immediate vicinity of a stream is called a riparian zone. Given the status of the ongoing Holocene extinction, streams play an important corridor role in connecting fragmented habitats and thus in conserving biodiversity; the study of streams and waterways in general is known as surface hydrology and is a core element of environmental geography. Brook A stream smaller than a creek one, fed by a spring or seep, it is small and forded. A brook is characterised by its shallowness.
Creek In North America and New Zealand, a small to medium-sized natural stream. Sometimes navigable by motor craft and may be intermittent. In parts of Maryland, New England, the UK and India, a tidal inlet in a salt marsh or mangrove swamp, or between enclosed and drained former salt marshes or swamps. In these cases, the stream is the tidal stream, the course of the seawater through the creek channel at low and high tide. River A large natural stream, which may be a waterway. Runnel the linear channel between the parallel ridges or bars on a shoreline beach or river floodplain, or between a bar and the shore. Called a swale. Tributary A contributory stream, or a stream which does not reach a static body of water such as a lake or ocean, but joins another river. Sometimes called a branch or fork. There are a number of regional names for a stream. Allt is used in Highland Scotland. Beck is used in Lincolnshire to Cumbria in areas which were once occupied by the Danes and Norwegians. Bourne or winterbourne is used in the chalk downland of southern England.
Brook. Burn is used in North East England. Gill or ghyll is seen in Surrey influenced by Old Norse; the variant "ghyll" is used in the Lake District and appears to have been an invention of William Wordsworth. Nant is used in Wales. Rivulet is a term encountered in Victorian era publications. Stream Syke is used in lowland Cumbria for a seasonal stream. Branch is used to name streams in Virginia. Creek is common throughout the United States, as well as Australia. Falls is used to name streams in Maryland, for streams/rivers which have waterfalls on them if such falls have a small vertical drop. Little Gunpowder Falls and The Jones Falls are rivers named in this manner, unique to Maryland. Kill in New York, Pennsylvania and New Jersey comes from a Dutch language word meaning "riverbed" or "water channel", can be used for the UK meaning of'creek'. Run in Ohio, Michigan, New Jersey, Virginia, or West Virginia can be the name of a stream. Run in Florida is the name given to streams coming out of small natural springs.
River is used for larger springs like the Silver Rainbow River. Stream and brook are used in Midwestern states, Mid-Atlantic states, New England. Bar A shoal that develops in a stream as sediment is deposited as the current slows or is impeded by wave action at the confluence. Bifurcation A fork into two or more streams. Channel A depression created by constant erosion. Confluence The point at which the two streams merge. If the two tributaries are of equal size, the confluence may be called a fork. Drainage basin The area of land. A large drainage basin such as the Amazon River contains many smaller drainage basins. Floodplain Lands adjacent to the stream that are subject to flooding when a stream overflows its banks. Gaging station A site along the route of a stream or river, used for reference marking or water monitoring. Headwaters The part of a stream or river proximate to its source; the word is most used in the plural where there is no single point source. Knickpoint The point on a stream's profile where a sudden change in stream gradient occurs.
Mouth The point at which the stream discharges via an estuary or delta, into a static body of water such as a lake or ocean. Pool A segment where the water is deeper and slower moving. Rapids A turbulent, fast-flowing stretch of a stream or river. Riffle A segment where the flow is shallower and more turbulent. River A large natural stream, which may be a waterway. Run A somewhat smoothly flowing segment of the stream. Source The spring, or other point of origin of a stream. Spring The point at which a stream emerges from an underground course through unconsolidated sediments or through caves. A stream can with caves, flow aboveground for part of its course, underground for part of its course. Stream bed The bottom of a stream. Stream corridor Stream, its floodplains, the transitional upland fringe Streamflow The water moving through a stream channel. Thalweg The river's longitudinal section, or the line joining the deepest point in the channel at each stage from source to mouth. Waterfall or cascade The fall of water where the stream goes over a sudden drop called a knickpoint.
The stream expends kinetic energy in "trying" to eliminate the
The Simi Hills are a low rocky mountain range of the Transverse Ranges in eastern Ventura County and western Los Angeles County, of southern California, United States. The Simi Hills are aligned east-west and run for 26 miles, average around 7 mi in north-south width; the Simi Hills are part of the central Transverse Ranges System. They lie entirely within southeastern Ventura County, with some southern and eastern foothills within western Los Angeles County; the Simi Hills are on the western edge of the San Fernando Valley. The Simi Valley lies to the north, the Conejo Valley lies to the southwest; the San Fernando Valley communities of Chatsworth, West Hills, Woodland Hills are in the eastern hills and adjacent valley floor in Los Angeles city and county. The cities of Thousand Oaks, Agoura Hills, Simi Valley city are in the hills and adjacent valleys within Ventura County; the two nearby mountain ranges are: the higher Santa Susana Mountains adjacent on the northeast across Santa Susana Pass.
The hills provide the complete or partial watersheds for several year-round creeks and numerous seasonal streams. They include Las Virgenes Creek, Moore's Canyon Creek, Bell Creek, Dayton Creek, Woolsey Canyon Creek, Brandeis Creek, Runkle Canyon Creek, Arroyo Simi, Palo Comado Creek, Cheeseboro Creek, Arroyo Calabasas. Bell Creek and Arroyo Calabasas are the headwaters of the Los Angeles River, by name its beginning with their confluence in nearby Canoga Park. 90% of the Santa Susana Field Lab property drains into the Los Angeles River via tributaries. Peaks in this region include Simi Peak, 2,403 ft, Chatsworth Peak, 2,314 ft, Escorpión Peak, 1,475 ft; because of its low elevation, the Simi Hills experience rainy, mild winters. Snow is rare in the Simi Hills in the highest areas. Summers are warm and dry and wildfires do occur here. Cool winds from the Pacific Ocean come from the Oxnard Plain and blow into the inland areas through the Santa Clara River Valley and the Conejo Valley, though some low hills, such as Conejo Mountain, block these winds from the Conejo Valley.
The Simi Hills further block these winds, which bring cool weather in both summer and winter from the San Fernando Valley. The southern lower hills are covered in grasslands and oak savanna; the northern rocky hills area is chaparral shrubland and oak woodlands. The Simi Hills are part of the California chaparral and woodlands ecoregion; the oaks include: the evergreen coastal live oak, the deciduous valley oak, the scrub oak. Riparian zone plants include California arroyo willows. Spring wildflowers include the redbush monkey flower, Plummer's mariposa lily, canyon sunflower. Poison oak is an important member of the native plant habitat community here; the Simi Hills is the principal, much wider, of only two terrestrial wildlife corridors linking the coastal Santa Monica Mountains with the inland Santa Susana Mountains, Topatopa Mountains, San Gabriel Mountains, all of the transverse ranges fauna community. The Simi Hills are the most critical wildlife corridor linkage for the Santa Monica Mountains to these and other Transverse Ranges further east.
The Simi's undeveloped native habitat provides routes that protect larger land wildlife of the Santa Monicas from genetic isolation. Large sections of the Simi Hills are protected by parks and open space preserves; the Santa Susana Field Laboratory property, a crucial wildlife corridor to the Santa Susanas, has been proposed for public open space parkland after the closed site's cleanup completion. The Simi Hills were inhabited for over 8,000 years by Paleo-indians and Chumash-Venturaño Native Americans for settlements and hunting grounds; the Chumash had the established village of Hu'wam in Cañon del Escorpión. It was a multicultural'crossroads' destination, where Chumash and Tataviam peoples traded and lived beside Bell Creek below Escorpión Peak, at the present day Bell Canyon Park; this peak in the Simi Hills is one of nine alignment points in Chumash territory and is essential to maintaining the balance of the natural world. Upstream were healing springs and are rock outcrop'grinding stones.'
The Burro Flats Painted Cave, an example of the Rock art of the Chumash people, is nearby. The Juan Bautista de Anza expedition passed through the area in 1769, being the first European sighting of the Simi Hills; the U. S. National Park Service administers the Juan Bautista de Anza National Historic Trail which enters at Moore Canyon in El Escorpión Park and crosses across the southern Hills through Upper Las Virgenes Canyon Open Space Preserve and Cheeseboro/Palo Comado Canyon Park to the Conejo Valley. In 1845 the land grant for Rancho El Escorpión, beside the Peak and named for it, was issued to one Chumash and two Tongva people and a rare instance of Native Americans being grantees, by Mexican Governor Pío Pico; the Rancho El Conejo was to the west, included that end of the Simi Hills. In the first half of the 20th century, there were four large movie ranches in the Simi Hills for filming motion pictures on location; the gated community of Bell Canyon began development of geographic Bell Canyon in the 1968.
To the north of U. S. 101, east of Thousand Oaks, west of Simi Valley the early 1960s suburban expansion of metropolitan Los Angeles brought the development of small to sized parcels of land in the Simi Hills. Hillside subd
Pratt & Whitney Rocketdyne
Pratt & Whitney Rocketdyne was a United States company that designed and produced rocket engines that use liquid propellants. It was a division of Pratt & Whitney, a owned subsidiary of United Technologies Corporation, it was headquartered in Los Angeles, California. In 2013, the company was sold to GenCorp. Pratt & Whitney Rocketdyne was formed in 2005 when Pratt & Whitney Space Propulsion and Boeing Rocketdyne Propulsion & Power were merged, following the latter's acquisition from Boeing by United Technologies Corporation. Boeing retained the 2,800 acre Rocketdyne Santa Susana Field Laboratory property above Canoga Park while a majority of the engineering and design continued to be carried out at the Pratt & Whitney Space Propulsion facility located on Beeline Highway outside West Palm Beach, Florida. In July 2012, United Technologies Corporation agreed to sell Pratt & Whitney Rocketdyne to GenCorp, which owns rocket engine producer Aerojet; the sale was completed in June 2013, when the company was merged with Aerojet to form Aerojet Rocketdyne.
Pratt & Whitney RocketdyneRL10 An American Society of Mechanical Engineers Historic Landmark developed by Pratt & Whitney. Used on the Saturn I, the upper stage of the Delta IV, the Centaur upper stage for the Atlas V and Titan rockets and on the vertical-landing McDonnell Douglas DC-X "Delta Clipper", it was intended to serve as the main propulsion engine for the Altair lunar lander. RS-68 First stage engine for the Delta IV. RS-25 Space Shuttle main engine. SJ61 A dual-mode ramjet/scramjet engine flown on the Boeing X-51 hypersonic demonstration vehicle. J-2X As of 2013 under development to be used on the Earth Departure Stage for the Block II of the Space Launch System. Rocketdyne Rocketdyne engines Commercial Spaceflight Federation Pratt & Whitney Rocketdyne company website
An aquifer is an underground layer of water-bearing permeable rock, rock fractures or unconsolidated materials. Groundwater can be extracted using a water well; the study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related terms include aquitard, a bed of low permeability along an aquifer, aquiclude, a solid, impermeable area underlying or overlying an aquifer. If the impermeable area overlies the aquifer, pressure could cause it to become a confined aquifer. Aquifers may occur at various depths; those closer to the surface are not only more to be used for water supply and irrigation, but are more to be topped up by the local rainfall. Many desert areas have limestone hills or mountains within them or close to them that can be exploited as groundwater resources. Part of the Atlas Mountains in North Africa, the Lebanon and Anti-Lebanon ranges between Syria and Lebanon, the Jebel Akhdar in Oman, parts of the Sierra Nevada and neighboring ranges in the United States' Southwest, have shallow aquifers that are exploited for their water.
Overexploitation can lead to the exceeding of the practical sustained yield. Along the coastlines of certain countries, such as Libya and Israel, increased water usage associated with population growth has caused a lowering of the water table and the subsequent contamination of the groundwater with saltwater from the sea. A beach provides a model to help visualize an aquifer. If a hole is dug into the sand wet or saturated sand will be located at a shallow depth; this hole is a crude well, the wet sand represents an aquifer, the level to which the water rises in this hole represents the water table. In 2013 large freshwater aquifers were discovered under continental shelves off Australia, North America and South Africa, they contain an estimated half a million cubic kilometers of "low salinity" water that could be economically processed into potable water. The reserves formed when ocean levels were lower and rainwater made its way into the ground in land areas that were not submerged until the ice age ended 20,000 years ago.
The volume is estimated to be 100 times the amount of water extracted from other aquifers since 1900. The system shows two aquifers with one aquitard between them, surrounded by the bedrock aquiclude, in contact with a gaining stream; the water table and unsaturated zone are illustrated. An aquitard is a zone within the Earth that restricts the flow of groundwater from one aquifer to another. An aquitard can sometimes, if impermeable, be called an aquiclude or aquifuge. Aquitards are composed of layers of either clay or non-porous rock with low hydraulic conductivity. Groundwater can be found at nearly every point in the Earth's shallow subsurface to some degree, although aquifers do not contain fresh water; the Earth's crust can be divided into two regions: the saturated zone or phreatic zone, where all available spaces are filled with water, the unsaturated zone, where there are still pockets of air that contain some water, but can be filled with more water. Saturated means; the definition of the water table is the surface where the pressure head is equal to atmospheric pressure.
Unsaturated conditions occur above the water table where the pressure head is negative and the water that incompletely fills the pores of the aquifer material is under suction. The water content in the unsaturated zone is held in place by surface adhesive forces and it rises above the water table by capillary action to saturate a small zone above the phreatic surface at less than atmospheric pressure; this is not the same as saturation on a water-content basis. Water content in a capillary fringe decreases with increasing distance from the phreatic surface; the capillary head depends on soil pore size. In sandy soils with larger pores, the head will be less than in clay soils with small pores; the normal capillary rise in a clayey soil can range between 0.3 and 10 m. The capillary rise of water in a small-diameter tube involves the same physical process; the water table is the level to which water will rise in a large-diameter pipe that goes down into the aquifer and is open to the atmosphere.
Aquifers are saturated regions of the subsurface that produce an economically feasible quantity of water to a well or spring. An aquitard is a zone within the Earth that restricts the flow of groundwater from one aquifer to another. A impermeable aquitard is called an aquiclude or aquifuge. Aquitards comprise layers of either clay or non-porous rock with low hydraulic conductivity. In mountainous areas, the main aquifers are unconsolidated alluvium, composed of horizontal layers of materials deposited by water processes, which in cross-section appear to be layers of alternating coarse and fine materials. Coarse materials, because of the high energy needed to move them, tend to be found nearer the source, whereas the fine-grained material will make it farther from the source (to the flatter parts of the basin or overbank areas—somet
Surface runoff is the flow of water that occurs when excess stormwater, meltwater, or other sources flows over the Earth's surface. This might occur because soil is saturated to full capacity, because rain arrives more than soil can absorb it, or because impervious areas send their runoff to surrounding soil that cannot absorb all of it. Surface runoff is a major component of the water cycle, it is the primary agent in soil erosion by water. Runoff that occurs on the ground surface before reaching a channel is called a nonpoint source. If a nonpoint source contains man-made contaminants, or natural forms of pollution the runoff is called nonpoint source pollution. A land area which produces runoff that drains to a common point is called a drainage basin; when runoff flows along the ground, it can pick up soil contaminants including petroleum, pesticides, or fertilizers that become discharge or nonpoint source pollution. In addition to causing water erosion and pollution, surface runoff in urban areas is a primary cause of urban flooding which can result in property damage and mold in basements, street flooding.
Surface runoff glaciers. Snow and glacier melt occur only in areas cold enough for these to form permanently. Snowmelt will peak in the spring and glacier melt in the summer, leading to pronounced flow maxima in rivers affected by them; the determining factor of the rate of melting of snow or glaciers is both air temperature and the duration of sunlight. In high mountain regions, streams rise on sunny days and fall on cloudy ones for this reason. In areas where there is no snow, runoff will come from rainfall. However, not all rainfall will produce runoff. On the ancient soils of Australia and Southern Africa, proteoid roots with their dense networks of root hairs can absorb so much rainwater as to prevent runoff when substantial amounts of rain fall. In these regions on less infertile cracking clay soils, high amounts of rainfall and potential evaporation are needed to generate any surface runoff, leading to specialised adaptations to variable streams; this occurs when the rate of rainfall on a surface exceeds the rate at which water can infiltrate the ground, any depression storage has been filled.
This is called flooding Hortonian overland flow, or unsaturated overland flow. This more occurs in arid and semi-arid regions, where rainfall intensities are high and the soil infiltration capacity is reduced because of surface sealing, or in paved areas; this occurs in city areas where pavements prevent water from flooding. When the soil is saturated and the depression storage filled, rain continues to fall, the rainfall will produce surface runoff; the level of antecedent soil moisture is one factor affecting the time. This runoff is called saturated overland flow or Dunne runoff. Soil retains a degree of moisture after a rainfall; this residual water moisture affects the soil's infiltration capacity. During the next rainfall event, the infiltration capacity will cause the soil to be saturated at a different rate; the higher the level of antecedent soil moisture, the more the soil becomes saturated. Once the soil is saturated, runoff occurs. After water infiltrates the soil on an up-slope portion of a hill, the water may flow laterally through the soil, exfiltrate closer to a channel.
This is called throughflow. As it flows, the amount of runoff may be reduced in a number of possible ways: a small portion of it may evapotranspire. Any remaining surface water flows into a receiving water body such as a river, estuary or ocean. Urbanization increases surface runoff by creating more impervious surfaces such as pavement and buildings that do not allow percolation of the water down through the soil to the aquifer, it is instead forced directly into streams or storm water runoff drains, where erosion and siltation can be major problems when flooding is not. Increased runoff reduces groundwater recharge, thus lowering the water table and making droughts worse for agricultural farmers and others who depend on the water wells; when anthropogenic contaminants are dissolved or suspended in runoff, the human impact is expanded to create water pollution. This pollutant load can reach various receiving waters such as streams, lakes and oceans with resultant water chemistry changes to these water systems and their related ecosystems.
A 2008 report by the United States National Research Council identified urban stormwater as a leading source of water quality problems in the U. S; as humans continue to alter the climate through the addition of greenhouse gases to the atmosphere, precipitation patterns are expected to change as the atmospheric capacity for water vapor increases. This will have direct consequences on runoff amounts. Surface runoff can cause erosion of the Earth's surface. There are four main types of soil erosion by water: splash erosion, sheet erosion, rill erosion and gully erosion. Splash erosion is the result of mechanical collision of raindrops with the soil surface: soil particles which are dislodged by the impact move with the surface runoff. Sheet erosion is the overland transport of sediment by runoff without a well d
A seep or flush is a moist or wet place where water groundwater, reaches the earth's surface from an underground aquifer. Seeps are not of sufficient volume to be flowing beyond their above-ground location, they are part of the limnology-geomorphology system. Like a higher volume spring, the water is only from underground sources. Seeps occur in lower elevation areas because water runs downhill, but can happen higher up if the groundwater present is abundant enough. Along with natural seeps, man made; this method can be useful for survival purposes and helps the local wildlife by adding another water source to the area. Seeps form a puddle, are important for small wildlife and butterfly habitat and moisture needs; when they support mud-puddling many butterfly species can obtain nutrients such as salts and amino acids, including some types that are endemic endangered species. Seep is used in environmental sciences to define an exfiltration zone where contaminated water, e.g. from waste dumps, leaves a waste system area.
Seeps are important smaller wildlife water sources, indicated by lower riparian vegetation. Seeps can contribute to streams. If a stream is flowing below a water table the stream receives contributions from the ground water via seepage; this allows for a drainage of the ground water along with creating a more substantial stream to flow. The seep could be effective during a rain less period of the area in which the seep can prolong the stream’s flow by adding water from the groundwater. Mud-puddling Rill Riparian zone restoration Soil mechanics: Permeability and seepage Meinzer, Oscar E. ed. Hydrology. New York: Dover, 1949. Print