Lesson 2
All about GIS
(which stands for Geographic
Information Systems)
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What is GIS?
Introduction: Paper maps
only tell us where a place
is. GIS uses digital maps
and information to help us
make decisions and solve
problems
Hardware: GIS runs on
mainframe computers,
PCs, small PDAs or even
mobile phones to organise
information and map the
results of investigations.
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Software
GIS software is a set of
computer ‘tools’ for
collecting, storing,
processing and displaying
sets of information linked
to places on maps.
There are different
types of GIS ‘tools’: for
instance, a GIS that
analyses land use is
different from a GIS
that maps the quickest
route to a fire.
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Maps
Electronic maps and images: An
essential component of any GIS is
some kind of map or image of an
area. This can be a digital map,
satellite image or aerial photograph.
Many GIS will use a full range of map
data and images as a base to link
information against.
The maps are produced either as
raster or vector data
Raster maps
These are images made by a series of coloured dots on a screen
(pixels), just like high quality digital photographs, e.g aerial
views are one source
Raster maps can be thought of as ‘unintelligent’ as you can only
obtain information that is visually represented on them.
Raster maps take up a lot of computer storage space but can be
very useful as background maps to other information.
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Maps
Vector maps Each vector map
feature is recorded using XY
coordinates.
These may be a single point
(like a trig point), lines (such
as roads) or polygons (such as
buildings or woods).
The referenced features of
vector maps make it possible
for a GIS to link information
from spreadsheets and
databases to the maps.
Vector data is stored in
themed layers such as
Roads, water, settlement
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Maps
Data:It is easier to make sense
of complicated spreadsheets
and databases when they are
linked to maps in a GIS.
It is estimated that over 80%
of all data has some link to a
geographic place.
People:The vital ingredient! We
need people who understand
digital maps and databases and
know how to use GIS to organise
the data on maps.
They can ask the right questions
and produce new maps showing
the results.
This helps to plan the way we
live and use our environment for
the future.
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An example of how
it works
The Hole Story
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The Hole Story
The vast networks of
underground pipes
supplying our water,
electricity and gas are
hidden from view, so how
do we know where it’s
safe to dig?
Louise works for a water
authority to maintain the
company's network of
water mains and sewers.
She uses a GIS to create
a complete overview of
the pipeline which helps
her to monitor its
condition and
performance.
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The Hole Story
To minimise the risks
involved in digging
trenches, laying cables
and other maintenance
and building projects,
utility companies must
share their underground
asset maps upon request
with other organisations.
A GIS is built up of lots
of different layers of
information which users
can Switch on and off
depending on their needs.
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The Hole Story
Information can be shared
between utilities via a secure
website.
The website uses a GIS to
pinpoint the location of water
mains, gas pipes, electricity
cables and sewers as well as
details of current and future
work
Allowing all the utilities to
access this information means
that all utilities can agree to
carry out work at the same time.
Digging up the road only once
helps to minimise public
disruption and saving time and
money.
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One more example
It’s a breeze
11
It’s a breeze
Wind farms can provide a source
of alternative energy but finding
the right location for the
turbines can be difficult.
Dave works for an energy
company that is keen to
investigate the use of wind
turbines as an alternative way of
generating power.
He is asked to work on a project
to identify suitable sites for a
new wind farm.
The location needs to balance
environmental concerns with
operational efficiency..
12
It’s a breeze
Dave has followed the debate in
the newspapers and knows that
the effect of the turbines’
appearance on the landscape is a
major concern.
Many other factors, however,
also need to be considered when
choosing a site.
These include wind speed, wind
direction, distance from the
existing electrical grid system,
access to the site, size of the
site and the shape and profile of
the land.
13
It’s a breeze
By inputting data from
various sources regarding
weather, civil and military
airfields, telecommunications
and environmental
organisations, Dave begins to
put together a case for the
available site.
He still needs to take into
account the height and
spacing of the turbines so
that they can produce the
required amount of
electricity balanced against
their visual impact
Anyone spy
anything
wrong with
this map?
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It’s a breeze
Dave adds height data and
information to produce a 3D
model giving a virtual view of
the site as it would appear
from different directions,
distances and perspectives.
This enables him to focus on
particular locations to check
the turbines’ impact on the
view.
The information Dave
produces is used to support
planning applications and to
reassure local residents that
the wind farm will cause
minimal disruption.
15
To find out if you could use a wind
turbine on your house
ASK YOUR PARENTS FIRST
Then go to
http://www.segen.co.uk/eng/wind/windspe
ed.htm
Enter business type – residential, your
name etc and press Lookup
If the answer is 5 or better still 5.5 m/s
then your home is potentially a good place
to put a small wind turbine!
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Now for the
worksheet and to
work towards your
homework
http://mapzone.ordnancesurvey.co.uk/
mapzone/giszone/english/
and
http://mapzone.ordnancesurvey.co.uk/
mapzone/giszone/english/gismissions/pa
ge1.htm
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Click on the ‘i’ by Lockerford to find …
Population - 2,000
A small village to the west of Melchester.
It grew on the site of a ford that farmers used
when bringing their cattle to Melchester
market.
Now seen as one of the most desirable and
expensive places to live in the area.
Lots of commuters choose to live there.
Latest flood information:
Casualties – 0
Evacuations - 100 people
Estimated insurance claims - £ 50,000
22
1. Locker Valley Storage basins
Total Cost = £ 5.0 million
Earth-moving equipment will dig
out two large basins connected to
the river by drainage channels.
At times of high water, flood
gates are opened allowing water
to drain away from the river into
the basins
The Locker Valley meadows are
home to many wetland bird
species that will be disturbed
during construction. However, long
term the wildlife will benefit.
The people of Lockerby are likely
to be upset by all the noise from
the earth moving machinery.
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Having gathered the information
You will need to put
in a score
But you cannot really
do that until you
know about ALL the
sites
Hence the worksheet
I hope you have open!
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2. Locker Brook Relief Channel
Total Cost = £ 10.0 million
A large drainage channel
connecting the Locker Brook to
the River Falmer.
At times of high water, a flood
gate is opened which allows the
floodwater to be safely diverted
past west Melchester.
No opposition whatsoever from
local residents, although the
nearby main road will need to be
closed during construction.
Some high quality farmland to the
south-west of Melchester will also
be lost.
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3. Melchester drain by pass
Total Cost = £ 12.0 million
A large underground tunnel
offering a more direct escape
route for floodwater from the
River Falmer.
At times of high water, the
tunnel is opened diverting
water from the meanders near
the town centre.
Little environmental impact but
local residents concerned about
possible damage to houses
caused by tunnel excavation.
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4. Falmer Ring Dyke
Total Cost = £ 15.0 million
A massive ringed embankment around
the Falmer Levels which would allow
floodwaters from the River Falmer and
the River Dank to be held back,
protecting all of Melchester.
Would cause significant damage to the
environment during construction due to
the amount of earth that would need
to be moved.
It is expected to fill only once every
200 years.
People living in north Melchester are
likely to be upset by the noise from all
the earth moving machinery required.
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5 Swinford temporary basin
Total Cost = £ 5.0 million
Removable flood walls that can be
mounted into place with relatively
little warning.
Effective with smaller floods but not
high enough to cope with 100 year
flood events such as that
experienced in 2001.
Little environmental impact.
Local residents in Swinford are
highly supportive of the proposal
although the people of Melchester
are concerned that it would merely
divert floodwater downstream.
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6. Bend Flood Wall
Total Cost = £ 5.0 million
A permanent flood wall made
from local stone built to protect
the village of Bend.
It would also allow access to
Bend and Narrowbridge during
times of flood when the main
road is blocked.
Effective with smaller floods but not
high enough to cope with 100 year
flood events such as that experienced
in 2001.
Local residents in Bend are highly
supportive of the proposal although
the Bridgefordshire Tourist Board is
concerned that it will ruin the lovely
scenic views.
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