1. The River Clwyd Chapter 4 What happens to the river when there is too much water? Next Page

2. 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 we’re going to look at) Discuss and then click here Before After Next PageBack to questions

3. Next Page What causes a river to flood? Discuss and then click here 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 Back to questions

4. Next Page How does it effect people? Discuss and then click here 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. Back to questions

5. Next Page Who is responsible for protecting us from floods? Discuss and then click here 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. The County Council and 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-agency.gov.uk/subjects/flood/ Back to questions

6. Next Page How do we avoid floods? Discuss and then click here 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. Back to questions A few hours later the flood has gone.

7. Next Page Which part of Ruthin flooded? Why and when did the floods happen? What caused the flooding? How often do the floods happen? The Ruthin Floods

8. Next Page Which part of Ruthin flooded? The main flooded area was Mwrog Street, Borthyn and Mill Street, in the lower parts of Ruthin. (Shaded red) Click here to see slide show pictures of the Ruthin floods Back to questions Photographs from Denbighshire County Council, Department of Transport and Infrastructure.

9. 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? Why and when did the floods happen? Next Page Back to questions

10. The increased flow of the river happened because of the great amount of water due to the heavy rain. The flood happened because: 1.the River Clwyd burst its banks on three separate occasions in two weeks. 2.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. What caused the flooding? Next Page Mwrog Stream Mwrog Stream Culvert approximately 600metres of underground tunnel Culvert Entrance Back to questions Culvert Exit

11. Next Page History of flooding: June 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. How often did the floods happen? Picture from Denbighshire Archives Back to questions

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? Back to beginning