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Deadwater (topography)
A deadwater is that part of an estuary through which there is little to no water flow. In situations where a river flow is weaker than the marine processes that build sand dunes, the river may be obstructed from flowing into the sea by the formation of a sand dune; that is, a sandbar. In such cases the river will often form an elongated estuary in the swales of the dune. When river flow increases, or once the estuary has built up a large mass of water, it breaches the sandbar and flows out to the ocean. If this breach occurs at the farthest end of the estuary from the river inflow, then water must flow through the whole length of the estuary in order to reach the sea. Thus the entire estuary is flushed, and there is no deadwater. On the other hand, if the breach occurs near the river inflow, then most of the estuary will not be flushed by the flow of the river into the sea, resulting in a large deadwater. Notes See also * Liman (landform) Liman (; ro, liman) is an enlarged ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Estuary
An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environments and are an example of an ecotone. Estuaries are subject both to marine influences such as tides, waves, and the influx of saline water, and to fluvial influences such as flows of freshwater and sediment. The mixing of seawater and freshwater provides high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world. Most existing estuaries formed during the Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea level began to rise about 10,000–12,000 years ago. Estuaries are typically classified according to their geomorphological features or to water-circulation patterns. They can have many different names, such as bays, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sand Dune
A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat regions covered with wind-swept sand or dunes with little or no vegetation are called ''ergs'' or ''sand seas''. Dunes occur in different shapes and sizes, but most kinds of dunes are longer on the stoss (upflow) side, where the sand is pushed up the dune, and have a shorter ''slip face'' in the lee side. The valley or trough between dunes is called a ''dune slack''. Dunes are most common in desert environments, where the lack of moisture hinders the growth of vegetation that would otherwise interfere with the development of dunes. However, sand deposits are not restricted to deserts, and dunes are also found along sea shores, along streams in semiarid climates, in areas of glacial outwash, and in other areas where poorly cemented san ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandbar
In oceanography, geomorphology, and Earth science, geoscience, a shoal is a natural submerged ridge, bank (geography), bank, or bar that consists of, or is covered by, sand or other unconsolidated material and rises from the bed of a body of water to near the surface. It often refers to those submerged ridges, banks, or bars that rise near enough to the surface of a body of water as to constitute a danger to navigation. Shoals are also known as sandbanks, sandbars, or gravelbars. Two or more shoals that are either separated by shared crest and trough, troughs or interconnected by past or present sedimentary and hydrographic processes are referred to as a shoal complex.Neuendorf, K.K.E., J.P. Mehl Jr., and J.A. Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. The term ''shoal'' is also used in a number of ways that can be either similar or quite different from how it is used in geologic, geomorphic, and ocea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liman (landform)
Liman (; ro, liman) is an enlarged estuary formed as a lagoon at the wide mouth of one or several rivers, where flow is constrained by a bar of sediments, as in the Dniester Liman or the Razelm liman. A ''liman'' can be maritime (the bar being created by the current of a sea) or fluvial (the bar being created by the slowed or turned flow of a sediment-saturated river). The term describes many wet estuaries in the Black Sea and the Sea of Azov; a synonymous term guba (губа) is used in Russian sources for estuaries of the Russian shores in the north. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
