Simulation of an Alternative Realisation of the Croatian Height Reference System

Abstract

The current Croatian height reference system (HVRS71) has been established using the so-called Second High Accuracy Levelling Network (IINVT) of the former Yugoslavia. This network survey was realised from 1970 to 1973. Today almost 50 years later, it is quite clear that a renewal of the Croatian height reference system is necessary. The survey and design of a new fundamental levelling network for the Republic of Croatia is an expected step. In Croatian particular case there is a significantly limiting key factor for the levelling network design. That limiting factor derives from the fact that the size and the specific shape of the Croatian territory in comparison with the standards of realization of levelling networks have a negative correlation. Considering the aforementioned facts, a careful and comprehensive analysis was conducted. As a basis for the analysis of this issue, a simulation of the new Croatian height reference system realisation was performed. The simulation is based on the grounds of IINVT network observations which had originally been used to create the current official height reference system of the Republic of Croatia, but with a modification of its geometrical configuration. In accordance with the need for continuous monitoring of height displacements of the same benchmarks that had been observed previously (the recent crustal movements issue), the principle of preserving as big as possible segment of the IINVT network configuration on the Croatian territory had been retained. One of the fundamental elements of the height reference system quality certainly is the quality of the absolute benchmark height positioning. In this paper it is shown how radical change of network configuration due to the adjustments to the specific shape of the Croatian territory affects the accuracy of the absolute benchmark height positioning.