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93-536: An ephemeral stream is that which only exists following precipitation . They are not the same as intermittent or seasonal waterbodies, which exist for longer periods, but not all year round. Ephemeral streams can be difficult to "conceptually defin[e]"; those that are discontinuous, due to altering between aggradation or degradation, have the appearance of continual change. Furthermore, the characteristics of terrain and rainfall are profound in affecting ephemeral streams. Ephemeral waterbodies experience formative change upon

186-433: A waka concerning death. Ephemerality has received increased attention from modern academics, in fields such as: literary studies , art history , book history, digital media studies , performance studies – "and the 'archival turn' in the humanities as a whole". The ephemerality of dance has engendered concern since at least the sixteenth century. Curators of modern and contemporary art have increasingly expressed

279-424: A lake , bay or ocean but joins another river (a parent river). Sometimes also called a branch or fork. A distributary , or a distributary channel , is a stream that branches off and flows away from a main stream channel, and the phenomenon is known as river bifurcation . Distributaries are common features of river deltas , and are often found where a valleyed stream enters wide flatlands or approaches

372-450: A region is ephemeral. Stream A stream is a continuous body of surface water flowing within the bed and banks of a channel . 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 usually called rivers , while smaller, less voluminous and more intermittent streams are known as streamlets , brooks or creeks . The flow of

465-403: A bed armor layer, and other depositional features, plus well defined banks due to bank erosion, are good identifiers when assessing for perennial streams. Particle size will help identify a perennial stream. Perennial streams cut through the soil profile, which removes fine and small particles. By assessing areas for relatively coarse material left behind in the stream bed and finer sediments along

558-658: A continuous aquatic habitat until they reach maturity. Crayfish and other crustaceans , snails , bivalves (clams), and aquatic worms also indicate the stream is perennial. These require a persistent aquatic environment for survival. Fish and amphibians are secondary indicators in assessment of a perennial stream because some fish and amphibians can inhabit areas without persistent water regime. When assessing for fish, all available habitat should be assessed: pools, riffles, root clumps and other obstructions. Fish will seek cover if alerted to human presence, but should be easily observed in perennial streams. Amphibians also indicate

651-470: A continuous or intermittent stream. The same non-perennial channel might change characteristics from intermittent to ephemeral over its course. Washes can fill up quickly during rains, and there may be a sudden torrent of water after a thunderstorm begins upstream, such as during monsoonal conditions. In the United States, an intermittent or seasonal stream is one that only flows for part of

744-422: A drainage network. Although each tributary has its own source, international practice is to take the source farthest from the river mouth as the source of the entire river system, from which the most extended length of the river measured as the starting point is taken as the length of the whole river system, and that furthest starting point is conventionally taken as the source of the whole river system. For example,

837-577: A hugely successful aggregator of ephemeral media". In 2009, Ian Christie considered that a substantial amount of modern media, aligned with "rapid proliferati[on]", "may prove much more ephemeral than the flip-book ". Wang Tao , Stevens and Rubem Fonseca evoked ephemerality via female characters; Virginia Woolf used the rainbow as a symbol whereas grass occupies a similar role in the Bible; F. Scott Fitzgerald and John Keats elicited melancholic ephemerality in showcases of consumption . Historically,

930-798: A large portion of Europe drains to the endorheic Caspian Sea, Europe's wet climate means it contains relatively few terminal lakes itself: any such basin is likely to continue to fill until it reaches an overflow level connecting it with an outlet or erodes the barrier blocking its exit. There are some seemingly endorheic lakes, but they are cryptorheic, being drained either through manmade canals , via karstic phenomena, or other subsurface seepage. A few minor true endorheic lakes exist in Spain (e.g. Laguna de Gallocanta , Estany de Banyoles ), Italy , Cyprus ( Larnaca and Akrotiri salt lakes) and Greece . Many small lakes and ponds in North Dakota and

1023-647: A matter of decades. Furthermore, ephemerality can be perceived as defiance of value or durability; common uses of the term indicate a "complicated relationship between temporality and value". Ephemerality is a matter of varying scale and can affect the entire spectrum of literature, from a "finely bound" Bible to a "hastily printed" handbill: "Paper is the medium of permanence and ephemerality at once". Due to them often outlasting their expressed purpose, these objects can be perceived as temporal and ontological oddities; ephemerality has been described as constitutionally liminal. Ephemerality has been seen as indicative of epochs like

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1116-709: A mountain range, cutting off water egress to the ocean. The inland water flows into dry watersheds where the water evaporates, leaving a high concentration of minerals and other inflow erosion products. Over time this input of erosion products can cause the endorheic lake to become relatively saline (a " salt lake "). Since the main outflow pathways of these lakes are chiefly through evaporation and seepage, endorheic lakes are usually more sensitive to environmental pollutant inputs than water bodies that have access to oceans, as pollution can be trapped in them and accumulate over time. Endorheic regions can occur in any climate but are most commonly found in desert locations. This reflects

1209-404: A path into mines or other underground chambers. According to official U.S. definitions, the channels of intermittent streams are well-defined, as opposed to ephemeral streams, which may or may not have a defined channel, and rely mainly on storm runoff, as their aquatic bed is above the water table . An ephemeral stream does not have the biological, hydrological, and physical characteristics of

1302-412: A perennial stream and include tadpoles , frogs , salamanders , and newts . These amphibians can be found in stream channels, along stream banks, and even under rocks. Frogs and tadpoles usually inhabit shallow and slow moving waters near the sides of stream banks. Frogs will typically jump into water when alerted to human presence. Well defined river beds composed of riffles, pools, runs, gravel bars,

1395-483: A perennial stream, fine sediment may cling to riparian plant stems and tree trunks. Organic debris drift lines or piles may be found within the active overbank area after recent high flow. Streams, headwaters, and streams flowing only part of the year provide many benefits upstream and downstream. They defend against floods, remove contaminants, recycle nutrients that are potentially dangerous as well as provide food and habitat for many forms of fish. Such streams also play

1488-523: A redistribution of water from these hydrologically landlocked basins such that endorheic water loss has contributed to sea level rise , and it is estimated that most of the terrestrial water lost ends up in the ocean. In regions such as Central Asia, where people depend on endorheic basins and other surface water sources to satisfy their water needs, human activity greatly impacts the availability of that water. Large endorheic regions in Africa are located in

1581-456: A river network is a particularly significant element in the hydrological transmission of waterborne diseases , via a direct and indirect presence in the transmission cycle – the nature of the disease and area covered are important factors as well. Diseases like malaria , dengue fever , chikungunya , zika and schistosomiasis are found in ephemeral waterbodies due to their vectors relation and/or reliance. Examples of ephemeral streams are

1674-483: A seasonal manner. Landscapes feature ephemeral changes of both natural and man-made origin. Furrows , haystacks and sheaves are ephemeral aspects of a landscape. Plants whose life cycle is significantly less than the time of a growing season are deemed ephemeral. Winter annuals , Epilobium and Senecio vulgaris are examples of ephemeral plants. The conditions for ephemeral plants are markedly present in deserts. Animals can be ephemeral, with brine shrimp and

1767-566: A similar interest; curator of said genres Jan Schall described them as varyingly ephemeral. Ephemerality present in digital literature and poetry has seen critical analysis. Russell questioned if scholarly conceptions of "the everyday" was deeply intertwined with ephemerality, despite attention to a relation being thus far faint. Social historians and historians of sound have contended their subject's ephemerality by utilising more material forms; creative soundwork has long been subordinate to these forms on account of its ephemerality. The ephemerality of

1860-406: A slow-moving wetted channel or stagnant area. This is evidence that iron-oxidizing bacteria are present, indicating persistent expression of oxygen-depleted ground water. In a forested area, leaf and needle litter in the stream channel is an additional indicator. Accumulation of leaf litter does not occur in perennial streams since such material is continuously flushed. In the adjacent overbank of

1953-508: A social norm that "the discourse will pass and be forgotten as the past". Ephemerality is a technologically and socially reliant concept – relative and historically changing. The rudimentary technology of early radio led to the media broadcast being ephemeral and for a substantial amount of time spoken communication was ephemeral. Written communication, historically and presently, has been influenced by ephemerality. The emergence of new digital media and technology develops what we deem ephemeral, to

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2046-401: A status as long being ephemeral, acknowledged by some affected in the then-present. The ubiquity of digital media has spurred the opinion that print material is comparatively less ephemeral. Elisa New and Anna Akhmatova varyingly opined that poetry is a means of repealing mortal ephemerality, with Akhamatova invoking the aphorism ars longa, vita brevis ("skillfulness takes time and life

2139-486: A stream as intermittent, "showing interruptions in time or space". Generally, streams that flow only during and immediately after precipitation are termed ephemeral . There is no clear demarcation between surface runoff and an ephemeral stream, and some ephemeral streams can be classed as intermittent—flow all but disappearing in the normal course of seasons but ample flow (backups) restoring stream presence — such circumstances are documented when stream beds have opened up

2232-424: A stream is a critical factor in determining its character and is entirely determined by its base level of erosion. The base level of erosion is the point at which the stream either enters the ocean, a lake or pond, or enters a stretch in which it has a much lower gradient, and may be specifically applied to any particular stretch of a stream. In geological terms, the stream will erode down through its bed to achieve

2325-574: A stream is controlled by three inputs – surface runoff (from precipitation or meltwater ), daylighted subterranean water , and surfaced groundwater ( spring water ). The surface and subterranean water are highly variable between periods of rainfall. Groundwater, on the other hand, has a relatively constant input and is controlled more by long-term patterns of precipitation. The stream encompasses surface, subsurface and groundwater fluxes that respond to geological, geomorphological, hydrological and biotic controls. Streams are important as conduits in

2418-524: A thin layer called sheet wash, combined with a network of tiny rills, which together form the sheet runoff; when this water is focused in a channel, a stream is born. Some rivers and streams may begin from lakes or ponds. Freshwater's primary sources are precipitation and mountain snowmelt. However, rivers typically originate in the highlands, and are slowly created by the erosion of mountain snowmelt into lakes or rivers. Rivers usually flow from their source topographically, and erode as they pass until they reach

2511-627: A vital role in preserving our drinking water quality and supply, ensuring a steady flow of water to surface waters and helping to restore deep aquifers. The extent of land basin drained by a stream is termed its drainage basin (also known in North America as the watershed and, in British English, as a catchment). A basin may also be composed of smaller basins. For instance, the Continental Divide in North America divides

2604-414: Is a large natural stream that is much wider and deeper than a creek and not easily fordable, and may be a navigable waterway . The linear channel between the parallel ridges or bars on a shoreline beach or river floodplain, or between a bar and the shore. Also called a swale . A tributary is a contributory stream to a larger stream, or a stream which does not reach a static body of water such as

2697-809: Is contingent. Baudelaire, who considered aesthetics to be centered around an interplay of the perennial and the ephemeral, defined the artistic component of modernity by its ephemeral quality. Sarah Kofman posited that art is utilised to abate the "intolerable nature of all ephemeral things". Ephemerality has been relevant to a considerable amount of art; various artists have drawn upon the matter to explore time, memory, politics, emotions, spirituality and death. The Dada , Fluxus , Surreal, and Futurist movements all incorporated ephemerality as have Kuba , Mono-ha , and ukiyo-e . Perceptions of ephemerality vary between cultures, from melancholy and mitigation to embrace. Performance art has frequently been described as ephemeral in nature; with regards to historical performances,

2790-441: Is known as surface hydrology and is a core element of environmental geography . A brook is a stream smaller than a creek, especially one that is fed by a spring or seep . It is usually small and easily forded . A brook is characterised by its shallowness. A creek ( / k r iː k / ) or crick ( / k r ɪ k / ): In hydrography, gut is a small creek; this is seen in proper names in eastern North America from

2883-403: Is one such case, with annual precipitation of 850 mm (33 in) and characterized by waterlogged soils that require draining. Endorheic regions tend to be far inland with their boundaries defined by mountains or other geological features that block their access to oceans. Since the inflowing water can evacuate only through seepage or evaporation, dried minerals or other products collect in

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2976-444: Is short"). Ephemeral objects chiefly disappear; when preserved it is often knowingly, having been "rescued from ephemerality", though this practice is still fraught with uncertainty and an object's ephemerality may only be suspended, thus still capable of being transitory. The legacy of ephemerality often manifests as "traces, glimmers, residues, and specks of things". Literature may contest, document or approximate ephemerality although

3069-425: Is sometimes termed a "young" or "immature" stream, and the later state a "mature" or "old" stream. Meanders are looping changes of direction of a stream caused by the erosion and deposition of bank materials. These are typically serpentine in form. Typically, over time the meanders gradually migrate downstream. If some resistant material slows or stops the downstream movement of a meander, a stream may erode through

3162-456: Is usually called a creek and marked on topographic maps with a solid blue line. There are five generic classifications: "Macroinvertebrate" refers to easily seen invertebrates , larger than 0.5 mm, found in stream and river bottoms. Macroinvertebrates are larval stages of most aquatic insects and their presence is a good indicator that the stream is perennial. Larvae of caddisflies , mayflies , stoneflies , and damselflies require

3255-627: The Bonneville flood . The Malheur / Harney lake system in Oregon is normally cut off from drainage to the ocean, but has an outflow channel to the Malheur River . This is presently dry, but may have flowed as recently as 1,000 years ago. Examples of relatively humid regions in endorheic basins often exist at high elevation. These regions tend to be marshy and are subject to substantial flooding in wet years. The area containing Mexico City

3348-1346: The Luni river in Rajasthan , India , Ugab River in Southern Africa , and a number of small ephemeral watercourses that drain Talak in northern Niger . Other notable ephemeral rivers include the Todd River and Sandover River in Central Australia as well as the Son River , Batha River , and the Trabancos River . Any endorheic basin , or closed basin, that contains a playa (dry lake) at its drainage lowpoint can become an ephemeral lake. Examples include Lake Carnegie in Western Australia , Lake Cowal in New South Wales , Mystic Lake and Rogers Lake in California, and Sevier Lake in Utah . Even

3441-942: The Sahara Desert , the Sahel , the Kalahari Desert , and the East African Rift : Endorheic lakes exist in Antarctica's McMurdo Dry Valleys , Victoria Land , the largest ice-free area. Much of Western and Central Asia is a giant endorheic region made up of a number of contiguous closed basins. The region contains several basins and terminal lakes, including: Other endorheic lakes and basins in Asia include: Australia , being very dry and having exceedingly low runoff ratios due to its ancient soils, has many endorheic drainages. The most important are: Though

3534-691: The Tombigbee River basin. Continuing in this vein, a component of the Mississippi River basin is the Ohio River basin, which in turn includes the Kentucky River basin, and so forth. Stream crossings are where streams are crossed by roads , pipelines , railways , or any other thing which might restrict the flow of the stream in ordinary or flood conditions. Any structure over or in a stream which results in limitations on

3627-713: The coastal plains around a lake or an ocean . They can also occur inland, on alluvial fans , or where a tributary stream bifurcates as it nears its confluence with a larger stream. Common terms for individual river distributaries in English-speaking countries are arm and channel . There are a number of regional names for a stream. A stream's source depends on the surrounding landscape and its function within larger river networks. While perennial and intermittent streams are typically supplied by smaller upstream waters and groundwater, headwater and ephemeral streams often derive most of their water from precipitation in

3720-488: The human condition , a phenomenon of physicality. A significant amount of living is ephemeral, considered by some as a component of everyday life: "we might best understand the ephemeral as a routine and constant force... that establishes the presence of the everyday". Ephemeral aspects are evident in communication, of both digitial and physical origin. In the digital realm, online interactions straddle permanency and ephemerality, new posts proliferate such that participants adopt

3813-412: The mayfly being examples. The placenta is considered an ephemeral organ present during gestation and pregnancy . Ephemerality is a component of olfaction , breathing, speech and memory, aligned with permanency in the latter. With regards to witnessing an artwork in a museum, limited research indicates that the ephemerality of solely gazing at the artwork results in greater remembrance compared to

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3906-480: The velocity of the stream. A perennial stream is one which flows continuously all year. Some perennial streams may only have continuous flow in segments of its stream bed year round during years of normal rainfall. Blue-line streams are perennial streams and are marked on topographic maps with a solid blue line. The word "perennial" from the 1640s, meaning "evergreen," is established in Latin perennis, keeping

3999-416: The water cycle , instruments in groundwater recharge , and 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

4092-443: The "touch of those who would erase queer possibility". Freud considered culture as the prevailing element exempt from ephemerality. Scheibe saw the likes of live theater, travel abroad, stand-up comedy, and political pundits as engendering greater ephemerality by reducing attention spans and sense of personal history. Karl Marx and Friedrich Engels ' perception of ephemerality "represents a thoroughly modern experience". Ephemerality

4185-405: The 21st century—the advent of the telegraph , camera , and film projector instilled an understanding of ephemeral media. Scholars such as Charles Baudelaire , Georg Simmel , and Walter Benjamin saw the distinctly and intentionally ephemeral practice of fashion as emblematic of modernity. Scholars have described ephemerality as affixed to the present , a present that is ephemeral insofar as it

4278-453: The French word endoréisme , which combines endo- ( Ancient Greek : ἔνδον éndon 'within') and ῥεῖν rheîn 'flow'. Endorheic lakes (terminal lakes) are bodies of water that do not flow into an ocean or a sea. Most of the water that falls to Earth percolates into the oceans and the seas by way of a network of rivers, lakes, and wetlands . Analogous to endorheic lakes is

4371-513: The High Castle and The Plot Against America depict Americana and the nation itself as ephemeral. Ephemerality has been central to Buddhism; Yogācāra teaches a version of ontology that centers around universal ephemerality . Ephemerality has been identified as relevant to queer cultures ; José Esteban Muñoz argued that queerness and ephemerality are intertwined, as the former has been expressed in methods which are prone to fade upon

4464-840: The Mid-Atlantic states (for instance, The Gut in Pennsylvania, Ash Gut in Delaware, and other streams) down into the Caribbean (for instance, Guinea Gut , Fish Bay Gut , Cob Gut , Battery Gut and other rivers and streams in the United States Virgin Islands , in Jamaica (Sandy Gut, Bens Gut River, White Gut River), and in many streams and creeks of the Dutch Caribbean ). A river

4557-646: The Printing Revolution, a greater expansion thereof, the Baroque era, the Victorian era , the Georgian era , modernity , or the "emergent post-print age". The likes of food, clothes, novels, zines , illnesses, breath, regimes, persons, glass, ash and ephemera have been said to illustrate and/or be affected by ephemerality. The new media of the 20th century conditioned perceptions of ephemerality in

4650-533: The atmosphere either by evaporation from soil and water bodies, or by plant evapotranspiration. By infiltration some of the water sinks into the earth and becomes groundwater, much of which eventually enters streams. Most precipitated water is partially bottled up by evaporation or freezing in snow fields and glaciers. The majority of the water flows as a runoff from the ground; the proportion of this varies depending on several factors, such as climate, temperature, vegetation, types of rock, and relief. This runoff begins as

4743-493: The balance between tectonic subsidence and rates of evaporation and sedimentation. Where the basin floor is dropping more rapidly than water and sediments can accumulate, any lake in the basin will remain below the sill level (the level at which water can find a path out of the basin). Low rainfall or rapid evaporation in the watershed favor this case. In areas where rainfall is higher, riparian erosion will generally carve drainage channels (particularly in times of flood), or cause

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4836-525: The base level of erosion throughout its course. If this base level is low, then the stream will rapidly cut through underlying strata and have a steep gradient, and if the base level is relatively high, then the stream will form a flood plain and meander. Typically, streams are said to have a particular elevation profile , beginning with steep gradients, no flood plain, and little shifting of channels, eventually evolving into streams with low gradients, wide flood plains, and extensive meanders. The initial stage

4929-597: The base stage of erosion. The scientists have offered a way based on data to define the origin of the lake. A classified sample was the one measured by the Chinese researchers from the University of Chinese Academy of Sciences. As an essential symbol of the river formation environment, the river source needs an objective and straightforward and effective method of judging . A calculation model of river source catchment area based on critical support flow (CSD) proposed, and

5022-460: The basin, eventually making the water saline and also making the basin vulnerable to pollution. Continents vary in their concentration of endorheic regions due to conditions of geography and climate. Australia has the highest percentage of endorheic regions at 21 per cent while North America has the least at five per cent. Approximately 18 per cent of the Earth's land drains to endorheic lakes or seas,

5115-537: The class of bodies of water located in closed watersheds (endorheic watersheds) where the local topography prevents the drainage of water into the oceans and the seas. These endorheic watersheds (containing water in rivers or lakes that form a balance of surface inflows, evaporation and seepage) are often called sinks. Endorheic lakes are typically located in the interior of a landmass, far from an ocean, and in areas of relatively low rainfall. Their watersheds are often confined by natural geologic land formations such as

5208-501: The creations were subject to being abruptly disregarded due to the cascading "gaze of fashion". Wallace Stevens adjusted his poetic standards due to a "perception of ephemerality" that living in New York City instigated. Art Spiegelman asserted that the format of comics, even during degradation, defies ephemerality, although they have been deemed as such. Women's writing, the likes of diaries and political pamphlets, have amassed

5301-564: The degree that a lake no longer forms. Even most permanent endorheic lakes change size and shape dramatically over time, often becoming much smaller or breaking into several smaller parts during the dry season. As humans have expanded into previously uninhabitable desert areas, the river systems that feed many endorheic lakes have been altered by the construction of dams and aqueducts. As a result, many endorheic lakes in developed or developing countries have contracted dramatically, resulting in increased salinity, higher concentrations of pollutants, and

5394-440: The disruption of ecosystems. Even within exorheic basins, there can be "non-contributing", low-lying areas that trap runoff and prevent it from contributing to flows downstream during years of average or below-average runoff. In flat river basins, non-contributing areas can be a large fraction of the river basin, e.g. Lake Winnipeg 's basin. A lake may be endorheic during dry years and can overflow its basin during wet years, e.g.,

5487-513: The driest and lowest place in North America, Death Valley (more specifically Badwater Basin ), became flooded with a short-lived ephemeral lake in the spring of 2005. Costelloe et al. (2009) describes salt lakes found in the arid zone of Australia as profoundly ephemeral. There are also ephemeral islands such as Banua Wuhu and Home Reef . These islands appear when volcanic activity increases their height above sea level, but disappear over several years due to wave erosion. Bassas da India , on

5580-639: The ecosystems of ephemeral pools. Ephemeral habitat patches have repeatedly been assessed as detrimental to metapopulation persistence, although metapopulations are not always negatively affected by ephemeral landscapes. These patches occur as a result of the habitat's turnover. Ephemeral streams have, relative to their perennial counterparts, lower species richness; the streams are "potentially demanding" for inhabitants, although some species do reside. Ephemeral rivers sometimes form waterholes in geological depressions or areas scoured by erosion, and are common in arid regions of Australia. The ephemerality of

5673-469: The end of a hydroperiod. "Due to lack of continuous hydrology data, the designation of sites as ephemeral or intermittent is necessarily tenuous". Ephemeral streams feature a low degree of hydrological connectivity. Small wetlands are often ephemeral and ephemeral ecosystems are often aquatic; ephemeral wetlands , streams and ponds are a varied and global occurrence. In northeastern United States , ephemeral freshwater systems are abundant and are "critical to

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5766-449: The ephemerality of dreams was utilised in ample East Asian literature as a metaphor for immaterial reality whereas Baroque writings depicted the matter as analogous to life. Scholar of comparative literature Stuart Lasine noted that writers have frequently invoked ephemerality as a negative aspect of the human condition . Ephemerality was profound to Dōgen and was intertwined with sorrow and regret; he used "the imagery of ephemerality" in

5859-707: The flow is reduced to a trickle or less. Typically torrents have Apennine rather than Alpine sources, and in the summer they are fed by little precipitation and no melting snow. In this case the maximum discharge will be during the spring and autumn. An intermittent stream can also be called a winterbourne in Britain, a wadi in the Arabic -speaking world or torrente or rambla (this last one from arabic origin) in Spain and Latin America. In Australia, an intermittent stream

5952-447: The form of rain and snow. Most of this precipitated water re-enters the atmosphere by evaporation from soil and water bodies, or by the evapotranspiration of plants. Some of the water proceeds to sink into the earth by infiltration and becomes groundwater, much of which eventually enters streams. Some precipitated water is temporarily locked up in snow fields and glaciers , to be released later by evaporation or melting. The rest of

6045-783: The former Tulare Lake . Because the Earth's climate has recently been through a warming and drying phase with the end of the Ice Ages, many endorheic areas such as Death Valley that are now dry deserts were large lakes relatively recently. During the last ice age, the Sahara may have contained lakes larger than any now existing. Climate change coupled with the mismanagement of water in these endorheic regions has led to devastating losses in ecosystem services and toxic surges of pollutants. The desiccation of saline lakes produces fine dust particles that impair agriculture productivity and harm human health. Anthropogenic activity has also caused

6138-563: The immateral nature means that there can only be an approximation: "In other words, there must always be an ephemeral beyond the ephemeral". Film has been used to document and combat ephemeral aspects of human development. Digital media's encompassing archival process means that information of varying importance can either be affixed or ephemeral, the former seen as the more generally common outcome. Digital personas, on account of precariousness and whim, can be entirely ephemeral, without any record. Grey literature has prove particularly vulnerable to

6231-457: The internet and features that engender ephemerality, such as link rot , has elicited concern in regards to scholarly practice. Like a blade of grass, My frail body Treading the path to Kyoto Seeming to wander Amid the cloudy mist on Kinobe Pass. Dōgen . Ephemerality has been studied in the context of dancing. Witnessing a dance that will be rendered ephemeral is resultingly commodified and of greater desire to prospecting audiences;

6324-585: The internet's ephemerality. Ephemeral acquired its common meaning of short-living in the mid-19th century and has connotations of passing time, fragility, change, disappearance, transformation, and the "philosophically ultimate vision of our own existence". Sarah Kofman questioned if "the beauty that conceals the evanescent nature of all things were itself ephemeral". Rather than melancholic, Sigmund Freud and Walter Pater viewed ephemerality as valuable; awareness and acceptance were to Freud commendable. Multiple scholars have viewed ephemerality as intrinsic to

6417-532: The lake has significant feeder rivers. The Kagera River, which flows into Lake Victoria near Bukoba's Tanzanian town , is the longest feeder, though sources do not agree on which is the Kagera's longest tributary and therefore the Nile's most remote source itself. To qualify as a stream, a body of water must be either recurring or perennial. Recurring (intermittent) streams have water in the channel for at least part of

6510-422: The largest of these land areas being the interior of Asia. In deserts, water inflow is low and loss to solar evaporation high, drastically reducing the formation of complete drainage systems . In the extreme case, where there is no discernible drainage system, the basin is described as arheic . Closed water flow areas often lead to the concentration of salts and other minerals in the basin. Minerals leached from

6603-404: The likes of airports, malls, supermarkets, office blocks, and hotels thus rendering them, per his definition, " non-places ". Architecture scholar Anastasia Karandinou argued that the practice's modern relation to ephemerality correlated with digital media's evolution, which she says has enabled new conceptions of space and everyday thinking. Of an indefinite and contentious nature, the definition of

6696-683: The mainly easterly-draining Atlantic Ocean and Arctic Ocean basins from the largely westerly-flowing Pacific Ocean basin. The Atlantic Ocean basin, however, may be further subdivided into the Atlantic Ocean and Gulf of Mexico drainages. (This delineation is termed the Eastern Continental Divide .) Similarly, the Gulf of Mexico basin may be divided into the Mississippi River basin and several smaller basins, such as

6789-760: The maintenance of forest biodiversity". Hydroperiod, predation, competition and food availability are among the "highly heterogeneous" elements of these features. In tropical biomes, amphibians often reside in ephemeral habitats during dry seasons; opportunistic species utilise similar and ephemeral habitats for food, sleep or mating. Environments akin to ephemeral ponds can be very significant sites of reproduction for amphibians; many other organism make use of ephemeral ponds, pools and streams to breed. Those which do utilise these sites are significantly constrained by time thus they mature, reproduce or disperse before evaporation. Ephemeral pools lasting only days or weeks are exclusively used for breeding by Fletcher's frog regardless of

6882-412: The meaning as "everlasting all year round," per "over" plus annus "year." This has been proved since the 1670s by the "living years" in the sense of botany. The metaphorical sense of "enduring, eternal" originates from 1750. They are related to "perennial." See biennial for shifts in vowels. Perennial streams have one or more of these characteristics: Absence of such characteristics supports classifying

6975-741: The movement of fish or other ecological elements may be an issue. Endorheic basin An endorheic basin ( / ˌ ɛ n d oʊ ˈ r iː . ɪ k / EN -doh- REE -ik ; also endoreic basin and endorreic basin ) is a drainage basin that normally retains water and allows no outflow to other external bodies of water (e.g. rivers and oceans ); instead, the water drainage flows into permanent and seasonal lakes and swamps that equilibrate through evaporation . Endorheic basins are also called closed basins , terminal basins , and internal drainage systems . Endorheic regions contrast with open lakes (exorheic regions), where surface waters eventually drain into

7068-453: The neck between two legs of a meander to become temporarily straighter, leaving behind an arc-shaped body of water termed an oxbow lake or bayou . A flood may also cause a meander to be cut through in this way. The stream load is defined as the solid matter carried by a stream. Streams can carry sediment, or alluvium. The amount of load it can carry (capacity) as well as the largest object it can carry (competence) are both dependent on

7161-462: The ocean. In general, water basins with subsurface outflows that lead to the ocean are not considered endorheic; but cryptorheic . Endorheic basins constitute local base levels , defining a limit of the erosion and deposition processes of nearby areas. Endorheic water bodies include the Caspian Sea , which is the world's largest inland body of water. The term endorheic derives from

7254-596: The origin of the Nile River is the confluence of the White Nile and the Blue Nile, but the source of the whole river system is in its upper reaches. If there is no specific designation, "length of the Nile" refers to the "river length of the Nile system", rather than to the length of the Nile river from the point where it is formed by a confluence of tributaries. The Nile's source is often cited as Lake Victoria, but

7347-460: The other hand, is a near-sea level island that appears only at low tide. On account of changing demarcation, shores exist as ephemeral. Only a small amount of southern Costa Rica 's secondary forests reach maturity, indicating that they may be "generally ephemeral". Deciduous forests, via the seasonal change of leaves, are subject to natural ephemeral changes. Ephemeral pools located in forests are commonly known as "vernal pools", often lasting in

7440-457: The point that ephemerality is perhaps an "outdated concept". Within the context of modern media dissemination, YouTube videos, viral emails and photos have been identified as ephemeral; as have means of advertising, both physical and digital and the internet collectively. Ephemeral media has been described as that which is brief in duration and/or circulation, adjacent to "the primary texts of contemporary entertainment culture". YouTube has "become

7533-598: The precarious survival of offspring. Fletcher's frogs use these sites to exploit them, by-passing predation and competition. Tadpoles , however, are hindered by ephemeral streams, as can surrounding systems. Limited and unpredictable food availability means ephemeral waterbodies may be rife with cannibalism . Specific adaptions to ephemeral pools are abundant. Human alterations to the habitats of ephemeral nectar that flying foxes consume has led to urban migration. Climate change significantly affects ephemeral freshwater systems and changes in climates may be precisely identified by

7626-469: The relationship between CSA and CSD with a minimum catchment area established. Using the model for comparison in two basins in Tibet (Helongqu and Niyang River White Water), the results show that the critical support flow (Qc) of the housing dragon song is 0.0028 m /s. At the same time, the white water curvature is 0.0085 m /s. Besides, the critical support flow can vary with hydrologic climate conditions, and

7719-548: The resulting memory from taking a photograph. Psychologists have studied why ephemerality may improve memory retention; social psychologist Karl E. Scheibe, conversely, suggested that ephemeral images are only memorable if repeated. The ephemerality of memory leads objects to assume the function of begeting remembrance on account of their greater stability. Objects which are ephemeral, per one perspective, are those whose compositional material experience chemical or physical changes and are thus permanently altered; this process occurs in

7812-771: The same is true of fairs . Muñoz posited that the physical proximation of dance, which coupled with the "shared rhythm", results in a unified yet ephemeral status of those engaged. La Sylphide sees ephemerality as a notable theme. Professor of Dance Mark Franko contended that the artform is approaching a state of being "post-ephemeral" while Diane Taylor viewed the lasting impact a performance may have as negating notions of ephemerality. The documentation of other ephemeral events: protests, installations, exhibitions, are often meager – public events, of varying size, naturally generate ephemeral material. "[Ephemerality] and disposability" have been perceived as components "of an American ethos"; alternative history novels such as The Man in

7905-425: The side of the stream or within the floodplain will be a good indicator of persistent water regime. A perennial stream can be identified 48 hours after a storm. Direct storm runoff usually has ceased at this point. If a stream is still flowing and contributing inflow is not observed above the channel, the observed water is likely baseflow. Another perennial stream indication is an abundance of red rust material in

7998-599: The surrounding rocks are deposited in the basin, and left behind when the water evaporates. Thus endorheic basins often contain extensive salt pans (also called salt flats, salt lakes, alkali flats , dry lake beds, or playas). These areas tend to be large, flat hardened surfaces and are sometimes used for aviation runways , or land speed record attempts, because of their extensive areas of perfectly level terrain. Both permanent and seasonal endorheic lakes can form in endorheic basins. Some endorheic basins are essentially stable because climate change has reduced precipitation to

8091-415: The traces: playbills, scrapbooks of newspaper clippings and material artifacts are themselves ephemeral. Literature is ephemeral, including definitions and "all printed texts". Ephemeral was first used colloquially in reference to printed matters. By 1750, an "expansion of all kinds of ephemeral print" had occurred. Hazlitt contended that such ephemerality was the result of widespread aestheticism , thus

8184-655: The vital support flow Qc in wet areas (white water) is larger than in semi-arid regions (heap slot). The proposed critical support flow (CSD) concept and model method can be used to determine the hydrographic indicators of river sources in complex geographical areas, and it can also reflect the impact of hydrologic climate change on river recharge in different regions. The source of a river or stream (its point of origin) can consist of lakes, swamps, springs, or glaciers. A typical river has several tributaries; each of these may be made up of several other smaller tributaries, so that together this stream and all its tributaries are called

8277-512: The water flows off the land as runoff, the proportion of which varies according to many factors, such as wind, humidity, vegetation, rock types, and relief. This runoff starts as a thin film called sheet wash, combined with a network of tiny rills, together constituting sheet runoff; when this water is concentrated in a channel, a stream has its birth. Some creeks may start from ponds or lakes. The streams typically derive most of their water from rain and snow precipitation. Most of this water re-enters

8370-495: The water level in the terminal lake to rise until it finds an outlet, breaking the enclosed endorheic hydrological system's geographical barrier and opening it to the surrounding terrain. The Black Sea was likely such a lake, having once been an independent hydrological system before the Mediterranean Sea broke through the terrain separating the two. Lake Bonneville was another such lake, overflowing its basin in

8463-521: The year and is marked on topographic maps with a line of blue dashes and dots. A wash , desert wash, or arroyo is normally a dry streambed in the deserts of the American Southwest , which flows after sufficient rainfall. In Italy, an intermittent stream is termed a torrent ( Italian : torrente ). In full flood the stream may or may not be "torrential" in the dramatic sense of the word, but there will be one or more seasons in which

8556-402: The year. A stream of the first order is a stream which does not have any other recurring or perennial stream feeding into it. When two first-order streams come together, they form a second-order stream. When two second-order streams come together, they form a third-order stream. Streams of lower order joining a higher order stream do not change the order of the higher stream. The gradient of

8649-601: Was furthermore prominent in the late 20th century, on account of multiple social features; Reiko Tomii described ephemerality as a "defining issue of the 1960s". In the 21st century, ephemerality "continues to signify concerns about the overflow of information, its evanescence, and questions of what or should be preserved". David Harvey defined postmodernism as "a total acceptance of ephemerality". Architecture of an ephemeral nature appears as increasingly commonplace, on account of global and capricious hyper-mobility and mass displacement. Marc Augé observed ephemerality as key to

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