Topic 5: MAP WORK

A map is a scaled representation the earth’s surface

on a flat material. For example a piece of paper,

wall, clothes and a piece of wood. Map reading is

the process of examining the given topographical

map, conventional symbols and signs Map

interpretation is the process of examining a given

topographical map of an area represented for the

purpose of identifying the geographical information

of an area.

TYPES OF MAPS

The classification of maps is based on the purpose

for which each map is drawn. Therefore map can be

categorized into three types as follows:

i) Sketch map

ii) Atlas map/ wall maps

iii) Topographical maps

i) Sketch maps; A map drawn from observation

(rather than from exact measurements) and

representing the main features of an area.

ii) Atlas map/ wall map; A collection of different

maps that have been bound together in one volume

to form a book. These maps are usually drawn to

scales example shows town and cities, hills,

mountains, valleys, forests, countries, etc.

iii) Topographical maps; Shows selected physical

and human features in an area and their positions

on the ground for example hills, village, mountains,

lakes, ponds, rivers

COMPONENTS/ESSENTIALS OF A GOOD MAP

A map is good if it contains all the essentials of

maps, therefore the essentials are good qualities of

maps. The essentials of a good map are:

1) Key. Used to interpret symbols and signs found

on a map. They appear in a box at one of the

bottom corner of the map. 2) Title; Used to show

what’s map is all about. This is the heading of the

map. It can appear on top of the map or anywhere

else

3) North direction; This is an indication of the north

direction. It shows where north is and by knowing

north one can know the direction and bearing of the

place.

4) Margin; This is a boundary or limit around the

map. It gives or shows the reader and interpreter

the end of the map.

5) Publisher and date publication; This shows when

the map was produced and a publisher.

6) Latitude and Longitude / Grid reference. It used

to locate the place on the map. For example the

map of Tanzania is located at latitude 6°00' south

of the equator and longitude 35°00' east of

Greenwich meridian.

7) A scale; It shows the relationship between map

distance and the actual ground distance for example

1cm to 10km means one centimeter on the map

represents ten kilometers on the ground MAP

SCALE Is the relationship or ratio between map

distance and actual ground distance. Scale = Map

distance Ground (actual) distance.

TYPES OF SCALE.

We can classify the scale according to the size in

our criteria. There are three types of scales;

a) Large scale.

They are used to present information on small areas

for example a map of village buildings and farms.

The map size involves all numbers less than

1:25000 I.e. 1:10000 and 1:5000 Characteristics of

large scale.

i) It has smaller numbers in the denominator.

ii) It shows features clearly

iii) It contains geographical details.

b) Medium scale.

They are used to represent medium details shown

on the map. i.e. 1:50,000 and 1:100,000. Example

of a map that can be drawn using medium scale is

a map of a district, region, city etc. c) Small scale.

They are used to present information that is long.

This type of scale covers a big area with less

detail. For example a map of a country, continent or

world. May involve numbers between 1 : 500,000 to

1 : 1000,000

Characteristics of small scale.

i) It has the largest denominator.

ii) Contains a lot of geographical information.

iii) It does not show geographical features clearly.

WAYS USED TO EXPRESS MAP SCALE.

i) Statement scale. Refers to the scale which is

expressed in terms of words or explanation. For

example one centimeter on a map is equivalent to

10 centimeters on the ground.

ii) Linear scale Also is called plain or graphic scale.

This is a line which is divided into two parts. The

primary division and secondary division. The

secondary are expressed in meters and placed on

the left side from zero and primaries are expressed

in kilometers and placed on the right side from

zero.

iii) Representative fraction (RF) scale

Is written as a fraction or ratio eg. 1:50,000 50,000

The distance on a map is expressed as fraction of

the actual distance on the ground. Therefore, RF

scale = map distance Ground distance. The top

number (numerator) represents the map distance on

the ground and is usually more than 1. Scale

conversion a) To change statement to R.F scale.

1cm represents 60km

Soln

1km=100000cm 60km= x 1:6000000 Therefore R.F

scale = 1:6000000 b) One centimeter represents

0.75km b) 1:250000 To convert into statement

scale If 1km = 100000 cm ? = 250000 cm

100000cm. x = 250000 cm x 1km 100000 cm

100000 cm X = 1 4 Thus, 1 cm represents 0.25

IMPORTANCE OF SCALE ON THE MAP

a) Scale help to calculate area of a map

b) It enable us to calculate distance on a map

c) Scale shows the relationship between map

distance and the actual ground distance d) Scale

help us to enlarge and reduce the area on a map or

the whole map

e) Scale can be used to calculate the vertical

exaggeration on a map f) Scale is used to calculate

the gradient on a map Question: Distinguish signs

from symbols

QUANTITATIVE INFORMATION ON MAPS

A) MEASURING DISTANCE ON THE MAP

Distance is the length of elongated features on the

earth’s surface such as road, railway, river etc. How

to measure distance. In order to obtain distance of

any feature on the map, consideration should be

made on whether the distance to be measured is

straight or curved. Straight distance For all straight

distances a ruler is used to obtain the distance

directly from the topographical map given. Curved

distance. It becomes difficult to obtain curved

distance of the features by the use of a ruler

directly from the topographical map when the area

is inclined. In this case the following devices can

be used:-

A. A pair of divider. A pair of divider is commonly

used to measure the distance. You should start by

breaking the length by using a pair of dividers then

transfer some of the already drawn straight lines.

Then transfer the measured line to the linear scale

or ruler for calculation to get the actual distance.

B. A piece of a string. Slowly measures the

distances by a piece of string along a given length

then transfer it to a linear scale or ruler for actual

calculation of the distance.

C. A piece of strip paper Slowly lay a piece of

paper along a given length then break your lengths

into short segments then transfer to the linear scale

for measuring and calculation. For example: The

railway distance from station A to B was 20 cm,

find ground distance in km if the scale used to

construct a map is 1:50000 20 cm map distance

Scale distance= map distance Actual distance

Scale: 1:50000 If 1km = 100000 cm ? = 50,000 cm

100000 cm = 1km x 50,000 cm 100000 cm

100000 cm = ½ km = ½ km x 20cm =10km. The

ground distance of railway from station A to B is 10

km

MEASURING AREAS ON A MAP/CALCULATE AREA

OF REGULAR IRREGULAR

Area size refers to the bigness or smallness of an

area on the earth’s surface i.e. the bigness or

smallness of earth’s surface from topographical

map consideration should be made whether the

area is regular or not.

E x e r c i s e 1)

To state the following.

a) map

b) map reading

c) Scale

d) Contour

2) Why do we study maps?

3) State the ways of expressing scale.

4) What is the importance of a scale?

5) List at least 3 methods of calculating the linear

distance of an object

6) The distance of the road is 16cm from Igurusi to

Chimala, convert the distance in kilometers if the

scale used is 1:100000 b) From the above convert

the same distance in km if the scale is changed to

1:50000

REGULAR SHAPE These are areas with definite

shapes such as squares, triangles etc. Their total

perimeters or areas are obtained by mathematical

formula i.e. length x width, side x side etc.

IRREGULAR SHAPE These are areas with indefinite

shapes such as lakes, farms, ponds etc where

these areas can be obtained by any of the following

three methods; a) Square method b) Strip method

c) Geometrical method

SQUARE METHOD

This is the most accurate and most widely method

used. Square methods are normally used as

follows;

a) Count all full squares that are complete

b) Count incomplete squares and divide them by 2

c) Add them with the full squares to obtain the total

area in km2

METHODS USED TO SHOW OR LOCATE POSITIONS

OF A PLACE ON A MAP.

The following are major methods used to show

positions of a place on a map.

i) Grid reference.

ii) Place name

iii) Bearing and compass direction.

iv) Latitude and longitude. Place name. You can

locate the position of a place by where the features

are found i.e. Kigoma, Mbeya, Dodoma, Lindi etc.

Grid reference. Grid reference is a network of

vertical lines and horizontal lines on a map. Vertical

lines whose numbers increases towards the east

are called easting. Horizontal lines whose numbers

increase towards the north is known as Northings.

Where horizontal lines and vertical lines meet or

cross each other they form a square known as grid

square. (G.S). A grid reference point is written

inform of six digits starting with three digits of

Eastings then three digits of nothings. ·A ·C D· ·B

31 32 33 34 35 36 37 38 39 40 41 42 09 08 07 06

05 04 03 02 01 To write down the grid reference of

point A, B, C, and D. A = 343086 B = 333036 C =

383077 D = 397046 NB: To write numbers of grid

reference starts with easting then northing.

LOCATION AND POSITION: COMPASS BEARING

AND DIRECTION

How to find direction of a place on map. Identify

them due to points on the given map. Points may

be given by using grid reference points, place name

or letter. Draw a straight line connecting the two

points Mark the major four cardinal points at the

starting point with the word from. Now look at the

question asked then provide your answer.

COMPASS BEARING.

Bearing are directions which measure degrees

clockwise from north. They are written in three

figures i.e. 0900 , 0450

HOW TO FIND BEARING ON THE MAP.

Identify the grid reference points given on the

maps. Draw a straight line connecting the two

points Draw the major four cardinal lines at the

starting Now look at the question asked use a

protector to measure degree clockwise from north

up to the line joining the two points. Then Provide

your answer in degrees BEARING. In bearing there

is;

a) Forward bearing

b) Backward bearing

a) Forward bearing Is a bearing into a subject.

Procedures to calculate forward bearing

i. Identify the two points.

ii. Join them with a straight lines

iii. Draw north direction on a second point.

iv. Measure the angle by using a protector.

v. State the bearing in terms of degrees of the

direction.

b) Backward bearing. Is the opposite of forward

bearing, it’s taken from the object to the observer

while forward bearing is taken from observer to the

object.

How to determine the back bearing.

i) Find forward bearing.

ii) Mark the cardinal point north direction of the

opposite point

iii) Find the bearing of the observer along the

straight line principally to determine the back

bearing = FB + OR – 1800 BB= FB +1800 if FB <

1800 BB= FB -1800 if FB >1800 For example: The

forward bearing (FB) of Tukuyu from Kyela is 0450 ,

Back bearing (BB) will be; BB = FB + or – 180. BB

= 45 + 180 (FB added because it’s not greater than

180) Therefore Back bearing is 2250

IMPORTANCE OF THE USE OF MAPS

a) People use them to reach their directions

b) Maps are used to describe the features of the

earth

c) Builders are maps to plan the best use of the

land

d) Road constructors use maps to construct new

roads

e) Maps are useful in military activities f)Maps are

used in conducting various geographical researchesKupata notes za Geography click hapa

** RECOMMENDED FOR YOU:**