Can you find 7

Hearts in this picture

here?

Next Geog Elect Class on Thursday

•Bring protractor •Bring calculator •Bring string

Map Reading & Basic

Techniques! Read and interpret

topographical maps

Mt MerapiMt Merapi

• Mt Merapi is an active volcano in Mt Merapi is an active volcano in Indonesia that has erupted many Indonesia that has erupted many

times in the past. In 2006, it erupted times in the past. In 2006, it erupted again, affecting the lives of the again, affecting the lives of the

thousands of people who live around thousands of people who live around it.it.

You can get info on Mt. You can get info on Mt. Merapi Merapi from satellite from satellite

images…images…

You can get info on Mt. Merapi from

photographs

Mt. Merapi Mt. Merapi Volcanic Volcanic Eruption in Eruption in May 2007May 2007

Large amounts of volcanic ash Large amounts of volcanic ash covered vehicles, making visibility covered vehicles, making visibility very poor. very poor.

Farming in fertile volcanic ash near Mt. Merapi

From Maps…From Maps…

What other ways can we get more information about Mt Merapi’s

height or geographical location?

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?

How to tell my friend how to get to the Post Office?

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.

72 73 74 75 76

85

84

83

How do I determine the exact location of a place using northings

and eastings?

•4 Figure Grid Reference

•6 Figure Grid Reference

To find the four figure grid reference, draw a “L” around the square

Which direction first?

Always take the northing or easting with the smaller value!

41 42

28

29

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

Steps to deriving at the grid Steps to deriving at the grid referencesreferences

1) Locate the grid square where the feature is found. 2) Read the easting (vertical line) on the left of the grid

square. 3) Read the northing (horizontal line) on the bottom of the

grid square. 4) The four-figure grid reference consists of both the easting

and the northing. To derive at the six-figure grid references, 5) Divide the grid square into ten equal parts along the

easting and northing, and number them from 0 to 9. 6) Estimate how far the centre of the feature is from the

easting and the northing, using the scale in tenths. 7) The six-figure grid reference consists of both the easting

and the northing and an estimation of how far the feature is from the easting and the northing based on a scale of 0 to 10.

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 distancesMeasuring distances1. Ruler

2. Pen

3. String

4. Piece of paper

Measuring distances• Scale: ratio of

a distance on a map to the actual distance on the Earth’s surface.

Depending on the area of Depending on the area of focus, you can choose to focus, you can choose to

zoom on the area at various zoom on the area at various scalesscales

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 (R.F.)2) As a representative fraction (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

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)

How do I know 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. ( ←)

Bench Mark

How to calculate height?

• A trigonometrical point, is a circular metallic disc placed in the ground to show that specific height.

• It is represented on a map 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

• 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

Vertical Height

Horizontal Distance

=

100m

60m

160m

60 m3.6 km

60 m

3600 m

3.6 km

=

= 60 ÷ 60

3600 ÷ 60

= 1

60

Gradient =

=1:60

Ver

tical

Hei

ght

Horizontal Distance

Reading and understanding the INFORMATION

Contour Lines can provide

2) Slope – Contour Spacing on a topographic map

indicates the slope of the land surface.– Steep: Contours are close together – Gentle: Contours are widely-spaced – Concave: the spaces between the

contours decrease as height increases – Convex: the spaces between the

contours increases as height increases – Uniform: the spaces between the

contours remain the same – Stepped: the wide contour spacing

alternates with narrow contour spacing

Steep Slope Gentle Slope

http://www.tpub.com/seabee/3-35.htm

Concave Slope Convex Slope

Hill

Mountain

Plateau

Plain

Valley

Ridge