Finding levelling involves determining differences in elevation between points on the ground. There are primary methods used to achieve this.
According to the provided references, the two main ways to find levelling are through:
Methods for Finding Levelling
1. Direct Levelling
Direct levelling is the most commonly used method for finding levelling.
- How it works: In this method, you measure the differences in elevation directly. This typically involves using a level instrument and a levelling staff to take readings that indicate the vertical distance between the line of sight of the instrument and the ground points.
2. Indirect Levelling
Indirect levelling is another approach to finding levelling, used when direct measurement is less practical.
- How it works: With indirect levelling, you don't measure the elevation difference directly. Instead, you calculate the differences in elevation from measurements of slopes and horizontal distances between points. Instruments like total stations are often used to measure these slopes and distances, and then trigonometry is applied to determine the elevation changes.
Summary of Methods
Here's a quick overview of the two methods:
| Method | How it Finds Levelling | Key Measurement(s) | Common Use |
|---|---|---|---|
| Direct Levelling | Measures differences in elevation directly. | Vertical distances (using level and staff). | Most commonly used method. |
| Indirect Levelling | Calculates differences in elevation from other data. | Slopes and horizontal distances. | Often used in challenging terrain. |
Choosing the appropriate method depends on factors such as the required accuracy, the terrain, available equipment, and site conditions. However, direct levelling is generally the standard practice due to its direct measurement approach.
