Micro, Macro & Mezzo Geoinformation (Jun 2020)
The planning of the first and second order relative gravimetric networks for the territory of the Republic of Albania
Abstract
This paper presents the first and second order gravimetric relative network planning for the territory of the Republic of Albania, as well as the calculation of free-air anomalies, Bouguer anomalies, and Bouguer gravity. The planning of the first and second order relative gravimetric network is done for the whole territory of the Republic of Albania, based on the three absolute gravimetric points. The planning of the first order network is done using the 1 point/1000km2 surface criteria, while the second order network planning is done again using the 1 point/100km2 surface criteria. The ArcGis software tested the best dot coverage of the network of triangles based on two criteria set out as above. The tests done on all three gravimetric absolute points shows that the best coverage of the whole territory, with first and second order points has absolute gravimetric points at Saranda station. So, taking this fact into consideration, a grid network has been built in ArcGis software based on regular triangles. As a result, 30 first-order relative and 289 second order relative points were obtained, for which the calculations of free-air anomalies, Bouger anomalies and Bouguer gravity using WGS84 parameters were performed in Excel. To enable the calculation of free-air anomalies, Bouguer anomalies, and Bouguer gravity, first must be calculated the normal ellipsoid gravity, then the gravity of height and finally the reduction of free-air. Based on the measured gravity (which in our case was obtained the measured gravity point at the Saranda station) by adding free-air reduction and then removing the normal gravity value, the free-air anomalies were calculated. Bouguer anomaly calculation first must be reduced to topography with the Bouguer plate, and then we remove the gravity of height at the gravity point P₀. Bouguer gravity is calculated from the measured gravity (which in our case is taken the measured gravity point at the Saranda station) by removing the Bouguer plate and adding free air reduction. The calculations were performed in Microsoft excel software, where based on the values obtained from ArcGis software 10.2.2. maps were constructed for free-air anomaly, Bouguer anomaly, and Bouguer gravity for both planned ranks, which are presented within this paper.
