Surveying is divided into several branches, each serving a specific purpose:

1. Plane Surveying

Assumes the Earth's surface is flat and projects it onto a horizontal plane. Used for smaller areas such as building sites, schools, and villages.

2. Geodetic Survey

Takes into account the curvature of the Earth's surface. Used for large areas like national surveys and mapping entire regions.

3. Topographical Surveying

Involves measuring and plotting both natural features (rivers, hills, forests) and man-made features (roads, buildings), considering their horizontal and vertical positions.

4. Cadastral Surveying

Focuses on defining land boundaries and property details. Essential for land registration, ownership disputes, and construction projects.

5. Engineering Surveying

Collects special information needed for construction projects such as roads, bridges, and buildings.

6. Hydrographic Surveying

Studies and measures water bodies, including lakes, rivers, and coastlines.

Surveyors use various tools depending on the type of survey being conducted:

Measuring Tools

Supporting Equipment

• Ranging Poles: Long poles used to mark points and create straight lines
• Pegs: Small wooden stakes driven into the ground to mark survey stations
• Arrows: Metal pins used to mark chain positions during measurements
• Plumb Bob: A weighted string used to ensure vertical alignment
• Cross-Staff: A tool for setting out right angles
• Notebook and Pencil/Pen: For recording field measurements

Levelling Equipment

• Leveling Staff: A graduated ruler (usually 4m long) used to measure height differences
• Dumpy Level: An optical instrument that establishes horizontal lines and measures vertical distances
• Auto Level: A more advanced instrument that automatically compensates for slight tilts

1. Chain or Tape Survey

This is the simplest method, using a chain or measuring tape to measure linear distances between points. It is suitable for small, flat, and open areas.

Steps in Chain Surveying:

1. Conduct reconnaissance (walk around the area to understand its layout)
2. Select survey stations (corners of the area to be measured)
3. Mark stations with pegs
4. Measure distances between stations using the chain or tape
5. Record all measurements in a notebook

2. Prismatic Compass Survey

Uses a prismatic compass to measure horizontal angles between survey lines. Useful for areas with irregular shapes.

3. Plane Table Survey

Involves mapping an area directly onto a sheet of paper placed on a leveling table. The surveyor draws the features while in the field.

4. Levelling

A technique used to measure height differences between points and create accurate elevations. This is essential for construction projects and creating topographic maps.

Simple Example - Determining Height Difference: If a leveling instrument is set up at point A and reads 2.5m on a staff at point A, and then reads 1.8m on a staff at point B, the height difference is: $2.5m - 1.8m = 0.7m$ Point B is 0.7m higher than point A.

1. Reconnaissance (Preliminary Inspection)

• Visually inspect and walk around the land to get an overall view
• Note key features like boundaries, corners, trees, and rivers
• Helps in choosing the appropriate scale for map-making

2. Actual Survey (Secondary Survey)

• Precisely observe, measure, and record directions, angles, distances, and elevations
• Use appropriate surveying tools and equipment

3. Presentation

• Present collected data in the form of maps, plans, or reports

Surveying plays a vital role in national development:

1. Land Management: Helps determine land boundaries and ownership, preventing disputes
2. Construction Planning: Provides accurate measurements for building roads, houses, and bridges
3. Mapping: Creates detailed maps showing physical features and boundaries
4. Agriculture: Helps in planning irrigation systems and assessing land use
5. Environmental Planning: Assists in assessing flood risks and soil erosion
6. Mining: Used to locate and map mineral deposits

In Tanzania, surveying is essential for land registration processes in rapidly growing areas like Kigamboni in Dar es Salaam or Mwenge in Dodoma. When families purchase plots of land, surveyors are hired to measure boundaries, mark corners with pegs, and create site plans that are submitted to the district lands office. This ensures secure land ownership and prevents costly boundary disputes. Additionally, before constructing schools or health facilities, engineering surveys determine the correct elevations to ensure proper drainage and foundation stability.