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Sustainable
Development Index
Caring for
the Thames | Wildlife
Survival | Environmental Issues
What are the major environmental issues for
the Thames in London?
People depend on rivers for water supply, waste
disposal, transport and leisure. Flat river valleys
are an ideal place to build houses. Large settlements
like London therefore place a heavy strain on
rivers flowing through them. Below is some information
about the main environmental issues that affect
the Thames in London. London is an urban area
so environmental issues are sometimes different
from those in a rural area. There is also some
ideas of what you can do to help the river have
a positive future.
1. Rural Issues: The
Thames upstream of Teddington
2. Overcrowding
3. Altering the flow of the
river
4. Building on the foreshore
5. Building up the river
bank
6. Rubbish In large cities
7. Cleaning London's waste
8. Water pollution from drains
9. Taking too much water
10. Building on the flood
plain
11. Flooding from the
sea
1.
Rural Issues: The Thames upstream of Teddington
Teddington in west London marks the
divide between the tidal and non-tidal Thames.
Upstream, the river flows through many urban and
rural areas. The main environmental impacts in
rural areas tend to come from agriculture, which
can pollute the river, and recreational use, for
example by walkers and boats.
Don't forget that the river is all
one system so what happens on the river and tributaries
upstream can affect the Thames in London. The
main impact is from the volume of water that flows
over the weir at Teddington. In times of heavy
rain, there is lots of flood water pouring through
London. This speeds the river up and makes it
more difficult for wildlife to survive. In times
of drought, there is sometimes hardly any water
flowing over Teddington weir - people have used
it all before it gets to London. This makes any
pollution in the river more concentrated. To find
out why, read the information on Flooding and
Using too much water.
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2.
Overcrowding
London is the most crowded place in the UK, and
all the people have a big effect on the River
Thames.
In the rural parts of the Thames valley, there
are a variety of habitats for wildlife such as
open areas, woods, hedges and river banks. There
are quiet areas undisturbed by people, providing
safe habitats for wildlife. The air tends to be
cleaner. A big settlement like London is busy
and noisy with lots of people, buildings, roads
and cars. Gases generated by cars and industry
pollute the atmosphere.
Impacts
- the amount and variety of habitats available
to other creatures is reduced
- noise and numbers of people can discourage
wildlife
- air pollution is washed down by the rain and
enters water courses
What we can do?
- protect and increase the number of habitats
in London (even a wildlife friendly garden can
help!)
- be sensitive in areas where wildlife lives
- treat other creatures with respect
- take fewer car journeys - try walking, cycling
or public transport!
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3.
Altering the flow of the river
The Thames is a fast flowing and naturally flooding
river. This movement of water is important for
the animals that live in the river. However, many
people would like to build a permanent barrier
across the river to stop the flooding. This barrier
may make the Thames a difficult place for wildlife
to survive.
The tidal river provides a range of habitats
for invertebrates, birds and fish. It can be divided
into 3 main zones:
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Freshwater zone: Teddington to Battersea
Brackish zone (mixture of fresh and salt
water): Battersea to Gravesend
Marine zone (salt water): Gravesend
to the sea
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All the creatures living in the tidal river are
adapted to living in fast flowing conditions where
water levels rise and fall dramatically. Most
are adapted for life in either freshwater or salt
water - not many can survive the mix of water
in the brackish zone. These zones can move and
the wildlife moves with them. When it rains heavily,
the freshwater zone shifts downriver. During period
of drought, the marine zone creeps upriver.
Some fish need to migrate between zones to complete
different parts of their life cycle. Examples
are eels, smelt and flounder, which you can easily
net at the right time of year. The tide plays
an important part in this fish migration. For
example, flounder fry spawn in the estuary and
move upriver on the rising tide. When the tide
starts to fall, they rest in pools on the foreshore
until the next tide comes to sweep them further
upriver. The foreshore is therefore a vital habitat
for migrating fish.
There is currently a strong lobby to build a
barrier across the Thames, for example at Wandsworth,
in order to dam the river and control the tides.
This would make the river easier to use by leisure
craft as it would raise the level of the river
so that boats could get to the riverside at all
times. The proposal is that the barrier would
be open around the time of high water to let the
tide go in and out for a few hours. There is also
strong opposition to this idea.
Impact
A barrier could
- interfere with the tides and hamper fish migration
- alter habitats to which river wildlife are
adapted
- increase pollution as the tide has less time
to "flush out" dirty water to the
sea
- making water levels in London rise by blocking
the drains carrying water into the river
What we can do?
Find out more about the arguments for and against
a barrier and make your own decision as to whether
a barrier would improve the Thames.
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4.
Building on the foreshore
Since Roman times, people have been taking land
away from the river by building on the foreshore.
Even today people build on the foreshore to provide
more riverside property. But when people build
on the foreshore, they take up space that the
river and river wildlife needs. This can have
a very big impact on the shape and speed on the
river, which will also affect the river wildlife.
When the Romans founded Londinium, the Thames
was 3 times as wide as it is today. Soon London
became an international port and in order to make
it easier for the boats, the Romans built wharves
out into the river and deeper water. (Wharves
are places to load and unload boats). Since then,
people have narrowed the river for all sorts of
reasons - to make river walks, to get more building
land, to build flood defences or to build tunnels
and sewers alongside the river. For example, a
huge sewer and the District Line tube were built
along the foreshore in Victorian times - this
is what is beneath your feet as you walk along
the Victoria Embankment. This process is called
encroachment.
The most serious encroachment has been in central
London. The narrowing of the river channel makes
the river flow much faster. It also raises the
level of the water.
Impacts
- destroys the foreshore habitat thus reducing
the number of invertebrates who can live there
- removes shallow areas at the side of the river
used by migrating fish and feeding birds such
as herons
- fast river flows make central London a more
hostile place for wildlife
- higher water levels increases the risk of
flooding
What we can do?
Protest if you hear of a plan to encroach on the
foreshore!
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5.
Building up the river bank
Riverside property has always been a popular place
for people to build on. Over the years, much of
the natural river bank has been covered by buildings
and materials such as concrete and brick. The
sides of the river have been changed as well,
as people have replaced natural slopes with walls.
All of these changes have affects on river wildlife
and the movement of the river itself.
A natural river bank does not have a straight
edge, often slopes into the river gently, is made
of natural materials such as earth or clay and
provides a habitat for plants and animals. Only
1% of the river bank in London is natural - the
rest has been embanked (built up) and covered
with materials such as metal or concrete. The
vertical walls that can be seen in central London
are the results of encroachment. In some places,
the river bank does slope into the river but has
been covered in materials such as paving stones
or concrete to prevent the bank being eroded.
The shape of the river wall and the material
used affects what can still live there. Vertical
walls are less wildlife friendly than sloping
ones. Sheet piling makes it impossible for plants
and animals to exist, and the use of concrete
or stone allows little more than a bloom of algae
to survive. In places where blocks of stone or
concrete are used, plants can establish themselves
in the cracks. Sometimes wharves have old wooden
piles (big pieces of wood) attached to them -
this was to stop the boats banging against the
wall. Plants and creatures can live in these,
especially if the wood is rotten.
Impacts
- covering natural banks stops plants growing;
animals are unable to burrow into the bank
- plants cannot establish themselves on vertical
sheet piling or smooth concrete
- fewer plants mean fewer animals further up
the food chain
What we can do?
- some community groups have improved their
local river bank, for example by planting reed
beds or installing hanging baskets. To find
out more about this kind of work, get in touch
with the Thames Explorer Trust
- the Environment Agency who look after the
river encourage any new building on the bank
to be "wildlife friendly" by including
places that wildlife can live
- at the Millennium Dome, some of the wharves
were removed and replaced with terraces suitable
for a variety of wildlife
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6.
Rubbish In large cities
People produce huge amount of rubbish. Some
of this rubbish is not disposed of property and
may end up in rivers and other waterways. Much
modern rubbish is designed to last, and may take
hundreds of years to disappear. Rubbish not only
looks bad, but can be harmful to animals that
live in or near the river.
All the litter in the river comes from people.
Floating rubbish gets left on the foreshore twice
daily by the tide and is an obvious form of pollution
that threatens wildlife. Because the river flows
in as well as out, the same piece of rubbish can
take months to make its way down to the sea. Rubbish
gets into the river in all sorts of ways. It is
a convenient rubbish bin for passers by, a dump
for supermarket trolleys and for builders' rubble.
Some rubbish just gets blown in or is washed from
the street down the drain into the river. Some
enters the river via the sewage system).
How long the rubbish stays in the river depends
on what it is made of. Some plastics are not biodegradable
and take years to break up and disappear. Other
materials such as paper degrades quickly. Metals
and pottery can last thousands of years - the
foreshore is an excellent place to investigate
the rubbish of past generations of Londoners!
Some rubbish floats and gets washed out to sea.
Items like supermarket trolleys tend to stay in
the same place.
Impact
- rubbish looks ugly and makes people think
that the Thames is dirtier than it is and not
worth caring for
- creatures can get trapped inside rubbish like
bottles, packets and plastic bags
- fishing lines and can holders can ensnare
both birds and fish
- sharp objects such as fishing hooks and broken
bottles are a danger to humans as well as to
the wildlife
- polystyrene from such things as cups and packaging
breaks down into small pieces and can get eaten
by birds.
What we can do?
- never drop litter - take it home with you
if you can't find a bin
- make sure you put litter in a bin so it does
not blow out
- join Thames21's
Adopt-a-River scheme. This is open to schools,
local communities and businesses. Each group
adopts and cares for a stretch of the Thames,
reports litter and any problems
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7.
Cleaning London's waste
London produces lots of waste. Not just rubbish,
but water waste as well. Everything we put down
the toilet and sink must be cleaned out of the
water before it is put back into rives and streams.
Sometimes, things like chemicals are difficult
to get out of the water and eventually find their
way into rivers and streams.
The dirty water we have used in our homes goes
through the sewers to one of the sewage treatment
works in the Thames area. The main ones are at
Beckton and Crossness east of London and at Mortlake
in west London. The dirty water is cleaned and
the effluent (cleaned water) is returned to the
river.
However, some pollutants are not easy to remove.
The rubbish that we put down the toilet such as
sanitary items, condoms and cotton buds sometimes
slip through the filters and ends up back in the
river. Some household chemicals are also difficult
to remove. Take a look in your kitchen cupboard
and see how many different chemicals are going
down your plug hole! Chemicals used in the medicines
that we take can pass through our body into the
sewage system. These chemicals may not be removed
at the sewage treatment works and can build up
in rivers. Some recent evidence has suggested
that hormones used in birth control pills are
finding their way into river systems.
Impacts
- the rubbish we put down toilets can damage
river creatures
- chemicals can accumulate in rivers and cause
damage and genetic changes to river wildlife
What we can do?
- only put toilet paper and what has passed
through you down the toilet
- reduce use of chemical cleaners in the home.
For example, dilute disinfectants and use sparingly
- buy cleaners that are environmentally friendly
and do not contain phosphate
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8.
Water pollution from drains
All the drains we see on roads eventually empty
into the Thames or its tributaries. Lots of pollutants,
like oil and chemicals, can get washed down those
drains when it rains. Sometimes, waste from people's
homes can go down the drain if the toilets are
not connected up properly. Any waste that gets
into rivers may harm the wildlife that lives there.
In Victorian times, the Thames became very polluted.
Filthy water from factories and the newly invented
water closets (toilets) poured straight down drains
into the river, killing all the wildlife. Londoners
still drank river water and thousands died of
cholera. In the 1960's, a big clean up began:
sewage treatment was improved and factories had
to reduce their polluting discharges. The Thames
is now one of the cleanest city rivers in Europe.
However, pollution does still enter the Thames
in London through the drainage system.
There are several ways in which drains emptying
into the river can cause pollution.
Surface water from roads and roofs
The rain that falls in a town normally gets channelled
down gutters into the drainage system and is put
straight into to the river. It does not get cleaned
first. This means that any dirt or oil on the
roads gets washed straight into the river system.
Pollutants poured down drains
Some people use a drain in the road outside or
in their garden to dispose of oil or dirty water.
This generally goes straight into the river.
Bad plumbing
Badly connected toilets can also cause pollution.
Sometimes bad plumbers or people doing DIY connect
their toilet systems to the drainage system instead
of the sewerage system. This means that sewage
goes directly into the nearest river. This problem
occurs mainly on the tributaries of the Thames.
Sewage pollution
In much of London, the drainage and sewerage systems
are combined. This is good news in some ways,
as it means that a lot of the dirty water that
goes down drains is taken to the sewage works
where it is cleaned before being returned to the
river. But when rain is heavy, the system gets
too full and raw sewage overflows through storm
drains into the river. This sewage is mixed with
other pollutants such as oil from the roads and
can be a deadly mixture.
The reason that London's sewerage and drainage
system cannot cope any more is because it was
built in Victorian times to serve a much smaller
population. More people means more sewage and
because more of the land is covered in concrete,
more rain water gets channelled down the drains.
The
Environment Agency keeps an eye on levels
of pollution - it has eight monitoring stations
in the London area which monitor how much oxygen
there is in the water. The information is fed
to a computer. If levels drop, they send in two
boats, Thames Bubbler and Thames Vitality, which
pump oxygen into the river where it is needed.
This system is world famous and has prevented
many fish deaths. However the long term solution
is to replace the old Victorian sewerage/drainage
system with a modern system that does not allow
sewage into the river.
Impacts
- raw sewage reduces oxygen levels, suffocating
river wildlife. This is because sewage contains
lots of bacteria who gobble up all the oxygen
- oil can coat the feathers of river birds,
causing them to drown or die of hypothermia
- river pollution makes the river look and smell
bad
What we can do?
- don't put oil or water containing dangerous
chemicals down the drain - take it to a used
oil bank. For information on your nearest one,
call the Oil Bank Line on 0800 66 33 66
- employ a qualified plumber when installing
new toilets
- report any river pollution you see to the
Environment Agency Hotline on 0800 80 70 60
- support improvements to the sewage system,
which improves water quality in rivers. This
might mean your family has to pay higher water
bills!
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9.
Taking too much water
Everyone needs water! Human beings need water.
The Thames needs water to flow. River wildlife
needs water to live in. This sounds obvious, but
sometimes we take out more water than is healthy
for the river system.
There are 124 water treatment works taking water
from the Thames and its tributaries. No water
is taken from the Thames between Teddington and
the sea. This is because the water may be salty
or too dirty. The water is cleaned before it is
sent to our homes. When we have finished using
the water, it goes to the sewage work, where it
is cleaned and returned to the river. If you live
in London, the water that you drink has probably
been through 7 other people. As our bodies are
70% water, you could say we are made of the Thames.
It is in our interest to keep the river as clean
as possible!
World demand for water is doubling every twenty-one
years. For example, the average Londoner uses
160 litres of water a day compared to 150 litres
in 1995. (We each need around 80 litres per day
to live comfortably). In developing countries,
some people have only two litres a day, but in
the USA consumption is 500 litres a day per person.
Demand increases where water is pumped to the
home and where labour-saving devices such as washing
machines are used. The
Environment Agency predicts that by the year
2015, London will find it hard to meet demand.
Over 7 million people in the Thames region get
their water from the Thames and its tributaries
and more people are moving into the area. The
Thames Valley is the most densely populated part
of Britain. Water companies are under pressure
to abstract (take out) more water and build more
reservoirs. The
Environment Agency, who are responsible for
the river, limits the amount of water that is
abstracted.
Demand is increasing but the supply of water
is not. Weather conditions have become more extreme
with periods of drought followed by heavy rainfall.
Storms do not give "the right kind of rain"
because water quickly escapes to the sea via the
rivers. It is better when rainfall is slow and
steady, allowing time for water to fill reservoirs
or gently percolate underground. Leaking pipes
can also lose water - In 1999, they caused a daily
loss of over 900 million litres by Thames Water
- enough to supply 5.6 million homes.
Problems occur during periods of low rainfall
when there is not enough water entering the river
to compensate for what we take out. We sometimes
take out so much water that we stop the Thames
flowing - people have seen the river just upstream
of the Hampton works (photo 9) flowing backwards
as the works sucks up the water for our use.
Impacts
- any pollution in the water gets more concentrated
as there is no fresh water to dilute it
- if water levels are low, the water heats up
more quickly in hot weather. Oxygen levels drop,
because warm water cannot carry as much oxygen
as cooler water
- homes of creatures living in the river bank
underwater are exposed when water levels fall
- plants on the river bank die
- building reservoirs can lead to loss of countryside
and even more abstraction
What we can do?
- fix leaking taps
- report major leaks to water companies so they
can fix them quickly
- use water wisely. Treasure your water! For
example, don't leave taps running when cleaning
teeth or washing vegetables, take a shower rather
than a bath, use washing machines and dishwashers
with full loads, avoid garden sprinklers and
water when the sun is low, put a brink in your
toilet cistern to reduce flushing water and
mend leaking taps
- contact your local water company for more
ideas on saving water
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10.
Building on the flood plain
Flooding on the Thames is a natural process. When
the river overflows its banks and floods, the
water must have somewhere to go. The water spreads
out over the flood plain. People have built upon
the Thames floodplain, so the water has nowhere
to go. The result is that when the river floods,
property and homes are destroyed. We must find
a balance that allows the river to flood naturally,
but doesn't damage people's property.
Flooding is a natural process. When a river gets
full with rain water, it breaks its banks and
the water spreads out over the flood plain. The
water then soaks into the ground or returns to
the river as levels drop. The rich river silt
(mud) that is left behind makes the earth good
for agriculture. The wide flat Thames Valley has
a large fertile flood plain, which is why it has
been an important area for farming for hundreds
of years.
Problems arise when people build on the flood
plain. Flat river valleys have always been popular
places to build houses, so for hundreds of years
people have been battling to stop the river flooding
out over the valley floor.
London is protected from the Thames flooding
by the Thames Barrier and by an unbroken line
of flood defence that stretches alongside the
river from Teddington down to the Barrier and
beyond. This defence consists of flood walls,
humps in roads and pavements or even defences
built into houses themselves.
Building on the flood plain and erecting flood
protection can make the risk of flooding worse.
For example, in London:
- covering the flood plain with tarmac and buildings
means that the water cannot drain away slowly
and naturally. Instead the water escapes down
drains in the road and gets back into the river
very quickly. This makes the river levels rise
and speeds up the flow of water
- building out into the river (encroachment)
has made the Thames narrower, making the river
deeper and faster and more liable to flood
- building high flood defences to contain the
Thames has made the level of the river higher.
Impacts
- building on the flood plain reduces the amount
and variety of habitats available to other creatures
- rain falling on London washes oil and dirt
down the drains into the river, polluting the
water
- when the drainage system gets very full, rain
water and sewage mix. Raw sewage then gets swept
into the river, reducing oxygen levels
- speeding up the river flow makes it a more
hostile environment for river creatures, who
can get swept away by the current
- high flood walls make it difficult for people
to see the river
What we can do?
- do not build in areas that are liable to flood
- stop building on sites that are not already
covered with buildings or concrete, for example,
open land, school playing fields
- where possible, remove high flood walls and
build flood defences further back from the river,
allowing the river to flood more naturally
- build roads, car parks etc of materials that
allow water to seep into the ground and not
rush down the drains
- keep roads as oil free as possible
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11.
Flooding from the sea
The Thames is a tidal river that empties into
the sea. That means the for part of the river,
the sea affects how much water is in the river
and what the river level is. Sometimes, too much
water comes in from the sea and causes the river
to flood. This flooding has been getting worse
recently, putting London in danger.
London and the Thames estuary is under constant
threat of flood - the cause of this flooding is
not heavy rain but the sea. Between Teddington
and the sea, the river is tidal, which means the
river rises and falls with the tides. London risks
flooding for the following reasons:
- In the Ice Age heavy glaciers covered the
United Kingdom. The North of Britain was pushed
down by the weight of the ice and the south-east
consequently rose. When the glaciers melted,
Scotland began to rise and the south-east to
sink at a rate of about 1cm every ten years.
This effect is called isostatic rebound
- Global warming is causing glaciers to continue
to melt and sea levels all around the world
are rising. Scientists disagree about what causes
global warming. Many believe that gases emitted
by such things as cars and industry have created
the "greenhouse effect"
- London is sinking under its own weight!
- Industry used to pump water from the springs
below London. Nowadays there are fewer industries
in the capital and the level of water in the
ground is rising.
All the above factors are happening very slowly.
The most immediate risk to London is an unusually
high tide, which is caused when the following
two things happen at the same time:
1. There is an unusually high tide. Some tides
are higher than others - a few times a year, there
are extremely high tides.
2. A deep depression (area of low pressure) moves
south down the North Sea from Scotland. This creates
a hump of water which gets bigger as the North
Sea narrows. This wall of water then gets pushed
up the Thames estuary.
The Thames Barrier was finished in 1982 and opened
in 1984 to protect London from the threat of flooding
from the sea. To stop land flooding between the
Barrier and the sea, high walls were built at
the same time. It is predicted that given rising
sea levels, the Barrier will only be effective
until 2030.
Impacts
- The Thames Barrier does not have a great impact
on the Thames environment in London at the moment.
But if it is shut more frequently, it could
disturb fish migration
- In the future, rising sea levels will affect
not only human settlements but also coastal
and riverside habitats.
What we can do?
- reduce the rate of global warming. We can
help by being more energy efficient. There are
many ways we personally can use less of the
fuels that create greenhouse gases. For example,
we can walk or cycle rather than go by car.
We can recycle our rubbish so that factories
do not have to make more bottles, cans and paper.
We can buy goods that are produced locally rather
than transported from far away countries. We
can campaign against polluting industries and
demand a better public transport system so we
do not have to rely on cars. This may sound
a complicated way of helping to stop London
flood, but it shows that how we live can have
an impact on the environment
- stop building on the flood plain and in some
areas remove some flood defences to allow the
Thames to spread over its flood plain. This
means learning to live with natural forces rather
than fight against them
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Sustainable
Development Index
Caring for
the Thames | Wildlife
Survival | Environmental Issues
|
