Barometric Levelling in Civil Engineering

Barometric levelling is a technique used in civil engineering for measuring differences in elevation. It is based on the principle that atmospheric pressure decreases with height. In this technique, a barometer is used to measure the atmospheric pressure at two different points, and the difference in pressure is used to calculate the difference in elevation between the two points.

Principle of Barometric Levelling

The principle of barometric levelling is based on the fact that atmospheric pressure decreases with height. This means that the pressure at a higher elevation is lower than the pressure at a lower elevation. The decrease in pressure is due to the decrease in the weight of air above the elevation.

Process of Barometric Levelling

The process of barometric levelling involves the following steps:

1. Measuring the atmospheric pressure at two different points using a barometer.

2. Calculating the difference in pressure between the two points.

3. Using the difference in pressure to calculate the difference in elevation between the two points.

4. The accuracy of the measurement depends on the accuracy of the barometer and the calibration of the instrument.

Applications of Barometric Levelling

Barometric levelling is used in civil engineering for the following applications:

1. Determining the elevation of a point or a series of points.

2. Measuring the height of a building or a structure.

3. Monitoring the subsidence of buildings or structures.

4. Monitoring the changes in the water table.

Advantages of Barometric Levelling

1. It is a simple and easy technique.

2. It can be used for measuring differences in elevation over long distances.

3. It does not require the use of expensive equipment.

Disadvantages of Barometric Levelling

1. It is affected by changes in atmospheric pressure due to weather conditions.

2. It is affected by changes in temperature.

3. It is not as accurate as other techniques, such as differential levelling.

Conclusion

Barometric levelling is a useful technique for measuring differences in elevation in civil engineering. It is based on the principle that atmospheric pressure decreases with height. Although it has some limitations, it remains a simple and effective technique that is widely used in civil engineering.