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Map Reading & Basic
Techniques! Read and interpret
topographical maps
Understanding our Understanding our environmentenvironment
• Read and interpret physical and human features on topographical maps. • Basic techniques of interpreting and evaluating geographical data, which
may be represented in various forms, such as graphs, photographs and satellite maps.
Make sure you are familiar with the following components of map-reading
Reading Topographical maps1. Map Symbols (Legend) 2. Grid References3. Compass Points 4. Scales (Large Scale/ Small Scale) 5. Reading Contour Lines
What do all the lines What do all the lines
and and symbolssymbols mean?mean?
Reading Topographic
al mapsMap Symbols
(Legend)
Map Symbols (Legend)
How do I find out
How do I find out
wherewhere a particular a particular
landform is found
landform is found
on the map?on the map?
How do I specify How do I specify the the locationlocation of a physical or
of a physical or human feature?human feature?
Northing and Easting Northing and Easting
Eastings are vertical grid lines that increase from west to east.
Northings are horizontal grid lines where their numbers increase from south to north.
Reading Topographical maps
Grid References
Four Figure Grid Reference:
North to South Grid Lines: Eastings
East to West Grid Lines: Northings1521
Six figure grid references
• 180443
• 184441
• 181447181447
• 186448186448
• 188445188445
Reading Topographical maps
Grid References
Six Figure Grid Reference:
North to South Grid Lines: Eastings
East to West Grid Lines: Northings
155217
How to get to How to get to
that place I that place I
want to go to on want to go to on
the map?the map?
Which Which directiondirection
should I go?should I go?
Reading Topographical maps
Compass Points
N
North Point
Cardinal Points 12 Intermediate Points
• North East (NE) • North West (NW) • South East (SE)• South West (SW) • North-North-East (NNE) • East-North-East (ENE) • East-South-East (ESE) • South-South-East (SSE) • South-South-West (SSW) • West-South-West (WSW)• West-North-West (WNW) • North-North-West (NNW) North (N) South (S)North (N) South (S)
East (E) West (W)East (E) West (W)
Determining Directions• BearingsBearings are
compass directions, which are used to obtain the precise directions of one place or feature with another.
• They are measured in degrees in a clockwise directionclockwise direction from the northnorth.
How to Determine Directions using
Bearings?
1) To measure the bearing of B from A, draw a straight line straight line joining the two points. joining the two points.
2) Draw a line parallel to the line parallel to the Grid NorthGrid North through A.
3) Place the centre of the protractor over A, with the 0° on the protractor pointing to the North.
4) Read the bearing off the protractor where the line AB cuts the outer edge of the protractor.
A
B N
131°
A
B
N
The bearing of B from A is 100°
A
C
Let’s Practice how to read bearings
N
The bearing of C from A is 180° + 50° = 230°
What happens if I want to drive or take a bus to my destination?
How do I find out what is the distance between the two points?
So that I can estimate how much time I need to get there?
Measuring distances• Scale: ratio of
a distance on a map to the actual distance on the Earth’s surface.
Representing a Scale on a Representing a Scale on a mapmap
1)1) As a statement in words As a statement in words • For example, 1 centimetre represents 1
kilometre. • This means that 1 centimetre on a map
represents 1 kilometre on the Earth’s surface.
• Therefore, if the distance of a road measured on a map is 9 centimetres, the actual distance of the road is 9 kilometres.
Representing a Scale on a Representing a Scale on a mapmap
2) As a representative fraction 2) As a representative fraction (R.F.)(R.F.)
• This is expressed as a ratio or fraction, for example, 1:25 000 or 1/ 25 000 may mean 1 milimetre represents 25 000 milimetres or 1 centimetre represents 25 000 centimetres and so on.
• Distances can be easily calculated using the R.F. For example, if the distance of a HDB flat from a bus stop is 2 centimetres on a map (1 centimetre represents 25 000 centimetres), then the actual distance is = 2 X 25 000 centimetres = 50 000 centimetres or 0.5 kilometres
Representing a Scale on a Representing a Scale on a mapmap
3)3) As a line or linear scaleAs a line or linear scale• A linear scale consists of a line that is
divided into units and sub-units such that measurements can be read off easily and accurately.
• A linear scale can be easily converted into a scale using a statement or a R.F.
• For example, in the diagram below, a distance of 1 kilometre on the linear scale measures 2 centimetres. This means that 2 centimetres represent 1 kilometres or 1 centimetre represents 0.5 kilometres. Metres 1000 0 1 2 3 kilometres
A linear scale
B) Reading Topographical maps
4) Scales (Large Scale/ Small Scale)
4) Scales (Large Scale/ Small Scale)
Measuring distancesMeasuring distances1. Ruler
2. Pen
3. String
4. Piece of paper
How the height of the mountain I am
climbing?
How do I find out how
steep is the road I am going on?
Representing heights
• Spot height– indicates the specific height of a point on a map. – Spot heights are not marked on the ground –
they are found only on maps, represented by the a symbol ( ), with its height written next to it.
• Bench mark– Surveyor’s mark cut in some durable material
such as a rock or a building. – It indicates the height of a place above sea level. – A bench mark is represented by a symbol. ( ←)
• A trigonometrical point, is a circular metallic disc placed in the ground to show that specific height.
• It is represented on a ma by a symbol shown by a small triangle or a circle with a black dot inside, represents a concrete pillar called a trigonometrical station.
• The height of a trigonometrical station is very accurately calculated above mean sea level. This height is printed alongside the trigonometrical point on the map.
• Trigonometrical stations are usually found on hilltops and mountain peaks.
426
2546
3281
Representing heights
• Gradient refers to the slope of a feature, such as a road, railway, or river.
• A gradient may be written as an angle or as an ratio between the vertical rise in a given horizontal distance.
Representing heights
Calculating gradient