Backwater (river)

Last updated

A backwater is a part of a river in which there is little or no current. It can refer to a branch of a main river, which lies alongside it and then rejoins it, or to a body of water in a main river, backed up by the sea tide or by an obstruction such as a dam. [1] Manmade restrictions to natural stream flow or temporary natural obstructions such as ice jams, vegetation blockage, or flooding of a lower stream can create backwater. [2]

Contents

Alternative channel

A Kerala houseboat in Kumarakom, India Alappuzha Boat Beauty W.jpg
A Kerala houseboat in Kumarakom, India

If a river has developed one or more alternative courses in its evolution, one channel is usually designated the main course, and secondary channels may be termed backwaters. [3] The main river course will usually have the fastest stream and will likely be the main navigation route; backwaters may be shallower and flow more slowly, if at all. Some backwaters are rich in mangrove forest. [4] This results in a more diverse environment of scientific interest and worthy of preservation. [5] [6] Backwaters also provide opportunities for leisure activities such as canoeing and fishing. [7] [8]

The term has been applied as a metaphor to physical and social areas that have been bypassed. It may apply to places that have been neglected in economic development, [9] or in the expression a "cultural backwater". [10]

Water backed up by an obstruction

Kumarakom lake in Kerala backwaters KumarakomHouseBoat.jpg
Kumarakom lake in Kerala backwaters

When a section of a river is near the coast or another feature that sets its base level, the section influenced by the conditions at its mouth is termed a backwater. If a river flows into a lake or sea, it is the region in which the slope of the river decreases because the lower water flux permitted at the mouth causes the water to back up. Where the river outlet is strongly affected by tides, the cyclic change in base level changes the portion of the river that is a backwater. As a result, fresh and salt water may become mixed to form an estuarine environment. [11]

See also

Related Research Articles

<span class="mw-page-title-main">Brackish water</span> Water with salinity between freshwater and seawater

Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater and fresh water together, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root brak. Certain human activities can produce brackish water, in particular civil engineering projects such as dikes and the flooding of coastal marshland to produce brackish water pools for freshwater prawn farming. Brackish water is also the primary waste product of the salinity gradient power process. Because brackish water is hostile to the growth of most terrestrial plant species, without appropriate management it is damaging to the environment.

<span class="mw-page-title-main">River Ravensbourne</span> Right-bank tributary of the Thames in London

The River Ravensbourne is a tributary of the River Thames in south London, England. It flows into the tidal River Thames at Deptford, where its tidal reach is known as Deptford Creek.

<span class="mw-page-title-main">River source</span> Starting point of a river

The headwater of a river or stream is the farthest point on each of its tributaries upstream from its mouth/estuary into a lake/sea or its confluence with another river. Each headwater is considered one of the river's source, as it is the place where surface runoffs from rainwater, meltwater and/or spring water begin accumulating into a more substantial and consistent flow that becomes a first-order tributary of that river. The tributary with the longest course downstream of the headwaters is regarded as the main stem of that river.

<span class="mw-page-title-main">River Wandle</span> Tributary of the River Thames, England

The River Wandle is a right-bank tributary of the River Thames in south London, England. With a total length of about 9 miles (14 km), the river passes through the London boroughs of Croydon, Sutton, Merton and Wandsworth, where it reaches the Thames. A short headwater – the Caterham Bourne – is partially in Surrey, the historic county of the river's catchment. Tributaries of the Wandle include Carshalton Ponds and Norbury Brook.

<span class="mw-page-title-main">Coquille River (Oregon)</span> River in Oregon, United States

The Coquille River is a stream, about 36 miles (58 km) long, in southwestern Oregon in the United States. It drains a mountainous area of 1,059 square miles (2,740 km2) of the Southern Oregon Coast Range into the Pacific Ocean. Its watershed is between that of the Coos River to the north and the Rogue River to the south.

<span class="mw-page-title-main">Tidal creek</span> Inlet or estuary that is affected by ebb and flow of ocean tides

A tidal creek or tidal channel is a narrow inlet or estuary that is affected by the ebb and flow of ocean tides. Thus, it has variable salinity and electrical conductivity over the tidal cycle, and flushes salts from inland soils. Tidal creeks are characterized by slow water velocity, resulting in buildup of fine, organic sediment in wetlands. Creeks may often be a dry to muddy channel with little or no flow at low tide, but with significant depth of water at high tide. Due to the temporal variability of water quality parameters within the tidally influenced zone, there are unique biota associated with tidal creeks which are often specialised to such zones. Nutrients and organic matter are delivered downstream to habitats normally lacking these, while the creeks also provide access to inland habitat for salt-water organisms.

<span class="mw-page-title-main">Stamford Brook</span> Subterranean river in London, England

Stamford Brook was a tributary of the Tideway stretch of the River Thames in west London supplied by three headwaters. Historically used as an irrigation ditch or dyke the network of small watercourses had four lower courses and mouths.

<span class="mw-page-title-main">Periyar River</span> River in Kerala, India

Periyar, IPA:[peɾijɐːr], is the longest river and the river with the largest discharge potential in the Indian state of Kerala. It is one of the few perennial rivers in the region and provides drinking water for several major towns. The Periyar is of utmost significance to the economy of Kerala. It generates a significant proportion of Kerala's electrical power via the Idukki Dam and flows along a region of industrial and commercial activity. The river also provides water for irrigation and domestic use throughout its course besides supporting a rich fishery. Due to these reasons, the river has been named the "Lifeline of Kerala". Kochi city, in the vicinity of the river mouth draws its water supply from Aluva, an upstream site sufficiently free of seawater intrusion. Twenty five percent of Kerala's industries are along the banks of river Periyar. These are mostly crowded within a stretch of 5 kilometres (3 mi) in the Eloor-Edayar region (Udhyogamandal), about 10 kilometres (6 mi) north of Kochi harbor.

<span class="mw-page-title-main">Cache River (Illinois)</span> River in Illinois, United States

The Cache River is a 92-mile-long (148 km) waterway in southernmost Illinois, in a region sometimes called Little Egypt. The basin spans 737 square miles (1,910 km2) and six counties: Alexander, Johnson, Massac, Pope, Pulaski, and Union. Located at the convergence of four major physiographic regions, the river is part of the largest complex of wetlands in Illinois. The Cache River Wetlands is America's northernmost cypress/tupelo swamp and harbors 91 percent of the state's high quality swamp and wetland communities. It provides habitat for more than 100 threatened and endangered species in Illinois. In 1996, the Cache was designated a Wetland of International Importance by the Ramsar Convention.

<span class="mw-page-title-main">River engineering</span> Study of human intervention in the course, characteristics, or flow of rivers

River engineering is a discipline of civil engineering which studies human intervention in the course, characteristics, or flow of a river with the intention of producing some defined benefit. People have intervened in the natural course and behaviour of rivers since before recorded history—to manage the water resources, to protect against flooding, or to make passage along or across rivers easier. Since the Yuan Dynasty and Ancient Roman times, rivers have been used as a source of hydropower. From the late 20th century, the practice of river engineering has responded to environmental concerns broader than immediate human benefit. Some river engineering projects have focused exclusively on the restoration or protection of natural characteristics and habitats.

<span class="mw-page-title-main">Conolly Canal</span> Canal in India

Conolly Canal, sometimes spelled as Canoly Canal, is the part of the West coast canal (WCC) network of Kerala and the canal was constructed by combining the rivers and streams along the coast with the intention of creating a vast waterway from Kozhikode to Kochi. It was constructed in the year 1848 under the orders of then collector of Malabar, H.V. Conolly, initially to facilitate movement of goods to Kallayi Port from hinter lands of Malabar through Kuttiyadi and Korapuzha river systems.

<span class="mw-page-title-main">Culham Lock</span> River lock in Oxfordshire, England

Culham Lock is a lock on the River Thames in England close to Culham, Oxfordshire. It is on a lock cut to the north of the main stream, which approaches the large village of Sutton Courtenay. The lock was built of stone by the Thames Navigation Commission in 1809.

<span class="mw-page-title-main">Stream</span> Body of surface water flowing down a channel

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.

<span class="mw-page-title-main">River</span> Natural flowing watercourse

A river is a natural flowing watercourse, usually a freshwater stream, flowing on the surface or inside caves towards another waterbody at a lower elevation, such as an ocean, sea, bay, lake, wetland, or another river. In some cases, a river flows into the ground or becomes dry at the end of its course without reaching another body of water. Small rivers can be referred to by names such as creek, brook, and rivulet. There are no official definitions for the generic term river as applied to geographic features, although in some countries or communities, a stream is defined by its size. Many names for small rivers are specific to geographic location; examples are "run" in some parts of the United States, "burn" in Scotland and Northeast England, and "beck" in Northern England. Sometimes a river is defined as being larger than a creek, but not always; the language is vague.

<span class="mw-page-title-main">Avulsion (river)</span> Rapid abandonment of a river channel and formation of a new channel

In sedimentary geology and fluvial geomorphology, avulsion is the rapid abandonment of a river channel and the formation of a new river channel. Avulsions occur as a result of channel slopes that are much less steep than the slope that the river could travel if it took a new course.

<span class="mw-page-title-main">Bulstake Stream</span> Stream in Oxfordshire, England

Bulstake Stream, also spelt Bullstake Stream, is a backwater of the River Thames at Oxford, England.

<span class="mw-page-title-main">Meander cutoff</span>

A meander cutoff is a natural form of a cutting or cut in a river occurs when a pronounced meander (hook) in a river is breached by a flow that connects the two closest parts of the hook to form a new channel, a full loop. The steeper drop in gradient (slope) causes the river flow gradually to abandon the meander which will silt up with sediment from deposition. Cutoffs are a natural part of the evolution of a meandering river. Rivers form meanders as they flow laterally downstream, see sinuosity.

<span class="mw-page-title-main">Slough (hydrology)</span> Type of wetland

A slough is a wetland, usually a swamp or shallow lake, often a backwater to a larger body of water. Water tends to be stagnant or may flow slowly on a seasonal basis.

<span class="mw-page-title-main">Salt River (California)</span> River in California, United States

The Salt River is a formerly navigable hanging channel of the Eel River which flowed about 9 miles (14 km) from near Fortuna and Waddington, California, to the estuary at the Pacific Ocean, until siltation from logging and agricultural practices essentially closed the channel. It was historically an important navigation route until the early 20th century. It now intercepts and drains tributaries from the Wildcat Hills along the south side of the Eel River floodplain. Efforts to restore the river began in 1987, permits and construction began in 2012, and water first flowed in the restored channel in October 2013.

References

  1. Merriam Webster Dictionary
  2. Langbein, W. B.; Iseri, Kathleen T. (1960). "General Introduction and Hydrologic Definitions, Manual of Hydrology: Part 1. General Surface-Water Techniques" (PDF). pubs.usgs.gov. Geological Survey Water Supply Paper 1542-F. U.S. Geological Survey. Retrieved February 10, 2019.
  3. Wargrave Local History Society Latest News - November 2003 Hennerton and the Backwater Archived 2011-07-24 at the Wayback Machine
  4. "Chettuva in Thrissur: Flaunting Kerala's biggest mangrove forest". OnManorama. Retrieved 2018-08-28.
  5. "E. HOHAUSOVÁ, P. JURAJDA Restoration of a river backwater and its influence on fish assemblage Czech J. Anim. Sci., 50, 2005 (10): 473–482" (PDF). Archived from the original (PDF) on 2017-07-05. Retrieved 2010-07-29.
  6. "John C. Marlin BACKWATER RESTORATION OPPORTUNITIES: ILLINOIS RIVER Waste Management and Research Center, Illinois Department of Natural Resources One" (PDF). Archived from the original (PDF) on 2016-03-03. Retrieved 2010-07-29.
  7. "Vistt Thames Free Family Fun". Archived from the original on 2012-01-25. Retrieved 2010-07-29.
  8. "Suggested paddles Cliveden Reach on the Thames". Archived from the original on 2010-07-23. Retrieved 2010-07-29.
  9. The Cambridge Economic History of Modern Britain
  10. Yee, Amy (2002-05-10). "A Cultural Backwater No Longer". Wall Street Journal. ISSN   0099-9660 . Retrieved 2018-10-07.
  11. Southard, John B. (2006). "Chapter 5: Open-Channel Flow" (PDF). An Introduction to Fluid Motions, Sediment Transport, and Current-generated Sedimentary Structures. MIT OpenCourseWare . Retrieved 16 March 2010.