The Determination of Plumb Line Deviation Using Satellite/Levelling Technique

The article deals with adopting the GNSS/levelling technique to calculate the plumb line deviation. The topic focuses on the possibility of determining normal heights using satellite measurements. Even though there are many local algorithm models of plumb line deviation, finding the model parameters is not an easy task, especially for large coverage areas, and the calculation accuracy is hard to be attained as well. The distance between any two baselines, the azimuth and geodetic height differences can be easily obtained using GNSS relative positioning technology; while the normal height difference can be obtained using precise trigonometric leveling method. Therefore, it is an ideal way to use GNSS/levelling technique to determine the deviation along the plumb line in small study areas. This technique is mostly suitable for countries where a local geodetic network doesn’t exist, which in turns prevents finding a full-fledged solution of many practical engineering problems. An example of testing the described methodology in Lebanon is presented, where the results show the superiority of GNSS/levelling technique as it is applicable to calculate accurately the influence value of error affected by the plumb line deviation.