‘Geodesy’ is the branch of physics that deals with the study of accurate measurement of earth’s geography, mass distribution, orientation, crystal motions, etc. It varies concerning time. The phenomena of performing Geodesy using GPS(Global Positioning System) through satellite for navigation purpose and to measure the position of points in terrestrial base stations (Simply measures earth’s Geodynamical phenomena during surveying for some projects) is known as Geodetic survey.
Accuracy and precision of the geodetic survey depend upon the observed values in the field. GPS traces the position correctly with the help of satellites. These satellites are also used by scientist to monitor plate tectonics motions, earthquakes, volcanic hazards, landslide hazards, groundwater pressure, etc.
Features of Geodetic Survey
a. This survey is carried out when the area is greater than 250 km².
b. Earth is assumed spherical to determine the precise position of the points.
c. This survey is generally conducted by national survey departments.
d. Spherical trigonometry is taken into action. Surface lines are taken as the curve lines and triangles are taken as spherical triangles.
e. The precision of the geodetic survey is very high.
Objectives of the Geodetic Survey:
a. To detect the horizontal and vertical movements of land.
b. To monitor and overcome the structural deformations and erection of all problems of structures occurred due to crustal movements and gravitational forces.
c. It can be a reference for civil engineers to be alert before, during and after construction from failure and damages.
d. To measure the area of large land (like the area of the state of the country).
Importance of Geodetic Survey:
a. It provides the exact points needed for the project in the survey.
b. It can be beneficial for the construction of structures like roads and highways.
c. It can be a danger alarm or alertness to improve the fluctuation & chance of failure of constructions.
Satellite is the most important and commonly used geodetic survey instrument. 90 % of surveys conducted by satellites are geodetic survey. Examples of this survey are:
a. Area calculation of large states.
b. Preparation of contour map of a large area with the help of satellites.
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