A tidal creek or tidal channel is a narrow

inlet An inlet is a typically long and narrow indentation of a shoreline such as a small arm, cove, bay, sound, fjord, lagoon or marsh, that leads to an enclosed larger body of water such as a lake, estuary, gulf or marginal sea. Overview In ...

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 enviro ...

that is affected by the ebb and flow of ocean

tides Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables ...

. Thus, it has variable

salinity Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...

and

electrical conductivity Electrical resistivity (also called volume resistivity or specific electrical resistance) is a fundamental specific property of a material that measures its electrical resistance or how strongly it resists electric current. A low resistivity in ...

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 A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor ( anoxic) processes taking place, especially ...

. 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 Water quality refers to the chemical, physical, and biological characteristics of water based on the standards of its usage. It is most frequently used by reference to a set of standards against which compliance, generally achieved through tr ...

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. 11-09-04-fotoflug-nordsee-by-RalfR-011

Terminology

A "creek" normally refers to a tidal water channel in

British English British English is the set of Variety (linguistics), varieties of the English language native to the United Kingdom, especially Great Britain. More narrowly, it can refer specifically to the English language in England, or, more broadly, to ...

and in other parts of the

Anglosphere The Anglosphere, also known as the Anglo-American world, is a Western-led sphere of influence among the Anglophone countries. The core group of this sphere of influence comprises five developed countries that maintain close social, cultura ...

. This is the case in many countries in the

Commonwealth A commonwealth is a traditional English term for a political community founded for the common good. The noun "commonwealth", meaning "public welfare, general good or advantage", dates from the 15th century. Originally a phrase (the common-wealth ...

, such as

The Bahamas The Bahamas, officially the Commonwealth of The Bahamas, is an Archipelagic state, archipelagic and island country within the Lucayan Archipelago of the Atlantic Ocean. It contains 97 per cent of the archipelago's land area and 88 per cent of ...

, as well as some parts of the United States (near the

Chesapeake Bay The Chesapeake Bay ( ) is the largest estuary in the United States. The bay is located in the Mid-Atlantic (United States), Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula, including parts of the Ea ...

, parts of

New England New England is a region consisting of six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the ...

, and southern Florida). In the tidal section of the

River Thames The River Thames ( ), known alternatively in parts as the The Isis, River Isis, is a river that flows through southern England including London. At , it is the longest river entirely in England and the Longest rivers of the United Kingdom, s ...

in London, the names of the rivers that flow into it all become Creeks for the lower section that is tidal; thus, for example, the

River Lea The River Lea ( ) is in the East of England and Greater London. It originates in Bedfordshire, in the Chiltern Hills, and flows southeast through Hertfordshire, along the Essex border and into Greater London, to meet the River Thames at Bow Cr ...

becomes Bow Creek in its tidal section. In parts of southwest England and

Wales Wales ( ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by the Irish Sea to the north and west, England to the England–Wales border, east, the Bristol Channel to the south, and the Celtic ...

, the term "pill" is used, and is found in placenames such as Huntspill. A narrow channel between islands in the

Florida Keys The Florida Keys are a coral island, coral cay archipelago off the southern coast of Florida, forming the southernmost part of the continental United States. They begin at the southeastern coast of the Florida peninsula, about south of Miami a ...

is known there as a creek. On the

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

and

Pakistan Pakistan, officially the Islamic Republic of Pakistan, is a country in South Asia. It is the List of countries and dependencies by population, fifth-most populous country, with a population of over 241.5 million, having the Islam by country# ...

borders, the term also applies to the salt water inlets enclosed by

mangroves A mangrove is a shrub or tree that grows mainly in coastal saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen and remove sal ...

. Creeks are found dispersed all along the Indian coast. A "tidal course" is the more general term for any elongated indentation or

valley A valley is an elongated low area often running between hills or mountains and typically containing a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over ...

in a

wetland A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor ( anoxic) processes taking place, especially ...

originated by tidal processes along which water flows pumped by tidal influence. It includes a series of indentations within a wide spectrum of sizes (width, length, and depth) and with at least two levels of inundation. Subtypes are tidal rills, tidal grooves, tidal gullies, that normally do not contain water even during neap low tide, and tidal creeks and tidal channels, that have water permanently. A tidal course creates a system for its ecosystem that circulates water, sediments, organic matter, nutrient, and pollutants. A tidal course is essential to the surrounding flora and fauna because they provide protection, nutrients, a place to reproduce, and a habitat for juvenile species before they go into the ocean.

Development

Whereas areas of coastline that experience high wave activity are usually characterized by

beaches A beach is a landform alongside a body of water which consists of loose particles. The particles composing a beach are typically made from Rock (geology), rock, such as sand, gravel, shingle beach, shingle, pebbles, etc., or biological s ...

, areas sheltered from wave action may develop tidal wetland systems. In these areas, upland creeks drain towards the shore, draining the high part of the coast. At some point they become tidal, technically estuarine. As they come closer to shore, they often become very sinuous, due to the flatness of the land. In addition to draining upland

fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salt (chemistry), salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include ...

(in many instances) tidal creeks form by the ebb tide seaward flow and downward incision of the water as it flows from inland to the shore. At high tide and

spring tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables ...

, large areas are covered with water. This huge volume of water retreats at the start of the ebb tide in a surge. Later on during the ebb tide, water remains only in the creeks and the current is mainly a river (drainage) current and not tidal. Tidal creeks deposit sediment in a process called accretion, during the flood tide, which can maintain a flat plain by counteracting

sea level rise The sea level has been rising from the end of the last ice age, which was around 20,000 years ago. Between 1901 and 2018, the average sea level rose by , with an increase of per year since the 1970s. This was faster than the sea level had e ...

or land

subsidence Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope mov ...

. High tidal flow will maintain channels, while slower flow velocity can lead to closure of tidal creeks as they become clogged with sediment. Well-developed wetlands have sharp-banked tidal creeks, with vegetation stabilizing the sides of the creeks. Such tidal creeks will also be connected in networks: a multitude of smaller creeks called first-order creeks will feed into large ones, creating complex patterns of drainage.

Human impact

Especially in areas prone to compaction or subsidence - like peat wetlands - human use of tidal creek flow can lead to the expansion of the creeks. Natural subsidence is compounded by anthropogenic sediment compaction, lowering the land level.

Deforestation Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. Ab ...

and other human-development-related processes can destabilize the banks of creeks and increase the amount of sediment in them. This slows the velocity of the water, which means that instead of cutting deeper channels, the water flows gently farther inland in shallow channels. Human development in tidal areas often results in diking, which changes the course of the tidal creeks and the salinity of the tidal area into freshwater. Restoration of tidal wetlands begins with restoration of the creek systems, which determine the shape of the land, the nutrient and salinity levels, and the type of vegetation and animal communities in a wetland.

Examples

There are thousands of examples of tidal creeks throughout the world. A few specific ones are: * Burn of Ayreland, Mainland, Orkney, Scotland * Americano Creek, California, US * Crooked River, Florida, US * Ennore Creek, Chennai, India * Thane Creek, Mumbai Metropolitan Region, Maharashtra, India * Gorai Creek, Mumbai, Maharashtra, India * Vasai Creek, Thane, Maharashtra, India * Dubai Creek, United Arab Emirates

Footnotes

References