DBPapers
DOI: 10.5593/sgem2017H/33/S12.045

THE IMPORTANCE OF TERRAIN CORRECTIONS OF GRAVITY DATA IN HYDROLOGICAL MODELING

N. S. Asimopolos, L. Asimopolos
Thursday 23 November 2017 by Libadmin2017

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgemviennagreen.org, SGEM2017 Vienna GREEN Conference Proceedings, ISBN 978-619-7408-27-0 / ISSN 1314-2704, 27 - 29 November, 2017, Vol. 17, Issue 33, 363-370 pp; DOI: 10.5593/sgem2017H/33/S12.045

ABSTRACT

Within the global hydrological cycle, by redistributing the water masses, there are variations of the gravitational field as a result of changing the subsurface density and the atmospheric masses. For the use of gravimetric data in the hydro-geological modeling it is necessary to correct the direct and indirect effect of gravity due to the altitudes at each point on the topographic surface. Also, based on the variation of the gravitational field according to the selected time intervals (monthly, seasonal, yearly), the input parameters can be calculated in the complex global water transport system modeling. Mass redistribution of atmospheric and ocean water can be modeled using gravimetric data. This is related to the accurate determination of geodetic surfaces such as geoid, quasi-geoid and co-geoid. The geoid and co-geoid separations are determined by the Remove-Restore technique by combining the gravitational data sets with the geopotential model using a two-dimensional Fast Fourier Transform. Also, are calculated the field corrections. Geoid is the equipotential surface that best defines the overall sea level, in the sense of the smallest squares method, and the quasi-geoid is the surface parallel to the Telluroid that is transferred to the middle sea level.
Geoid and quasi-geoid are approximately the same on the ocean surface. However, the separation between quasi-geoid and geoid can reach with few meters in the high mountain areas. By applying the indirect effect corrections on the field of gravity anomalies and introducing the corrected value into the Stokes formula we obtain the co-geoid. In the paper we calculated and presented these three surfaces and their separations for the territory of Romania, as well as their importance for the hydro-geological studies.

Keywords: hydrological modeling, gravity, geoid, quasi-geoid