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27-463: In North America, "slough" may refer to a side-channel from or feeding a river, or an inlet or natural channel only sporadically filled with water. An example of this is Finn Slough on the Fraser River , whose lower reaches have dozens of notable sloughs. Some sloughs, like Elkhorn Slough , used to be mouths of rivers, but have become stagnant because tectonic activity cut off the river's source. In

54-406: A cutoff , forms. When deposition finally seals off the cutoff from the river channel, an oxbow lake forms. This process can occur over a time from a few years to several decades, and may sometimes become essentially static. Gathering of erosion products near the concave bank and transporting them to the convex bank is the work of the secondary flow across the floor of the river in the vicinity of

81-431: A bog or swamp and then evaporating completely. When a river reaches a low-lying plain, often in its final course to the sea or a lake , it meanders widely. In the vicinity of a river bend, deposition occurs on the convex bank (the bank with the smaller radius). In contrast, both lateral erosion and undercutting occur on the cut bank or concave bank (the bank with the greater radius). Continuous deposition on

108-425: A meandering river erodes through the neck of one of its meanders . This takes place because meanders tend to grow and become more curved over time. The river then follows a shorter course that bypasses the meander. The entrances to the abandoned meander eventually silt up, forming an oxbow lake. Because oxbow lakes are stillwater lakes, with no current flowing through them, the entire lake gradually silts up, becoming

135-421: A neat pile in the center of the bowl. This is the mechanism that leads to the formation of point bars and contributes to the formation of oxbow lakes. The primary flow of water in the bowl is circular and the streamlines are concentric with the side of the bowl. However, the secondary flow of the boundary layer across the floor of the bowl is inward toward the center. The primary flow might be expected to fling

162-539: A part of an endangered environment: wetlands. They act as a buffer from land to sea and act as an active part of the estuary system where freshwater flows from creeks and runoff from the land mix with salty ocean water transported by tides. Restoration is a big effort in California wetlands to restore slough and ridge landscapes. Examples of restoration projects on slough landscapes include The Elkhorn Slough Tidal Wetland Project, Dutch Slough Tidal Restoration Project, and

189-400: A river bend. The process of deposition of silt, sand and gravel on the convex bank is clearly illustrated in point bars . The effect of the secondary flow can be demonstrated using a circular bowl. Partly fill the bowl with water and sprinkle dense particles such as sand or rice into the bowl. Set the water into circular motion with one hand or a spoon. The dense particles quickly sweep into

216-458: A river over time. The development of this landscape is thought to occur by the preferential formation of peat in bedrock depressions. Multiple of these deposits mounted on top of the surrounding bedrock can become elongated alongside the slough and create flow diversions within the system. Different rates of this peat accumulation could be triggered by variations in microtopography that alter plant production and vegetation type. Water flow might be

243-487: A study done on Elkhorn Slough in California the mean prey richness for fish was greatest near the ocean and lowest inshore. This allows for a higher availability of food to enhance the function of inshore habitats and emphasizes the importance of invertebrate prey populations and how they influence plant production. Birds also inhabit sloughs, making them hotspots for birdwatching , with the Elkhorn Slough being one of

270-557: Is a stub . You can help Misplaced Pages by expanding it . Oxbow lake An oxbow lake is a U-shaped lake or pool that forms when a wide meander of a river is cut off , creating a free-standing body of water. The word "oxbow" can also refer to a U-shaped bend in a river or stream, whether or not it is cut off from the main stream. In South Texas , oxbows left by the Rio Grande are called resacas . In Australia , oxbow lakes are called billabongs . An oxbow lake forms when

297-778: Is either stagnant or slow flowing on a seasonal basis. Vegetation patterns in a slough are largely determined by depth , distribution, and duration in the environment. Moreover, these same variables also influence the distribution, abundance, reproduction, and seasonal movements of aquatic and terrestrial life within the sloughs. Sloughs support a wide variety of plant life that is adapted to rapidly changing physical conditions such as salinity , oxygen levels and depth. In general, sloughs are microhabitats high in species diversity. Open water sloughs are characterized by submerged and floating vegetation which includes periphyton mats dominated by sawgrass typically. The topographical and vegetation heterogeneity of ridge and slough landscape influences

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324-671: The Sacramento River , Steamboat Slough was an alternate branch of the river, a preferred shortcut route for steamboats passing between Sacramento and San Francisco . Georgiana Slough was a steamboat route through the Sacramento–San Joaquin River Delta , from the Sacramento River to the San Joaquin River and Stockton . A slough, also called a tidal channel, is a channel in a wetland . Typically, it

351-604: The McDaniel Slough wetland enhancement project. [REDACTED] Wetlands portal Finn Slough Finn Slough is a tiny Fraser River fishing community, sometimes referred to as Gilmore or Tiffin Slough. It is located at the south end of No. 4 Road in the Gilmore area of Richmond , British Columbia , Canada. The community has approximately 30 residents who live in wooden houses, both floating and built on pilings, along

378-439: The convex bank and erosion of the concave bank of a meandering river cause the formation of a very pronounced meander with two concave banks getting closer. The narrow neck of land between the two neighboring concave banks is finally cut through, either by lateral erosion of the two concave banks or by the strong currents of a flood . When this happens a new, straighter river channel develops—and an abandoned meander loop, called

405-403: The convex bank provides the centripetal force necessary for each parcel of water to follow its curved path. The boundary layer that flows along the river floor does not move fast enough to balance the pressure gradient laterally across the river. It responds to this pressure gradient, and its velocity is partly downstream and partly across the river toward the convex bank. As it flows along

432-412: The dense particles to the perimeter of the bowl, but instead the secondary flow sweeps the particles toward the center. The curved path of a river around a bend makes the water's surface slightly higher on the outside of the bend than on the inside. As a result, at any elevation within the river, water pressure is slightly greater near the outside of the bend than on the inside. A pressure gradient toward

459-406: The environment include periphyton , marsh plant communities, tree islands, alligators , wading birds , and marsh fishes, invertebrates , and herpetofauna . A slough can form when a meander gets cut off from the main river channel creating an oxbow lake that accumulates with fine overbank sediment and organic material such as peat . This creates a wetland or swamp environment. One end of

486-590: The floor of the river, it sweeps loose material toward the convex bank. This flow of the boundary layer is significantly different from the speed and direction of the primary flow of the river, and is part of the river's secondary flow . River flood plains that contain rivers with a highly sinuous platform are populated by longer oxbow lakes than those with low sinuosity . This is because rivers with high sinuosity have larger meanders, and greater opportunity for longer lakes to form. Rivers with lower sinuosity are characterized by fewer cutoffs and shorter oxbow lakes due to

513-432: The health of a river ecosystem by trapping sediments and agricultural runoff, thereby removing them from the main river flow. However, this is destructive of the oxbow lake ecosystem itself. Oxbow lakes are also vulnerable to heavy metal contamination from industrial sources. Oxbow lakes may be formed when a river channel is straightened artificially to improve navigation or for flood alleviation. This occurred notably on

540-426: The key to preventing an accumulation of organic sediment in sloughs due to the fact that accumulation leads to lowering water depths and instead allows for the growth of vegetation. Overall little quantitative data on the degradation of slough landscape exists. Slough and ridge landscape has been greatly degraded in terms of both topographic and vegetation changes over time. Topographical changes create an increase in

567-663: The marshy river bank. Many of the buildings were built between the late 19th century and 1950s and many have decayed severely, while some have been carefully restored. Finn Slough was founded by Finnish settlers who came to Richmond in the 1880s. Most of these residents made a good living from fishing and became local landowners. The sleepy and decaying village of Finn Slough has been repeatedly photographed, and it appears on numerous postcards sold throughout Vancouver tourist shops. 49°6′47″N 123°6′56″W  /  49.11306°N 123.11556°W  / 49.11306; -123.11556 This Metro Vancouver -related article

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594-482: The oxbow configuration then continues to receive flow from the main channel, creating a slough. Sloughs are typically associated with the ridge formations found in their presence. Such a landscape consists of mosaic linear ridges, typically of some sort of grass such as sawgrass ridges in the Florida Everglades , that are separated by deeper water sloughs. Edges of sloughs are layers of sediment deposited by

621-746: The premier birdwatching sites in the western United States. Over 340 species have been seen visiting, including several rare and endangered species. Bird species seen in sloughs include acorn woodpecker , brown pelican , Caspian tern , great blue heron , great egret , great horned owl , snowy plover , and white-tailed kite . Sloughs are largely influenced by human development such as urban and agricultural expansion , industrial and agricultural practices, water management practices, and humans influence on species composition . Uses of identifying these aspects of human involvement can help to better predict restoration efforts to be made in managing sloughs. Examples of attributes that are affected by human stress upon

648-468: The productivity and diversity of birds and fish adapted to that wetland . Fish that typically inhabit sloughs include tidewater goby, California killifish , mosquitofish , and topsmelt . Food habits of fish within sloughs consist of preying upon invertebrates ; mostly epifaunal crustacean followed by epifaunal and infaunal worms and mollusks. Fish can feed on zooplankton and plant material. Research on prey species for fish in sloughs found that in

675-544: The relief between ridge crests and slough bottoms. Vegetation changes consist of an increase in the amount of dense grass and decrease in the area of open water, creating a blurring of the directional ridge and slough pattern. Historical everglade and slough landscape has been greatly affected and degraded by human activity. Open water sloughs support important ecological functions that have been seen to be sensitive to hydrologic and water quality problems stemmed from human activities. Sloughs are ecologically important as they are

702-509: The shorter distance of their meanders. Oxbow lakes serve as important wetland ecosystems. In the United States, oxbow lakes serve as the primary habitat for water tupelo and the iconic bald cypress . The numerous oxbow lakes of the Amazon River are a favorable habitat for the giant river otter . Oxbow lakes may also be suitable locations for aquaculture . Oxbow lakes contribute to

729-590: The upper Rhine in Germany in the nineteenth century. An example of an entirely artificial waterway with oxbows is the Oxford Canal in England. When originally constructed, it had a very meandering course, following the contours of the land, but the northern part of the canal was straightened out between 1829 and 1834, reducing its length from approximately 146 to 125 km (91 to 77 + 1 ⁄ 2  mi) and creating

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