Justification of the height models available in Latvia

Abstract

After improvement of geodetic networks in the territory of Latvia, situation is arisen that heights of geodetic points have changed. Therefore authors study in the research, what regularities form between the Baltic normal height system of year 1977 (BHS-77) and Latvian Normal Height System LHS-2000,5 height systems in the given points, as well as what inaccuracies can be observed, if ADTI map sheets are transformed by use of the determined methodology of recalculation of heights. Aim of the work is to research and analyse measurement data available in reports of improvement of local geodetic network of Ventspils, Jelgava, and Kuldga and to compare values of heights of geodetic points with historical values of heights, as well as to give valuation about alignment of height systems. For the achievement of the aim following tasks are set: to analyse measurements available in the reports of local geodetic networks; to evaluate height differences between points in BHS-77 and LHS-2000,5 height systems; to give proposals in relation to compatibility of BHS-77 un LHS-2000,5 height systems. After valuation of data, we can draw conclusion that mutual compatibility of quasigeoid models LV’98 and LV’14 in all areas of measurement is regarded as appropriate. The historical heights of points of the local geodetic networks in comparison to improved levelled heights of BAS-77 are regarded as rather appropriate in local geodetic networks of Jelgava and Kuldga; however, in local geodetic network of Ventspils, they are regarded as inappropriate.