Region of freshwater influence

Region of Freshwater Influence (ROFI), a term coined by Prof. John Simpson[1] of the University of Wales, Bangor, and co-authors, in 1993 in Oceanologica Acta[2] for the Rhine river plume. The term refers to regions where rivers debouch into estuaries and coastal shelf seas where the currents patterns are governed by density differences between salt sea water and fresh river water. In other words, a ROFI is the region between the shelf sea regime and the estuary where the local input of freshwater buoyancy from the coastal source is comparable with, or exceeds, the seasonal input of buoyancy as heat which occurs all over the shelf.[3] Americans usually use the term river plume where Europeans use ROFI.

See also

External links

  • "Regions of Freshwater Influence". University of Wales, Bangor. Retrieved 2017-11-26.


  1. ^ John Simpson. "Biography". University of Wales, Bangor. Archived from the original on 2011-07-16. Retrieved 2009-10-29.
  2. ^ Simpson, J.H.; Bos, W.G.; F. Shirmer; A.J. Souza; T.P. Rippeth; S.E. Jones; D. Hydes (1993). "Periodic stratification in the Rhine ROFI in the North Sea". Oceanologica Acta. 16 (1): 23–32.
  3. ^ Simpson, J.H. (1997). "Physical processes in the ROFI regime". Journal of Marine Systems (12): 3–15.
Coastal geography

Coastal geography is the study of the constantly changing region between the ocean and the land, incorporating both the physical geography (i.e. coastal geomorphology, geology and oceanography) and the human geography (sociology and history) of the coast. It includes understanding coastal weathering processes, particularly wave action, sediment movement and weather, and the ways in which humans interact with the coast

Continental shelf

A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water known as a shelf sea. Much of the shelves were exposed during glacial periods and interglacial periods. The shelf surrounding an island is known as an insular shelf.

The continental margin, between the continental shelf and the abyssal plain, comprises a steep continental slope followed by the flatter continental rise. Sediment from the continent above cascades down the slope and accumulates as a pile of sediment at the base of the slope, called the continental rise. Extending as far as 500 km (310 mi) from the slope, it consists of thick sediments deposited by turbidity currents from the shelf and slope. The continental rise's gradient is intermediate between the slope and the shelf.

Under the United Nations Convention on the Law of the Sea, the name continental shelf was given a legal definition as the stretch of the seabed adjacent to the shores of a particular country to which it belongs.


In the geography of rivers, streams, and glaciers, a debouch, or debouche, is a place where runoff from a small, confined space emerges into a larger, broader space. The term is of French origin and means to cause to emerge. The term also has a military usage.


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. They are subject both to marine influences—such as tides, waves, and the influx of saline water—and to riverine influences—such as flows of fresh water and sediment. The mixing of seawater and fresh water provide 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, harbors, lagoons, inlets, or sounds, although some of these water bodies do not strictly meet the above definition of an estuary and may be fully saline.

Many estuaries suffer degradation from a variety of factors including: sedimentation from soil erosion from deforestation, overgrazing, and other poor farming practices; overfishing; drainage and filling of wetlands; eutrophication due to excessive nutrients from sewage and animal wastes; pollutants including heavy metals, polychlorinated biphenyls, radionuclides and hydrocarbons from sewage inputs; and diking or damming for flood control or water diversion.


An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island in a river or a lake island may be called an eyot or ait, and a small island off the coast may be called a holm. A grouping of geographically or geologically related islands is called an archipelago, such as the Philippines.

An island may be described as such, despite the presence of an artificial land bridge; examples are Singapore and its causeway, and the various Dutch delta islands, such as IJsselmonde. Some places may even retain "island" in their names for historical reasons after being connected to a larger landmass by a land bridge or landfill, such as Coney Island and Coronado Island, though these are, strictly speaking, tied islands. Conversely, when a piece of land is separated from the mainland by a man-made canal, for example the Peloponnese by the Corinth Canal or Marble Hill in northern Manhattan during the time between the building of the United States Ship Canal and the filling-in of the Harlem River which surrounded the area, it is generally not considered an island.

There are two main types of islands in the sea: continental and oceanic. There are also artificial islands.

Liverpool Bay

Liverpool Bay is a bay of the Irish Sea between northeast Wales, Cheshire, Lancashire and Merseyside to the east of the Irish Sea. The bay is a classic example of a region of freshwater influence. Liverpool Bay has historically suffered from reduced oxygen content from prior massive discharges of sewage sludge, according to C.Michael Hogan.The rivers Alt, Clwyd, Dee, Ribble and Mersey drain into the bay. The bay is littered with wrecks and has many dive sites. The bay also contains several oil and gas fields including the Douglas Complex, with a combined daily capacity (January 2008) of 60,000 barrels. The UK's first major offshore wind farm, North Hoyle, is located in the south of the bay, which is a busy shipping route to the Mersey Docks.

The land area around the bay is occasionally referred to as the "Liverpool Bay Area". Though the term is seen by some as a possible official alternative to Merseyside, it is more often used to describe a much wider area which may include the West Lancashire towns of Ormskirk and Skelmersdale to the north, St Helens and Warrington to the east and Chester plus North Wales to the south. In this sense, it is often promoted by local thinkers and urbanists to encourage regional co-operation in both economic and cultural terms. It is not recognised by the British Government as a strategic economic sub-region, however. Despite having its advocates, the term is still not particularly common in the area.

The English portion of Liverpool Bay is one of the 120 natural areas into which England is divided by Natural England for conservation purposes.


Mudflats or mud flats, also known as tidal flats, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A recent global analysis suggested they are as extensive globally as mangroves. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of estuarine silts, clays and marine animal detritus. Most of the sediment within a mudflat is within the intertidal zone, and thus the flat is submerged and exposed approximately twice daily.

In the past tidal flats were considered unhealthy, economically unimportant areas and were often dredged and developed into agricultural land. Several especially shallow mudflat areas, such as the Wadden Sea, are now popular among those practising the sport of mudflat hiking.

On the Baltic Sea coast of Germany in places, mudflats are exposed not by tidal action, but by wind-action driving water away from the shallows into the sea. These wind-affected mudflats are called windwatts in German.

Outline of oceanography

The following outline is provided as an overview of and introduction to Oceanography.

Surf zone

As ocean surface waves come closer to shore they break, forming the foamy, bubbly surface called surf. The region of breaking waves defines the surf zone. After breaking in the surf zone, the waves (now reduced in height) continue to move in, and they run up onto the sloping front of the beach, forming an uprush of water called swash. The water then runs back again as backswash. The nearshore zone where wave water comes onto the beach is the surf zone. The water in the surf zone, or breaker zone, is shallow, usually between 5 and 10 m (16 and 33 ft) deep; this causes the waves to be unstable.


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