41 - Humber Estuary : Description

Physical and functional links to other National Character Areas

The Humber Estuary is one of Britain’s largest estuaries and drains one-fifth of the land mass of England. Several major rivers thus drain into the Humber upstream, including the Don, Aire and Ouse, while the rivers Trent, Hull and Ancholme join the estuary within the area. Actions and measures taken upstream will therefore impact on the estuary, just as high tide levels in the estuary will affect the tidal stretches of the rivers flowing in. Management of the upper stretches of the River Hull in the Holderness NCA, will be key to alleviating flood risk in the city of Hull itself, while the managed realignment of the banks, especially in the upper estuary in the Humberhead Levels NCA, can increase the capacity of the estuary to hold both river and tidal floodwaters.

The estuary forms an important ecological corridor, in particular for salmonids accessing spawning grounds in the Ouse and Trent. It also supports a large grey seal colony at Donna Nook, just down the coast within the Lincolnshire Coast and Marshes.

The open water of the estuary has high suspended sediment loads which, as the tides go in and out, feed a dynamic and rapidly changing system of accreting and eroding intertidal and subtidal mudflats, sand flats, saline lagoons, salt marsh and reedbeds. Sediment from the North Sea and from eroding soft coastlines further up the coast is needed to contribute to the constant reforming of the Spurn peninsula.

There is a major aquifer within the underlying Chalk, supplying large urban areas, major industrial complexes and the productive agriculture within both the NCA and adjacent NCAs. The adjacent NCAs -notably Humberhead Levels, Holderness and Lincolnshire Coast and Marshes – also provide important roosting and foraging areas to support the internationally significant bird populations.

The elevated rolling hills of the Yorkshire Wolds to the north and the Lincolnshire Wolds to the south are clearly visible from the low-lying land within the NCA, while also providing expansive views out over the estuary. The estuary is a very busy waterway, with both passenger and commercial traffic accessing the many ports both within the estuary and upstream. It is thus a key link to north-west Europe. Historically, however, the wide estuary has had limited connections between the north and south sides, but these are now linked by the Humber Bridge.

Distinct areas

• Spurn Point, a 5 km long sand and shingle spit.

The Humber Estuary today

The Humber Estuary is one of the largest river estuaries in Britain. Flowing east, the River Humber is at first constrained by the elevated land of the chalk uplands of the Yorkshire Wolds and Lincolnshire Wolds but then opens up into a wide and expansive stretch of open water before joining the North Sea beyond Spurn Point. High flood banks contain the estuary but the open waters and long views provide the dominant focus within much of the area. On the north bank, there are extensive areas of low-lying flat and productive farmland alongside the urban area of Hull, its major passenger port and its industrial complexes. On the south side, there are further ports and extensive industrial complexes of oil and chemical tanks, towers, chimneys, warehouses and storage areas, with some agricultural land.

The waters of the Humber Estuary contribute to a landscape that is always changing due to the tidal movements, exposing extensive mudflats at low tide, and the effects of the changing weather. Large ships, including ferries, container ships and cargo ships, are constantly moving in and out of the estuary. There are a number of prominent and iconic features in this open estuarine landscape including the Humber Bridge, Hull’s tidal surge barrier, The Deep on the water’s edge at Hull, and the lighthouses and Vessel Traffic Services control tower on Spurn Point. Some of the finest views of the estuary come from the Humber Bridge which links the north and south banks.

Most of the farmed landscape is open and expansive with large regular fields, large farmsteads with big sheds, few visible field boundaries and very limited tree cover. This is particularly so on the north side, where much of the land has been formed by reclamation of salt marshes from the estuary, by drainage of wet alluvial soils or by the process of ‘warping’; the seasonal tidal impoundment of farmland with water rich in silt. As a result, the farmland is fertile, drained by a network of ditches, and supports productive arable farming.

In other areas, on slightly higher drier land, hedgerows are more frequent and create a slightly more enclosed landscape, but always influenced by the nearby wide expanse of water in the estuary. Here, there are scattered small villages and those traditional buildings remaining are built of soft red brick, produced from local brick works at Beverley to the north and at Barton Clay Pits on the south bank. Some buildings closer to the coast are traditionally built with cobbles.

Within the predominantly arable farmland, there are areas of saltmarsh and reedbeds along tidal channels which cross the drained marshes, while the Barton Clay Pits provide open water, reedbeds and other wetland habitats, making them of value for birds and other wildlife, such as otters and water voles.

Around Hull, which lies where the River Hull joins the estuary, are varied urban fringe land uses, along with market gardens. The industrial complexes – with their oil and gas refineries, warehouses, towers, chimneys and lighting columns – are a major and distinctive feature of the estuary, especially on the south bank around Immingham and towards Grimsby, and around Hull on the north bank, which also has a passenger port.

These complexes contrast strongly with the remote and distinctive peninsula of Spurn Point, a long sand and shingle spit which extends out across the mouth of the Humber Estuary, providing some shelter from the North Sea. It comprises sandy beaches on the east side, which are exposed to the action of the North Sea, while on the sheltered west side sediment has been deposited, and extensive mudflats and saltmarshes have developed. The form of the Spurn peninsula responds constantly to wave action and the deposition of sediments brought down from the Holderness coast, and tends to move westwards over time. The peninsula supports colonies of breeding little terns and offers birdwatching experiences of international interest, especially during bird migration, and is designated as a National Nature Reserve. The distinctive landscape and history of the wider area is reflected through its recognition as Heritage Coast.

In the estuary, mudflats cover extensive areas and are exposed at low water. The estuary is also designated a Special Protection Area as it provides significant feeding, roosting and nesting areas for overwintering, migratory and breeding birds; large flocks of waders can often be seen feeding and flying along the shorelines. The estuary regularly supports over 150,000 waterbirds in the non-breeding season, including important populations of golden plover, black-tailed godwit, bar-tailed godwit, ringed plover and lapwing. Other species include wigeon, teal, mallard, shelduck, knot, oystercatcher, avocet, sanderling, dunlin, ruff, curlew, redshank, and turnstone. Bitterns now regularly breed in the reedbeds and marsh harriers hunt overhead. Many of these birds rely upon areas adjacent to this NCA for roosting and feeding.

The estuary is a Ramsar site and Special Area of Conservation, and thus of international importance, for its dynamic coastal and intertidal geomorphological processes and habitats, notably coastal lagoons, fixed dunes, stable dunes, shifting dunes and mudflats and sand flats, and is the third largest Site of Special Scientific Interest in England. It supports both river and sea lamprey, and a large breeding colony of grey seals. It is an important migration route for salmon and sea trout accessing their spawning grounds in the Ouse and Trent. The vegetation is also of interest as several scarce plants occur here at or close to the northern or southern limits of their range on the east coast. Work is being undertaken to address the coastal ‘squeeze’ of intertidal habitats between rising sea levels and flood defences and, in some instances, to increase the capacity of the estuary to hold flood water, through realigning the flood banks, such as at Alkborough.

The elevated Chalk ridge that forms the Yorkshire and Lincolnshire Wolds meets the estuary in the west of the NCA, creating low cliffs of geological interest and also providing striking views out over the expanse of water.

The landscape through time

Some 100,000 years ago the coastline was further west, along the line of the Cretaceous Chalk, which forms the raised ridges of the Yorkshire and Lincolnshire Wolds and underlies the rest of the area. During the last ice age, an advancing ice front blocked the mouth of the River Humber, holding back the water to form a huge lake extending inland, the Lake Humber. As the ice retreated, the meltwater poured out over the till (boulder clay), sands and gravels deposited by the ice sheet, cutting a channel to escape out to the sea and forming a wide, shallow river valley.

A moraine ridge, now called the Binks, was deposited seaward of the tip of the Spurn peninsula, creating sheltered conditions thus allowing shingle and sands to settle. Sand dunes formed on these deposits, raising the level above the highest tides and enabling vegetation to encroach, thus creating the peninsula. The peninsula remains in a constant state of flux, responding to wave action and the deposition of sediments, with the southern end protected within the curve of the Binks and the northern end attached to the Holderness coast.

The sea levels rose slowly after the ice age, vast quantities of sand and gravel were pushed onto the coast, and the Humber changed from a river valley to a saltwater estuary. Now the underlying geology is largely obscured by the Pleistocene deposits, with cliffs of Cretaceous Chalk exposed where the Humber flows between the Yorkshire and Lincolnshire Wolds, forming a flooded valley.

Archaeological evidence shows that the estuary has been a key trade and communication route between the North Sea and the Pennines, and also to the Midlands via the Trent, since prehistoric times. Significant palaeo-environmental and archaeological evidence is preserved within the wetland soils. For instance, bronze-age boats, suitable for both river and sea use, and fishtraps have been discovered in the intertidal areas. There is also evidence of early settlement on higher, drier land, while the lower wetlands provided fishing and fowling as well as summer grazing for the surrounding settlements.

As the northern frontier of the Roman Empire, several Romano-British settlements were established nearby, notably Brough. Place names indicate that both the Saxons and Danes settled in the area. The Humber continued to have great importance for trade and communication, with populations and wealth increasing through the medieval period.

There is evidence on the north bank that some drainage of the marshes began as long ago as 180 AD, and local abbeys began to promote drainage schemes in the 12th century. However, from the 17th century, the processes of coastal reclamation, drainage and enclosure had a significant impact on the rural landscape on the north side of the estuary. Dutch engineers carried out extensive drainage works, including cutting new drainage channels, enlarging watercourses, constructing flood protection berms and installing sluices and pumping systems, thus effectively reclaiming extensive areas from the sea. On the south side, flood defences were built to protect the developing towns and industrial areas.

The practice of warping – flooding areas with tidal waters carrying fertile alluvial silt – was also introduced by the Dutch in the 18th century. Warping drains, with their high flood embankments, are still visible today although the practice has long ceased. Later, Parliamentary enclosures produced the landscape of regular, geometric fields, mostly enclosed by dykes, with associated large brick-built isolated farmsteads, as seen at Sunk Island. Brick pits, based on Pleistocene clays, were excavated at Barton, while shingle was removed from the Spurn peninsula, resulting in increased erosion, which led to the construction of protective groynes, thus affecting the natural processes of accretion and erosion.

In the 16th and 17th centuries, the area declined in prosperity as a result of competition for trade and improvements to inland transport systems. Hull, however, prospered and became the principal port and town in the area, with fine municipal architecture built in the 19th century in the town centre. Defensive structures were also constructed from this period onwards to protect the coastline from attack.

The Humber Estuary’s importance for defence continued with a late-19th-century coastal artillery battery and minefield control centre built at Paull Point, followed in the 20th century by a First World War acoustic mirror near Kilnsea and two forts at the estuary mouth, then the construction of Second World War anti-aircraft batteries, along with bombing decoys for the main Humber docks at Little Humber. Spurn Point has always been important as a prominent location, with a 19th-century lighthouse and now a tower for the control of vessel movements, a lifeboat station and a bird observatory.

The proximity of deep water, especially on the south side of the estuary, enabled the expansion of several ports which now handle high volumes of goods (approximately 30 per cent of Britain’s shipping tonnage) going both in and out of the country. Immingham has developed as a major container port, as well as importing cars. The associated expansion of industrial complexes, transport links and urban areas has brought with it a loss of tranquillity. The building of motorways and the construction of the Humber Bridge in 1981 have linked the ports and industrial areas with their hinterlands, reducing the separation between the north and south banks and encouraging further development.

The uptake of agri-environment schemes in this area has not been high, with most relating to the management and restoration of wetland habitats such as salt marsh, inter-tidal habitats and reed beds. Farms remain large, averaging 120 ha, and there has been a slight decline in grass area in favour of oilseeds and vegetables. In an area dominated by arable cropping, livestock numbers are low, with a shift from cattle to sheep and a significant reduction in pig numbers, between 2000 and 2009.