Head of tide

Head of tide or tidal limit[2] is the farthest point upstream where a river is affected by tidal fluctuations,[3] or where the fluctuations are less than a certain amount.[4] This applies to rivers which flow into tidal bodies such as oceans, bays and deltas.

Though this point may vary due to storms, spring tides, and seasonal or annual differences in water flows, there is generally an average point which is accepted as the head of tide (in Great Britain this is the Normal Tidal Limit, typically noted on Ordnance Survey maps as 'NTL').[1] A river's tidal data are recorded at various locations downstream of this point. A river's head of tide may be considered the upper boundary of its estuary.

The head of tide is important in surveying, navigation, and fisheries management, and thus many jurisdictions establish a legal head of tide. As the head of tide is useful for navigation, separate maps can be made of the tidal zones up to the head of tide, such as was done in New Jersey.[5]

The head of tide may be many miles upstream from the river's mouth. For example, on the Hudson River, it is located 140 miles (225 km) upstream, near Albany, New York. On the Saint Lawrence River, tides affect the river up to Lake St. Pierre.[6]

Cromwell Weir - Nottinghamshire (Geograph 2561867 by Jonathan Thacker)
Cromwell Weir marks the tidal limit of the River Trent, a major river in England[1]

See also


  1. ^ a b 121 Lincoln & Newark-on-Trent (Map). 1 : 50,000. OS Landranger Map Series. Ordnance Survey. 2004. ISBN 9780319227213.
  2. ^ "tidal limit". Australian Water Information Dictionary. Commonwealth of Australia Bureau of Meteorology. 2015. Retrieved 22 February 2015.
  3. ^ Richard A. Davis (Jr.); Richard A. Davis, Jr.; Robert W. Dalrymple (20 October 2011). Principles of Tidal Sedimentology. Springer Science & Business Media. p. 82. ISBN 978-94-007-0123-6.
  4. ^ William H. Conner; Thomas W. Doyle; Ken W. Krauss (24 June 2007). Ecology of Tidal Freshwater Forested Wetlands of the Southeastern United States. Springer Science & Business Media. p. 36. ISBN 978-1-4020-5095-4.
  5. ^ New Jersey Archived 2013-02-13 at the Wayback Machine
  6. ^ [1]
Augusta, Maine

Augusta is the state capital of the U.S. state of Maine and the county seat of Kennebec County.The city's population was 19,136 at the 2010 census, making it the third-least populous state capital in the United States after Montpelier, Vermont, and Pierre, South Dakota, and the ninth-most populous city in Maine. Located on the Kennebec River at the head of tide, Augusta is home to the University of Maine at Augusta. Augusta is also the principal city in the Augusta-Waterville Micropolitan Statistical Area.

Brunswick, Maine

Brunswick is a town in Cumberland County, Maine, United States. The population was 20,278 at the 2010 United States Census. Part of the Portland-South Portland-Biddeford metropolitan area, Brunswick is home to Bowdoin College, the Bowdoin International Music Festival, the Bowdoin College Museum of Art, the Peary-MacMillan Arctic Museum, and the Maine State Music Theatre. It was formerly home to the U.S. Naval Air Station Brunswick, which was permanently closed on May 31, 2011.

Calais, Maine

Calais is a city in Washington County, Maine, United States. As of the 2010 census, it had a population of 3,123, making Calais the third least-populous city in Maine (after Hallowell and Eastport). The city has three Canada–US border crossings (also known as ports of entry) over the St. Croix River connecting to St. Stephen, New Brunswick, Canada.

Calais has been a city of commerce and is recognized as the primary shopping center of eastern Washington County and of Charlotte County, New Brunswick. Retail, service, and construction businesses are the primary components of the Calais economy.

Coquille River (Oregon)

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.

Exeter (CDP), New Hampshire

Exeter is a census-designated place (CDP) and the main village in the town of Exeter in Rockingham County, New Hampshire, United States. The population of the CDP was 9,242 at the 2010 census, out of 14,306 people in the entire town of Exeter.

Hardscrabble River

Hardscrabble River is the estuary of Wilson Stream, a small river in Washington County, Maine. From its source (44°59′46″N 67°16′55″W) in Charlotte, Wilson Stream runs about 10 miles (16 km) southeast to Dennys Bay. It changes name to Hardscrabble River at about the point where it is crossed by U.S. Route 1 (44°56′02″N 67°13′34″W). This section of the stream separates Pembroke on its left bank from Dennysville and Edmunds on its right.

Head Tide Historic District

The Head Tide Historic District encompasses a formerly industrial, now rural village at the head of tide of the Sheepscot River in Alna, Maine. The area had been industrially active since the mid-18th century, but its mills declined and were all destroyed by 1949, leaving a predominantly residential area with a number of houses dating mainly to the period before 1860. The district was listed on the National Register of Historic Places in 1974.

Maine Guide

This article is about wilderness guides. For the former minor-league baseball team, see Maine Guides.

Maine Guides are individuals certified to accompany travelers on a number of outdoor activities in the wilderness of the State of Maine, in the United States.

Metepenagiag Miꞌkmaq Nation

Metepenagiag (pronounced MET-EHH-PE-NAH-GHEE-AH), also known as Red Bank is a Mi'kmaq First Nation band government in New Brunswick, Canada on the other side of the Miramichi river from Sunny Corner.

Newmarket (CDP), New Hampshire

Newmarket is a census-designated place (CDP) and the main village in the town of Newmarket in Rockingham County, New Hampshire, United States. The population of the CDP was 5,297 at the 2010 census, out of 8,936 people in the entire town of Newmarket.

Old Town, Maine

Old Town is a city in Penobscot County, Maine, United States. The population was 7,840 at the 2010 census. The city's developed area is chiefly located on the relatively large Marsh Island, though its boundaries extend beyond that. The island is surrounded and defined by the Penobscot River to the east, and the Stillwater River to the west.

Oyster River (New Hampshire)

The Oyster River is a 17-mile-long (27 km) river in Strafford County, southeastern New Hampshire, United States. It rises in Barrington, flows southeast to Lee, then east-southeast in a serpentine course past Durham to meet the entrance of Great Bay into Little Bay. The bays are tidal inlets of the Atlantic Ocean, to which they are connected by a tidal estuary, the Piscataqua River. The freshwater portion of the river is 14.1 miles (22.7 km) long, and the tidal river extends 2.9 miles (4.7 km) from Durham to Great Bay.The Oyster River reaches tidewater at the base of a dam in the center of Durham, just west of the river's crossing by NH Route 108. Due to siltation, the river is only fully accessible to motorized boats west of the Durham Water Plant for approximately three hours on either side of high tide. Boaters have noticed the increasing effect of siltation on navigation since 1998.

Pembroke, Maine

Pembroke is a town in Washington County, Maine, United States. The population was 840 at the 2010 census. The town is home to a reversing falls on Mahar's Point.

Pennamaquan River

The Pennamaquan River is a short, 8.1-mile (13 km) river in the U.S. state of Maine, draining from medium-sized, low-elevation Pennamaquan Lake into Cobscook Bay.

Piscataqua River

The Piscataqua River () is a 12-mile-long (19 km) tidal river forming the boundary of the U.S. states of New Hampshire and Maine from its origin at the confluence of the Salmon Falls River and Cocheco River. The drainage basin of the river is approximately 1,495 square miles (3,870 km2), including the subwatersheds of the Great Works River and the five rivers flowing into Great Bay: the Bellamy, Oyster, Lamprey, Squamscott, and Winnicut.

The river runs southeastward, with New Hampshire to the south and west and Maine to the north and east, and empties into the Gulf of Maine east of Portsmouth, New Hampshire. The last 6 miles (10 km) before the sea are known as Portsmouth Harbor and have a tidal current of around 4 knots (7.4 km/h; 4.6 mph). The cities/towns of Portsmouth, New Castle, Newington, Kittery and Eliot have developed around the harbor.

Siuslaw River

The Siuslaw River ( sy-YEW-slaw) is a river, about 110 miles (180 km) long, that flows to the Pacific Ocean coast of Oregon in the United States. It drains an area of about 773 square miles (2,000 km2) in the Central Oregon Coast Range southwest of the Willamette Valley and north of the watershed of the Umpqua River.It rises in the mountains of southwestern Lane County, about 10 miles (16 km) west of Cottage Grove. It flows generally west-northwest through the mountains, past Swisshome, entering the Pacific at Florence. The head of tide is 26 miles (42 km) upstream.It is part of the homeland of the Siuslaw people, after whom it is named. Citizens of the Siuslaw nation lived in villages along the river until 1860 when they were forcibly removed to an Indian reservation in Yachats whereupon their homes, farms, gardens and villages were destroyed and occupied by U.S. settler-colonists.The valley of the river has been one of the productive timber regions in Oregon. The lower course of the river passes through Siuslaw National Forest.

The Coos Bay branch of the Coos Bay Rail Link crosses many bridges as it follows the narrow, winding valley of the Siuslaw River to the swing bridge at Cushman.

The river has historically been a spawning ground for Chinook and coho salmon. Although the Chinook population is substantial, coho numbers have declined from an annual average of 209,000 fish between 1889 and 1896 to just over 3,000 fish between 1990 and 1995. The estuary of the river is surrounded by extensive wetlands that are a significant habitat for migratory birds along the coast. It is one of the very few Western Oregon rivers where all major forks are undammed.

Umpqua River

The Umpqua River ( UMP-kwə) on the Pacific coast of Oregon in the United States is approximately 111 miles (179 km) long. One of the principal rivers of the Oregon Coast and known for bass and shad, the river drains an expansive network of valleys in the mountains west of the Cascade Range and south of the Willamette Valley, from which it is separated by the Calapooya Mountains. From its source northeast of Roseburg, the Umpqua flows northwest through the Oregon Coast Range and empties into the Pacific at Winchester Bay. The river and its tributaries flow entirely within Douglas County, which encompasses most of the watershed of the river from the Cascades to the coast. The "Hundred Valleys of the Umpqua" form the heart of the timber industry of southern Oregon, generally centered on Roseburg.

The Native Americans in the Umpqua's watershed consist of several tribes, such as the Umpqua (a band of the Coquille for which the river is named), and the Kalapuya. These tribes witnessed much of the Great Flood of 1862, during which the Umpqua and other rivers rose to levels so high that even the oldest Indians had never seen a greater flood.

Wave base

The wave base, in physical oceanography, is the maximum depth at which a water wave's passage causes significant water motion. For water depths deeper than the wave base, bottom sediments and the seafloor are no longer stirred by the wave motion above.

Ocean zones
Sea level


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