Quantitative Information on Maps

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.

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:

1. Square method
2. Strip method
3. Geometrical method

Square method. This is the most accurate and most widely used method. Square methods are normally used as follows:

1. Count all full squares that are complete
2. Count incomplete squares and divide them by 2
3. Add them with the full squares to obtain the total area in km²

The following are major methods used to show positions of a place on a map.

1. Grid reference
2. Place name
3. Bearing and compass direction
4. Latitude and longitude

Grid Reference

Grid reference is a network of vertical lines and horizontal lines on a map. Vertical lines whose numbers increase towards the east are called easting. Horizontal lines whose numbers increase towards the north are known as northings. Where horizontal lines and vertical lines meet or cross each other they form a square known as grid square. A grid reference point is written in the form of six digits starting with three digits of eastings then three digits of northings.

A = 343086 B = 333036 C = 383077 D = 397046

NB: To write numbers of grid reference starts with easting then northing.

Place Name

You can locate the position of a place by where the features are found i.e. Arusha, Mbeya, Dodoma, Mtwara etc.

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.

How to find bearing on the map:

1. Identify the grid reference points given on the maps.
2. Draw a straight line connecting the two points.
3. Draw the major four cardinal lines at the starting point.
4. Use a protractor to measure degree clockwise from north up to the line joining the two points.
5. Then provide your answer in degrees.

Bearing

In bearing there is:

1. Forward bearing
2. Backward bearing

Forward bearing. Is a bearing into a subject.

Procedures to calculate forward bearing:

1. Identify the two points.
2. Join them with a straight line.
3. Draw north direction on a second point.
4. Measure the angle by using a protractor.
5. State the bearing in terms of degrees of the direction.

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:

1. Find forward bearing.
2. Mark the cardinal point north direction of the opposite point.
3. Find the bearing of the observer along the straight line principally to determine the back bearing.
4. BB = FB + 180° if FB < 180° BB = FB – 180° if FB > 180°

The forward bearing (FB) of Tukuyu from Kyela is 45°, 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 225°.

1. People use them to reach their directions.
2. Maps are used to describe the features of the earth.
3. Builders use maps to plan the best use of the land.
4. Road constructors use maps to construct new roads.
5. Maps are useful in military activities.
6. Maps are used in conducting various geographical researches.