Flooding on the river Lea is a natural phenomenon which needs to be managed.

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Mujibur Rahman 11A                Geography coursework                

FLOODING ON THE RIVER LEA IS A NATURAL PHENOMENON WHICH NEEDS TO BE MANAGED

The catchments area of the river Lea covers 1,420 square kilometers of land. It has a length of 85 kilometers (23 miles) which is from the source to the mouth. The source is in the north west of Luton in the Chiltern Hills and the mouth is a meander which leads to the Thames (the Bow Creek). The lower course of the river Lea is tidal because it has waves coming in from the Thames. 10% of the lakes connecting to the river Lea are tidal.

The River Lee or River Lea (both spellings are in general use) is a river in England. It originates at Luton in the chalk beds of the northeast Chiltern Hills and flows generally east and then south to London where it joins the River Thames. Once an important commercial waterway, certain sections were canalized as part of the River Lea Navigation. Another artificial channel, the New River was constructed to take clean water to London from the Lee and its catchments areas and bypass the polluting industries that had developed in its downstream reaches. The New River is a man made waterway in England, opened in 1613 to supply London with fresh drinking water. It starts in between Ware and Hertford in Hertfordshire and travels 20 miles down to Stoke Newington. Among the districts it flows through are (from north to south). The River Lea Navigation is a canalized river incorporating - as the name suggests - the River Lea (also known as the River Lee).

The Lea is a major tributary of the River Thames and was once used by Viking raiders. In more peaceful times, it became important for the transport of grain from Hertfordshire, but navigation of its southern-most tidal reaches ('Bow Creek') was difficult due to its tortuous meanders. The River Lea Act 1766 provided for the construction of a new stretch of canal, the Limehouse Cut to bypass these tight bends.

The River Lea or Lee runs from Luton in Bedfordshire to the River Thames in east London. Evidence of Bronze and Iron Age settlements have been found along the length of the river and the Romans built Ermine Street parallel to the Lee shortly after they arrived in Britain around two thousand years ago. During the 19th century the river formed part of the boundary between Saxon England to the west and the invading Vikings to the east, led by King Alfred the Great and Guthrum respectively. It is said that when the Danes sailed up the river in around 895AD and established a base near Ware, Alfred stranded them there by reducing the level of the river.  He did this by building an embankment and weir near the Thames, and dividing the river just above Waltham Abbey.  How true this is we do not know, but the remains of Viking ships have been found near Hertford and Stanstead Abbots, the river does split into three near Waltham Abbey and the names Kings Weir and Blackwall date back to these times. During the mid 1700's the navigation was much improved that land surrounding the Lee near Stratford was ideally placed for industries that London did not want right on it's doorstep, such as slaughterhouses or gas works, but did want products from. By all accounts it was not hard to see (or smell) where the early bone china produced at Bow.

As well as manufacturing industry, the Lee Valley became one of the largest areas in the country for horticulture.  By the 1930's almost half the glasshouses in England were here, growing a variety of fruit, vegetables and flowers. This was due to the quality of soil, good water supply, and easy access to the markets of London and the availability of seasonal labour from the capital.  The extraction of good quality gravel, deposited in the valley during the ice age, also became a major activity, particularly Ware although there are still some working sites, most have now been returned to nature, many as lakes used for fishing and water sports. In 1967, an act of parliament established the Lee Valley Regional Park Authority to develop the areas along the Lee, many of them by now derelict, for recreation and wildlife. Today it is mainly pleasure boats and waterbirds that travel up and down the river in place of the barges carrying grain or coal.  Although the river has always had an important role to play, providing power for the many small mills that were constructed along it's route, some of which are still standing today.

In this assignment I’m going to explain how flooding on the river Lea is a natural phenomenon, which needs to be managed effectively.

Physical processes which increase the risk of flooding

  1. Precipitation

The amount and the type of precipitation affect the risk of flooding in the river. This is a major concern because it is one of the main causes of flooding in the area. Lea Valley has an annual rainfall of 637mm. also the type of rainfall affects the risk of flooding, the reason for this is that in the summer the river experiences a lot of flash floods caused by a long period of hot weather which cause the ground to become hard and dry so it cannot absorb any water to saturate the soil. Furthermore the type of precipitation matters because in the winter when it starts snowing, the snow eventually melts and has nowhere to go, this then runs into the river causing it to flood.

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  1. High Tide

A daily tide which comes and in and out of the sea. This is a major threat to the people living around the area as it can be very high, which sometimes rises above all the barriers and walls which causes severe floods. This is because the river is tidal over its last 8.8km.

  1. London Clay 

London is built upon an impermeable material, clay. Clay is impermeable because it does not let water pass through. This is a rising problem as the water is getting stored on the clay which ...

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