Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

The Humber Estuary and Holderness Coast


Published on

Published in: Technology
  • Be the first to comment

  • Be the first to like this

The Humber Estuary and Holderness Coast

  1. 1. Table of Contents Foreward 1 Introduction 2 The Wider Coast 6 Flamborough Head and Bridlington Bay 9 The Holderness Coast 13 The Humber estuary 20 The Lincolnshire coast 32 Coastal Zone Management 38 Issues 43 This report provides an overview of the current knowledge on coastal processes and landforms in the Humberside and Lincolnshire coastal zone. An accompanying report - Humber estuary and Coast: Management Issues - has been produced as a guidance to assist coastal planners, managers, engineers and environmental scientists involved in the management of the Humberside coastline.
  2. 2. Foreward Humberside is a coastal county. From the mudflats of the Humber and the eroding coast of Holderness, to the holiday beaches of Bridlington and the dramatic cliffs of Flamborough, the coast is one of enormous landscape contrasts. There are other contrasts too – some of the industrialised banks of the Humber contrast vividly with the teeming wildlife which use the adjacent mudflats, while the urbanised areas of Hull and Grimsby contrast with the peaceful agricultural scenery of coastal Holderness. These contrasts provide much of the interest and fascination of the Humberside coast but they also provide some difficult problems, for Humberside is facing some of the most complex coastal and estuarine issues. Although coasts provide some of the most desirable places for humans to live and work they also present enormous risks. The attractions of flat, fertile land for agriculture and urban development, the advantages of access to ports and harbours for both trade and fisheries and the benefits of recreation on both shore and water, all contribute to the desire for a coastal location. But set against these advantages must be the risks from flooding and erosion – natural forces which characterise all coasts but which people have always tried to minimise by using a variety of engineering works from flood embankments to harbour walls. In the past these attempts to reduce the risks associated with a coastal location have been small scale and localised but more recently we have come to realise that our continued use of the coast involves interference with its natural processes on a scale which may actually increase the risks rather than reduce them. In particular we are beginning to appreciate that coastal areas do not exist in isolation – what we do to one area affects not only our neighbours but areas quite remote from us. These problems are particularly true of the Humberside coast. We are just beginning to realise that what we do on the Holderness coast may have an effect, not only in the Humber Estuary, but in Lincolnshire and possibly many other North Sea coastal areas. These complex interconnections mean that we should take a wider look at our coasts than we have up to now and attempt to place our individual plans into this wider framework. This report, commissioned by Humberside County Council's Environment Sub-Committee of the sets out to provide this wider view of our coastline. It attempts to bring together much of the research, conducted over the past few years, which has examined the natural and human processes of the Humberside coast and to place this into a framework which will be of value to planning authorities and others, whose decisions now on coastal and estuarine developments will have repercussions far into the future. Humber estuary & Coast Page 1 1994
  3. 3. The coast between Flamborough Head and Gibraltar Point, with the Humber estuary occupying a central position, may appear at first sight to consist of a series of quite distinct shorelines, ranging from cliffs to mudflats, unrelated in any way to one another. Introduction However, the high chalk cliffs of Flamborough, the soft clay cliffs of Holderness and the beaches of Lincolnshire – as well as the areas in between – are all connected to each other by tidal flows, wave action and the movement of sand and mud on the sea bed, in fact by a complex of coastal processes. The wide expanses of mud and sand within the Humber estuary are themselves linked to these coastal areas by similar processes. Indeed we may think of all these different shorelines as parts of a single coastal machine – a machine whose function we must understand if we are to make it work efficiently. In order to be able to manage this coast, we must first understand the function of the coastal machine and the connections between each of its parts. Once these connections have been recognised, we can make more informed management decisions which both prevent damage occurring to the machine and also make it work to its optimum for our own use. The coasts of Humberside and Lincolnshire, together with the Humber, form a single management unit. The coast is very important to us both for economic and re creational purposes and the need to understand the coastal machine arises from our desire to live, work, visit or exploit the coast and estuary as well as the need to protect or enhance our investment in this zone. There is also an increasing desire to protect wildlife, so the maintenance of a natural coastal environment for plants and animals is very important to us. In order to understand this complex coast, it may help to consider how the area has developed over the past 100 thousand years. Humber estuary & Coast Page 2 1994
  4. 4. Origins Before the last ice age, some 100 thousand years ago, Holderness and East Lincolnshire did not exist and the coastline was much further west, following the base of the chalk ridge which now forms the Lincolnshire and Yorkshire Wolds and which ends in the high chalk cliffs of Flamborough Head. At this time, the sea had cut a cliff into the chalk, and beaches stretched along a line running through Driffield, Beverley, Cottingham and Louth. This ancient coastline can still be seen at Sewerby, since the present coastline has cut through the old coast at right angles, exposing the line of the cliff and beach. The coastline before the last ice age: A high chalk cliff, similar to Flamborough today, ran along the eastern edge of the Yorkshire and Lincolnshire wolds. The mouth of the Humber estuary was also much further west, meeting the sea where the Humber Bridge now stands, having cut a gap – the Humber Gap – in the chalk ridge which forms the Wolds. This landscape was changed completely by the last ice age which lasted until 10,000 years ago. Perhaps the most important outcome of this ice age was the formation of Holderness – a completely new section of our country. The ancient beaches of Driffield, Beverley, Cottingham and Louth are now buried beneath a blanket of stone, sand and mud some 20-50m thick – called boulder clay – pushed there by the advancing glaciers some 50 thousand years ago. The coastline after the last ice age: Holderness, the outer Humber estuary and eastern Lincolnshire appeared for the first time. This blanket of boulder clay pushed our coastline eastwards forming a new and irregular outline which the sea has now begun to reshape. In some places this reshaping takes the form of erosion – Humber estuary & Coast Page 3 1994
  5. 5. where land is removed by the action of the sea – while at other locations deposition of the eroded material is taking place, extending the shore into the sea. During this last ice age, a large proportion of the water of the world's oceans was locked up in the ice sheets which covered the land surface. The southern North Sea was initially covered by this ice but, at the end of the ice age, as the ice melted there was a long period during which sea levels had not yet risen to their present level. During this period, which lasted until about 6000 years ago, the southern North Sea was not a sea at all, but a swampy area receiving the waters of the Thames, Humber and Rhine. By 6000 years ago the North Sea had filled with water, and the level of the sea had reached approximately its present level. The rising sea level swept before it vast quantities of sand and gravel which formed the beaches of a new coastline. At the same time waves and currents developed in the deepening waters which began to erode the soft muddy sediments of the new land – which we know as Holderness. The Humber estuary gradually changed from a river valley when sea levels were low, to a large salt water estuary as sea levels rose. This new estuary received much of the sands and muds swept up by the rising sea and from the erosion of the outer shores. The Future Although our present sea level was more or less reached 6000 years ago, there have been minor changes since then and these will continue into the foreseeable future. Most of these changes are due to the sinking of the land rather than the rising of the sea. Indeed the whole of southeast England is gradually sinking while the north is rising – the result of the removal of the vast weight of ice which had depressed the north during the ice age. Within the Humber estuary, sea level over the past 50 years has risen at a rate of 3mm per year. If this rate continues, it will mean an increase of 192mm (19.2cm) in sea level by 2050. After the last ice age, sea level rose rapidly until by 6,000 years ago it was almost the same shape as that today. Since then, however, minor changes have occurred - changes which are still taking place today. However, the sinking of the land is not the only factor involved in sea level rise. Global warming due to increased carbon dioxide in the atmosphere may cause warming and therefore expansion of the ocean water. This in turn may cause an increase in the rate at which sea level is rising. In fact, predictions of an Humber estuary & Coast Page 4 1994
  6. 6. increase in sea levels of 33-39cm by the year 2050 are currently being made. If this future rise is added to the current rate of sea level rise, the total annual increase in the Humber may be a maximum of 1.13cm per year, which will mean sea level will be over 0.5m (1.5 feet) higher in 2050 A.D.– with serious implications for those who live in areas of Humberside at, or even below, high tide levels. Future increases in sea level due to global warming are predicted - one set of predictions is shown here. This everrising nature of the sea means that low-lying areas of land need embankments if they are to be protected from flooding. Such protection is now provided along almost the entire length of shores of the Humber estuary and the Lincolnshire coast. The predicted rise in sea level means that important decisions will have to be taken – decisions which may include how to increase the standard of our defences, but which may also address more radical appraisals such as whether we ought to be living or working in areas which are increasingly at risk from flooding or erosion. Large areas of Humberside and Lincolnshire lie below the high water mark: almost 4 million people live in this potential flood zone. Humber estuary & Coast Page 5 1994
  7. 7. We can think of the coast as a large machine whose function is to absorb the energy of the waves and currents The Wider Coast a function which is summed up in the phrase 'Coasts Stop Waves!' Although this may seem a simple enough job, the coastal machine is in fact extremely complicated due to the variety and timing of the waves and currents and the range of materials from which the coast is formed. Each area of different wave energy or sediment type may appear large enough to us to consider as a single unit – areas such as the Humber estuary for example – but this may be likened to looking at the gear box of a car and ignoring the rest of the engine. In order to understand the individual units we must first understand the whole – then concentrate on its parts. One way in which the coast can absorb wave energy is by developing a shape – as seen on a map – which meets the waves head-on. The most powerful waves in the Humberside section of the North Sea arrive from the north east, in which direction lies the longest open stretch of water – extending up to the Arctic. In response to these waves, therefore, the coast of Humberside and Lincolnshire is gradually developing a shape which lies at right angles to this wave approach direction and parallel to the crest of the waves. Any other orientation of the shore means that the waves would strike it at an angle and force movements of sand or mud along the coast – so changing the coastal shape. However, this simple picture is complicated by the fact that the coast is not free to change along its whole length. At Flamborough and Cromer resistant chalk reaches the coast and here no change in the shoreline can take place. Between these two hard points the coast is developing a smooth bay whose general orientation is parallel to the north easterly wave crests. In some places, this will mean that erosion will have to take place to remove any land which is jutting out from the smooth line of the bay, while inlets and estuaries such as the Humber and the Wash, will partially fill in with fine grained sediment. Humber estuary & Coast Page 6 1994
  8. 8. Along the Holderness coast, the formation of the bay is now marked by erosion. If sea levels remain stable, the bay will not retreat back as far as the ancient coastline at the foot of the Wolds, but instead form a cliff and beach line some miles eastwards. This is because the bed of the North Sea is now covered with thick boulder clay and sediments, which means it is much shallower than it used to be and therefore generates waves which are far less powerful. Between the two headlands at Flamborough and Cromer a wide bay is gradually taking shape However, the effects of sea level rise will complicate this process so that higher seas will eventually negate the shallowing affect of the boulder clay, causing a retreat of the coastline towards its ancient, pre-glacial position. This process of coastal development appears to be taking place over such a long time period – thousands of years – that it need not concern us – but this is not the case. Any management of our coastline which stops the natural development of erosion and accretion along the shore between Flamborough and Gibraltar Point will set up tensions which will become steadily bigger over quite short time periods. For example, the construction of sea walls, whether to protect against flooding or erosion, prevents the movement of the shore towards its ultimate goal of a smooth bay shape, while these and other constructions, such as groynes or jetties, affect the movement of sediment along the coast – again The erosion of the Holderness coast will eventually come to a natural halt some 5,000 to 10,000 years from now. The position of the final coastline and therefore the time taken to reach it will depend upon the rate and amount of sea level rise. Humber estuary & Coast Page 7 1994
  9. 9. preventing the natural development. The forces which then develop on these artificial fixed points will be the same as those which now impinge on Flamborough Head – but nothing we can build will equal Flamborough in size or extent. This may mean that we will have to be continually maintaining such structures and at a more frequent rate as the pressures on them increase. Coastal Cells The idea of a coastal cell is one which is central to recent developments in coastal management. A 'cell' is defined as an section of coast which is self contained – so that changes within it do not affect its neighbouring coastal sections. This definition is normally applied only to the movement of sand and shingle so that in effect the cell is a self contained sediment system. The coast of Britain has been divided into stretches known as ‘cells’: coarser sands and shingle do not move across cell boundaries. The coastline of England has been divided into a series of 'cells' based on this idea that interruptions to the movement of sand or shingle along the beaches or sea bed within one cell should not significantly affect beaches in an adjacent cell. From the diagram of these coastal cells we can see that Humberside's coastline together with most of the Lincolnshire coast is contained within a cell, in fact Cell No 2, extending between Flamborough Head and Gibraltar Point – one of the main reasons for the choice of the boundaries to the coastal area included in this study. There are some drawbacks to the idea of coastal cells, most notably the fact that the division of the coast takes into account only the movement of sand and shingle close to the shore, and does not include consideration of finer sediments such as muds. Moreover, it does not consider the importance of the processes within the Humber estuary and only deals with the general case in other areas, ignoring infrequent but potentially important events, such as major storms. The coastal cell shown here is probably incomplete, in fact the whole coast between Flamborough and Cromer – that is between the two fixed points set by the Chalk outcrops – may have been a better choice for the cell. Within this larger cell a bay appears to be forming and the movement of sand and shingle, although not entirely confined within this boundary, tends to move within rather than across its limits. Humber estuary & Coast Page 8 1994
  10. 10. The hard chalk cliffs of Flamborough Head mark both the northern end of the chalk ridge which forms the Lincolnshire and Yorkshire Wolds and the boundary of the Coastal Cell. Flamborough Head & Bridlington Bay The headland projects 6km into the North Sea and hence plays an important part in influencing processes in this region and, therefore, in determining the shape of the coast. Yet, although the headland forms an obvious divide between the two bays of Filey and Bridlington, there is nevertheless a good deal of sediment movement between the two bays – another example of the difficulties of defining a completely self-contained coastal section. As a result, it is important to consider the coastal processes within Filey Bay as well as those in the Flamborough to Gibraltar Point cell, despite the fact that Filey lies outside our study area. Humber estuary & Coast Page 9 1994
  11. 11. The beaches of Filey, well known to its holiday makers, are only the tip of a huge sand deposit which forms the sea bed within the outer Bay. Although some sand movement between beach and outer sand areas takes place, for the most part this sea bed sand remains undisturbed. However, during exceptionally severe storms, perhaps only once every 50 years or so, the approach of storm waves from the north causes a southerly transport of sediment. Sand is eroded from the sea bed and carried south around Flamborough to Bridlington Bay – the amount involved is approximately 40,000m³ in a single storm. The massive headland at Flamborough causes the tidal flow to rotate within the Bridlington Bay. Although this figure is small, such a rate of sediment removal would result in the total removal of sand from Filey Bay in 300 years. The fact that there is sand at Filey means that these losses are continually being made good. The balance is restored by a tidal current which moves sand northwards once again. The projection of Flamborough into the North Sea causes an interruption to the southwards passing tidal wave causing a huge whirlpool-like current in Bridlington Bay. This circular movement of water flows clockwise during the flood tide and anticlockwise during the ebb tide. This movement of the tides within Bridlington Bay causes sand to accumulate in the centre of the Bay just as tea leaves will collect in the centre of a cup if the tea is swirled around. This sand deposit is known as the Smithic Sand and is of the utmost importance to both the holiday and the fishing industries of Bridlington. The tidal circulation results in alternate movements of fine sand from one bay to another. Humber estuary & Coast Page 10 1994
  12. 12. During spring tides, the clockwise moving flood tide is much faster than the ebb, and although sand moves both ways, more tends to move in a clockwise direction and thus escapes northwards into Filey Bay. The amount moved on each spring tide is extremely small, but calculations show that, over a year, it amounts to almost exactly 1/50th of the amount removed from Filey Bay during the 50 year storm. This may appear too good to be true, but of course this balance has been achieved over a period of thousands of years and represents the result of what is no more than a random set of processes. Flamborough – Cliffs, Caves and Coves Flamborough Head itself consists of tall chalk cliffs up to 30m in height which are formed into a series of small bays in which sandy and rocky beaches occur. Since chalk dissolves in rain water – but not in sea water – the cliffs themselves have formed into a series of caves and stacks by solution and rockfall, and are receding at a rate of about 3cm per year. The chalk cliffs give way to softer clay cliffs at Sewerby, where the ancient pre-ice age cliff is exposed. These cliffs are receding due to a combination of wave action and landslides in a similar manner to those cliffs south of Bridlington. However, the rate of erosion is slower due to the protection from waves provided by Flamborough Head itself. Although the Flamborough and Bempton cliffs appear to us to be of predominant, indeed unique, value, both as landscape and for its wildlife, the area offshore of the headland is, perhaps, of even greater importance. The area offshore of the headland is composed of a rock platform extending 1km offshore, where it falls away to a lower level. This platform is cut by wave action acting on large boulders and gravels on the platform which grind down the chalk giving it a rough, pitted surface. This chalk wave cut platform provides one of the most important marine habitats in our coastal area and indeed, in England. The combination of shallow water and the rough surface of the rock platform both ensure an abundant and diverse marine community. This is enhanced by the fact that Flamborough lies at the western end of a major step in the bed of the North Sea, a step which forces an upwelling of water and, with it, nutrients for marine plants and animals. This abundance of marine life means food for other animals, principally the birds whose choice of nesting sites on Flamborough Head is as much due to the nearby food source as to the excellent accommodation provided by the cliffs themselves. As a result of this unique marine and cliff environment, Flamborough Head and the Bempton Cliffs are now protected as a Heritage Coast, a Site of Special Scientific Interest and a Special Protection Area. They are also likely to be designated a Special Area of Conservation under the UK's implementation of the European Community's Habitat Directive. The offshore environment is designated a Sensitive Marine Area. Humber estuary & Coast Page 11 1994
  13. 13. Bridlington The sea front of Bridlington has, for over 100 years, been entirely protected by sea walls. The north promenade was constructed first, reclaiming some land from the sea, while the south promenade was not built until considerable erosion had taken place. This explains the departure of the line of the coast from the broad sweep of Holderness to the north of the harbour. There is also a marked stagger in the coast at the southern limit of the wall where the cliff to the south of the sea defences is continuing to erode. In front of the sea wall a wide beach is encouraged by the presence of wooden groynes which serve to trap sand which is moving along the nearshore zone. The resulting beach not only protects the sea wall, but is beloved of generations of Bridlington holiday makers. The Bridlington beaches are, however, merely the shoreward extremity of the vast deposit of the Smithic Sand stretching far out into the Bay – on stormy days the waves can be seen breaking on this sand bank a mile out from the shore. Without the Smithic Sand, Bridlington's beaches would disappear with disastrous results both for tourism and the fishing industry – the sand being an important nursery and feeding ground for several fish species. Any attempts to remove the sand, as valuable aggregates for example, should be considered extremely carefully before any irrevocable decisions are reached. Humber estuary & Coast Page 12 1994
  14. 14. Holderness has the unusual claim that it is the youngest natural area of the English countryside. The Holderness Coast Of course, many coastal areas have been artificially reclaimed from the sea but only Holderness can boast a natural youthfulness – of a mere 10,000 years! The whole of this land was added on to the edge of the Yorkshire Wolds during the last ice age, brought in as a mass of mud and rock by the advancing ice sheet and left as a huge waste land of mud and pools as the ice receded. Vegetation soon covered the area and soon after the first humans ventured in – probably after walking across the bed of what is now the North Sea from the continent. Although the addition of 400 square kilometres to our national area by the receding ice sheets may be regarded as a benefit, it does bring with it some attendant problems. The land was, until quite recently, a boggy, wet area full of meres and lakes – just as it was left by the receding ice sheet. These meres have now almost all been drained – with the exception of Hornsea Mere – but the soils remain 'strong': heavy and lacking in many nutrients which other areas take for granted. It is not accidental that many Holderness farmers grow crops such as broad beans which add nitrogen to the soil. More dramatically, the coast of Holderness betrays its youth by its rapid changes – brought about by an erosion rate which is among the fastest in Europe. Just as for any adolescent, this natural process of change will eventually lead to a mature adult coast, although in the meantime it causes immense problems to those who live and work near it. Over the past 50 years more reliable measurements have been collected which allows a figure to be given to the rate of recession – amounting to 2m per year, although this is an average over a long period of time. The coast actually recedes as a series of small landslides, which can take a 10 to 20m (30 to 60 feet) bite out of the cliff top at one time followed by a period of several years in which no further movement takes place at that point. Humber estuary & Coast Page 13 1994
  15. 15. Over 30 villages have been lost to the sea here since Roman times, their positions shown now only on this map, which also shows that the coast was then over 5.6km (3.5 miles) seaward of its present position although this is no more than a rough estimate. Why is the coast eroding so fast? Although it appears a simple enough process, the erosion of the Holderness coast is really quite complex: Firstly, we have seen that the dominant north-easterly waves are trying to re-shape the coast between Flamborough and Cromer into a smooth bay. This inevitably means that some of the Holderness coast will be removed in order to achieve a more efficient coastal shape. The continued erosion of the Holderness coast has resulted in the loss of many villages - shown here in a map compiles in 1924. Secondly, although waves can easily erode the coast, which is made up of soft boulder clay, these actually do relatively little direct erosion. Instead, waves reaching the base of the cliff continually pound at the boulder clay, causing it to break up into its constituent parts – mud, sand and the occasional stone or larger rock. This eventually leads to a notch being cut into the base of the cliff. The rate of this erosion process is, however, quite slow – less than 10cm per year. Removal of this small amount of material from the base of the cliff causes the cliff face to steepen so that it eventually reaches a critical angle – at which point it collapses under its own weight – aided by rain water which seeps into the cliff top and lubricates the soils within the cliff face. Humber estuary & Coast Page 14 1994
  16. 16. This collapse usually takes the form of a landslip with a marked landward rotation, the upper portion of the cliff normally remaining intact as it slides down. This explains why the grass cover from the top of the cliff can often be seen at a strange angle lower down the cliff. The material derived from the cliff is removed by currents caused by waves reaching the coast at an angle, forcing water to move in a Wave action merely triggers the slumps which cause the retreat of the Holderness coast. The weight of the cliff material and its lubrication by percolating rain water are the main reasons for the slumps. current along the shore. Waves from the north and north east cause a southerly current along the Holderness coast, and sediment is therefore carried in this direction. The collapsed material is gradually removed by waves until the base of the new cliff is again exposed, when the process of wave undermining begins once more, so triggering yet another landslide. The process of erosion is obvious enough to anyone visiting this coast; a less obvious but even more powerful erosion process is, however, occurring at the same time beneath the sea. The sea bed, which itself consists of the same glacial muds, sands and boulders as the cliffs, is also being eroded by the action of the waves, causing a deepening of the area fronting the cliff. This means that the sea is continually able to reach the base of the cliff. The erosion of the cliffs and the seabed results in vast amounts of sediment finding its way into the sea – every year about 1 million m³ of sediment results from cliff erosion and 2 million m³ from the erosion of the seabed up to 2km offshore – 3 million cubic metres in total. All this material is carried south by the wave driven currents – moving this amount of material would keep a fleet of 300 articulated lorries busy every day of the year! The cliffs of Holderness are made up of a mixture of mud, sand and boulders, known as boulder clay. This consists of about 72% mud, 27% sand and 1% boulders and large pebbles and each of these portions behaves in a different way. The mud is suspended in the water and is easily transported southwards by the longshore currents – this material causes the muddy appearance of the sea immediately offshore so characteristic of the Holderness coast. Most of this mud passes into the Humber Humber estuary & Coast Page 15 1994
  17. 17. estuary where it forms mudflats which are important in providing protection from flooding to much of the area fronting the estuary. The smaller amounts of sand are also easily transported south by wave action, although this moves at a slower rate than the mud. Some of this sand is therefore able to form a beach in front of the cliff when wave conditions allow – usually occurring during calmer conditions. Cliff erosion in Holderness results in massive quantities of sand and mud falling into the sea - this is moved south by wind-driven waves and currents. During stormier conditions this sand is rapidly removed, most of it southwards towards Easington and Kilnsea where it drifts offshore into the North Sea. Some of the beach sand however moves offshore during storms, away from the base of the cliff, where it forms offshore bars – only to return to the cliff foot once the storm is over. The larger stones and pebbles are dragged along the seabed but only during more extreme storm conditions since they require more energy to move them. This material gradually moves southwards and eventually reaches Spurn, where in the past it added to the development of a shingle ridge here. The presence of a beach has an important effect since it serves to slow down incoming waves and protects the base of the cliff from erosion. This means that the waves can only reach the cliff during higher stages of the tide, thus reducing the exposure time of the cliff to waves and decreasing the amount of erosion. The power of the North Sea waves however is sufficient to remove most of the beach sand as soon as it is eroded from cliff – so that Holderness beaches are almost always thin and unable to stop wave erosion. During the winter it is usually The beaches of Holderness are extremely sensitive to wave conditions, during calm periods beach sand builds up against the cliff, but, during storms, the sand is transferred to sandbars just offshore. Humber estuary & Coast Page 16 1994
  18. 18. easy to scrape the thin sand cover from the underlying clay with your finger and it is only in high summer that beaches can build up enough to make a decent sand castle! Hornsea Not all of the Holderness coast is eroding – some stretches have been artificially defended. One such development is at Hornsea. Here, the 2km frontage of the town is protected by a concrete wall built in 1924 and a groyne field designed to trap the sediment in a similar manner to that at Bridlington. Cliff erosion has continued either side of the Hornsea defences and the town now projects into the sea, forming an artificial headland. This headland will become more pronounced as time progresses, leading to an increase in its exposure to the forces of the waves. Mappleton A different type of sea defence was constructed to protect Mappleton in 1991. Here a rock armour protection was provided for the base of a 500m stretch of cliff, with two rock groynes extending into the sea, one at either end of the cliff protection. This rock armour provides protection from erosion to the base of the cliff and the groynes are designed to encourage the development of a wide beach, again providing protection to the cliff. The angle of the cliff behind the defences has been reduced to prevent further slumping of the face. Withernsea This coastal town is protected in a similar manner to that of Hornsea, its defence works being built during Victorian times. However, storms during the winter of 1992/93 caused the removal of most of the beach fronting the wall, in places up to 4.2m of sand being stripped by the sea, exposing the foundations to the sea wall. This has lead to cracks appearing in the wall and houses along the sea front experienced shock-waves large enough to be measured on the earthquake scale. Emergency repairs have had to be undertaken here, and rocks, similar to those used for the Mappleton defences, have been placed along the base of the wall to provide further protection. Easington There are currently no protection works here, although a large installation responsible for receiving gas from the North Sea gas fields is now within 25m of the cliff edge. Plans are currently being drawn up for defence works for this installation and possibly for the village of Easington itself. Easington marks the point at which the southwards travelling sand derived from the erosion of the cliffs moves offshore. This is a result of a combination of the change in the direction both of the coast at this point and of the tidal currents, the latter caused by the interaction of tides in the North Sea and those Humber estuary & Coast Page 17 1994
  19. 19. within the Humber estuary. Not all the sand leaves the upper shoreline here, a small proportion carries on along the shore towards Spurn where it forms an essential part of its natural maintenance. A careful study of the map shows that the Holderness coast does not follow a straight line drawn between Bridlington and Kilnsea, but takes the form of a shallow bay whose southern limit lies at Easington. South of this the shore turns westwards towards Spurn so that the Dimlington to Easington reach acts as headland. The reason why this is so is not fully understood, although it could be that the wider zone of shoal water immediately offshore here reduces the power of the waves, so that erosion rates are very slightly lower here than further north. This may not be a noticeable difference over short time periods – such as the past 50 years, but sufficient to cause a long term change in coastal shape. Disappearing Holderness Although the natural coastal processes will lead eventually to the formation of a large scale bay between the hard points of Flamborough and Cromer there already exist several smaller and shallower bays nested inside each other – rather like a set of Russian Dolls! Most of these smaller bays are not permanent features since their headlands are eroding along with the rest of the coast but there is one set of features which have fixed headlands and which therefore may develop into permanent bays – these fixed headlands are the artificial defences at Bridlington, Hornsea, Mappleton and Withernsea. Although these fixed headlands have been in place only for a relatively short time period some evidence already exists to suggest that they are causing bays to form between them. South of Hornsea, for example, a bay is already developing southwards towards Withernsea as can be seen on the map. Once this bay extends between the two hard points it will continue to develop until it is deep enough to prevent sand escaping around the headlands. At this stage the beaches within the bay will begin to widen and deepen and form an effective natural protection against further wave erosion – so that the bay may become stable. Research into the area between Hornsea and Coastal defences at Bridlington, Hornsea and Withernsea have halted erosion, but it continues elsewhere forming shallow bays between the defended towns. Humber estuary & Coast Page 18 1994
  20. 20. Mappleton indicates that a stable bay between these two hard points will have a maximum depth of 650m located 2km south of Hornsea and will take approximately 250 years to develop. Similar bays will form elsewhere – wherever artificial hard points provide the necessary headlands. If this conclusion is correct and stable bays will form between hard defences, then this provides an obvious method of protecting Holderness against A coastal defence at Easington could complete the sequence of bays and eventually halt the erosion of this coastline. further erosion. The present town defences, together with a few more strategically placed hard points, may be sufficient to reduce and eventually stop erosion along the whole coast. Two problems face such an apparently desirable conclusion: Firstly, as the bays develop, so the wave pressure on the headlands will increase, and the cost and difficulty of maintaining these may become impossible to sustain. This pressure will be due partly to the concentration of wave energy on any projecting headland but also because the sea bed will continue to erode offshore and the resulting deeper water will allow more wave attack at the shore. Secondly, although the erosion of the Holderness coast is seen by those who live or work there as an evil which must be prevented, it may be viewed entirely differently from the viewpoint of those who live or work on adjoining coasts. The mud and sand which is produced from the Holderness erosion is carried along the coast and helps to prevent erosion there. Thus the Humber estuary needs all the mud it can receive from Holderness in order that accretion on the estuary bed can keep pace with sea level rise. Without such mud the estuary would become deeper and the tidal range, and hence flooding of the low lying lands surrounding the estuary, would increase. Similarly the beaches of Lincolnshire may be fed by sand moving south from Holderness. Preventing Holderness erosion could cause even more dramatic erosion on this coast than is already occurring. Such arguments mean that a simple decision to defend the Holderness is not as easy as may be thought at first sight. The relative economics of cost versus benefit can be calculated for the Holderness coast, although the outcome of even this limited exercise is not obvious – but it is clear that an entirely different answer would be gained if such a study were to be extended to include the Humber Estuary – while extending the economics to include the whole southern North Sea and its coastline would result in yet another set of conclusions. Humber estuary & Coast Page 19 1994
  21. 21. 120km long and over 14km wide at its broadest, the Humber estuary drains over one fifth of England and forms the heart of the county of Humberside The Humber estuary playing an important role in the development of its coast as well as in the lives of a large proportion of its inhabitants. The history of the Humber may go back millions of years and is largely unknown to us, but we may pick up the story a mere 100 thousands years ago. At this time, before the last glaciation, Holderness did not exist, the coastline ran along the eastern edge of the Yorkshire and Lincolnshire Wolds and the mouth of the Humber intersected this coastline almost exactly where the Humber Bridge now stands. At this time, then, the Humber was 50km (31 miles) shorter than it is now and had probably been in existence for several million years. This picture was changed completely by the last ice age. At its maximum extent, the ice front ran along the Wolds' edge and plugged the mouth of the estuary. The river water draining eastwards from central England ponded back behind this ice plug forming a lake over the Vale of York. Humber estuary & Coast Page 20 1994
  22. 22. The Humber estuary, draining one fifth of England and over 10km long provides the physical and economic forces for the region. The retreat of the glacier at the end of the ice age – some 10,000 years ago – unplugged this lake and the river water poured out across the muddy waste of boulder clay left by the retreating ice and which we now call Holderness. The ice front by this time lay along the north bank of the Humber, marked today by a ridge of mud and sand. One end of the ridge forms the church hill at Paull and the other end the Binks seaward of Spurn. This ridge diverted the river water giving the channel a marked bend at Skitter Point – a bend still there today as can be seen on the map. At this stage in the development of the Humber the sea level was still very low so that the southern North Sea was dry and the Humber was a river rather than an estuary. However, by 9000 years ago the sea was rising rapidly and had entered the lower part of the estuary as we know it – a tongue of sea water probably extended up to Trent Falls by this stage and evidence from Hull Market Place suggests that it also extended up the River Hull for some distance. The geological history of the Humberside coast is dominated by the events of the last ice age: here position of the glacial moraines are shown which still act as natural breakwaters. The sea continued to rise creating, by 6000 years ago, a wide shallow estuary whose inner section, west of the chalk Wolds was inherited from the older Humber but whose outer section Humber estuary & Coast Page 21 1994
  23. 23. – from the Wolds to Spurn was entirely new – the first new estuary in Britain for millions of years. The Humber estuary has accumulated massive amiunts of sand and mud over the past few thousand years: as shown in this map of the extent of the estuary about 6,000 years ago. This new estuary rapidly began to infill with mud and sand – a process of infilling which has continued right up to the present day – and much of these deposited muds have been reclaimed for agriculture and urban development over the past 2000 years. Indeed most of the city of Hull is built on reclaimed salt marshes – which has the important implication that all this urban area lies below the highest level of the tide. This has meant that the shape of the estuary has changed considerably and now has the classic estuary form – often described as a trumpet shape – which is similar to every other large estuary in the world. However, the kink in this classic shape given to the Humber by the retreating ice front at Skitter Point perhaps means that it should be called saxophone – rather than trumpet-shaped! Almost all the mud and sand which has brought about this infilling of the estuary has been brought in from the sea. The rivers Trent and Ouse do bring a very small amount of sediment down from their large drainage areas but the proportions of marine to river sediment are approximately 30 to 1 at the moment, although the contribution from rivers may have been slightly larger at some times in the past – such as immediately after the forests were cleared for agriculture 2 or 3 thousand years ago. Processes in the Humber The main sources of the sediment deposited in the Humber are the North Sea and from erosion of the Holderness coast. The North Sea has sediment suspended in its waters as a result of inputs from the North Atlantic and the English Channel as well as that eroded from its own bed. This probably accounts for about 60% of the annual input of sediment into the estuary. The erosion of the Holderness coast to the north of the estuary also represents a source of sediment for the Humber, accounting for about 37% of the total yearly input. The other 3% is made up from sediments carried into the estuary from the rivers draining into it. It is worth noting that the amount of sediment input by rivers has fallen by a third since 1900. The processes within the estuary, whether they are erosion, sedimentation or sediment transport are mainly driven by the tides (this is in contrast to the open coast, where wave action is usually dominant). The tide is in fact a very long wave of water which moves southwards down the North Sea and passes Humber estuary & Coast Page 22 1994
  24. 24. into the estuary. At the mouth of the Humber, this wave is over 500km long but only 6m high so that it is impossible to see any slope on the water surface. Yet stand on the quay side and watch this wave pass and it appears that the water level is rising as the front of the wave passes – the flood tide – and falling as the back of the wave moves past. The whole process takes exactly 12.4 hours – the tidal period – from one high tide to the next. As this tidal wave passes up the estuary it undergoes a series of changes which influence the processes and therefore, the shape of the estuary. Firstly, the decreasing width of the estuary initially causes an increase in the height of the tide – the tidal range increases from 5.7m at Spurn to a maximum of 7.1m at Saltend. However, upstream of Saltend, the frictional effect of the ever-decreasing width of the estuary starts to cause a decrease in tidal range. Secondly, although at the mouth the flood and ebb tides take exactly half the 12.4 hours tidal period to rise or fall this changes as the tide drags in the shallow water of the estuary until at Selby, some 110km inland, the flood takes only 2.4 hours to rise while the ebb lasts for 10 hours. This means that flood tide currents are stronger than the ebb, since the same amount of water has to move in a shorter time period, so that the flood carries more sediment into the estuary than the ebb currents carry back out. This is one of the main reasons why the estuary has infilled so rapidly with marine muds and sands. As the tide passes up the estuary, two changes occur: the tidal range decreases and the length of the flood tide decreases relative to the ebb tide. Another reason is that the fresh river water tends to float on top of the salt marine water so that any river sediments are carried out to sea while the marine sediments are carried into the estuary. The bottomhugging tidal currents carry the muds and sands inland towards Trent Falls where they concentrate, making this section of the Humber the muddiest in eastern England. The brown, muddy, waters of the Humber are, of course, infamous. It should be stressed, however, that this Humber mud is perfectly natural, harmless material and in no way reflects the level of pollution. In fact, the mud particles actually reduce pollution by attracting any polluting chemicals to them and then depositing these on the bed of the estuary where they are covered over. Humber estuary & Coast Page 23 1994
  25. 25. The Future of the Humber Despite the urban, industrial and commercial activity in and around the Humber, it remains of enormous importance to wildlife as this map of its designated conservation areas shows. The Humber is, indeed, a very healthy estuary whose importance for nature conservation may be seen in the number and extent of its nature reserves. Most recently classified as a Special Protection Area and Ramsar site and likely to be designated a Special Area of Conservation under the Habitats Directive, the estuary's nature reserves extend over almost its whole area with the exception of the middle reach around the city of Hull. The birds of the estuary are particularly well known and 9 bird species of international importance use the estuary for feeding. In turn this bird life reflects the teeming invertebrate life of the mudflats, rich in worms and crustacea on which the birds feed. Far from being a dirty river, the Humber is in fact a model of how estuarine-based industry, urbanisation and agriculture can exist in harmony with its wildlife. This optimistic picture may, however, have a down side. Recently, the rate of siltation in the estuary has reduced dramatically perhaps indicating that there has been a drop in the amount of sediment being supplied to the estuary. This has serious implications in view of rising sea levels since the mudflats and saltmarshes, already reduced in area by reclamation, will not be supplied with enough silt to be able to keep pace with the rising water level. The immediate implications for the estuary are obvious, an increase in sea level will mean increased risks of flooding – but the failure of the mudflats to keep up with this rise will mean that wave and tidal current erosion of the flood defences (which protect almost the entire shores of the estuary from flooding) will increase. The loss of saltmarsh and mudflat areas will also have serious implications for the conservation status of the estuary since they form its principal wildlife habitats. The causes of this drop in mud supply are discussed later in this report, but the immediate implication is that the sources of material to the estuary, for example from the Holderness coast, become even more crucial to the well being, not only of the wildlife of the Humber, but to the safety and economy of its half a million inhabitants who live below the high water mark. Flooding in the estuary is caused by exceptionally high tides known as surges. These have occurred at frequent intervals throughout history and have caused devastation and hardship. Perhaps the most well known event was the great tide of 1953 when over 300 people were drowned and millions of pounds of property ruined. As can be seen from the diagram, these surges are becoming higher and higher each Humber estuary & Coast Page 24 1994
  26. 26. Although water levels in the Humber vary enormously depending on the tide and weather conditions, there has been an overall rise in the average sea level over the past 50 years. year as sea level rises, so that the 1953 surge now looks quite puny compared with the 1978 surge, for example. These more recent surges have not caused damage or flooding on the scale of the 1953 surge due to the provision of more efficient flood defences along the Humber banks. To provide acceptable standards of defence these embankments need to be raised to keep pace with sea level rise and a recent programme of maintenance has been suggested by the flood protection authority – the National Rivers Authority. However, while the importance of flood protection for cities such as Hull is indisputable, there has recently been some questioning of the role of flood embankments along the estuary. Confining the tide to a narrow channel between high flood embankments may actually cause an increase in tidal range and increase the risk of floods. Where flood embankments are not essential, for example where they protect low grade agricultural land, it may be more efficient to move the defences landward a short distance. This would allow the development of natural mudflats and salt marshes which themselves reduce tidal range and flood risk as well as providing protection for the embankment against wave erosion. The saving in cost for the defences may be considerable and a secondary benefit would be the gain in natural habitat for wildlife. This concept of 'managed retreat' is one now under consideration by both statutory and voluntary groups who are responsible for the management of the Humber. Spurn Head The 8km long projection of Spurn Head occupies an apparently precarious position at the mouth of the Humber estuary. This thin strip of land consists of a sandy beach capped with dunes up to 15m high, although at its landward end, where the peninsula is at its narrowest, it is no more than a few metres in height. The peninsula has in the past been cited as a text-book example of a spit – that is a tongue of sand carried out into the mouth of a bay or estuary by long shore drift. However, recent research suggests that things are more complex than this. There are two major problems with the standard explanation of the origin of Spurn. Firstly, the tidal range at the mouth of the Humber estuary is much too large for the development of a spit – all other spits in the UK have a tidal range of between 2m and 4m whereas at Spurn it is 6m. Secondly, the mouth of the Humber is known for its exceptionally fast tidal currents. These are easily capable of eroding the sandy beaches and dunes of Spurn – which should disappear within a few days when acted upon by such tidal action. Humber estuary & Coast Page 25 1994
  27. 27. So what is protecting the peninsula from erosion? Once again the history of the Humber can provide the answer. As we saw the retreating ice from the last glaciation paused at a position roughly following the line of the north bank of the estuary, depositing a ridge of glacial sediments – known as a moraine – washed out from the glacier snout. The evidence suggests that this moraine continues around the tip of Spurn and then, as shown on the map, northwards into the offshore zone of Holderness. It is this moraine ridge – especially the seaward section known as The Binks – which surrounds the tip of Spurn and protects it from the waves and tidal currents which otherwise would have washed it away – or prevented it forming in the first place. Sand and shingle resulting from the erosion of the Holderness coast was carried southwards by wave action and ended up in the shelter of the Binks, forming the foundations of the Spurn peninsula. Sand dunes then formed on this foundation material so raising the level of the surface above the highest tides and allowing vegetation and human colonisation to take place. The problem with this is that whereas the southern end of the peninsula is held within the curve of the Binks, the northern end is attached to the Holderness coast – which is eroding westwards at 2m a year. This means that the northern end of the peninsula must act as a form of hinge, connecting the moving 'root' at Kilnsea with a stationary 'island' at the southern end. The northern end of Spurn was, until quite recently composed of a shingle ridge rather than sand dunes. During storms this shingle was washed up the outer beach by the waves and spilled over the crest of the ridge thus rolling it westwards. This is apparently the way in which the hinge section of the peninsula kept up with the movement of the Holderness root. The shingle however is now gone and sandy beaches and sand dunes have replaced the ridge. During storms, sand tends to move seaward rather than landwards like shingle, so that instead of rolling over as happened previously, the northern section of Spurn now erodes away. The reason for the loss of shingle is surprising – it was apparently taken away by the bargeload in the 18th and 19th centuries and used for ballast for the whalers which operated out of the port of Hull. Probably as a result of this removal of shingle, between 1849 and 1851 several breaches occurred in the peninsula and these were repaired by 19th century engineers who dumped chalk boulders in the gaps. To prevent further erosion, wooden groynes were constructed to widen the beach. The wide beach also encouraged the development of sand dunes and brushwood fences were built to speed up the process – thus the self-maintaining shingle ridge was replaced by erodable sand. The sandy ridge lasted well enough for over 100 years – but only in the shelter of the groynes and sea walls built to protect them. Over the past few years these defences have deteriorated and the immediate result has been massive erosion of the neck of Spurn so that today it is only a few metres wide and there are grave fears for its continued existence. Humber estuary & Coast Page 26 1994
  28. 28. It appears therefore that the current Spurn, far from being a natural feature, is in fact largely artificial and has relied on the protection of wooden groynes and concrete walls for its survival. The question now facing the Yorkshire Wildlife Trust, who currently own the peninsula, is whether the original natural processes can be restored or whether they must simply accept the changes which are now taking place to Spurn. One thing is clear, any attempt to protect the present peninsula with further artificial defences would be not only prohibitively expensive but must lead, inevitably, to its ultimate destruction – Spurn cannot be tied down but must be free to move as the Holderness coast retreats. The future may show us a very different Spurn – but there is every indication that it will remain in one form or another for many centuries to come. The estuary mouth Standing at Cleethorpes or Spurn at high tide and looking across the Humber one could be forgiven for thinking that the estuary is immensely wide and deep. In fact, when compared to other estuaries or rivers the opposite is true. Firstly, the estuary is extremely shallow – the average depth is only 4m and in many places it is possible to walk across at low tide. This shallow cross section is not accidental, it has developed due to infill by marine sands and muds over the past 6000 years so that as the tide enters the estuary the water drags of the bed which both reduces the tidal range and slows down the tidal current. If this were not the case then perhaps the tide would swing down the Trent and flood most of the Midlands! Secondly, although the mouth of the Humber appears to be very wide – 14km at high tide – in fact it is narrower than would be expected for the volume of water which must pass through it in each tide – 1000 million cubic metres. This is enough water to fill 500,000Olympic swimming pools and yet this is achieved in the 6.2 hours of the flood tide! Squeezing this volume of water through the Humber mouth causes high current speeds – normally sufficient to erode the mouth and widen it. This does not happen in the Humber because the glacial moraines left by the ice form the banks of the channel at the mouth – not only along the northern shore (see above) but also along the south shore between Grimsby and Tetney. These moraines are not easily eroded so that the mouth remains relatively narrow and current velocities high. Sunk Island - an island no more The south bank and channel of the outer Humber is the workshop of the estuary. The town of Grimsby stands at the entrance to the estuary and is dominated by its docks and Victorian water tower. West of Grimsby industries line the estuary banks, with several new power stations and petro-chemical industries forming the skyline, while the central channel is one of the busiest shipping lanes in Britain with vessels moving to and from Immingham, Hull and other ports and wharves further inland. But this busy scene is not reflected in the activity on the North Bank. Here, the peaceful agricultural life of south Holderness, with its scattered villages, contrasts dramatically with the south bank, it is not until Saltend is reached that any industrial activity is to be seen. And yet, despite this contrast in human activity, the North Bank is having major impact on the south Bank in these outer reaches of the estuary – an impact which is causing some concern and which can only be understood by examining the history of Sunk Island. Humber estuary & Coast Page 27 1994
  29. 29. The importance of the Humber for navigation means that it boasts an unequalled series of historic maps and charts: this is the Scott chart of 1794. During the initial stages of the development of the Humber, indeed right up to the early 17th century, the outer Humber estuary was much wider than it is at present – Patrington Haven for example stood on the estuary banks and not 3km inland as it does now. However, a sandbank began to develop in the centre of the estuary which by 1675 was high enough for it to be reclaimed – the original Sunk Island. To the north of this island the Patrington or North Channel flowed from the tip of Spurn across what is now Spurn Bight and rejoined the main estuary at Stone Creek. As siltation continued, progressive reclamation took place, so that by 1800 the western and northern arms of the North Channel were reclaimed to join Sunk Island to the mainland. Since then, more reclamation has taken place, the last as late as 1970. The effect of this has been to reduce the width of this section of the estuary by a considerable amount. In turn this has increased the current velocities in the narrower section so that the banks and bed have begun to erode – in effect the Humber is trying to return to the wider section it enjoyed before reclamation of Sunk Island took place. Of course, this has serious implications for the flood embankments which prevent tidal inundation of the reclaimed land, since the removal of the mudflats has led to an undermining of the defences. One of the most significant changes in the dynamics of the Humber was caused by the progressive reclamation of Sunk Island But infinitely more important, at least from the economic view point, is the effect on the flood embankments which protect the industries and Humber estuary & Coast Page 28 1994
  30. 30. port facilities along the south bank – since the impact of Sunk Island's reclamation is on the whole estuary and is not confined to its own shore. Over the past 50 years the erosion along the south bank has become extremely worrying and the NRA are forced to spend more and more time and money in repair work to avoid a major flooding catastrophe. In some places the mudflats fronting these embankments have experienced over 10cm of erosion per year so that the toe of the flood embankments are exposed to wave attack. The answer to these difficulties is simple enough in theory, but almost impossible in practice – Sunk Island should be given back to the estuary so reducing current speeds and taking the pressure of the south bank flood defences. This may involve the managed retreat of the south bank of the Island – or could mean the re-instatement of the old Patrington Channel, leaving Sunk Island as a true island once again. Either way, the political and economic obstacles to such a solution are so great that it is difficult to see how it could progress. The alternative is to 'make do and mend' – that is, continued repair work to the defences. All of these problems facing the outer estuary will of course be amplified if the source of sediments from Holderness is reduced. It is perhaps not too much of an oversimplification to say that the Humber's industries rely on its mudflats – we interfere with these at our peril. The Inner estuary – the rise and fall of Read's Island Upstream of the Humber Bridge the estuary is predominately experiencing net deposition. This is because currents are capable of transporting sediments into this area during the flood, although they are not capable of removing the sediment during the ebb. Despite the fact there is net accretion, however, local erosion associated with the continually shifting channels also occurs with erosion and accretion alternating over small areas and short time periods. The inner Humber, west of the bridge, experiences rapid and dramatic changes in the position of its main channel and its sand banks. Since there is a large amount of sediment in the inner estuary, the water nearly always appears colouring of the Humber estuary & Coast Page 29 1994
  31. 31. waters is brown. This entirely natural and is a result of suspended sediments and does not represent pollution. One result of the channels movements in the inner Humber has been the rapid growth of Read’s Island from a small sandbank in the mid 19th century and, more recently, its equally rapid erosion. Observations of channel movement have shown that there is generally a shift between two extremes. One extreme is when the main channel takes a sinuous course through the upper estuary, flowing to the north of Whitton sand and then south of Read's Island. The other extreme is when the main channel takes a more direct route from Trent Falls, flowing through the middle of the estuary.The movement of the main channel between these two extremes is very important. When in its sinuous phase saltmarshes on the banks of the estuary close to the channel experience erosion. This explains, for example, the dramatic loss of saltmarsh between Hessle and Brough over the last 20 years. Recent movement of the channel has also led to the erosion of an island close to the Humber Bridge – Read's Island. This was reclaimed in the nineteenth century from saltmarsh which had developed on a mid-channel mud bank. This period of devastating erosion over the past decade has now been replaced here by rapid accretion as the main channel once more moves northwars. Sea Level Rise and the Humber Probably the most important issue regarding the future of the estuary is the way in which it will react to rising sea level. Theoretically, the increases in sea level should be balanced by continued deposition throughout the estuary so that the level of the mudflats and saltmarshes keep pace with average water levels. Although this response to sea level rise is observed in most of the estuaries of the east coast there is some disturbing evidence from the Humber, already discussed in this report, which suggests that it may not apply here. The importance of the Humber for navigation means that extremely accurate charts are available of its channels and shoals. These charts are regularly updated and an examination of a series of these made Humber estuary & Coast Page 30 1994
  32. 32. over the past 80 years suggests that the mudflats of the estuary may have changed from a pattern of overall accretion to one of erosion some 40 years ago. If this is so, and further work still needs to be done, then reasons for the failure of these areas to keep up with sea level rise must be found. Several possibilities suggests themselves. First there may have been a decrease in the silt and mud which enters the estuary from the North Sea. This sediment is partly provided by the erosion of the Holderness coast and the adjacent sea bed and partly from many other sources throughout the North Sea and the North Atlantic. There is no evidence for any marked decrease in the erosion rates of Holderness although some slight change must have occurred as a result of the protection of the towns of Hornsea and Withernsea. No records have been made of the background sediment concentration of the North Sea over the years so that it is impossible to judge whether this has fallen – if it has then the implications are serious not only for the Humber but also for all the accreting coastlines of the North Sea. Equally, any fall in the sediment concentration of the sea may affect pollution levels since sediment acts as a sort of 'scavenger' of pollutants fastening them to sediment grains and eventually carrying them down to the sea bed where they are covered over. The other possible explanation for the failure of the Humber mudflats to keep up with sea level rise is that dredging of the outer navigation channels removes sediment which enters from the North Sea before it has chance to reach the higher mudflat areas. Again, no evidence is available to support or deny such an explanation and it remains only a possibility – nevertheless one which we should investigate as a matter of urgency. If we cannot find any explanation for the apparent failure of the Humber mudflats to accrete, then the future of the Humber is difficult to foresee. Loss of habitat for wildlife is certainly one outcome, but even more serious for those who live and work here may be the increase in flood risk as sea level rises and mudflat levels fall. We may be able to offset such risks by constructing higher and higher flood embankments but the costs – both in economic and aesthetic terms will be very great. Humber estuary & Coast Page 31 1994
  33. 33. From the holiday beaches of Cleethorpes and Skegness to the wide marshes of Saltfleetby, the Lincolnshire coast is one of contrast. The Lincolnshire Coast The coast between Cleethorpes and Gibraltar Point can be divided into three sections each with a different landscape character determined mainly by natural coastal processes but in some areas dominated by human use and coastal defences. Between Cleethorpes and Mablethorpe lies an accreting shoreline whose wide sandy beaches, dunes and salt marshes are among the least known areas of the British coast. Further south, between Mablethorpe and Skegness, erosion becomes the predominant process. The beaches are being pushed landwards onto the low dune ridge and has led to the provision of a continuous flood defence embankment. Finally, the slight change in the orientation of the coast south of Skegness marks a change from dominantly erosion to accretion of the sand beach, dunes and saltmarsh in the important nature reserve at Gibraltar Point. Humber estuary & Coast Page 32 1994
  34. 34. Although the whole of this coastal zone, east of the Lincolnshire Wolds is underlain by boulder clay deposited during the last ice age, just as happened in Holderness, there is one fundamental difference here – the Lincolnshire coastline is made up of a wide strip of recent sediments deposited by marine processes. This suggests that, although erosion now dominates the south of the coast, at one time accretion must have been widespread here, prompting the obvious question – why the change? The geology of the Lincolnshire coast shows an eastward sequence of chalk, glacial tills and recent moraine mud. No clear answer to such a question is available. One suggestion is that, prior to the 13th century, the Lincolnshire coast may have been protected by a barrier of small islands made up of boulder clay, possibly part of a glacial moraine. The shelter afforded by this barrier would have allowed mudflats and saltmarshes to be deposited in the calmer water between the barrier and the coast, which would have formed a sort of lagoon. The 13th century, however, was extremely stormy, and the barrier was eroded exposing the lagoon and its salt marshes to the full power of the North Sea waves. The marshes began to erode and the fine grained muds replaced by a sandy beach. Some of this sand was blown onshore to form a line of sand dunes, some of which are still to be seen. This process of advancing beaches and retreating marshes has continued over the past 500 years for much of the coast although differences do exist which have led to the three distinctive sections mentioned above. These differences are explored below. Cleethorpes to Mablethorpe In the northern section of the shoreline, that is between Cleethorpes and Mablethorpe, the boulder clay islands that protected the coast prior to the 13th century, have not been entirely eroded away and can still be detected as a marked offshore ridge – known as the Saltfleet Overfalls. This submarine ridge has continued to protect the shoreline of northern Lincolnshire against the full power of the North Sea, although sea level rise has meant that the original lagoon has long since disappeared. Indeed, the protection offered the shoreline by the offshore ridge is minimal, but enough to allow sand to accumulate, and this has built up an extremely wide beach – over 2 km in some places. Humber estuary & Coast Page 33 1994
  35. 35. In turn, the beach absorbs the wave energy and allows finer muds to settle out on the upper shore so that a line of salt marshes has developed along almost the whole of this section of shoreline. This sequence of a wide sandy beach backed by muddy salt marshes, is most unusual – normally salt marshes only develop in the shelter of estuaries and bays – and shows the importance of the offshore ridge here in the development of the coastal character. The history of this section of the coast shows the way in which humans have taken advantage of this natural offshore protection: During the Iron Age (about 2 thousand years ago) the coast between Cleethorpes and Mablethorpe followed a line stretching from Cleethorpes, through Tetney and reaching the present coast again between Theddlethorpe and Mablethorpe, and was fronted by an extensive area of saltmarsh. Early AngloSaxon settlers constructed a sea dyke or embankment between North Coates and North Somercotes and, by the 11th century, the marsh between the dyke and the boulder clay was reclaimed. Between Cleethorpes and Mablethorpe the coast has suffered enormous changes over the past centuries as more and more land was reclaimed from the sea. Throughout the stormy period of the 13th century, the shoreline remained roughly parallel with the line of the ancient sea dyke – trending northwest/southeast, but, by 1600, saltmarsh had advanced further seaward at two locations – at Horse Shoe Point and Donna Nook. These two bulges in the coast were subsequently reclaimed, the reclamations providing more shelter and encouraging further development of saltmarsh, which was progressively reclaimed over the following 300 years. By 1930, the outline of the present coast was all but complete. However, the effect of the reclamation has been to change the orientation of the coast. Prior to reclamation, the coast was orientated in such a way that the dominant north-easterly waves provided a south-easterly movement of sand. This sediment then moved south along the entire stretch of coast from Cleethorpes to Gibraltar Point. Humber estuary & Coast Page 34 1994
  36. 36. However, after reclamation, Donna Nook formed a 'headland' dividing this stretch of coast into two shoreline stretches each with different orientations. To the west of Donna Nook the orientation of the coast has been rotated slightly towards the north – which has had the effect of reversing the transport of sediment along this section of the coast. The dominant north-easterly waves now result in a westwards flowing sediment transport path. To the east of Donna Nook, the transport of sediment remains the same. However, the change in the orientation of the westernmost section of the coast has resulted in the removal of part of the source of sediment for the rest of the coast east of Donna Nook, and may have resulted in an increase in the erosion south of Mablethorpe. Mablethorpe to Skegness South of Saltfleetby the salt marshes disappear. The coast is no longer protected by an offshore ridge but receives the full force of the north easterly waves and the result is erosion. Initially this erosion resulted in the landward movement of the beach as it was pushed over the ancient salt marsh muds – still to be seen emerging at the front of the beach in many places along this coast. This landward march of the shoreline has resulted in the loss of five medieval parish churches – Mablethorpe St. Peters, Trusthorpe, Sutton, Chapel and Skegness. Historical evidence from parish records and other sources has indicated that there have been many breaches in the old sea embankments along this stretch of coast, and it is estimated that up to 1km of land has been flooded since 1200. But it was not until after the devastating flood of 1953 that the entire stretch of coast between Mablethorpe and Skegness was completely and adequately protected by a concrete flood defence wall, one which now protects over 20 thousand hectares of land and over 15 thousand homes. The provision of this concrete embankment has certainly stopped the landward trend of the beaches, but the result has been that the beach is now pushed up against an unyielding wall of concrete and becomes narrower and narrower. This loss of beach has caused consternation, both because of the increased damage to the flood wall and therefore in flood risk – but also because of the importance of the beach to the holiday industry here. In an attempt to halt this process an imaginative scheme has recently been initiated which will 'feed' the beach with sand dredged from some distance offshore. Over the next five years, the 24km stretch of beach between Mablethorpe and Skegness will have its height and width increased, both protecting the flood embankment and providing holiday makers with their preferred environment. Skegness to Gibraltar Point South of Skegness the coastline changes orientation slightly, and accretion once again becomes dominant over erosion. The change in orientation of the shoreline into the massive embayment of The Wash has resulted in the deposition of the sands transported south along the Lincolnshire coast. The resultant sand bars have Humber estuary & Coast Page 35 1994
  37. 37. formed a complex pattern of spits, sand dunes and saltmarshes which are now part of the Gibraltar Point nature reserve. Once again, this change from accretion to erosion is probably the result of offshore sand banks which provides protection to the upper shore against wave attack, as well as a source of sand for the spit which has extended by over 6km from just south of Skegness. The interesting feature about this section of the coast, however, is the fact that despite the southwards growth of successive spits, the coast is actually extending eastwards rather than southwards. This is because each successive spit has developed in a position further east than the previous one, the southwards limit of each spit eventually being the same. At the point where the open coast of Lincolnshire turns into the huge bay of the Wash, a series of sand and shingle bars and spits separated by saltmarsh has formed - Gibraltar Point The area to the south of Skegness now consists of a series of dune lines with intervening saltmarsh, and the area appears to be experiencing a repeated cycle of development, which since 1600 has resulted in an advance of the low water mark by over 1km. Humber estuary & Coast Page 36 1994
  38. 38. The Future Clearly, the most overriding concern for the Lincolnshire Coast is the erosion of the foreshore between Mablethorpe and Skegness, and the implications this, and a predicted future increase of sea level, will have for the continued protection of the hinterland from flooding. The present situation, with concrete sea walls, is preventing the natural response of the shoreline to an increasing sea level and is instead leading to erosion and steepening of the beach. Allowing this to continue would necessitate the construction of ever-bigger walls to protect the coast. The proposed beach recharge scheme, however, will provide a wide beach in front of the sea wall and negate the affect of erosion. However, the present erosion of the foreshore indicates that the newly deposited beach is also likely to suffer erosion, and the beach nourishment will have to be periodically 'topped up' if it is to remain effective as a flood defence. Humber estuary & Coast Page 37 1994
  39. 39. This report has shown that the Humberside coast and the coastal cell within which it sits is an extremely complex machine – whose care and maintenance require a far larger manual than we have provided here. Management of the coast concerns us all in Britain and especially those who live in Humberside, which is so reliant on its coast and estuary. Coastal Zone Management Although integrated management of the coast has been largely ignored until quite recently there has just been a massive upsurge of interest and awareness in the subject. Over the past five years Government Departments and voluntary bodies have thought, written and to some extent, acted along entirely new lines – attempting to understand the natural coast and to try and fit our use of it into this natural framework. This new approach has been called Coastal Zone Management and those responsible for the coast have responded to it with enthusiasm. Although this enthusiasm should be wholeheartedly welcomed there is one over-riding problem – who exactly is responsible for the coast? The answer is extremely complex. Responsibility for the coastline does not rest with a single organisation, different bodies having various duties for which they are responsible. The level at which these duties is administered also varies from European and National level down to local authority responsibilities. Some of the main organisations and their responsibilities are briefly outlined below: At the national level the Ministry of Agriculture, Fisheries and Food (MAFF) have a number of responsibilities relating to coastal protection, flood defence, developments below the low water mark (which often can include coastal protection works), disposal of waste at sea and fisheries. MAFF do not have a direct involvement in coastal defence whether for coastal protection against erosion or defence against flooding. Instead they devolve this responsibility through their Operating Authorities. The Operating Authority for coastal protection against erosion is the relevant maritime local District or Borough Council. These have powers to protect the coast and can apply for grants from MAFF to carry out approved works in this area. Humberside's coast falls within the districts of East Yorkshire and Holderness, while the Lincolnshire coast falls within the bounds of East Lindsey. However, the coastal protection responsibilities of the Maritime Authorities do not stretch into the Humber estuary where Humber estuary & Coast Page 38 1994
  40. 40. flooding rather than erosion is seen as the main management issue. For this reason the responsibility under MAFF for the management of the estuary passes to the flood authority. This second Operating Authority is the National Rivers Authority (NRA) which has management responsibility under MAFF for flood defence and coastal protection as well as conservation responsibilities in coastal waters and coastal water quality (which is often controlled by EC legislation). The defence of the open coast of Humberside and Lincolnshire sit he responsibility of the local authorities under the overall control of MAFF. Provision and maintenance of flood defences in the Humber are the responsibility of the National Rivers Authority Regional Groups. The NRA is divided into several regional sections. Responsibility for the North Humberside coast and the north bank of the Humber estuary rests with Northumbria and Yorkshire Region, while Lincolnshire and most of the south bank of the Humber estuary falls within Anglian Region. Even more confusing, the estuarine section of the Trent upstream of Trent Falls is in the Severn Trent Region. The outer two divisions meet along an imaginary line along the centre of the estuary so that the management system divides into two – or three – sections an estuary which must be seen as a single integrated unit. The water quality of the estuary is managed as a single system, with the three NRA regions joining forces on the Humber Estuary Committee. Although all other functions of the NRA are split between the regional divisions there is increasing recognition of the need for an integrated approach. Humber estuary & Coast Page 39 1994
  41. 41. In England, the government’s statutory advisor on nature conservation is English Nature. Its work includes the establishment of National Nature Reserves, Marine Nature Reserves and the notification of Sites of Special Scientific Interest. English Nature have launched a major campaign for coastal management in England called the Living Coast. As a part of this initiative they are taking the lead in drawing up a management plan for the Humber which attempts to draw together many of the strands of management for the estuary, while a similar project has recently been set up to highlight the importance of the Sensitive Marine Area at Flamborough Head. Land use policies for the areas bordering the coast and estuary are largely the responsibility of local government. The strategic planning framework is set out in the County Councils' Structure Plans whilst the Borough Councils' Local Plan and District Development Plans provide guidance at a more detailed level. National and regional guidance is provided by the Department of the Environment through, for example, Planning Policy Guidance Notes (PPGs) and Regional Planning Strategies. Ports and Harbours along the coast and in the estuaries are administered by the relevant Port Authority. In the Humber this authority is the Associated British Ports who act both as port managers and as the Humber Conservators – with responsibility for all navigational activities in the estuary. Other national bodies, including English Heritage, the Department of Trade and Industry and Transport as well as the Countryside Commission, Crown Estate Commissioners (who own most of the seabed and foreshore) and the Joint Nature Conservation Committee also have various responsibilities. There is also a wide range of voluntary bodies who have an interest in the coastal zone of the region, including the RSPB, the County Wildlife Trusts and the Council for the Protection of Rural England to name but a few. These organisations play a central part in the management of the coast, both advising statutory bodies and keeping an independent surveillance of their activities. Some of these also own and operate nature reserves as well as attempting to maintain the natural environment as far as possible. With such a wide range of authorities having responsibility for certain aspects of the coast, it is often difficult for a co-ordinated approach to coastal issues to be taken. However, several initiatives have been instigated which aim to address some of the potential management problems. These initiatives often draw together all interested and relevant parties and aim to take into account the needs of different organisations. Such initiatives aim to produce management plans for particular stretches of the coastline and usually require the integration of economic and environmental considerations. The first of these initiatives which has been instigated by MAFF is a series of Shoreline Management Plans (SMPs). These are designed to look at the processes which characterise a particular length of shoreline – usually coinciding with one of the coastal cells. The SMPs will then use this understanding to advise on general future planning for the coast in such a way as to avoid major interference both with existing natural processes and also with adjoining coastal regions. Humber estuary & Coast Page 40 1994
  42. 42. In coastal areas where erosion is the key issue the lead authorities for Shoreline Management Plans will usually be the Maritime Operating Authorities working under funding from MAFF. Where coastal flooding is the main problem the appropriate region of the NRA will normally take the lead. A number of Regional Coastal Groups have also been set up around the country and for the Flamborough Head to Gibraltar Point coastal cell the Humber Estuary Coastal Authorities Group (HECAG) has been formed. Areas of nature conservation interest on the Humberside and Lincolnshire coasts: it is only by understanding the processes of these coastal areas that we can hope to manage and maintain them. However, one of the main problems with such an approach is that the authority of most of the interested bodies have set limits and there is no framework to allow the crossing of these boundaries. For example, responsibilities of the Maritime Authorities are not continued into the Humber estuary – Holderness Borough Council stretches into the Humber as far as Hull but further west Hull itself and Beverley, Boothferry and Glanford are not Maritime Authorities even though they border the estuary. However, aswe have seen, the processes at work in the estuary and on the coast are inextricably linked. As well as the development of the Shoreline Management Plans, a number of other initiatives and policy documents have been issued or are in preparation which have an important role in the coastal management of the region. These include: • The Humber Management Plan being prepared by English Nature. • The Humber Catchment Management Plan issued in 1994 by the NRA. • The Humber Tidal Flood Defence Strategy being prepared by the NRA. • Holderness coast protection planning carried out by the Humberside Coast Protection Joint Committee. • Planning policies prepared by the Local Authorities. Humber estuary & Coast Page 41 1994
  43. 43. • Nature Reserve management plans, including a Spurn Management Plan currently being prepared by the Yorkshire Wildlife Trust. All of these initiatives provide for important aspects of the management of the wider coast of the region and therefore overlap to some extent. The co-ordination of all those which refer to the Humber, as well as that of many other activities in the estuary including academic research, education, industrial activity and environmental quality initiatives, has been undertaken by the Humber Estuary Standing Conference – set up by Humberside County Council and the National Rivers Authority. Humber estuary & Coast Page 42 1994
  44. 44. The new approach to coastal zone management both in Britain and throughout the world has been one in which we aim to work with the natural coastal processes rather than against them. Issues This approach, sometimes called 'soft engineering' to contrast it with the hard engineering of past years in which concrete, wood and stone were used to resist natural processes, clearly demands an understanding of the natural coast as a basic requirement. Unfortunately, in most cases, we are far from such an understanding, even on a very simple level. This report has attempted to summarise the understanding which we now have of the Humberside coastal area and to point out some of the ways in which this understanding could influence our management decisions. It has also shown up many of the gaps in our knowledge of this important coast. Some of the management issues for our coast which follow from this outline of process are summarised here, so too are many of the gaps in our knowledge of the processes on this coast – gaps which prevent us from undertaking clear and efficient management in the immediate future. Erosion We know the Holderness coast is eroding, but recent work suggests that so is the Humber Estuary. There are several possible explanations for this: • The North Sea may be getting less muddy. • Dredging could be resulting in an overall loss of mud from the estuary. • Holderness may be eroding less rapidly – possibly due to protection works. • The reclamation of salt marshes and mudflats, for example at Sunk Island, and of other construction works in the estuary may be having a long term impact on the intertidal erosion rates. We need to understand these issues if we are to manage the coast and estuary wisely. Humber estuary & Coast Page 43 1994
  45. 45. Coastal Protection Coastal defence against erosion can cause many more problems than it solves due to: • Loss of sediment supply to beaches and mudflats. • Soft engineering may be currently the fashionable method of coastal defence but beach nourishment, requiring offshore dredging, may do more harm than good to our regional coastline by increasing shoreline wave attack and harming valuable fishing grounds. • The proliferation of rock armour around our coast is an issue which needs to be addressed immediately. Hard defences such as these have been demonstrated over many years to cause as many problems as they solve while rock armour itself is arguably the most ugly form of protection to impose on our shoreline. • The emergence of short protected sections of coastal as artificial headlands, for example as at Hornsea and Withernsea, could have important long term effects on the coastal processes over a very wide area. Accretion Accretion is necessary: • To provide natural defences (beaches, mudflats) against flooding – and erosion. • To keep pace with sea level rise – almost 0.4 cm a year in the Humber. • To provide habitats – such as mudflats, saltmarshes and sand dunes – for wildlife. The maintenance of the accretion levels in the Humber is essential if risks to the urban and industrial are to be minimised. The importance of movements of mud and sand between North Yorkshire (especially Filey Bay), Holderness, the Humber and Lincolnshire are a central issue to be addressed in any coastal management plan. Pollution Although this report has not dealt specifically with water quality issues in the coast and estuary, several issues have been raised: • The Humber is a relatively unpolluted estuary with a high conservation status. Humber estuary & Coast Page 44 1994
  46. 46. • Pollutant levels are reduced in muddy waters which partly accounts for the Humber's excellent record. Any reduction in mud content, however, will be harmful to the estuary and to the North Sea. • Pollutants introduced on the north bank of the Humber tend to move to the south bank of the estuary in a complex pattern which makes tracing sources extremely difficult. • Pollutants from the North Sea – including material from the Tyne/Tees, and even from Dounreay and Sellafield, enters the Humber along the north bank and these should be monitored. • An integrated pollution policy to cover the whole estuary and link it with the North Sea is a priority. Sea Level Rise Careful assessment of the nature and effects of sea level rise on the coast of our region is essential. The issues include: • Erosion: some evidence suggests this may increase with sea level rise. • Accretion: some evidence suggests this is not keeping pace with sea level. • Flooding: increased risks are likely due to higher water levels and also due to more complex factors such as flood protection works forcing an increased tidal range further into the Humber estuary. • Pollution: changes in the flushing time of the estuary may cause changes in the residence times of sewage and other pollutants. • Salinities: increased salinity in the inner estuary may affect water tables inland. Policy • The proliferation of plans for the Humber and the coast should be rationalised. These include: the Coastal Management Group's shoreline strategy (Local Maritime Authorities); the English Nature Estuary Management Plans; the NRA Humber Catchment Plan; the NRA Flood Defence Strategy Plan; the Humberside County Council Structure Plan; the Joint Advisory Committee for Holderness Erosion coastal defence plans. • Policies should include the whole coast and should not concentrate exclusively on either the Humber or the coast, and certainly not on the North Bank or the South Bank. Humber estuary & Coast Page 45 1994
  47. 47. • The coastal cell identified by MAFF stretches from Flamborough to Gibraltar Point and ignores most of the Humber estuary. This is not adequate. Movements into the Wash and into Filey Bay are crucial and the Humber must form an integral part of the whole. • The Government have identified the need for strategic plans for coastal areas. The Humberside coast is a test case for these plans. The way we manage our coast will not only be seen as a model for the nation but is closely watched by the international community. Some Management Questions Risk management – should we move away from our coast? Areas below high water mark or threatened by coastal erosion must be regarded as high risk for people and property. The Department of the Environment's Planning Policy Guidance Note (PPG20) recommends no further development in these areas – but should we continue to protect the existing development? Won't this merely increase the risks? Sediment management – should we treat our coastal sand and mud as a valuable resource to be conserved at all costs? If so should we consider coastal defence of Holderness as a major loss of this resource? Since this material enters the North Sea and perhaps is deposited on the coasts of Germany, Netherlands and Denmark should we not consider Holderness mud as part of a European resource and obtain funding for research and compensation for land and property loss from the EU? Estuary management – interference in the Humber in the past has exacerbated the risk of tidal flooding. Should we attempt to restore the natural estuary wherever possible? Coastal management – beach feeding appears to be a soft engineering option, going with nature rather than against it, but may alternatively be seen as attempting to reverse natural processes. Should we look on our beaches as a diminishing resource, one that we must learn to live without? Pollution management – pollution should be tackled at source, environmental technology is available and must be implemented. But pollutants, including radionuclides, which do enter our coast and estuary can be reduced if they are deposited and covered over on the sea bed. For this we should maintain high sediment levels – is this another case for reducing coastal defences? Some Controversial Suggestions: • Abandon, or relocate settlements further inland, on eroding coasts, perhaps over the next two centuries. • Restore the Patrington Channel. This could reduce tidal levels at Hull and Immingham by up to 0.5m and save in flood defence and risk avoidance – as well as bringing conservation benefits to the estuary. • Stop dredging the Humber or at least examine the implications of the dredging. Are the costs of defending the low lying areas greater than the benefits of increased ship size? If not then Humber estuary & Coast Page 46 1994
  48. 48. reduce the depth of the navigation channel and stop further dredging. Alternatively consider alternative dredge spoil dumping areas further inland in the estuary. • Re-open the Broomfleet Channel in the inner estuary, this would allow the channel system here to stabilise and avoid the present rapid swings from bank to bank which are causing so much difficulty to landowners and navigation interests. • Consider temporary defences for any property which must be defended and for which a positive cost-benefit ratio can be shown. The defences should be removed before long term changes in the coast are set up. • Consider acquiring coastal domestic properties at risk from flooding or erosion and leaseletting back to the owners for their lifetime. This would allow properties to be withdrawn from the market at natural breaks in their occupation and prevent their long term use and eventual catastrophic removal by natural processes. • Consider national or even European funding for compensation for land or property lost to erosion. Acknowledgements This study was commissioned by the Environment Sub-Committee of Humberside County Council and prepared by the Institute of Estuarine and Coastal Studies at the University of Hull. The views expressed are those of the Institute of Estuarine and Coastal Studies and are not necessarily those of Humberside County Council. Photography: Innes Studio Illustrations: Visage Design Trade Scanning: GKD Printing: Wyke Printers Humber estuary & Coast Page 47 1994