Misplaced Pages

#684315

86-440: The river is an 18 km meandering river with 30 tributaries and various morphological features. Owing to the size and area of its location, the river has a history of disastrous floods . The Kwikwetlem first nations were the first humans to live in the area, followed by settlers thousands of years later. After settlers arrived the river would soon be altered many times for the resources it holds. The most recent changes are

172-478: A "special concern" under COSEWIC . In 2014, a Species at Risk project was completed and both the great blue heron as well as the blue-listed red-legged frog were identified along the Coquitlam River. Red-legged frogs were observed in the upper reaches, however possible breeding habitat was also identified and recommended as a viable location for restoration. Due to the sensitive nature of this amphibian , it

258-484: A couple days following larger precipitation events. The river also has a long history of flooding with the largest known flood on record occurring in 1921. This flood resulted in a discharge of 665 m/s and the second largest flood occurred in 1961 with a discharge of 476 m/s. The Coquitlam River is a part of the Fraser Lowland ecosection and Coastal Western Hemlock biogeoclimatic zone. The undeveloped land surrounding

344-511: A critical part of this ecosystem, providing a source of food for species such as black bears and bald eagles . After spawning, the fish carcasses decompose on banks and release nutrients in the soil for vegetation such as salmonberries . Species status's are classified under the BC's conservation ranks. Red list: "Any species or ecosystem that is at risk of being lost ( extirpated , endangered or threatened )". Blue list: "Any species or ecosystem that

430-554: A drying pond or an entire ocean, it can be said to be extirpated or locally extinct in that pond or ocean. A particular total world population can be more or less arbitrarily divided into 'stocks' or 'subpopulations', defined by political or other geographical delimitations. For example, the Cetacean Specialist Group of the International Union for Conservation of Nature (IUCN) has assessed the conservation status of

516-452: A maximum at the apex to zero at a crossing point (straight line), also called an inflection, because the curvature changes direction in that vicinity. The radius of the loop is the straight line perpendicular to the down-valley axis intersecting the sinuous axis at the apex. As the loop is not ideal, additional information is needed to characterize it. The orientation angle is the angle between sinuous axis and down-valley axis at any point on

602-405: A meander because helicoidal flow of water keeps the bank washed clean of loose sand, silt, and sediment and subjects it to constant erosion. As a result, the meander erodes and migrates in the direction of the outside bend, forming the cut bank. As the cut bank is undermined by erosion, it commonly collapses as slumps into the river channel. The slumped sediment, having been broken up by slumping,

688-411: A meander is part of an entrenched river or part of a freely meandering river within a floodplain, the term slip-off slope can refer to two different fluvial landforms that comprise the inner, convex, bank of a meander loop. In case of a freely meandering river on a floodplain, a slip-off slope is the inside, gently sloping bank of a meander on which sediments episodically accumulate to form a point bar as

774-431: A meandering watercourse is termed meander geometry or meander planform geometry. It is characterized as an irregular waveform . Ideal waveforms, such as a sine wave , are one line thick, but in the case of a stream the width must be taken into consideration. The bankfull width is the distance across the bed at an average cross-section at the full-stream level, typically estimated by the line of lowest vegetation. As

860-401: A non-mathematical utility as well. Streams can be placed in categories arranged by it; for example, when the index is between 1 and 1.5 the river is sinuous, but if between 1.5 and 4, then meandering. The index is a measure also of stream velocity and sediment load, those quantities being maximized at an index of 1 (straight). Local extinction Local extinction , also extirpation , is

946-628: A region as the ecosystem matures and reaches a climax community . A local extinction can be useful for research: in the case of the bay checkerspot butterfly , scientists, including Paul R. Ehrlich , chose not to intervene as a population disappeared from an area in order to study the process. Many crocodilian species have experienced localized extinction, particularly the saltwater crocodile ( Crocodylus porosus ), which has been extirpated from Vietnam, Thailand, Java, and many other areas. Major environmental events, such as volcanic eruptions, may lead to large numbers of local extinctions, such as with

SECTION 10

#1732836909685

1032-428: A river meanders. This type of slip-off slope is located opposite the cutbank. This term can also be applied to the inside, sloping bank of a meandering tidal channel. In case of an entrenched river, a slip-off slope is a gently sloping bedrock surface that rises from the inside, concave bank of an asymmetrically entrenched river. This type of slip-off slope is often covered by a thin, discontinuous layer of alluvium. It

1118-413: A self-intensifying process...in which greater curvature results in more erosion of the bank, which results in greater curvature..." The cross-current along the floor of the channel is part of the secondary flow and sweeps dense eroded material towards the inside of the bend. The cross-current then rises to the surface near the inside and flows towards the outside, forming the helical flow . The greater

1204-410: A species has an intrinsic extinction-ability (incidence function). Some species exploit or require transient or disturbed habitats, such as vernal pools, a human gut, or burnt woodland after forest fires , and are characterised by highly fluctuating population numbers and shifting distributional patterns. Many natural ecosystems cycle through a standard succession , pioneer species disappear from

1290-608: A species that have been reintroduced into parts of their historical range. This has happened with red wolves ( Canis rufus ) in the United States in the late 1980s and also grey wolves in Yellowstone National Park in the mid-1990s. There have been talks of reintroducing wolves in Scotland, Japan, and Mexico. When the local population of a certain species disappears from a certain geographical delimitation, whether fish in

1376-434: A symmetrical valley sides. He argues that the symmetrical valley sides are the direct result of rapid down-cutting of a watercourse into bedrock. In addition, as proposed by Rich, Thornbury argues that incised valleys with a pronounced asymmetry of cross section, which he called ingrown meanders , are the result of the lateral migration and incision of a meander during a period of slower channel downcutting . Regardless,

1462-413: A waveform the meandering stream follows the down-valley axis, a straight line fitted to the curve such that the sum of all the amplitudes measured from it is zero. This axis represents the overall direction of the stream. At any cross-section the flow is following the sinuous axis, the centerline of the bed. Two consecutive crossing points of sinuous and down-valley axes define a meander loop. The meander

1548-420: Is a meandering river with various features such as large boulders, riffles , undercut banks , sidebars, islands, oxbow lakes , large woody debris and small woody debris. The sediment that is carried in the river is composed of glacial sands , gravel , clays , silts and some boulders. The primary source of this sediment is Or Creek which supplies large amounts of cobbles, sand and silts. The Coquitlam River

1634-407: Is also located in a coastal western hemlock biogeoclimatic zone . This climatic zone and its position on a mountain means that it has a mean annual precipitation of 3498 mm. The mean daily discharge is roughly 14.35 m/s, however due to the high annual precipitation, the discharge can regularly increase to anywhere between 20 m/s and 50 m/s. These high discharge events have been known to last

1720-419: Is called lateral accretion. Lateral accretion occurs mostly during high water or floods when the point bar is submerged. Typically, the sediment consists of either sand, gravel, or a combination of both. The sediment comprising some point bars might grade downstream into silty sediments. Because of the decreasing velocity and strength of current from the thalweg of the channel to the upper surface of point bar when

1806-529: Is of special concern". Yellow list: "Any species or ecosystem that is at the least risk of being lost". The following lists are not exhaustive, and were created using personal observations as well as observations from previous habitat assessments and reports of the area. The Coquitlam River is named for the Kwikwetlem First Nations (kʷikʷəƛ̓əm) who have lived in the region for at least the last nine thousand years. kʷikʷəƛ̓əm translates to "Red fish up

SECTION 20

#1732836909685

1892-424: Is produced by the gradual outward migration of the meander as a river cuts downward into bedrock. A terrace on the slip-off slope of a meander spur, known as slip-off slope terrace , can be formed by a brief halt during the irregular incision by an actively meandering river. The meander ratio or sinuosity index is a means of quantifying how much a river or stream meanders (how much its course deviates from

1978-458: Is readily eroded and carried toward the middle of the channel. The sediment eroded from a cut bank tends to be deposited on the point bar of the next downstream meander, and not on the point bar opposite it. This can be seen in areas where trees grow on the banks of rivers; on the inside of meanders, trees, such as willows, are often far from the bank, whilst on the outside of the bend, the tree roots are often exposed and undercut, eventually leading

2064-520: Is so exceedingly winding that everything winding is called meandering.’ The Meander River is south of Izmir, east of the ancient Greek town of Miletus , now Milet, Turkey. It flows through series of three graben in the Menderes Massif, but has a flood plain much wider than the meander zone in its lower reach. Its modern Turkish name is the Büyük Menderes River . Meanders are a result of

2150-507: Is the formation of a sinuous course as the channel migrates back and forth across the axis of a floodplain . The zone within which a meandering stream periodically shifts its channel is known as a meander belt . It typically ranges from 15 to 18 times the width of the channel. Over time, meanders migrate downstream, sometimes in such a short time as to create civil engineering challenges for local municipalities attempting to maintain stable roads and bridges. The degree of meandering of

2236-478: Is the length along the centerline. Once a channel begins to follow a sinusoidal path, the amplitude and concavity of the loops increase dramatically. This is due to the effect of helical flow which sweeps dense eroded material towards the inside of the bend, and leaves the outside of the bend unprotected and vulnerable to accelerated erosion. This establishes a positive feedback loop . In the words of Elizabeth A. Wood: "...this process of making meanders seems to be

2322-405: Is the most common type of fluvial lake, is a crescent-shaped lake that derives its name from its distinctive curved shape. Oxbow lakes are also known as cutoff lakes . Such lakes form regularly in undisturbed floodplains as a result of the normal process of fluvial meandering. Either a river or stream forms a sinuous channel as the outer side of its bends are eroded away and sediments accumulate on

2408-430: Is two consecutive loops pointing in opposite transverse directions. The distance of one meander along the down-valley axis is the meander length or wavelength . The maximum distance from the down-valley axis to the sinuous axis of a loop is the meander width or amplitude . The course at that point is the apex. In contrast to sine waves, the loops of a meandering stream are more nearly circular. The curvature varies from

2494-421: The 1980 Mount St. Helens eruption , which led to a fern spike extinction. Heat waves can lead to local extinction. In New Zealand, during the summer of 2017–2018, sea surface temperatures around parts of South Island exceeded 23 °C (73 °F), which was well above normal. Air temperatures were also high, exceeding 30 °C (86 °F). These high temperatures, coupled with small wave height, led to

2580-527: The Ancient Greeks as Μαίανδρος Maiandros ( Latin : Maeander ), characterised by a very convoluted path along the lower reach. As a result, even in Classical Greece (and in later Greek thought) the name of the river had become a common noun meaning anything convoluted and winding, such as decorative patterns or speech and ideas, as well as the geomorphological feature. Strabo said: ‘...its course

2666-719: The Black Sea stock of harbour porpoise ( Phocoena phocoena ) that touches six countries, and COSEWIC , which only assesses the conservation status of wildlife in Canada, even assesses Canadian species that occur in the United States or other countries. While the IUCN mostly only assesses the global conservation status of species or subspecies, in some older cases it also assessed the risks to certain stocks and populations, in some cases these populations may be genetically distinct. In all, 119 stocks or subpopulations across 69 species had been assessed by

Coquitlam River - Misplaced Pages Continue

2752-575: The Coast Mountains near Indian Arm . It flows south into Coquitlam Lake , a reservoir behind the Coquitlam Dam . The Coquitlam River then continues past the dam flowing south until it reaches the Fraser River at the border between Coquitlam and Port Coquitlam . The Coquitlam River spans a total of 18 km from the dam to its outlet and receives sediment and water from 30 tributaries . It

2838-476: The Ozark Plateau . As noted above, it was initially either argued or presumed that an incised meander is characteristic of an antecedent stream or river that had incised its channel into underlying strata . An antecedent stream or river is one that maintains its original course and pattern during incision despite the changes in underlying rock topography and rock types. However, later geologists argue that

2924-449: The bedrock are known as either incised , intrenched , entrenched , inclosed or ingrown meanders . Some Earth scientists recognize and use a finer subdivision of incised meanders. Thornbury argues that incised or inclosed meanders are synonyms that are appropriate to describe any meander incised downward into bedrock and defines enclosed or entrenched meanders as a subtype of incised meanders (inclosed meanders) characterized by

3010-403: The hydrology of the river. In response to increased demand, another larger dam was completed in 1915, however unlike previous dams, fish access to the lake was completely blocked. further impacting the river's ecology. The watershed was logged extensively throughout the 1900s which has resulted in heavy sediment loads to occur during high precipitation events. Throughout the 1950s and 60s it

3096-569: The BC Species at Risk Act and The Committee on the Status of Endangered Wildlife in Canada ( COSEWIC ) lists. The Coquitlam River is located within the Coquitlam River Watershed, which has a total area of 340 km and formed during the last glacial advance. The watershed is split into two sections, the upper and lower Coquitlam River Watershed. Its source is Disappointment Lake, which is in

3182-474: The Coquitlam Lake dam, logging upstream, and gravel removal. Since the dam's installation, salmon have been cut off from the valuable rearing habitat of the upper Coquitlam River. To attempt to reverse this, Fisheries and Oceans Canada plan to transport up to 100 returning coho salmon. This plan was presented in 2020 and will likely occur over a 5-year trial period. This transportation will also be managed by

3268-749: The Coquitlam River Watershed Community Initiative, and continue today with others, such as the Coquitlam River Watershed Society established in 1998. To rejuvenate the salmonid species in the river, the Port Coquitlam & District Hunting and Fishing Club has operated the Grist Goeson Memorial Hatchery through the Department of Fisheries and Oceans (DFO) Salmonid Enhancement Program (SEP). At

3354-458: The Grist Goeson Memorial Hatchery. There is a protected Wildlife Management Area found on the north side of the Coquitlam and Fraser Rivers confluence. This land is managed by the BC's Ministry of Forests, Lands, Natural Resources Operations and Rural Developments (FLNRORD). The great blue herons found on this reserve are blue-listed species under the BC Species at Risk Act (SARA) and are listed as

3440-435: The absence of secondary flow we would expect low fluid velocity at the outside bend and high fluid velocity at the inside bend. This classic fluid mechanics result is irrotational vortex flow. In the context of meandering rivers, its effects are dominated by those of secondary flow. Secondary flow : A force balance exists between pressure forces pointing to the inside bend of the river and centrifugal forces pointing to

3526-434: The accumulation of woody debris in the lower reaches of the river which could be used for habitats. There are several popular parks and trails along the banks of the river including Coquitlam River Park, Lions Parks, and Gates Parks. The river is also popular with local fishermen. There have been numerous initiatives to address and educate the public about the issues that threaten the Coquitlam River. These began in 1996 with

Coquitlam River - Misplaced Pages Continue

3612-411: The average fullbank channel width. The length of the stream is measured by channel, or thalweg, length over the reach, while the bottom value of the ratio is the downvalley length or air distance of the stream between two points on it defining the reach. The sinuosity index plays a part in mathematical descriptions of streams. The index may require elaboration, because the valley may meander as well—i.e.,

3698-551: The bottom from the outside to the inside. The flow is supplied by a counter-flow across the surface from the inside to the outside. This entire situation is very similar to the Tea leaf paradox . This secondary flow carries sediment from the outside of the bend to the inside making the river more meandering. As to why streams of any size become sinuous in the first place, there are a number of theories, not necessarily mutually exclusive. The stochastic theory can take many forms but one of

3784-429: The boundary layer. Therefore, within the boundary layer, pressure force dominates and fluid moves along the bottom of the river from the outside bend to the inside bend. This initiates helicoidal flow: Along the river bed, fluid roughly follows the curve of the channel but is also forced toward the inside bend; away from the river bed, fluid also roughly follows the curve of the channel but is forced, to some extent, from

3870-544: The case of the Anderson Bottom Rincon, incised meanders that have either steep-sided, often vertical walls, are often, but not always, known as rincons in the southwest United States . Rincon in English is a nontechnical word in the southwest United States for either a small secluded valley, an alcove or angular recess in a cliff, or a bend in a river. The meanders of a stream or river that has cut its bed down into

3956-464: The channel of a river, stream, or other watercourse is measured by its sinuosity . The sinuosity of a watercourse is the ratio of the length of the channel to the straight line down-valley distance. Streams or rivers with a single channel and sinuosities of 1.5 or more are defined as meandering streams or rivers. The term derives from the winding river Menderes located in Asia-Minor and known to

4042-408: The curvature of the bend, and the faster the flow, the stronger is the cross-current and the sweeping. Due to the conservation of angular momentum the speed on the inside of the bend is faster than on the outside. Since the flow velocity is diminished, so is the centrifugal pressure. The pressure of the super-elevated column prevails, developing an unbalanced gradient that moves water back across

4128-421: The dam and the water diversion to Buntzen Lake affects fish and wildlife in the river and surrounding riparian zone . The barrier created by the dam restricts migration between the upper and lower parts of the watershed, which impacts salmon species in particular who used the lake as a hatching site. As a result, sockeye salmon have become almost entirely extirpated in the Coquitlam River. The dam also reduces

4214-405: The downvalley length is not identical to the reach. In that case the valley index is the meander ratio of the valley while the channel index is the meander ratio of the channel. The channel sinuosity index is the channel length divided by the valley length and the standard sinuosity index is the channel index divided by the valley index. Distinctions may become even more subtle. Sinuosity Index has

4300-806: The end of the Pleistocene when the sea level rose, and these islands most likely had the same complement of species as found on the mainland, counting the species which still survive at present on a statistically large enough amount of islands will give the parameters with which certain groups of species such as plants or birds will become less biodiverse on a given island over a given period of time, depending on its size. The same calculations can also be applied to determine when species will disappear from nature parks ('islands' in many senses), mountain tops and mesas (see sky islands ), forest remnants or other such distributional patches. This research also demonstrates that certain species are more prone to extinction than others,

4386-547: The formation of both entrenched meanders and ingrown meanders is thought to require that base level falls as a result of either relative change in mean sea level , isostatic or tectonic uplift, the breach of an ice or landslide dam, or regional tilting. Classic examples of incised meanders are associated with rivers in the Colorado Plateau , the Kentucky River Palisades in central Kentucky , and streams in

SECTION 50

#1732836909685

4472-428: The full force of the flood. After a cutoff meander is formed, river water flows into its end from the river builds small delta-like feature into either end of it during floods. These delta-like features block either end of the cutoff meander to form a stagnant oxbow lake that is separated from the flow of the fluvial channel and independent of the river. During floods, the flood waters deposit fine-grained sediment into

4558-404: The fullbank channel width and 3 to 5 times, with an average of 4.7 times, the radius of curvature at the apex. This radius is 2–3 times the channel width. A meander has a depth pattern as well. The cross-overs are marked by riffles , or shallow beds, while at the apices are pools. In a pool direction of flow is downward, scouring the bed material. The major volume, however, flows more slowly on

4644-425: The generation of hydro-electricity with a dam . The river's long history and importance have led to conservation efforts by different organizations for some of the various mammals , birds , fish , and plants . Some attempts have been made to rejuvenate the salmonid species with hatcheries and direct human intervention to assist wild salmonids. The area is also known to have some species which are included on

4730-424: The hatchery, tens of thousands of juvenile fish are released each spring. These efforts has led to a rebound in coho , chum and pink salmon populations, with approximately 4 times the amount of salmon returning compared to their lowest numbers. However, other species such as sockeye salmon and steelhead trout are either not returning at all or in very low numbers. This is likely due to long-lasting impacts from

4816-416: The inner side, which forms a meandering horseshoe-shaped bend. Eventually as the result of its meandering, the fluvial channel cuts through the narrow neck of the meander and forms a cutoff meander. The final break-through of the neck, which is called a neck cutoff , often occurs during a major flood because that is when the watercourse is out of its banks and can flow directly across the neck and erode it with

4902-443: The inside bank of a river bend. On the inside bend, this sediment and debris is eventually deposited on the slip-off slope of a point bar. Scroll-bars are a result of continuous lateral migration of a meander loop that creates an asymmetrical ridge and swale topography on the inside of the bends. The topography is generally parallel to the meander, and is related to migrating bar forms and back bar chutes, which carve sediment from

4988-406: The inside of the bend where, due to decreased velocity, it deposits sediment. The line of maximum depth, or channel, is the thalweg or thalweg line. It is typically designated the borderline when rivers are used as political borders. The thalweg hugs the outer banks and returns to center over the riffles. The meander arc length is the distance along the thalweg over one meander. The river length

5074-450: The inside to the outside bend. The higher velocities at the outside bend lead to higher shear stresses and therefore result in erosion. Similarly, lower velocities at the inside bend cause lower shear stresses and deposition occurs. Thus meander bends erode at the outside bend, causing the river to becoming increasingly sinuous (until cutoff events occur). Deposition at the inside bend occurs such that for most natural meandering rivers,

5160-404: The interaction of water flowing through a curved channel with the underlying river bed. This produces helicoidal flow , in which water moves from the outer to the inner bank along the river bed, then flows back to the outer bank near the surface of the river. This in turn increases carrying capacity for sediments on the outer bank and reduces it on the inner bank, so that sediments are eroded from

5246-580: The local extinction of bull kelp ( Durvillaea spp.) from Pile Bay . Lagoa Santa, a lake located in Lagoa Santa, Brazil , has lost almost 70% of the local fish species over the last 150 years. These include Acestrorhynchus lacustris , Astyanax fasciatus , and Characidium zebra . This could be caused by the introduction of non-native species, like Talapia rendalli , into the lagoon, changes in water level and organic pollution. Local extinctions can be reversed, in some cases artificially. Wolves are

SECTION 60

#1732836909685

5332-420: The meanders are fixed. Various mathematical formulae relate the variables of the meander geometry. As it turns out some numerical parameters can be established, which appear in the formulae. The waveform depends ultimately on the characteristics of the flow but the parameters are independent of it and apparently are caused by geologic factors. In general the meander length is 10–14 times, with an average 11 times,

5418-418: The more heterogeneous braided river deposits. There are two distinct patterns of scroll-bar depositions; the eddy accretion scroll bar pattern and the point-bar scroll pattern. When looking down the river valley they can be distinguished because the point-bar scroll patterns are convex and the eddy accretion scroll bar patterns are concave. Scroll bars often look lighter at the tops of the ridges and darker in

5504-504: The most general statements is that of Scheidegger: "The meander train is assumed to be the result of the stochastic fluctuations of the direction of flow due to the random presence of direction-changing obstacles in the river path." Given a flat, smooth, tilted artificial surface, rainfall runs off it in sheets, but even in that case adhesion of water to the surface and cohesion of drops produce rivulets at random. Natural surfaces are rough and erodible to different degrees. The result of all

5590-514: The outer bank and redeposited on the inner bank of the next downstream meander. When a fluid is introduced to an initially straight channel which then bends, the sidewalls induce a pressure gradient that causes the fluid to alter course and follow the bend. From here, two opposing processes occur: (1) irrotational flow and (2) secondary flow . For a river to meander, secondary flow must dominate. Irrotational flow : From Bernoulli's equations, high pressure results in low velocity. Therefore, in

5676-403: The outside bend of the river. In the context of meandering rivers, a boundary layer exists within the thin layer of fluid that interacts with the river bed. Inside that layer and following standard boundary-layer theory, the velocity of the fluid is effectively zero. Centrifugal force, which depends on velocity, is also therefore effectively zero. Pressure force, however, remains unaffected by

5762-529: The outside of the curve and deposit sediment in the slower flowing water on the inside of the loop, in a process called lateral accretion. Scroll-bar sediments are characterized by cross-bedding and a pattern of fining upward. These characteristics are a result of the dynamic river system, where larger grains are transported during high energy flood events and then gradually die down, depositing smaller material with time (Batty 2006). Deposits for meandering rivers are generally homogeneous and laterally extensive unlike

5848-415: The oxbow lake. As a result, oxbow lakes tend to become filled in with fine-grained, organic-rich sediments over time. A point bar , which is also known as a meander bar , is a fluvial bar that is formed by the slow, often episodic, addition of individual accretions of noncohesive sediment on the inside bank of a meander by the accompanying migration of the channel toward its outer bank. This process

5934-475: The physical factors acting at random is channels that are not straight, which then progressively become sinuous. Even channels that appear straight have a sinuous thalweg that leads eventually to a sinuous channel. In the equilibrium theory, meanders decrease the stream gradient until an equilibrium between the erodibility of the terrain and the transport capacity of the stream is reached. A mass of water descending must give up potential energy , which, given

6020-482: The river for their own purposes. The first dam was built at the mouth of Coquitlam Lake in 1892 to provide a source of drinking water for the growing colony of New Westminster . In 1905 the Vancouver Power Company completed construction on a second dam and a tunnel to nearby Buntzen Lake for power generation. As a result, a large portion of the Coquitlam River's flow was diverted out of the watershed altering

6106-461: The river includes an oxbow lake, wetlands, and side channels. This riparian habitat includes a variety of vegetation from evergreens such as western red cedars to deciduous black cottonwoods . This forested area provides cover for animals such as black-tailed deer and racoons within the urban landscape in the lower reaches of the river. The river and its tributaries are home to 24 different species of fish, 5 of these salmonids. These salmon are

6192-678: The river width remains nearly constant, even as the river evolves. In a speech before the Prussian Academy of Sciences in 1926, Albert Einstein suggested that because the Coriolis force of the earth can cause a small imbalance in velocity distribution, such that velocity on one bank is higher than on the other, it could trigger the erosion on one bank and deposition of sediment on the other that produces meanders However, Coriolis forces are likely insignificant compared with other forces acting to produce river meanders. The technical description of

6278-481: The river" in reference to an early sockeye salmon species that once spawned in Coquitlam Lake. The Kwikwetlem were renowned for their canoe and paddle craftsmanship. The Kwikwetlem lived throughout the Coquitlam River watershed and would have relied on fishing, gathering, and trade with other First Nations living along the Fraser River. European settlers first arrived in the region in the mid-1800s and began using

6364-416: The same velocity at the end of the drop as at the beginning, is removed by interaction with the material of the stream bed. The shortest distance; that is, a straight channel, results in the highest energy per unit of length, disrupting the banks more, creating more sediment and aggrading the stream. The presence of meanders allows the stream to adjust the length to an equilibrium energy per unit length in which

6450-417: The sediment is deposited the vertical sequence of sediments comprising a point bar becomes finer upward within an individual point bar. For example, it is typical for point bars to fine upward from gravel at the base to fine sands at the top. The source of the sediment is typically upstream cut banks from which sand, rocks and debris has been eroded, swept, and rolled across the bed of the river and downstream to

6536-505: The shape of an incised meander is not always, if ever, "inherited", e.g., strictly from an antecedent meandering stream where its meander pattern could freely develop on a level floodplain. Instead, they argue that as fluvial incision of bedrock proceeds, the stream course is significantly modified by variations in rock type and fractures , faults , and other geological structures into either lithologically conditioned meanders or structurally controlled meanders . The oxbow lake , which

6622-445: The shortest possible path). It is calculated as the length of the stream divided by the length of the valley . A perfectly straight river would have a meander ratio of 1 (it would be the same length as its valley), while the higher this ratio is above 1, the more the river meanders. Sinuosity indices are calculated from the map or from an aerial photograph measured over a distance called the reach , which should be at least 20 times

6708-411: The sinuous axis. A loop at the apex has an outer or concave bank and an inner or convex bank. The meander belt is defined by an average meander width measured from outer bank to outer bank instead of from centerline to centerline. If there is a flood plain , it extends beyond the meander belt. The meander is then said to be free—it can be found anywhere in the flood plain. If there is no flood plain,

6794-419: The stream carries away all the sediment that it produces. Geomorphic refers to the surface structure of the terrain. Morphotectonic means having to do with the deeper, or tectonic (plate) structure of the rock. The features included under these categories are not random and guide streams into non-random paths. They are predictable obstacles that instigate meander formation by deflecting the stream. For example,

6880-403: The stream might be guided into a fault line (morphotectonic). A cut bank is an often vertical bank or cliff that forms where the outside, concave bank of a meander cuts into the floodplain or valley wall of a river or stream. A cutbank is also known either as a river-cut cliff , river cliff , or a bluff and spelled as cutbank . Erosion that forms a cut bank occurs at the outside bank of

6966-416: The swales. This is because the tops can be shaped by wind, either adding fine grains or by keeping the area unvegetated, while the darkness in the swales can be attributed to silts and clays washing in during high water periods. This added sediment in addition to water that catches in the swales is in turn is a favorable environment for vegetation that will also accumulate in the swales. Depending upon whether

7052-439: The termination of a species (or other taxon ) in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinctions . Local extinctions mark a change in the ecology of an area. It has sometimes been followed by a replacement of the species taken from other locations, such as with wolf reintroduction . Glaciation is one factor that leads to local extinction. This

7138-406: The trees to fall into the river. A meander cutoff , also known as either a cutoff meander or abandoned meander , is a meander that has been abandoned by its stream after the formation of a neck cutoff. A lake that occupies a cutoff meander is known as an oxbow lake . Cutoff meanders that have cut downward into the underlying bedrock are known in general as incised cutoff meanders . As in

7224-462: Was also common practice to extract gravel directly from the stream bed, although this stopped in 1965 when the B.C. Gravel Removal Order was passed. The Coquitlam Lake dam continues to provide power to the residents of Metro Vancouver and is owned and operated by the provincial energy authority, BC hydro . The lake is also one of three reservoirs used by Metro Vancouver and provides drinking water to 900,000 people. The flow reduction caused by

7310-462: Was also recommended to avoid pond draining and ditch cleaning during breeding times. Meander A meander is one of a series of regular sinuous curves in the channel of a river or other watercourse . It is produced as a watercourse erodes the sediments of an outer, concave bank ( cut bank or river cliff ) and deposits sediments on an inner, convex bank which is typically a point bar . The result of this coupled erosion and sedimentation

7396-564: Was the case during the Pleistocene glaciation event in North America. During this period, most of the native North American species of earthworm were killed in places covered by glaciation. This left them open for colonization by European earthworms brought over in soil from Europe. Species naturally become extirpated from islands over time. The number of species an island can support is limited by its geographical size. Because many islands were relatively recently formed due to climate change at

#684315