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PCP Teachers Notes 1—About The Parrett Catchment Project The Parrett Catchment Project (PCP) is a partnership, established in 2000, whose long term goal is to reduce the frequent and severe flooding in the lower Parrett basin. The partnership can do this by developing a way to manage the use of land and water which can easily be continued but with mini- mal long term effects on the environment (i.e. is sustainable). The partnership’s way of managing land and water will also need to try and benefit the economic, social and cultural life of the catchment and protect and improve the environment for future generations.

The Parrett catchment covers half of , incorporating 180 parish councils and approximately 138,000 households. The major towns in the catchment are , , and . The catchment covers lots of different scenery from the arable uplands around Sherborne to the wet grass- lands of the and Moors.

Twenty seven stakeholder organisations now form the PCP partnership. The project is paid for by a group of nine organisations, including and the . In 2002 the PCP also won lots of financial support and recognition as part of the European ‘Joint Approach for Managing Flooding’ (JAF) project. The JAF project also gets money from the Environment Agency.

The money from the JAF project has enabled the PCP to deliver its innovative ‘Farming Water’ pro- gramme, which is made up of a number of demonstration and awareness raising projects: · Flood retention schemes · Flood storage schemes · Woodland development · Arable reversion to · Soil management · Monitoring

The JAF project also encourages co-operative working with partner organisations in and The Netherlands, where there are lots of existing programmes already that provide ‘Farming Water’ schemes.

To date the PCP has successfully delivered many of the components of the JAF project, and now that we are in the final year of JAF we are reviewing the future direction of the PCP and future funding sources.

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PCP Teachers Notes 2 - What Causes Flooding?

These notes may be useful to share with children during Task 3:

Floods are not caused by any single thing and flooding in different places is usually the result of a different combination of issues. For example, snow can contribute to flooding in some places, but not others, and construction on the floodplain can make flooding worse sometimes, but not always. All floods have one thing in common however, and that is that there is a period when there is a lot of rainfall and the cannot take the water from the land to the sea quickly enough, so they overtop their banks and inundate the surrounding area. High rainfall is usually the main cause of flooding, but other

MAKE IT WORSEMAKE problems usually make it worse. They are: LOTS OF THINGS CAN FLOODING OR CAUSE

Lower capacity of rivers—in other words, they can not 1 hold as much water. The capacity of a river is reduced when:

The river is already at a high level, which reduces the amount of extra water it can take. A prolonged period of heavy rain or melting of snow can cause higher a) than normal water levels in rivers.

The cross section of a river with a high water level and what happens when there is heavy rain. Page 45

PCP Teachers Notes 2 - What Causes Flooding?

When a river is full of deposited silt, it reduces the size of the channel, making a river smaller and unable to cope with high rainfall levels. The effect is the same as if it had a high water level—the river cannot accommodate much extra water and may burst its b) banks.

The tide can also make water levels higher than usual, especially in areas where the tide comes up the river. A high tide also has an impact further upstream as it prevents the river from discharging water to the sea. As a consequence, the river can back up like a c) clogged drain and gradually fill up to the point where it bursts its banks. Page 46 PCP Teachers Notes 2 - What Causes Flooding? 2 Increased runoff from land in the catchment Soil cannot absorb water from heavy rain because:

The ground is frozen or covered in a deep layer of snow. The soil becomes less permeable, and a larger amount of rainfall than usual runs off the land and drains into rivers, a) which may be unable to cope with the increased flow.

The soil has already absorbed as much rainfall as it can and is saturated. When this happens, the ground has no further capacity to absorb any more water and any rain b) that falls on it runs straight off and into rivers and streams.

The soil has been compacted, meaning that it has been trampled or compressed, creating a hard top layer that is c) not permeable. Under the soil, the rock is impermeable. Some kinds of rock are more porous than others and can absorb water. Different types of rock also hold it for different lengths of d) time.

The ground has been covered with an impermeable surface such as concrete or tarmac or e) buildings have been constructed. Roofs and other impermeable surfaces do not soak up water, so rain runs straight off them, down the drains and into rivers.

Note: Flash flooding is a particular type of very short-term flood—it happens when there is ex- ceptionally heavy rain (during a thunderstorm, for example) and usually only lasts a very short time. They are, however, very dangerous as they are notoriously difficult to predict and people may not get very much warning about them.

WHERE IS FLOODING MOST LIKELY TO HAPPEN?

The floodplain is the flat, relatively low lying area of land around a river and is the first place to be affected when a river bursts its banks. It is also a place where a lot of development and construction has often taken place. Because rivers have, historically, been such important places for industry and transport, towns are usually built on their banks. More recently, people have built new homes near rivers because they are attractive places to live. These trends have put properties at greater risk of flooding. Page 47

PCP Teachers Notes 3 —What features of the Parrett Catchment make it prone to flooding?

Earlier on we learnt a lot about what causes flooding or makes it worse throughout the world — rivers that have been straightened, woodland destroyed, land that has been made impermeable. Now it is time to look at some features specific to the Parrett catchment make flooding a problem in the area.

1) ‘EXTREME’ RAINFALL From the previous exercise you will know that the Parrett Catchment is not especially wet, so flooding isn’t due to a high average rainfall. Flooding only happens when there is excessive or extreme rainfall. In winter 2000 the rainfall experienced in Somerset was extreme. Two storms hit Somerset very close together allowing the rivers little time to evacuate the water from the first storm. With climate change extreme events are predicted to become more frequent.

2) DRAINING THE FLOODPLAIN The levels and moors have been gradually drained by man for agriculture over the centuries. The river system in this area does not act like a natural floodplain. It is man- aged by man through a system of , locks, weirs and spillways. Large parts of the area are only a few metres above sea level.

3) POOR AGRICULTURAL LAND MANAGEMENT Changes in the way middle and upper catchment farmland is farmed can make a sig- nificant difference to flooding in the lower catchment. Poor farming practices can lead to compacted and capped soils which are impermeable to rainwater. Water runs quickly off fields often taking soil with it and depositing it in drains and on highways. During a rainstorm blocked drains and ditches can lead to serious localised flooding.

4) RUN-OFF FROM URBAN DEVELOPMENT Over the past 10 years, more and more homes have been built in the catchment. The hard surfaces of these developments, including tile, concrete, brick and Tarmac, do not soak up water. Rain runs straight off the roofs and roads and into the drains and rivers very quickly, placing stress on the drainage and river system.

5) LOSS OF WETLAND HABITATS Originally the Somerset Levels and Moors were wetlands, naturally flooded by a mix- ture of seawater and river water every winter. Wetlands, such as wet , reed- beds and wet woodland, act like giant sponges absorbing huge volumes of floodwater. By turning wetlands into farmland the amount of water that can be stored naturally in the catchment has been dramatically reduced.

6) REDUCED RIVER CAPACITY As indicated by the brown colour, the waters of the River Parrett are laden with silt or suspended solids. This silt is deposited along the sides of the river channels as mud and this reduces the size of the channel, making it smaller and less able to carry high volumes of water after rain storms.

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PCP Teachers Notes 3 —What features of the Parrett Catchment make it prone to flooding?

6) RIVER BANKS FAILING In the Parrett catchment thankfully flooding has never happened due to river bank fail- ure. At the moment the banks are strengthened and upgraded regularly by the Envi- ronment Agency. But, with sea level rise in mind the tidal river banks cannot continue to be raised forever, because the river will get higher and higher thus increasing the danger. Other solutions are being sought.

7) FAILURE OF PUMPING STATIONS When floods accumulate on the floodplain some of the water is unable to drain away naturally, so it must be pumped out of the moors and returned to the river once the river level has dropped by a series of pumping stations. The pumping stations on the Levels and Moors are old and need to be maintained to ensure that they are in good working order for when they are required. So far no has failed in its job, but if any were to fail this could lead to a pooling of huge volumes of floodwater in a small area i.e. on one or two moors. The flood would be metres deep and undoubtedly houses would be flooded and villages cut off from other towns and villages.

8) THE LARGE TIDES The River Parrett flows into the Severn Estuary. So up to Oath near it is a tidal river, affected by the natural fluctuations in the level of the sea. The Severn Estuary has the second highest in the world with a 7 metre difference be- tween high tide and low tide. When the tide is very high (during full moon) sea water flows up the River Parrett reducing the amount of river water that can flow down to the sea. This is not a problem until the rivers become swollen with rainwater from a very heavy storm. With nowhere for the extra water to go, the rivers backs up like clogged drains and fill up to the point where they burst their banks. This is what happened in 2000.

9) DEVELOPMENT ON THE FLOODPLAIN Development is still taking place in the floodplain. By housing people in an area at risk from flooding is putting those people in danger. Development is also reducing the abil- ity of the floodplain to absorb floodwaters by increasing the amount of hard non-porous surfaces.

10) LOSS OF WOODLAND Compared to other UK counties Somerset has a lower than average coverage of wood- land. Trees help to improve soils so that they absorb more rainwater than other land uses. Tree roots help stabilise soils, holding them in place during heavy rainfall. Tree trunks create resistance against floodwater helping to slow the speed of floodwater. By removing trees all these benefits are lost.

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PCP Teachers Notes 4 - What Can Be Done About Flooding?

For centuries, people have tried new ways of controlling flooding. The most effective flood defences protect urban areas, because so much costly damage would be done if they were badly flooded and very large numbers of people could suffer.

For example: According to the Environment Agency, a flood in central London would: stop the underground running, disrupt power, gas and telephones—it would take months to repair the damage and for businesses to start running again and could cost over £30,000,000,000.

Most flood defence measures in some way involve increasing the ability of rivers to cope with extra water.

INCREASING THE CAPACITY OF RIVER CHANNELS

Deepening rivers: dredging and raising river banks: Rivers can be made deeper by dredging, which involves removing silt from river channels by using machines, either standing on the river bank or mounted on barges that float on the water. They act like diggers, lifting up the mud and sand at the bottom of the river that restricts the amount of water it can take. Another option is for them simply to stir up all the sediment and let the river’s current take it out to sea. A digger on a barge dredging a river

Although dredging can be a useful way to make rivers deep enough to take ships when they lead to important ports, it is not always the most efficient way of preventing flooding, as the sediment often builds up again very quickly, especially in the tidal sections of rivers.

The above diagram shows how the effect of heavy rain and increased flow on an undredged and a dredged river.

A further way of deepening a river is to raise its banks. The name for a raised bank that parallels the side of a river is a levee and they may be created naturally, or by man to prevent flooding. Levees are usually constructed by piling earth up on cleared land next to the river. They work by stopping the river from bursting its banks when its level is high.

They do, however, have their drawbacks as they can make the river less attractive to look at, or block the views of people who live next to it... PCP Teachers Notes 4 - What Can Be Done Page 50 About Flooding? If a levee fails, the flooding that happens is generally much worse than it would have been had the land been able to flood naturally (e.g. the recent floods in New Orleans in America). Therefore, they must be very carefully designed and built and require regular maintenance to make sure they are up to the standard necessary to be able to protect the surrounding area from flooding.

The above diagram shows the effect of heavy rain when a river’s banks have been raised by building levees, or left as they are.

Widening rivers Widening rivers has the same effect as deepening them or building a relief channel—it increases the amount of water that can be contained within the channel, so that when there is extra flow, the land does not become flooded. It is, however, often difficult to widen rivers, especially in towns because there may not be any room to do so. Often buildings are built very close to the water’s edge and they would have to be bought and knocked down before the river could be widened.

Relief channels Often, rivers that have to cope with a great deal of extra water when it rains need help and this can be achieved by building a second river, increasing the amount of water remains within river channels, rather than flooding land. These manmade rivers are called flood relief channels and are usually built in urban areas.

Example of a Relief Channel: The scheme that has now been named the Jubilee River. It is 7 miles long and extends from upstream of Maidenhead to down- stream of Windsor, both of which have suffered severe and regular flooding in the past. If the area were to flood badly, some 5,000 homes and 700 businesses would be affected and the main motorway into London from would be closed for as long as it took for the flooding to pass. The new channel has been designed to look like a natural river by making sure it has some water in it all year round; the water level is controlled by a set of gates. It has been designed with the environment in mind and has pro- vided new habitats for wildlife. It is a nice place to for people to spend their leisure time. Page 51

PCP Teachers Notes 4 - What Can Be Done About Flooding? STORING FLOODWATER

Creating reservoirs by building One method of storing floodwater is by constructing a and storing water in a reservoir. This is not normally done on small rivers and catchments as the dam must be built so that most of the length of rivers in the catchment are behind it. Otherwise, very little of the extra water that runs off land during heavy rain would be held back by the dam.

As we learnt earlier, dams can be very useful for electricity generation, but the reservoir must be kept quite full if it is to produce a lot of electricity. If the reservoir is too full, however, it will not be able to store very much water when there is heavy rain. They are also very expensive to build and the consequences are very destructive if they fail.

Deliberate flooding of rural land Some towns and cities are protected by the deliberate flooding of other areas where less damage will be done by the water. Rural land on a river’s floodplain is normally used as the damage done would cost less to repair and there would be much smaller losses of income to businesses than if a town or city were to be flooded. Although many rural landowners do not mind their land being flooded temporarily to protect lives and properties, it can cause major inconvenience and loss of income if the land is flooded for too long, which is considered by some to be unfair.

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PCPWhat Teachers are Notes the solutions 5 - What are to theflooding? solutions to flooding in the Parrett Catchment?

Earlier on we learnt a lot about the causes of flooding in the Parrett catchment. Now it is time to look at some of the measures being taken in the Parrett catchment to reduce the flood risk.

1) ‘EXTREME’ RAINFALL There are no solutions to this one. We simply have to weather what comes our way and prepare ourselves as best we can. There are measures that homeowners and business owners should take to protect themselves from flooding, such as using stone flooring rather than carpet, installing plug sockets high up the walls, using flood-guards and sand bags to prevent floodwater coming in through front and back doors.

2) DRAINING THE FLOODPLAIN Today we have little choice but to live with the waterway system that the monks and subsequent landowners have created on the levels and moors. As such we must ensure that the system of sluices, locks, weirs and spillways continue to be maintained and continue to move water around the floodplain as efficiently as they can.

3) GOOD AGRICULTURAL LAND MANAGEMENT Changes in the way middle and upper catchment farmland is farmed can make a significant difference to flooding in the lower catchment. Many farmers are taking measures to ensure that their land can absorb as much rainwater as possible, by plant- ing different crops during the wet season, harvesting at different times, planting wide strips of grass alongside waterways to slow runoff and trap soil.

4) STORING RUN-OFF FROM URBAN DEVELOPMENT Over the past 10 years, more and more homes have been built in the catchment, but many developers are now making sure they include ponds, channels, reedbeds and lagoons in their designs, so that rain runs off the tile, Tarmac, concrete and brick and into these storage ponds. This takes the strain off the drainage system and rivers.

5) CREATING AND ENHANCING NEW WETLAND HABITATS Over the last few years conservation organisations like the and the Royal Society for the Protection of Birds (RSPB) have been buying large areas of farmland and have converted this land back into wetlands. These areas are now thriv- ing with wildlife, and they are particularly good habitats for migrating birds to stop off on their long flights.

6) MAINTAINING THE RIVER CHANNELS The waters of the River Parrett are laden with silt or suspended solids and we cannot stop that being the case. But when this silt is deposited along the sides of the river channels as mud and the Environment Agency uses a dredger to remove the silt. Dredgers are boats that can scrape the mud away from the river banks and river bed and then place the mud up high on the river bank so the river channel is kept open.

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PCP Teachers Notes 5 - What are the solutions to flooding in the Parrett Catchment?

7) STRENGTHENING THE RIVER BANKS The river banks are strengthened and upgraded regularly by the Environment Agency to prevent any breaks ever happening. In the future landowners that own land away from houses and businesses might agree to allow the river banks to be broken deliber- ately to allow the river water through to flood their land safely. This would help to store floodwaters in times of need.

8) MAINTAINING THE PUMPING STATIONS The pumping stations on the Levels and Moors are maintained by the Environment Agency to them in good working order.

9) STOPPING THE SEVERN ESTUARY TIDES There has been an idea to build a big near the mouth of the River Parrett for over 100 years. But with sea-level rise becoming more of a threat this idea is becom- ing more and more popular. Recently many studies have been carried out to decide whether it is a good idea to stop all the tides coming up the river, to stop only the larg- est tides (like the Thames barrier) or to have a sluice at all. The debate continues.

10) RESTRICTING DEVELOPMENT IN THE FLOODPLAIN Development is still taking place in the floodplain but the Environment Agency is work- ing hard to prevent developments being built in areas at real risk from flooding.

11) PLANTING WOODLAND Recognising that trees help to improve the quality of the soil, stabilise soils, and cre- ate resistance against floodwater many farmers and landowners are planting trees on large areas of their land. Landowners must take care only to plant native trees (trees that are natural to ) so that they look natural and so our local wildlife can their home in the trees.

Teachers Notes 6 - Answers to questions on PCP 2 Page 54

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Clatworthy Brendon Hills PCP Teachers Notes 7- Answers to photo locations on PCP3 Page 55

s el ev lls L i et H rs ck e to m an So u he Q T

⇒Clue: Look at how flat the land is and those are ⇒Clue: This picture is looking North and that’s the drainage channels—what does that suggest about the in the background. height of the land?

al an in C ra on D t or un o Ta em nd g a ed er s S t g’ a in gw K id Br

⇒Clue: Boats used to use this stretch of water to ⇒Clue: That water is not a river, it is manmade and used transport goods between two towns in the catchment. to drain low-lying land.

t et on rr nt Pa au e T h at f t e o n th To ou he M T

⇒Clue: This is near a river mouth and that is the Quan- ⇒Clue: this is the and the building suggests tock Hills on the horizon. this picture was not taken in the countryside. PCP Teachers Notes 8 - Answers to Parrett Page 56 Catchment WordSearch

P A R R E T T Q U B D R A H C A R C A N N I N G T O N N E Y S T E A R T I N T E C O L D B O O N A C O R R N V O R H K N I E E I T Y E S D T L N S G S H E R B O R N E U T W N A E N A I O M T R O T M E A T T E L Y R R R I N O T R E M O S T E P O V S N W O D K C A L B G C L N K I L E V E L S A M L N O T G N I L L E W Page 57

Teachers Notes 9– Useful Sites To Visit in the Parrett Catchment

Langport and Visitor Centre

01458 250350 The Visitor Centre is the gateway to the Moors, one of lowland Britain's most un- changed landscapes. Enjoy displays and exhibits about life past and present in this unique area. The Discovery Room is a hands on and fun opportunity to discover the River Parrett Trail from source to mouth. Discover this fascinating area on foot, or by cycle. A range of top quality cycles suitable for all ages is available for hire. The 1¼ mile Parrett cycleway leads to a network of quiet lanes which you can explore by following our suggested cycle routes. Link : http://www.riverparrett-trail.org.uk Email : [email protected] Address Langport & River Parrett Visitor Centre Westover, Langport, Somerset TA10 9RB Opening Times April to September, 10am to 6pm October to March, 10am to 4pm (except Mondays) Fees Exhibition Entry : Free Facilities Free parking, toilets, bicycle hire, sales & repairs shop, full disabled access and disabled bike hire. Education pack available free of charge. Close to Langport town centre facilities

Willows & Wetlands Visitor Centre 01823 490249 Home to a family run 150 year old traditional industry Winner of the NFU Countryside Award - Rural Attraction of the year award 2002 Specialises in: Features and traditions of the West , River Parrett and Tone valleys. growing and basket making. Also houses an RSPB display of wading birds and wildlife. Video and guided tours available. Link : http://www.coates-willowbaskets.co.uk Email : [email protected] Address Coates and Wetlands Meare Green Court, , Taunton. TA3 6HY Opening Times Exhibition & Shop : Monday to Saturday 9am to 5pm; Closed Sundays. Tours : Monday to Friday (excluding Bank Holidays) between 10am & 12pm and 2pm & 4pm. Fees Exhibition Entry : Free. Guided Tours : £2.50 Adults, £1.25 Children / Concessions. Tours : Monday to Friday (excluding Bank Holidays) between 10am & 12pm and 2pm & 4pm. Facilities Free parking, shop, toilets, partial disabled access, walks. Courtyard Tearooms

Page 58 Ashford Education Centre, Somerset

Based on a water treatment site, this centre has the opportunity for tours and environmental stud- ies including river and pond investigations. Due to the safe access to three different stretches of water, river studies are especially popular.

Facilities • fully equipped classroom seating up to 60 pupils • toilets • disabled access and toilet (please ask for further details) • extensive exhibition area • and video • literature and field study equipment to use during the visit • water treatment works • outdoor study benches • three streams running through the site • reservoir.

Address Ashford WTW, Mill Farm Hill, Nr Cannington, Somerset TA5 2NQ

Directions From Bridgwater take A39 to through Cannington and towards . After the Can- nington roundabout take the second left signposted Charlinch. The water treatment works and education centre are on your left. Entrance is through the second gate.

West Sedgemoor RSPB Reserve

This reserve forms part of the Somerset Levels and Moors, one of England's largest remaining wet systems. Large numbers of wading birds breed here and the winter floods attract Be- wick's swans, and thousands of teals, wigeons and lapwings. Swell Wood, an ancient deciduous wood on the southern edge of the reserve, has one of the UK's largest heronries, which is best visited between March and June.

Facilities • 500m and 1.8km nature trail in Swell Wood • 2 Hides (Swell Wood Hide has wheelchair access) • Disabled Access • Group bookings accepted • Guided walks available

Address Near Fivehead, Somerset Tel: 01458 252805

Directions East of Taunton. The Swell Wood car park is signposted just off the A378 Taunton to Langport road. It is 1 mile/1.6 km east of Fivehead.