The River Clwyd

1
The River Clwyd
Chapter 4 What happens to the river when there is
too much water?
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2
Discuss and then click here
What is a flood?

• A flood is water in a place that is normally
  considered to be dry, in other words - water in
  the wrong place e.g.
• in a house when a pipe bursts or a sink
  overflows.
• in a playground when it rains too much
• alongside a river when the water goes over its
  banks (this is the type of flood were going to
  look at)

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3
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What causes a river to flood?

• A river floods when it has too much water in it.
  This is caused by
• an unusually heavy downpour of rain
• a few continuous days of heavy rain
• a quick melt of a large quantity of snow

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4
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How does it effect people?

• A river flood can cause a great deal of hardship
  and misery
• at its worst it can cause people to die.
• it can wash away or damage houses causing
  people to lose valuable treasures and furniture
  and to be homeless.
• it can damage roads and railway tracks
  stopping help arriving and people getting away.
• it can cause crops to be ruined and the death
  of animals.
• it can damage factories and businesses
  causing businesses to close and people to lose
  jobs.
• Water from a flood is dirty with mud and the
  contents of drains. It ruins furniture and the
  house itself. It takes a long time to dry out and
  it is altogether a very expensive business
  emotionally and materially.

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5
Who is responsible for protecting us from floods?
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• The Environment Agency is responsible for helping
  us avoid floods
• they identify areas likely to flood
• they help plan to avoid floods
• they tell us what to do if there is a flood
• they keep an eye on water levels
• they warn us if we are in danger of flooding
• they carry out schemes to prevent flooding
• The County Council also work to help us avoid
  flooding by carrying out necessary schemes to
  stop floods occurring.

Visit the Environment Agency website to see if
your area is at risk of flooding or if there is a
flood alert in action. http//www.environment-agen
cy.gov.uk/subjects/flood/
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6
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How do we avoid floods?
One way is to build flood defences in the form of
embankments. These raise the level of the land
and stop flood waters spreading. These are built
away from the river to allow room for more water
to collect. You can also divert rivers away from
built up areas and therefore avoid flooding
properties. Another solution is to set aside
large areas or lakes to contain the flood waters
without damage to people, properties or land. The
flood waters can then be controlled.
The embankment holds the water back. It allows an
area for the flood water to collect. The water is
higher than the surrounding farmland.
A few hours later the flood has gone.
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7
The Ruthin Floods
Which part of Ruthin flooded? Why and when did
the floods happen? What caused the flooding? How
often do the floods happen?
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8
Which part of Ruthin flooded?
Click here to see slide show pictures of the
Ruthin floods
The main flooded area was Mwrog Street, Borthyn
and Mill Street, in the lower parts of Ruthin.
(Shaded red)
Photographs from Denbighshire County Council,
Department of Transport and Infrastructure.
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9
Why and when did the floods happen?
There was exceptionally heavy rain on the days of
the floods. Look at the graph of rainfall in
Ruthin. What days do you think the floods
happened on?
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10
What caused the flooding?

• The increased flow of the river happened because
  of the great amount of water due to the heavy
  rain. The flood happened because
• the River Clwyd burst its banks on three separate
  occasions in two weeks.
• the Mwrog Stream culvert, which takes the water
  under the road, became blocked. This meant the
  water ran down the road and then into the River
  Clwyd.

Mwrog Stream
Culvert Exit
Mwrog Stream Culvertapproximately 600metres of
underground tunnel
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11
How often did the floods happen?
History of floodingJune 1931 Depths of water
2 to 3 feet. Mwrog Street, Borthyn and Mill
Street. October 1966 - Mwrog Street, Borthyn and
Mill Street. 1980s few details 1990 flooded
during Urdd Eisteddfod March 1998 Mwrog Street
Residents looked on as gallons of muddy water
came into their homes when a main culvert
collapsed and sent a torrent down the street.
Vale Advertiser. October and November 2000
Mwrog Street, Borthyn and Mill Street flooded.
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Picture from Denbighshire Archives
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12
What happens to the river when there is too much
water?
See if you can answer the questions click on
the question to see the answer.
What is a flood? What causes a river to
flood? How does it effect people? Who is
responsible for protecting us from floods? How
can we avoid floods? The Ruthin Floods Which
part of Ruthin flooded? Why and when did the
floods happen? What caused the flooding? How
often did the floods happen?
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