ERRORS IN LEVELLING
Levelling is a technique used to determine the relative height of points on the Earth’s surface. It involves measuring the vertical distance between two points using a levelling instrument such as a spirit level, optical level, or digital level. Errors in levelling can occur due to a variety of reasons, some of which include:
- Instrumental errors: Levelling instruments are prone to errors due to their design, manufacture, and calibration. These errors can include incorrect readings, parallax errors, bubble errors, and temperature-related errors.
- Human errors: Human errors such as misreading the staff or not holding the staff vertically can also cause errors in levelling. Inaccurate sighting or recording of readings can also lead to errors.
- Atmospheric conditions: Atmospheric conditions such as heat waves, temperature inversions, and refraction can cause errors in levelling. These conditions can cause the level line to bend, resulting in incorrect readings.
- Obstructions: Obstructions such as buildings, trees, or other objects can block the line of sight between the instrument and the staff, resulting in errors in levelling.
- Incorrect levelling methods: Using the wrong method for levelling or not following the correct procedure can also cause errors. For example, using a staff that is not properly graduated or not using a level tripod can lead to incorrect readings.
It is important to be aware of these sources of error and take steps to minimize them when performing levelling to ensure accurate results.
