| Abstract: |
The economic development of any country requires a comprehensive and modern geodetic control networks. The geodetic control networks, in classical geodesy, provide a basis for mapping, cadastral applications and large engineering projects. On the other hand, these geodetic control networks have several benefits in modern geodesy and geodynamics such as the determination of the crustal movements, which are useful in earthquakes monitoring, plate boundary determination, studying the sea surface topography and its variation with time, the computations of the orbits of the artificial geodetic satellites, and improving the knowledge of the earth gravity field. These recent applications of geodetic control networks require high accurate network coordinates.The first order geodetic control network of Egypt consists of two main networks, namely: network 1 and network 2. Network 1 consists of 195 stations distributed in 10 sections, forming approximately a T shape, covering the Nile valley and the north coast, with a fundamental point on Mokattam hills to the east of Cairo. Network 2 consists of 207 stations, forming three main blocks, divided in to 13 sections. Block 1 covers a part of Sinai and some parts of the upper eastern desert near the Red Sea shore (4 sections). Block 2 covers a part of the western desert in the area between Assiut and Aswan (4 sections). Block 3 covers the lower eastern desert and part of the Red Sea coast (5 sections).During the last few decades, several trials have been made to adjust the Egyptian geodetic control network. The first trial has been made by ESA for network 1 using the adjustment in blocks, which is an approximate technique of adjustment. So, each section has been adjusted separately with constraints from the previous sections. Moreover, no reduction of the observations has been performed, which means that the geoid information has been neglected completely during the network computations. Consequently, an accumulation of the systematic errors was expected in the final results of that adjustment.
|
|
|