Humber Estuary
The Humber Estuary, located on the east coast of Britain, is the largest coastal plain estuary in the country and one of the longest, extending 50 miles (80 kilometers) from Goole to Spurn Head. It serves as the outlet for the Ouse and Trent rivers, draining a significant portion of England and contributing the largest single supply of freshwater from Britain to the North Sea. Characterized by its macrotidal nature, the estuary has one of the highest tidal ranges in Britain, with substantial sediment movement that shapes its dynamic habitats, including mudflats, sand flats, and salt marshes.
The Humber estuary is recognized for its rich biodiversity, providing essential habitats for numerous bird species, including those of international importance. Human activity has heavily influenced the estuary, with major ports at Hull and Grimsby and various industrial operations affecting its ecology. Conservation efforts are underway to manage these challenges, including the designation of the area as a "Wetland of International Importance" under the Ramsar Convention, as well as its classification as a Special Area of Conservation and Special Protection Area. Future management will focus on adapting to climate change and preserving the estuary's unique ecosystems while addressing the impacts of human development.
Humber Estuary
- Category: Marine and Oceanic Biomes.
- Geographic Location: Europe.
- Summary: The Humber is the largest coastal plain estuary on the east coast of Britain; it supports significant wetland and coastal habitats.
The Humber Estuary provides the outlet for the Ouse and Trent rivers, which together drain one-fifth of the land surface of England. This catchment of more than 9,266 square miles (24,000 square kilometers) provides the largest single supply of freshwater from Britain into the North Sea. The high levels of suspended sediment within its waters feed a highly dynamic geomorphological system with accretion and erosion of intertidal and subtidal areas.
As the largest coastal plain estuary on England's east coast, the Humber is also one of the longest in Britain, stretching 50 miles (80 kilometers) from Goole to Spurn Head at its mouth. It is 9 miles (14 kilometers) across at its widest point. Due to its position within the North Sea basin, it is macrotidal, with the second-highest tidal range in Britain after the Severn Estuary. It has a mean spring tidal range of 18.7 feet (5.7 meters) at Spurn Head, which increases up the estuary to more than 23 feet (7 meters) at locations around 28 miles (45 kilometers) inland.
The important habitats within the estuary—such as mudflats, sand flats, and salt marsh—are maintained by the copious amounts of sediment brought in with the tide and carried down the Ouse and Trent rivers. An estimated 1,654 tons (1,500 metric tons) of clay and silt are carried in with every tide from the eroding shores outside the estuary, and more than 1.1 million tons (1 million metric tons) of material is estimated to be present within the water column at any time. This sediment is constantly deposited, worn away, and redistributed within the estuary as part of every tidal cycle. The deposited sediments provide material that is essential to maintain the estuary's important intertidal and subtidal habitats, which are highly dynamic in response to physical and biological variables.
One of the key geographical features of the estuary is the long, curling spit of Spurn Head, which extends from the northern bank of the estuary where it meets the North Sea. This headland is nearly 3 miles (5 kilometers) long but less than 164 feet (50 meters) wide in places. It is made up of sand and shingle eroded from the coastline farther north, which is washed southward by longshore drift to accumulate as a long embankment inside the mouth of the estuary. The spit is occasionally breached by the sea but then reforms through further deposition. In its lee forms a sheltered area of mudflats, which are used by large numbers of wading birds. The headland itself also forms a major navigational landmark for thousands of migrating birds.
Biodiversity
Within the estuary are significant wetland and coastal habitats. Nearly one-third of the estuary is exposed at low tide, with sand flats in the outer estuary and mudflats further inland. The inner estuary supports substantial areas of reed bed, but areas of salt marsh are limited in extent due to land-use changes over the past 300 years. Where salt marsh is present, it is backed by grazing marsh in the middle and outer estuary; on the south coast, it is backed by low sand dunes with marshy slacks and brackish pools. Beyond these transitional zones, the estuary is bordered mostly by grazing and arable land.
Breeding, wintering, and migrating birds make extensive use of the Humber Estuary, which is recognized as one of the most important such areas in Europe, with nine species of international importance present. There are breeding populations of bittern, marsh harrier, avocet, and little tern. Important numbers of waterbirds, especially geese, ducks, and waders, are supported during the migration periods and in winter. These include species such as the bar-tailed godwit, golden plover, dunlin, knot, bittern, and shelduck. The area regularly supports more than 187,000 individual waterfowl.
Effects of Human Activity
The estuary has two large ports at Hull and Grimsby and has an average of 40,000 ship movements per year. Its ports make up the United Kingdom's largest harbor complex, transporting 14 percent of the country's overseas trade. Other industries along the estuary include chemical works, oil refineries, and power stations.
This human use of the estuary has involved processes such as dredging, land drainage, and flood management, which have affected the estuary's ecology over the centuries. Approximately 222,400 acres (90,000 hectares) of land around the estuary exists due to historical land reclamation, and, as such, it is below the spring high-tide level, currently protected by 146 miles (235 kilometers) of coastal defenses. In the future, these areas will be at risk from the changing conditions caused by sea-level rise, coastal erosion, and climate change.
Conservation Efforts
Proactive management will be required to protect the estuary and the surrounding area, including the creation of space to enable managed retreat in response to sea-level rise; maintenance of the sediment budget within the estuary, acceptance of dynamic change within the estuary system; maintenance of a range of habitat types, together with healthy populations of the associated species; and enhancement of water quality.
The estuary is designated a "Wetland of International Importance" under the Ramsar Convention. It is also a designated Special Area of Conservation (SAC) and Special Protection Area (SPA). These two designations make the estuary a Natura 2000 site, which is a site that provides vital habitats to rare, endangered, and vulnerable species, and the sites are protected by the European Union.
Recent projects on the estuary at Paull Holme Strays and Alkborough Flats have indicated how the estuary might be managed in the future. At these two sites, seawalls have been moved back, and more than 1,236 acres (500 hectares) of land have been allowed to flood to create new intertidal areas. This managed realignment will lessen the chance of flooding elsewhere along the estuary shore, preventing damage to homes and businesses and creating valuable habitats for birds and other wildlife.
Bibliography
Allen, J., et al. The Humber Estuary: A Comprehensive Review of its Nature Conservation Interest. Institute of Estuarine and Coastal Studies, 2003.
Fujii, T. "Spatial Patterns of Benthic Macrofauna in Relation to Environmental Variables in an Intertidal Habitat in the Humber Estuary, UK: Developing a Tool for Estuarine Shoreline Management." Estuarine, Coastal and Shelf Science, vol. 75, no. 1-2, 2007, pp. 101-22.
"Humber Estuary European Marine Site." Humber Management Scheme, 2012, www.humberems.co.uk. Accessed 30 Oct. 2024.
Lonsdale, Jemma-Anne, et al. "Managing Estuaries Under a Changing Climate: A Case Study of the Humber Estuary, UK." Environmental Science & Policy, vol. 134, Aug. 2022, pp. 75-84, doi.org/10.1016/j.envsci.2022.04.001. Accessed 30 Oct. 2024.
Natural England. National Character Area Profile: Humber Estuary. Government of the United Kingdom, 2012.
Pollard, Michael. Great Rivers of Britain. Evans Brothers, 2002.