Flooding – Leigh and Medway: from 1600 to present

See also:
Navigation of the Medway 1500-1840
The Green Flood 1880

The Flooding of the Medway (Part I)

Tonbridge had been susceptible to flooding for hundreds of years, with the two hundred yard gap between the Castle and the station having to contain the waters of the Medway and the waters of the various tributaries running into it.

There were reports of flooding along the Medway as early as 1600, when for example, at Yalding, there was a petition because of the flooding which meant that people and even their animals, often had to live upstairs – their homes were cold damp and unhealthy.  Major flooding seems to have occurred on average every twenty-five years.

In 1853, one of the Medway’s worst flood disasters took place at Hadlow, when a wagon loaded with hop-pickers were plunged off the Upper Great Hartlake Bridge between Hadlow and Tonbridge and over 30 people drowned. There is a memorial to this particular disaster at Hadlow church.

And the aforementioned great flood of 1880 saw the whole of the fields above Tonbridge covered in water, flooding in the High Street, and even locally at Ramshurst.

It was reported that “The River Medway Company was notorious locally for lording it over the River but refusing to accept responsibility … and there was general relief when a receiver was appointed in 1910. By that time the river banks, bridges and locks were in such a bad state that the Medway Conservators had to be created by Act of Parliament to put things Right”.

Thus, on 16 April 1918 there is an article in The Free Press Tonbridge on flood prevention and important Medway improvements. It appears that a Medway reconstruction scheme has been undertaken, with the completion of the building of a new weir adjoining the Tonbridge Town Lock. It was expected that this weir would be the means of preventing the flooding of the town in future “and to make this desirable object as far as possible a certainty, several sluices are now to be constructed in the place of the present dry dock”. The article goes on to say that the work is being undertaken under the direction of Engineer, Mr Stantom and foreman, Mr Jupp – the intention to prevent floods and improve the river as a means of transit. “The weir is able to cope with an enormous quantity of water being 7 feet long and coming automatically into action as the level of the river rises. The construction necessitated considerable engineering ingenuity and a very large amount of material had to be utilised, including 22 tons of cement and about 150 cubic yards of gravel”. “The foundations of the concrete work had to be laid 2 feet 4 inches below the location of the river and the height of the weir from the overflow level to the bottom is nine feet”. A grant of £200 has been made by the Urban Council towards the weir improvement.

It meant that the old dry dock as the Town Lock was to be done away with, and in its place an enlarged channel would be constructed with 6 sluices. These sluices were intended to be utilised in letting away what flood waters the weir is unable to cope with if that is ever necessary!

Other improvements to be undertaken were the widening of Cannon Bridge … the deepening of the river all along its course . . . and the locks from Maidstone right up were to be considerably enlarged. The new locks would enable barges of 150 tons to be brought up river whereas the current limit had been 50 to 75 tons.

Thus a major scheme had been undertaken, which may have made the river more navigable, but flooding in the town remained as ever a problem.

Parish Magazine Article: November 2011: by Joyce Field

The Flooding of the Medway (Part II)

Despite the improvements at Tonbridge in 1918 and later, flooding remaining a regular problem.  Significant flooding occurred in the 1920s, in 1947, 1955, 1958, 1960, 1963, 1968, 1974, 1979, 2000/2001 and 2013/2014.

There were reports of flooding in 1955, when in January 1955, the Daily Telegraph and the News Chronicle had stories of floods through the whole of Tonbridge including the playing fields and along all the roads around the river and the High Street. There were pictures of The Playhouse Theatre in Tonbridge showing the actors using buckets to disperse the water.

And in 1958, it was reported that “A wall of water four foot high swept into Tonbridge High Street on the evening of 15 September … when the Medway broke its banks, pouring over the flood walls built to protect the centre of Tonbridge some 10 years earlier”. “Under and over the Great Bridge, the Medway roared and boiled with a frightening noise”.

However, the next major flood to equal that of 1880 was in 1968. On 20 September 1968 the Courier reported: “At first light on Monday morning (i.e. 16 September) the High Street torrent was as strong as it was during the dark nights of the terror . . . and by lunchtime on Monday the water was still chest high in some parts of the town, although in other areas the level was, thankfully, falling steadily”. Other quotations from reports at the time include: “A Kent & Sussex Courier van had floated out of the Bradford Street car park. When it reached the High Street, it was corralled by policemen who lashed it to a car park signpost”. “Cannon Street Bridge – built 50 years ago – was completely washed away … the first bridge there had been washed away in floods while it was being built over half a century ago”. “Nearly 40 pleasure craft lost …. “ “Riverside Cafe was nearly five feet deep in water”. “At Baltic Saw Mills, timber worth £1000 washed away … with the surging water picking up great baulks of timber and hurling them through the locks.” “Wallace and Tiernan Ltd – both factories under water”. The Whitefriars Press complained “The River Board should have let us know of the danger”. Chlorination Equipment which had been built in 1965 purposely “to be above the flood level, but the works and offices were inundated”. And “by midmorning Kent Fire Brigade had received more than 1000 calls”. The roads into Tonbridge were impassable except that from Tunbridge Wells. The view was that the flooding had been caused by nearly four inches of rain in the 48 hours up to the Monday morning following an exceptionally wet first two weeks of September when more than five inches of rain had fallen. As expected, many services failed. Telephones had failed, but engineers had continued working at the Avebury Avenue exchange – often having to wade through waist deep water – to keep vital lines open. Much gas and electricity failed, although amazingly many street lights stayed on through Sunday night. The Territorial Army Headquarters in Avebury Avenue became a refugee centre for hop-pickers from Stilstead Farm, Golden Green and the Army sent in amphibious vehicles. Houses were flooded up to window level in Hildenborough and the Old Hadlow Road and food was handed up on poles to families stranded in upper floors in Tonbridge, Hadlow and East Peckham. The Angel Hotel on the High Street was so badly damaged it had to be pulled down. The Angel Grounds – home of Tonbridge Football Club were swamped, walls ripped down and part of the stand smashed.

And although flood warnings had gone out, Tonbridge, being well used to minor flooding, had expected the trouble to be confined to the Sports Ground, The Botany and outlying areas. Photographs of this flood still seen in many shops at Tonbridge testify to how wrong this had been.

Leigh itself remained generally unaffected by the extent of the 1968 flooding at Tonbridge: however, the Green itself was for once virtually submerged under the amount of rainfall – covered by surface water which was unable to drain away. And Hever Castle had been under several feet of muddy water.

Parish Magazine Article: December 2011: by Joyce Field

The Flooding of the Medway (Part III)

After the major flooding of 1968, the authorities realized that something major had to be done. Despite such a flood being a one in a hundred year even, plans were afoot to ensure such a major event might be prevented in future.

In 1968 Tonbridge was not the only place to be flooded because of the overflowing of the Medway and its tributaries. The Authorities saw that there was the possibility of putting in a barrage on a fairly large flat area up to Penshurst. And they were aware that virtually all the land that would be temporarily under water was owned by one landlord – Lord De Lisle.

At Leigh Village Hall in July 1972, there was a public meeting to discuss the barrier scheme and in Leigh itself there was some lay objection to the building of the barrier at Leigh. Lord de Lisle was present at this meeting. Leigh itself was not unduly affected by the flooding frequently faced by Tonbridge and other towns in the Medway’s path. However, the planned barrier was proposed to be built at Leigh. For Leigh the arguments centred on whether such a barrier would be an advantage or disadvantage to the village – rather than its potential positive benefits elsewhere. However, in truth for Leigh the impact of the barrier, it was argued by those proposing it, would provide neither major benefits nor major detriments. Leigh’s own risk of flooding would not be increased and even with a heavy flood no built up area in Leigh would be flooded. However, it was argued by those against the proposal that much of the problems faced by the 1968 flood had been caused by neglect by the River Board – if the river had been cleaned, sluices improved, bottlenecks straightened out, there would not be a need for a barrage.

The conclusion of the meeting was that ”this Leigh Public Meeting … is totally opposed to the “Straight Mile Flood-water Storage” project. First because of its obvious and potentially harmful effects on the health, comfort and security of many citizens of Leigh; secondly, because of it a threat of longer, deeper and more frequent floods on rich agricultural land; thirdly, because the maximum advantages gained at our expense would have minimal effect on flood levels at Tonbridge”. “We urge the Kent River Authority to think again on a much bigger scale and on a more equitable basis: so that from the upper waters of the Eden in Surrey to the tidal reaches of the Medway, the rivers should be deepened, widened and bottle necks removed. All this in such a way as to control its flow, enhance the whole river environment with minimum disturbance to the rich farm land along its course. Finally this meeting is firmly resolved to join with every ally it can find in the Eden and Medway parishes to oppose the flood-storage scheme at any public enquiry and it wishes these views to be known as widely as possible”.

However, despite this local objection, the Act was passed in 1976 and the Leigh Barrage scheme did eventually go ahead and was built in 1981.

You can form your own views as to whether the local objections and fears have been proved or not.

Parish Magazine Article: January 2012: by Joyce Field.

The Flooding of the Medway (Part IV)

The Building of the Leigh Barrier

In 1981 the Leigh Barrier was built to address the flooding problem on the Medway and Eden: it has proved successful in reducing the water levels and averting major flooding.

The cause of the flooding problems around Tonbridge is the River Medway which flows more than 100 kilometres from its source in Ashdown Forest to its mouth at Sheerness. Its name is derived from the Celtic Medu meaning mead or sweet water and its power was used in Roman times for forges to create iron from the deposits of clay. As the river flows eastwards across the Vale of Kent, the gradient reduces and collects tributaries (feeder streams) that rise in other parts of the High Weald, such as the rivers Eden, Bourne and Teise. These rivers respond rapidly to rainfall and are subject to extremes of flow between summer and winter. The clay soils of the area drain rapidly and the spread of urban development has added to the river’s ‘flashy’ nature. Therefore, as we have seen, the area has suffered regularly from flooding of both property and agricultural land.

The Leigh Barrier is an ‘on line’ flood storage scheme. It uses a sluice (large moveable gates) in an embankment across the valley of the river to throttle flows to an acceptable maximum downstream. This reduces flooding downstream and holds floodwater in six kilometres of the valley which is unoccupied. The site selected for the storage reservoir was at Leigh and necessitated an embankment which was up to 5.7m (over 18 feet) high and a storage area of 278 hectares (1.1 square miles). The embankment is 1,300 m long (0.8 of a mile) and crosses a number of awkward features including the Powder Mill Stream, the railway embankment, the Tonbridge Bypass Embankment, Redlands gravel plants, two silt lagoons and Haysden Lake. The sluice is of heavy reinforced concrete with the base slabs being 2m (6’6”) thick in places and the external walls taper upwards from similar base dimensions. .

Under normal river conditions the gates do not impede the flow of the Medway in any way, but following heavy rain the river levels are monitored and if they reach a height that threatens flooding downstream, the barrier can control the flow. It does this by keeping water behind the barrier (impounding) and only allowing a proportion to continue its natural course towards Tonbridge. The water builds up behind the barrier depending on how much is entering the reservoir from the natural river flow and when the peak of the floodwater has passed, the contained water is released in a controlled manner.

River levels are monitored 24 hours a day electronically and can be remotely interrogated at 15 minute intervals and compared to different events in order to predict the way that he river will behave and the way the barrier can help.

Until the end of 2000 the barrier has operated 40 times. And there have been a few floods that needed the maximum reduction that the scheme offers.

In particular, the October 2000 floods – which saw widespread flooding across Hampshire, Isle of Wight, Sussex and Kent – the Leigh barrier went to work: the barrage filled in 7 hours – it usually takes 30 hours. 30mm of rain fell in one minute over the whole flood plain. Between 9-12 October, up to 15 cms of rain fell in Kent and the barrier started to impound – taking a percentage of water from the swollen river. The flow of the Medway was such that the reservoir was nearing its full capacity by mid-afternoon while allowing the maximum safe amount of water to continue its course. (The reservoir is designed to ensure that if full design capacity is reached there is one metre of freeboard remaining between the highest water level and the top of the embankment).

The Agency Engineers faced the task of ensuring that the volume of water allowed to pass through the gates did not overtop the defences in the town. If all the storage space behind the barrier was used up Tonbridge would have been flooded. If too much water had been allowed through, Tonbridge would have been flooded.

The rainfall in the autumn of 2000 was above the long term average in Kent. And as a result ground had become so saturated that the rivers began to react very quickly to rainfall as water that would have normally soaked into the ground ran off the land and into watercourse.

However, the floods of 2000 showed the ability of the barrier to limit flooding and Tonbridge stayed dry. Yet, although the risk of flooding can be reduced by the barrier, floods can never be prevented. And there have been occasions when the barrage has virtually or actually overflowed. And predictions about global warming mean that the future risk of flooding is uncertain, and that plans to raise the barrage further is a possibility.

Parish Magazine Article: February 2012: by Joyce Field.