The Thames Barrier

Holding back the sea, but for how long?

Architecture 533
London/Paris
4/20/2009

'The Thames Barrier - Holding back the sea, but for how long?' is a paper and presentation prepared for a graduate architecture theory course. The presentation and paper discuss the increased risk of flooding to the Thames Estuary around London, England. The Thames Barrier is a technological marvel built in the 1970s, but increased sea levels caused by global climate change is threatening to make the barrier obsolete and put London at risk. The paper and presentation examines the history, the causes, and presents a solution to the problem by studying what has been done in The Netherlands and Venice and applying to the Thames.

London is famous for its fog, rain and poor weather in general, but its regular battering from the sea is less known. The Thames, running through the heart of London, is a tidal river and undergoes a dramatic change in depth due to its proximity with the sea. Massive waves caused by storms as strong as hurricanes have subjected London to devastation reminiscent of New Orleans multiple times. Londoners began building walls to hold back the water in response to the unpredictable level of the Thames, which over time resulted in the Thames completely walled in. However, the battle with the river would not be so easily won. Faced with progressively worse flooding, Londoners in 1956 and engineered a system which was meant to last. The Thames Barrier Project was constructed in the 1970s and has the capacity to hold back water many feet higher than the highest recorded level, but a variety of developing conditions suggest that it will not be enough. Geographically speaking, London is sinking as while the sea is rising due to global warming which continuously increases the river's level. These combined factors will eventually make the Thames Barrier obsolete, but the timetable is debatable. Data suggests that a new barrier will need to be built before 2060, but its design should be drastically different from the traditional flood abatement methods. Mankind is partially to blame for the increased flood risk to London and the old method of flood remediation, a higher wall, clearly is not the ultimate solution and has been shown to exacerbate the effects of a storm surge on the Thames River. The future system should not simply be a larger, stronger barrier with higher walls, but instead incorporate natural flood remediation techniques. The battle with the Thames is not one humans can win for the long term with a rigid solution, so a more flexible, adaptable, and natural system of movable, low profile barriers and the return of vast acreages to the original marshland will allow future surges to disperse gently over land instead of trying to contain it within the river.

Image 1 - The Roman town of Londinium

The City of London owes its existence to the Thames River, yet it has been a stormy, two-millennial relationship. London's early history is rather vague, but what is known is that the Romans invaded in 43 CE and established a community by about 50 CE. They called it Londinium, the origin of today's London. The early settlement probably was in the location of an earlier settlement, but knowledge and archeological evidence of these settlements has been all but erased. What is known is that the city, like most cities, was located next to a navigable river to allow goods to be transported by boats up to the edge of the city wall to be unloaded. The Thames River at the time appears to have been much shallower and wider than it is today, and much of the area south of the river was swamp or marshland unsuitable for buildings which resulted in Londinium being built on the north bank (Wilson, 23-45).

Image 2 – A cross-section of the
Thames Embankment

Londinium was practically abandoned with the fall of the Roman Empire and claimed by the Saxons who were later conquered by the Normans in 1066. This lead to the gradual growth of London for the next several centuries, followed by rapid growth after the Great Fire in 1666 and explosive growth in the 19th century. Londoners treated the Thames as a shipping route and sewer until 1862, when the Thames Embankment was built to facilitate Joseph Bazalgette's new sewer system and made room for the subway lines. The embankment created 22 acres of new land which was immediately developed. Prior to the embankment the only structures built next to the water were wharves, piers, and London Bridge. This was due to the tide, which when it went out it exposed large tracts of silted, and until the late 19th century, putrid land along the banks. By the end of the 18th century most of the river along inner London was embanked or channeled, and the Fleet, Walbrook and Tyburn rivers were paved over and turned into glorified sewers (Milne, 77-98). All of the construction projects and improvements created a manufactured edge along the Thames River. The structures caused the river to be come deeper and faster as the smooth edge of the stone walls accelerated the flow rather than stall it as the rough natural edges did before. The massive piers of London Bridge and others caused the bottom of the river to be scoured out and contributed to the deepening of the Thames (Milne, 105-107). The man-made improvements of the Victorian Era turned London into a truly modern metropolis, the world's first. Unfortunately, the attempts to control the river would backfire, repeatedly, over the next hundred years.

The Thames River in London is tidal due to its proximity with the North Sea. While the Thames is over 200 miles long, London is situated around 40 miles upriver and is subjected to up to an 23 foot fluctuation in the water level. Twice daily the water rises and falls, but not always equally. The tides have been predicted and understood for hundreds of years and detailed charts have been published since the 1800s. However, the tide is not the only force responsible for the variation in the Thames' height (Environmental Agency).

London is sinking, and has been as long as people have lived there. The sinking is not due to any settling because of poor soil or depletion of the water table but due to geological reasons. The south end of the island is sinking down as the north rises upward as the weight of the glacier which melted at the end of the last Ice Age allows the land to decompress. This sinking amounts to up to a foot for every hundred years, meaning that the whole Thames estuary has dropped 20 feet during its two millennia of inhabitance (Milne, 39-45). Additionally, sea levels have been steadily rising up to ½" a year and represent the most problematic factor for London. The land sinking cannot be controlled, but the rising ocean is due to human influence on the global environment. If the current rate of melting the icecaps continues, the sea levels will be 4 feet higher by the end of this century. Also, with the increased amount of water in the oceans, the tides will likely be more pronounced (Hall, et al 1027-36).

Image 3 – Surges by Northern storms
are amplified by the 'funnel' of the
English Channel

The geographic location of London makes it vulnerable. While it is not located on the Atlantic side of the island, it still gets a fair amount of severe weather. Storms cross the Atlantic from the east on the Jet Stream, pass over Ireland and England and then move into the North Sea. The storm causes a surge in the sea due to wind but also due to the negative pressure the storm produces (Milne 12-29). The low pressure allows the sea to expand about ½" for each reduction of 10 millibars in air pressure. A major storm can reduce the air pressure by 100 millibars, or 5 inches, but is represents only a part of the problem. The strong wind is the real culprit, as it can push large waves outward from the center of the storm (G. Cole, 174). The position of England relative to the north coast of Europe makes for a relatively narrow gap, the English Channel, between the land masses with the narrowest part, the strait of Dover, located immediately south of the Thames estuary. Storm surges produced by a storm anywhere in the North Sea are forced southward through the Channel and because of the narrow strait water backs up as it passes through. The coastline acts like a funnel by gradually narrowing the space for the water to remain amplifying the wave effect (Prandle, 537). Unfortunately, the Thames Estuary points northwest where it meets the sea and acts as a scoop to capture the storm surges and allow them to travel upriver, all while the sea level rises as water backs up going through the strait. The storms can be surprisingly strong with recorded wind speeds of up to 92 mph, making them as strong as a Category 1 hurricane. In fact, many storms are remnants of Atlantic hurricanes make their way north carrying warm air with them and adding to their strength. It is this physical geography and weather of the region which puts the Thames at a high risk for surge flooding (Milne, 12-29).

Image 4 – London streets flooded in 1875

Storms have been affecting London for its entire existence. Strong winds and high waves on the North Sea were recorded by the Roman Navy around 50 BCE, but reports of flooding in London began in the middle ages. The first notable storm was in 1091, where many buildings in the London area lost their wood and thatch roofs. The debris landed in the Thames and floated downriver where the flotsam got stuck on the wooden London Bridge, eventually ripping it down and carrying it out to sea. In 1334, miles of countryside next to the estuary were turned into a 'salt marsh' for a month. 1362 saw more damage to London buildings including the destruction of St. Pancras Church. The next significant storm occurred in 1663 which famously flooded the House of Lords while the members were in session. It damaged many buildings, which were probably rebuilt just in time to be burned down by the Great Fire in 1666. The weather returned in 1703 by which time early meteorologists were able to predict during which times of the year the storms would be strongest and from which direction. Londoners also understood that, independently, high tide and storm surges were of little threat, but when combined they represented danger. The storms of the 18th century claimed ships as the primary victim and people began to accept occasional flooding as a way of life. London was savaged in 1874 and again in 1875 when storms ruined tons of goods sitting in railway yards and drowned many people. The population increase during this period lead to dense urban living with many people living in basements and ground floors, which were the easily flooded. The number of victims and the consecutive years with severe flooding illustrated the need for a warning system so people can evacuate low-lying areas when high waters were expected. This procedure was put into effect two years later in 1877 when an organized evacuation likely saved many lives ahead of a storm, but it turned out to be mostly unneeded as waters reached their peak at low tide. In spite of the false alarm, Parliament passed the Flood Act in 1879 which authorized the construction of walls along the Thames to fill in the spaces between the embankments built several years earlier. The 19th century's floods ended in 1881, which was a very cold year and thick ice formed on the river. The ice was broken up by and incoming storm and slammed against the sea walls, breaking them in several places and allowed icy water to flow through the streets (Milne, 36-59, 78-83).

Image 5 – Flooding along the Thames in
1923 with Parliament in the background

Forty years passed before the next major storm in 1928. The storm coincided with high tide and produced an 11 foot surge, killing 14 people and causing millions of pounds of damage. The storm spurred a renewed effort to improve flood defenses and prompted the development of an automated flood detection system and improved sea walls in the 1930s, but the outbreak of World War II put these projects on hold (Horner, 26-30). The post-war era was likely focused on rebuilding the buildings in the city which were bombed and burned rather than flood defenses. This proved to be misallocation of resources when in 25 years the sea again overflowed the walls.

Image 6 – Failure of sea walls in Essex
in 1953

The North Sea Flood of 1953 affected the whole eastern shore of England and the north shores of Belgium and The Netherlands. The storm followed the same paths as before by centering in the North Sea sending a surge southward to the English Channel where the waves broke across the Thames and Rhine estuaries (Wolf, 1368). By the morning of February 1, 1,825 people were dead in The Netherlands, 307 in England, 224 at sea and 24 in Belgium. In England over 1,000 square kilometers were swamped by brackish water and 24,000 buildings destroyed. Damage was estimated to be around 5 billion pounds and notable casualties included Parliament, whose basement was flooded once more, the normally dry Tower of London's moat was filled and several of the riverside Tube stations were flooded (Baxter, 1298-1310). Fortunately, there was no loss of life on the London Underground because it was evacuated several hours before the surge hit.

Image 7 – Flood damage in 1953

Warnings and evacuations were issued before the storm, but its ultimate strength was not known and people were caught unaware of how high the water would be. The waters rose to 18 feet above the high tide mark, overtopping the 1930s defense level by 8 inches. Normally the 8 inches of water would not cause so much damage, but many of the earthen sea walls were washed away releasing tens of millions of gallons on the countryside east of London. As dire as the situation had become, it could have been worse. The highest surge did not coincide with high tide, meaning that if it had been 3 hours earlier or later the water could have been up to 3 feet higher (Horner, 10-22).

Image 8 – Rejected barrier design proposals

In response to the 1953 flood the Greater London Council authorized a study in 1966 to prevent future floods by creating a defense which would be much greater than necessary. Up until that time, the method for improving flood defenses was to raise the walls by a foot or so each time they overflowed, expecting that such a severe storm couldn't possibly occur again. Of course, between 20 and 40 years later, just long enough to fade from memory, another one would again wash over the previous generation's defenses and raise the bar. The Greater London Council elected, this time, to take in account the increasing pattern of severity. They recruited Sir Herman Bondi, an engineer, to design the program for what would be required for defense. Bondi performed an extensive survey and determined that best solution were movable barriers, rather than a fixed barrage, which would allow shipping traffic to pass by. Bondi used the 1953 flood as a baseline and projected situations where that level would be exceeded. He eventually recommended that the defenses be designed to withstand a 1:2000 chance of flooding, or a height of 23½ feet above the highest tide. Bondi also assisted with the selection of the location of the barrier. Many sites were considered from as far east as Kent to as far west as next to London Bridge, right in the middle of the city. The site which was eventually selected in Woolwich Reach represented a compromise between the area the barrier would protect and the area of the river which would be serviced by large ships. The report also specified that the barrier should be low profile, rather than the large lift-gates used elsewhere because they were seen as unsightly. The barrier was to have 200' openings, the same width as the Tower Bridge so that medium sized ships would fit. The importance of accommodating large ships was steadily vanishing because the Docklands were being abandoned starting in the 1960s, so the barrier only had to allow medium-sized ships to pass through the gates (Horner, 41-51).

Image 9 – Draper's rotating gate mechanism

Parliament approved the barrier proposal with the Thames Flood Barrier and Protection Act of 1972, and engineers set about designing the project. Charles Draper, a lead engineer on the project, was at home with his family during Christmas and was drawn to a valve in his garage which was used to shut off the gas. The valve was cylindrical in shape, with part of it cut away allowing the gas to flow past it when it was rotated 90 degrees. He immediately embraced the circular design and developed a design. The circular segment would rest on the bottom of the river in a perfectly shaped trough. When needed, each gate would be rotated into place, sealing off the flow (Milne, 109-112). Their size was essentially unlimited except for the ability to manufacture the steel gates. The advantages of the circular design were immediately apparent. The gates resting on the riverbed would be unobtrusive to boats as well as visually. The gates would be extremely heavy, but by turning them on an axle much less power would be needed to raise or lower them than if they were lifted vertically out of the water or slid into place from the shore as the other design proposals called for. Also, because the gates were simply turned in place, fewer moving parts would be required (Beckett, 260-272).

Image 10 – The gates can be rotated
180 degrees for testing and maintenance

With Draper's circular gate technique the overall design began to take shape. The river would be divided into four, 200' wide main channels with one, 100' wide side channel on each side. The remainder of the river's width towards the shores would be populated with smaller gates as the water is too shallow to be navigable. Each pier would contain a hydraulic arm to rotate the gate on either side. Likewise, each gate had an arm on each end which would be tilted up or down causing the gate to spin. The arms would work in tandem, with one pushing while the other pulled to rotate the gate counterclockwise closed. The mechanism is similar to the movement of the pedals on a bicycle, and likewise the gates can be moved by one arm if needed. Additionally the gate can be over-rotated 180 degrees to allow to maintenance of the gate out of the water and are checked and tested monthly. Each gate can be independently operated, but typically they are operated by the adjacent control tower, The London Flood Room, which monitors both weather and sea levels. The gates take 30 minutes to close, starting with the ones closest to shore and finishing with the center two spans. The staged closing is to prevent creating unnecessary wave action on the river (Horner, 81-87).

The barrier is designed to be extremely resilient. The hydraulic components are very robust and the technology had been proven by the fact that many turn-of-the-18th-century power and pumping stations still use original parts. The arms and gates in the Thames Barrier were designed to last 200 years before wearing out. The gates themselves are made of 1½" steel plates and can take a direct hit from a ship without failure. Additionally, the piers are of concrete secured to bedrock and are pointed to deflect the water and any wayward ships (Horner, 93-98). This was tested in 1997 when a barge with gravel slammed into a pier and sank. The barrier was physically fine other than being scraped up, but the barge dumped its gravel on one of the gates preventing it from closing (ThamesWeb). In addition to the physical gate at Woolwich Reach, 11 miles of sea walls the same height as the barrier were built downriver and the existing movable gates elsewhere were improved to provide a continuous protection of 3 feet greater than the 1953 flood (Horner, 98).

Image 11 – Construction started in 1974
and was not completed until 1983,
four years behind schedule

Construction on the barrier began in 1974. The process of building the barrier was complicated by several factors, including that the shipping channel needed to be unobstructed and the ground under the riverbed was a different composition than was initially thought. The chalk bedrock was broken up into chunks instead of the flat continuous slab it was thought to be, so the pier foundations had to be re-engineered and lead to delays. Labor strikes and other complications pushed the completion date forward and the costs higher. Meanwhile, there was a constant fear that another flood would not only threaten London once more, but could also damage the incomplete barrier. A makeshift flood protection system was put into place during the period of construction, yet water twice in 1978 still reached 1 foot below the 1953 mark and partially flooded the pier cofferdams. Construction was largely underway in 1976 following the problems with securing the foundations to the bedrock. The barrier was expected to be finished by 1979 but, it was not finished until 1983. The barrier was officially dedicated on May 8, 1984 by Queen Elizabeth II. The ultimate cost was £564 million plus and additional £100 to shore up the walls downriver, which is equivalent to nearly $4 billion today; double the expected budget (Horner, 93-110).

The completed barrier was put to the ultimate test on November 9, 2007 when the barrier had to be closed twice to stop an equivalent surge to the 1953 flood. The barrier cannot remain closed for long, as water fills up ahead of the gates and the gates are lowered as soon as the tidal river equals the level of the rest of the river. The gates also cannot be abruptly lowered when there is a difference in levels as it will create a wave traveling upriver. Often when the gates are lowered they are opened partly, allowing the 'underspill' to flow under the gates minimizing the wave action (Coupe, 26-31). The barrier itself protects 125 square kilometers of London inhabited by 1.25 million people and property worth £80 billion (Fookes, 48-50).

The Thames Barrier physically is designed to last for two hundred years, but it will most likely be obsolete before that time. The designers and Sir Herman Bondi knew that the sinking of the English landmass by a foot per hundred years would gradually make the barrier ineffective, but what was not fully understood in the 1970s was the influence of global warming. It was observed that sea levels were slowly rising, but the reason why was not fully understood and they did not identify a rate at which the water was rising (Hall, et al 1027-1031). The increased rate at which the barrier is 'sinking' relative to the ocean level is cause for concern and begs for a solution.

Image 12 – Number of closures per
year with half occurring since 2000

Early estimates for the use of the Thames Barrier called for it to be closed once a year. This estimate was established on the relative frequency of the severe storms in the past which would have to be controlled. For the first 10 years of operation the barrier was closed on average once a year, as predicted. But then in the 1990s the number of threatening surges increased, forcing the closure an average of 3 times annually. This was little cause for alarm until in 1997 the barrier was subjected to an equivalent 1953 surge. The Barrier performed perfectly and there was no damage, but it was worrying that a purported '250-year' storm occurred twice in less than 50 years. Annual closure averages continued to increase when in 2000 and 2001 it was closed 6 and 11 times respectively. In 2007 the barrier was again closed 11 times, passing the 100-closure mark. 100 closures was the expected lifetime number, yet they occurred in only quarter of the expected time frame with half since 2000 (Environmental Agency). Obviously, the increased closures signaled a fundamental change in the sea conditions and called into question the longevity of the barrier. The criticism for the amount of money spent on the project evaporated as the Barrier proved again and again that it was well worth the investment (Hall, et al. 1031-1038).

While the Thames Barrier has saved property valued at many times the project's cost, including matching a 1953-sized storm, the barrier seems like it is not going to last as long as it was designed. With the sinking rate of one foot per century, and the rising sea level rate of about ½" per year produces a combined rate of over 4 feet by 2074. Since the barrier was only designed 3 feet higher than the 1953 surge, a storm of that magnitude would overtop the barrier by around 2060. Essentially, the global warming-induced rising sea levels have obliterated the margin of safety the engineers developed in 1972-74 (McRobie, et al. 1264-1268). The sea walls could be raised a few feet at a nominal expense and the Barrier itself could be allowed to overflow as a temporary measure, but ultimately the Barrier will have to be replaced or supplemented with a new, larger defense which will accommodate the rising sea levels as well as the continental sinking (Wood, et al 1420-1422).

London and the English Government should embrace the philosophy that the Thames Barrier will be obsolete and construction on a new barrier will need to be underway mid-century. The ultimate date at which the barrier will be useless is not clear yet, and there is a possibility that a global movement to reduce carbon emissions will result in the ocean stabilizing, but that is far from certain. As a result, planning should begin soon and a new technique of flood remediation, other than building walls, should be considered.

The traditional method of flood remediation in London was simple: build a wall to hold back the sea. The height and strength of the walls was determined by a trial-and-error method, where they would be built to the height of the previous storm surge. Unfortunately, typically in less than 50 years, just long enough for the previous disaster to be forgotten, another storm would damage the city. Each time though, the effects would be worse. The water would be higher, more damage would be done and more lives lost, but the storms themselves do not appear to be proportionally stronger. Until recently, the weather remained relatively stable, but continued human intervention with modifying the Thames exacerbated the flooding problem. The early Thames estuary consisted of marshland for most of the area south of the river. When regular flooding occurred, the marshlands south of the city would absorb the millions of gallons of water and as a result the city would be unaffected. In fact, this trend seems to have continued for most of London's history until the building boom after the Great Fire in the 17th century. The 18th century saw the improvement of the dock areas where many stone walls were built and much of the expansion occurred on the south bank. When the surge came in it would be contained by the hard stone surfaces until the 'weak link' was found either in the construction of the walls or an unprotected area and the tide surged in and filled up any low-lying areas. During the 19th century more marshland was filled and built upon and the edge of the Thames was fortified with a continuous wall for miles. This method of flood control ultimately exacerbated the situation, because instead of the waters being absorbed by the spongy marshland the water was met with an immobile wall. This explains why each subsequent flood seemed worse than the last; it wasn't as if the storm surges were stronger, it just had less room to dissipate. Instead of harmlessly filling a marsh the water simply collected in the 'bath tub' that the Thames became and overflowed the rim (Lavery, 1460-1461).

The pattern of solving the problem of too many walls by building more had not worked until the Thames Barrier in 1974. The reason the Thames Barrier worked, and has continued to be effective is that they built in anticipation. Bondi accepted the fact that the next major surge after 1953 would be more powerful, so built the flood cessation system to handle a 1953 level plus 3 feet, whereas the past method was to only allow for a foot or less of increase (Coupe 26-29). By 1974 London finally wised up and planned for the future. However, once again their solid barrier is likely to become inadequate, but building a larger, higher barrier is not the whole solution. The ultimate solution to accommodate the rising sea levels is to use a physical barrier, but also there must be a restoration of the natural way of flood remediation.

Image 13 – The Netherlands's
Oosterscheldekering, a fixed barrier

There are several precedents for a new barrier. The Dutch, who have been fighting the sea for centuries, have come up with a wide variety of barriers. The simplest, the lift gate, is probably the most common. It consists of a series of piers with gates which drop down and seal off the water. The best example is the Oosterscheldekering in The Netherlands, which seals off a portion of the Rhine delta. The structure is several miles long and is a large fixture along the coast and can stop a surge 12 feet high above high tide; such a storm has never occurred to date. The Oosterscheldekering is not conducive to shipping as large boats do not fit under the gates; shipping is facilitated by locks. It also is a fairly aggressive approach to the environment and has altered the marine area to a high degree (Wiki).

Image 14 – The Netherlands's Maeslantker-
ing, a mobile, land-based barrier

Another project within the Delta Project along the Rhine estuary is the Maeslantkering. The Maeslantkering is a swing gate which is stored on land and pivots out into the water to seal the canal. It is the largest mobile gate in the world consisting of two gates more than 500 feet long. There are no objects in the water because the canal needed to remain unobstructed as it is the primary shipping route to the port at Rotterdam (Wiki). Finished in 1991, it was closed the first and only time on November 8, 2007 which also required the Thames to be closed an unprecedented two consecutive tides (Fookes 48-50).

Image 15 – Venice's MOSE project
featuring sea-floor barriers raised by
pressurized air

Neither of the Dutch examples are really appropriate for the Thames. The Oosterscheldekering could always be used as an extreme measure, but it is such a heavy stroke on the estuary that it will be forever altered. The Maeslantkering, which is already one of the largest pieces of machinery every built, only closes a canal 1000 feet wide. The mouth of the Thames is over a mile, and to protect the outer reaches a barrier would be over 5 miles long. Consequently a third type of barrier suits the project the best, and that is an inflatable lift barrier which is currently being built to protect Venice, Italy from the floods of the Adriatic. Venice has long been flooded, and deals with the 'aqua alta' regularly, but because of the same situation that London faces with the gradual sinking and rapid rising sea levels they required physical flood control. The MOSE project (Modulo Sperimentale Elettromeccanico) consists of a physical barrage or dam with a series of inlets protect by the movable barriers. Similar to the Thames Barrier, the gates lay on the seabed in troughs and are raised 90 `degrees. The gates are hollow and are raised with pressurized air which makes them buoyant rather than with a mechanism for raising and lowering them. The advantage is that they are a continuous barrier, without piers, which lay out of the way on the seabed. The project, beginning 2003 is expected to be finished in 2012 (PBS).

Another key facet to the MOSE project is the restoration of the salt flats in and around the Venice Lagoon, which absorb the high tides (PBS, Wiki). Recognizing and incorporating a natural remedy for flood control is a vital component to the MOSE project and should be and equally important component in the future Thames Barrier. Thus a hybrid system of a physical barrier, which makes a minimal environmental, navigable and visual impact, coupled with the restoration of many square miles of marshland will allow the storm surges to splash against the barrier and gracefully dump into the marsh. Using the marsh as a pressure release valve will reduce the pressure on any walls and gates and restore a more natural process of flood remediation. As a result, the increasing cycle of severe surges should balance as the water is met with less solid walls resisting the flow and more area to dissipate the force and volume of water across.

Image 16 – The location of a MOSE-style
barrier should be at the mouth of the river
with restored marshland to the south

The new barrier and natural remediation will be a challenging process. First there is an extreme cost involved; second, land will need to be reallocated from those who own it now and third; the time required to build such a project. The cost will be enormous and people will likely object to the price just as they did when the Thames Barrier ran double over budget, but in the end it proved its worth, and a similar situation will befall the new barrier. The MOSE project will cost an estimated €4 billion when finished (Wiki), but the new Thames Barrier will most certainly cost several times that. Primarily the distance, which is several miles depending where the barrier is built, will physically require more materials and a longer build time. The barrier should be located as far down the estuary as possible to allow it to protect the largest area, with the restored marshes on the south side of the river where they once existed. South London cannot be realistically turned back into a swamp, but much of the farmland downriver, south of the Thames, is the ideal location for the new marshland. Naturally those who currently live and farm the land are going to be highly resistant to leaving and will have to be compensated appropriately adding another dimension to the problem (Hall, et al 1043-1049). There will also be technological challenges of restoring thousands of acres of marshland and ensuring that the surge will be properly handled. However, realistically we have the technology today to create such a system, what remains is the need and the will to build the new barrier.

The need for a new Thames barrier is at least 50 years away and is far from certain, but it is important to begin the planning process now. Recently in 2005, the Greater London Authority, formerly the Greater London Council, heard proposals for possible solutions to the risk to the Thames. The project has been unofficially dubbed the Thames Gateway and seeks to protect the communities around London and London itself from future flooding (Lavery, 1456-1460). Currently there are measures in place to prevent further damage to the tidal plain, by preventing people from building further in any low areas and encouraging an increase in density in the already built-up areas. This is a good start, but more needs to be done to encourage people to abandon the areas most at risk of flooding so they can be restored. Filling in the marsh was a gradual process over the last thousand years, and reversing that process will take some time as well. The emotional and political hurdles to the Thames Gateway project likely outweigh the technological and financial. Convincing people to abandon their homes and land is the greatest challenge which needs to be addressed now, before it is absolutely needed. The gradual abandonment of the area south of the Thames will allow people to adjust to the change and move at a comfortable pace (Lavery, 1471-1473). Bringing about change is difficult, so it is important for the Greater London Authority to effectively communicate the value of restoring the marshes as a better means of flood protection than building another high wall. Technology will continually improve barrier systems and the MOSE project will serve as an excellent example to study potential solutions for the Thames. Ultimately it is a question of when the Thames Barrier will need to be replaced, not a matter of if. By moving away from solid walls, which history shows makes flooding worse, and embracing a natural solution to flood abatement should improve the lifespan of the Thames Gateway to well over 200 years and protect London from storm surges into the foreseeable future.

Bibliography

Books:

Horner, Ray; Gilbert, Stuart. The Thames Barrier. London: T. Telford, 1984.

Howard, Philip. London's River. London: Hamilton, 1975.

Milne, Antony. London's Drowning. London: Thames Methuen, 1982.

Wilson, David Gordon. The making of the Middle Thames. Bourne End, Buckshire: Spurbooks, 1977.

Journal Articles:

Abbott, M. R. he Downstream Effect of Closing a Barrier across an Estuary with Particular Reference to the Thames. Philosophical Transactions of the Royal Society of London. Vol. 251, p. 426-439. 1959.

Baxter, Peter J. The east coast Big Flood, 31 January-1 February 1953: a summary of the human disaster. Philosophical Transactions of the Royal Society of London. Vol. 363, p. 1293-1312. 2005.

Beckett, A. H. River Thames - Removable Flood Barriers. Philosophical Transactions of the Royal Society of London. Vol. 272, p. 259-274. 1972.

Cole, G. The East Coast and London Tidal Flood Warning Systems. Philosophical Transactions of the Royal Society of London. Vol. 272, p. 173-178. 1972.

Coupe, George. Closing the floodgates. The Engineer. Vol. 292, p. 26-31. September 2003.

Fookes, Peter. Thames Barrier 21st Anniversary. Geology Today. Vol. 22, No. 2, p. 48-50. March/April 2006.

Hall, Jim W.; Sayers, Paul B.; Walkden, Mike J.A.; Panzeri, Mike. Impacts of climate change on coastal flood risk in England and Wales: 2030-2100. Philosophical Transactions of the Royal Society of London. Vol. 364, p. 1027-1049. 2006.

Horner, R. W. The Thames Barrier Project. The Geographical Journal. Vol. 145, No. 2 pp. 242-253. July 1979.

Lavery, Sarah; Donovan, Bill. Flood risk management in the Thames Estuary looking ahead 100 years. Philosophical Transactions of the Royal Society of London. Vol. 363, p. 1455-1474. 2005.

McRobie, Allan; Spencer, Tom; Gerritsen, Herman. The Big Flood: North Sea storm surge. Philosophical Transactions of the Royal Society of London. Vol. 363, p. 1263-1270. 2005.

Prandle, D. Storm Surges in the Southern North Sea and River Thames. Philosophical Transactions of the Royal Society of London. Vol. 344, p. 509-539. 1975.

Wolf, J.; Flather, R.A. Modeling waves and surges during the 1953 storm. Philosophical Transactions of the Royal Society of London. Vol. 363, p. 1359-1375. 2005.

Wood, Robert Muir; Drayton, Michael; Berger, Agnete; Burgess, Paul; Wright, Tom. Catastrophe loss modeling of storm-surge flood risk in eastern England. Philosophical Transactions of the Royal Society of London. Vol. 363, p. 1407-1422. 2005.

News Articles:

Black, Richard. Sea level rise by 2100 'below 2m'. BBC News. September 4, 2008.

Connor, Steve. Sea levels rising too fast for Thames Barrier. The Independent. March 22, 2008.

Various. North Sea flood tide fears recede. BBC News. November 19, 2007.

Various. On the rise: The Thames in 2100. BBC News. July 13, 2006.

Internet Sources:

Environmental Agency – The Thames Barrier. UK Environmental Agency (Official). Available at http://www.environment-agency.gov.uk/homeandleisure/floods/ 38353.aspx. Retrieved April 4, 2009.

Maeslantkering. Wikipedia. Available at http://en.wikipedia.org/wiki/Maeslantkering. Retrieved April 4, 2009.

MOSE Project. Wikipedia. Available at http://en.wikipedia.org/wiki/MOSE. Retrieved April 4, 2009.

North Sea flood of 1953. Wikipedia. Available at http://en.wikipedia.org/wiki/ North_Sea_flood_of_1953. Retrieved April 4, 2009.

NOVA: Sinking City of Venice. PBS Online. Available at http://www.pbs.org/wgbh/nova/ venice/solutions.html. Retrieved April 4, 2009.

Oosterscheldekering. Wikipedia. Available at http://en.wikipedia.org/wiki/ Oosterscheldekering. Retrieved April 4, 2009.

Roman London. Wikipedia. Available at http://en.wikipedia.org/wiki/Roman_London. Retrieved April 4, 2009.

Thames Barrier. Wikipedia. Available at http://en.wikipedia.org/wiki/Thames_barrier. Retrieved April 4, 2009.

Thames Barrier Clocks 100 Closures. ThamesWeb. Available at http://www.thamesweb.com/news_story.php?news_id=144. Retrieved April 4, 2009.

Terry Farrell. Thames Gateway. Available at http://www.terryfarrell.co.uk/projects/ masterplanning/mp_thamesGateway.html. Retrieved April 4, 2009.

Venice Water Authority. Responding to Climate Change 2008. Available at http://www.rtcc.org/2008/html/society-gov-4.html. Retrieved April 4, 2009.

Videos:

Levees. Modern Marvels. Perf. Max Raphael. DVD. The History Channel. August 30, 2006.

Thames Barrier, newspaper recycling, glassmaking. How do they do it? Perf. Robert Llewellyn. DVD. The Discovery Channel (UK). February 25, 2008.

Image Credits

Cover - Simpologist. Thames Barrier. Flickr. Available at: http://www.flickr.com/ photos/simpologist/64248038/. Retrieved April 19, 2009.
1 - Daniel Boulet. Roman London c. 1879 Print. Available at: http://www.bouletfermat.com/backgrounds/antique_bw_prints.html. Retrieved April 19, 2009.
2 - Nock, Oswald. Underground railways of the world. New York: St. Martin's Press, 1973.
3 - Milne, Antony. London's Drowning. London: Thames Methuen, 1982.
4 - Milne, Antony. London's Drowning. London: Thames Methuen, 1982.
5 - Topham Picturepoint. 0037262. Available at: http://www.TopFoto.co.uk. Retrieved April 4, 2009.
6 - UKColin. 1953 Flood. Available at http://en.wikipedia.org/wiki/ North_Sea_flood_of_1953. Retrieved April 4, 2009.
7 - Horner, Ray; Gilbert, Stuart. The Thames Barrier. London: T. Telford, 1984.
8 - Horner, Ray; Gilbert, Stuart. The Thames Barrier. London: T. Telford, 1984.
9 - Milne, Antony. London's Drowning. London: Thames Methuen, 1982.
10 - Adrian Pingstone. Thames Barrier 4 London ARP. Available at http://commons.wikimedia.org/wiki/File:Thames.barrier.4.london.arp.jpg. Retrieved April 4, 2009.
11 - Milne, Antony. London's Drowning. London: Thames Methuen, 1982.
12 - Alex Fortney. Closure Graph. Data from UK Environmental Agency.
13 - Vladimír Šiman. Oosterscheldekering-pohled. Available at http://commons.wikimedia.org/wiki/File:Oosterscheldekering-pohled.jpg. Retrieved April 4, 2009.
14 - Unie van Waterschappen. Maeslantkering-5. Available at http://www.uvw.nl/content/images/ Maeslantkering%20-%205%20JPEG.jpg. Retrieved April 4, 2009.
15 - Venice Water Authority. Responding to Climate Change 2008. Available at http://www.rtcc.org/2008/html/society-gov-4.html. Retrieved April 4, 2009.
16 - Terry Farrell. Thames Gateway. Available at http://www.terryfarrell.co.uk/projects/ masterplanning/mp_thamesGateway.html. Retrieved April 4, 2009.
Back - Vespa. Thames Barrier. Flickr. Available at http://www.flickr.com/ photos/vespa80/3164220988/. Retrieved April 19, 2009.