Introduction to Land Surveying Basics

• Surveying is the art and science of determining the relative positions of points on, above, or beneath the Earth's surface.
• Surveying also establishes new points on the ground.

Types of Surveying

• Plane Surveying assumes the Earth is flat and is suitable for small areas.
• Geodetic Surveying takes into account the Earth's curvature and is used for large areas and high precision.

Surveying Measurements

• Distance includes horizontal or slope distance between two points.
• Angle refers to horizontal or vertical angles.
• Elevation is the vertical distance above or below a reference datum.

Surveying Instruments

• Total Station measures angles and distances electronically.
• Theodolite measures horizontal and vertical angles.
• Level determines elevations and elevation differences.
• GPS/GNSS Receivers determines positions using satellite signals.
• Measuring Tape/Chain is used for linear measurements.

Surveying Methods

• Traversing establishes a series of connected lines and is used for control and boundary surveys.
• Leveling determines the elevations of points, useful for topographic surveys and construction staking.
• Triangulation/Trilateration determines positions based on angles and/or distances to known points and is useful for establishing control networks.
• GPS Surveying determines positions using GPS/GNSS receivers and has applications in control, topographic, and construction staking.

Surveying Errors

• Systematic Errors follow a pattern and can be corrected.
• Random Errors occur randomly and are difficult to eliminate.
• Mistakes are caused by carelessness or misunderstanding.

Surveying Accuracy and Precision

• Accuracy reflects how close a measurement is to the true value.
• Precision reflects how repeatable a measurement is.

Coordinate Systems in Surveying

• Horizontal Coordinate Systems:
  • Geographic Coordinates (Latitude, Longitude) use the Earth's surface as a reference.
  • Plane Coordinates (Northing, Easting) use a flat grid as a reference.
• Vertical Coordinate Systems:
  • Elevations are referenced to a vertical datum, like mean sea level.

Topographic Surveying

• Topographic surveying focuses on determining the positions and elevations of natural and artificial features on the Earth's surface.
• Topographic surveys are used to create topographic maps and digital elevation models (DEMs).

Applications of Topographic Surveying

• Mapping involves creating topographic maps for various purposes.
• Civil Engineering uses surveying for the planning and design of infrastructure projects.
• Construction uses surveying for staking out projects.
• Environmental Monitoring uses surveying to monitor changes in the Earth's surface.
• Land Development utilizes surveying in the planning and design of land development projects.

Topographic Surveying Methods

• Total Station Surveys use a total station to measure angles and distances to topographic features.
• GPS Surveys use GPS/GNSS receivers to determine the positions of topographic features.
• Aerial Surveys use aerial photography or LiDAR to collect topographic data.
• Leveling determines elevations of points using a level.
• Contouring creates lines on a map that connect points of equal elevation.

Topographic Maps

• Topographic maps are graphical representations of the earth's surface, showing positions and elevations of natural and artificial features.
• Topographic maps typically include contours to represent elevation.

Contour Lines

• Contour lines connect points of equal elevation.
• Contour Interval is the vertical distance between contour lines.
• Characteristics of Contour Lines:
  • Contour lines never cross each other, except in rare cases like overhanging cliffs.
  • Contour lines close on themselves, either on or off the map.
  • Contour lines form V-shapes when crossing streams, with the V pointing upstream.
  • Closely spaced contour lines indicate steep slopes.
  • Widely spaced contour lines indicate gentle slopes.

Digital Elevation Models (DEMs)

• DEMs are digital representations of the Earth's surface that store elevation data.
• DEMs can be used to create topographic maps, calculate volumes, and perform other spatial analyses.

Data Collection for Topographic Surveys

• Planning involves determining the scope of the survey and the accuracy requirements.
• Fieldwork involves collecting the necessary data using appropriate surveying instruments and methods.
• Data Processing involves processing the data to create topographic maps or DEMs.
• Quality Control involves verifying the accuracy of the data.

Importance of Topographic Surveys

• Topographic Surveys provide essential information for planning and design.
• Topographic Surveys support informed decision-making.
• Topographic Surveys enable effective communication of spatial information.
• Topographic Surveys facilitate sustainable development.