Introduction to Geographical Skills and Techniques

Table of Contents
1. Geographical Information Systems (GIS)
2. Aerial Photographs & Remote Sensing
3. Topographic Maps
4. Using Atlases
5. Map Skills
6. Fieldwork
View more

Geographical Information Systems (GIS)

What is GIS?

• Stores geographical data digitally on computers.
• Users upload specific data (street names, locations, dates, pipelines).
• Used by government, industries, planners, public and private sectors.
• People develop GIS software to capture geographic information.
• Helps in planning (settlements, dams), acting (pollution control), and evaluating (environmental impacts).
• Continuously updated by new data and technology.
• Provides specific customised geo-information.

Value of Digital Information

• Increases amount of stored, analysed and displayed data.
• Stored as numerical codes for letters, numbers and colours.
• Information can be selected, sorted, and shown graphically.

Aerial Photographs & Remote Sensing

Aerial Photographic Images

• Includes aerial photos, orthophoto maps, satellite images.
• Captured by aircraft or satellites.

Orthophoto Maps - Description

• Created from overlapping vertical aerial photographs corrected for scale.
• Map information is added to photos.
• Combination of map + photograph.
• Large scale (1:10 000), features appear larger.
• More realistic than topographic maps.
• Contour lines can be added for relief + flood-risk assessment.

Orthophoto Maps - Advantages

• Large scale makes features easy to identify.
• Quick and easy for updating maps.
• Covers urban & growth areas.

Orthophoto Maps - Disadvantages

• Not available for whole South Africa.
• Difficult public access to full-colour copies.

Orthophoto Developments

• Digital mapping cameras since 2008 record and correct scale automatically.

Satellite Images - Description

• Digital picture-like Earth representations from satellite sensors.
• Captured from visible & non-visible spectrum.
• Contain environmental information beyond human sight.

Satellite Image - Advantages

• Continuous worldwide coverage.
• Shows change over time.
• Easy GIS integration.
• Used to analyse environmental problems.

Satellite Image - Disadvantages

• Expensive satellites + ground stations.
• Requires highly skilled professionals.

Satellite Developments

• Modern imagery is detailed enough for accurate mapping.

Vertical Aerial Photographs - Description

• Overlapping vertical photos taken along flight paths.
• Used to create topographic maps.
• Large scale, showing larger features.

Vertical Aerial Photos - Advantages

• Key source for spatial data.
• Available in multiple scales nationwide.
• Historic archive since 1930 for monitoring growth & development.

Vertical Aerial Photos - Disadvantages

• Scale accurate only at centre of photo.
• Mostly black and white.
• Must be digitised before mapping.

Developments

• Automated cameras, improved film.
• Film-developed photos used less today due to digital mapping.

Topographic Maps

What are Topographic Maps?

• Created from vertical aerial photographs.
• Vertical view with many symbols.

Description

• Scale: 1:50 000 detailed colour map.
• Shows natural & constructed features.
• Includes line scale, grid references, title & key.

Advantages

• Colour coded with a user guide (map key).
• Shows height, distance and geo-referenced by latitude & longitude.
• Rich information about area.
• Full national coverage in South Africa.

Disadvantages

• No automatic 3D view - need to interpret height clues.
• Small print and symbol learning required.
• Costly and becomes outdated.

Developments

• Will remain useful but enhanced by GIS and remote sensing.
• Use will decline as GIS access rises.

Reading Topographic Maps

• Vertical view of terrain.
• Symbols are point, line and area types.
• Shapes may be regular (rectangular fields) or irregular (dams).

Map Symbols

• Act as language for objects.
• Shape/colour/size remain fixed.
• Placed in true position for direction & distance accuracy.
• Text used for place names.

Using Atlases

What is an Atlas?

• Toolkit showing location, climate, altitude, boundaries, population, resources, vegetation.
• Maps include keys for interpretation.

Types by Area Covered

• World maps - continents & oceans.
• Regional maps - part of a continent/country/province.
• Local maps - towns/cities.

Types by Topic

• Political maps - boundaries, colours, names.
• Relief maps - altitude, mountains, rivers.
• Thematic maps - climate, vegetation, population.

Atlas Skills

• Understand scale, symbols, and alphanumeric grids.

Map Skills

Compass Directions

• Compass needle points to magnetic north.
• Use 8 or 16 cardinal points.
• Align north on compass card with needle.

Coordinates

• Location described by latitude (N/S) & longitude (E/W).
• Creates a global grid called the graticule.

Map Projections

• Mercator - accurate direction, distorted area.
• Robinson - realistic shape, distorted direction/distances.
• Peters - accurate area, distorted shape.

Bearings

• Measured in degrees from true or magnetic north.
• Magnetic declination adjusts the difference.
• True bearing = measured bearing - declination.
• Magnetic bearing = true bearing + declination.

Measuring Bearings Steps

1. Identify FROM and TO.
2. Draw true north line from FROM.
3. Measure clockwise angle to the line.

Landforms from Contours

• Contours join equal heights.
• Interval = 20 m on topographic maps.
• Wide spacing = gentle slope.
• Close spacing = steep slope.
• Convex slope = wide → close.
• Concave slope = close → wide.

Distance Measurement

• Use map scale (ratio).
• Example: 1:50 000 means 1 cm = 0.5 km.

Using Ratio Scale

1. Measure map distance.
2. Multiply by scale factor.
3. Convert cm to km/metres.

Large vs Small Scale

• 1:50 000 = small-scale, less detail.
• 1:10 000 = large-scale, more detail.

Fieldwork

F - Finding a Topic

• Identify current local problems or issues.

I - Information Gathering

• Research before field investigation.

E - Engaging Stakeholders

• Identify information sources.
• Use surveys, questionnaires, observation, census.

L - Localise Investigation

• Conduct in local context with safety.

D - Data Gathering

• Quantitative or qualitative data.
• Use devices: recorder, thermometer, camera.

W - Working Effectively

• Time management and role allocation.

O - Organising Data

• Sort into facts, opinions, themes.

R - Recording & Reporting

• Write a structured report.

K - Key Findings & Recommendations

• Summarise findings.
• Recommendations and conclusions.