Horizontal displacement of control points using GNSS differential positioning and network adjustment

Abstract

We compute the horizontal displacement in the first/second-order and Merowe Dam control points in a subset of a hybrid triangulation network in northern Sudan. The Global Navigation Satellite Systems (GNSS) and least-squares network adjustment are jointly used to determine the horizontal displacement in the control points. The GNSS observations collected by relative positioning are validated over the control points to create a corresponding subnetwork adjusted by the least-squares. The baselines and network loops show good quality through the statistical indicators that measure the ratio, root mean square (RMS), and reference variance. We apply minimum-constrained adjustment (MCA) and zero-constrained adjustment (ZCA) methods on the subnet. After adjustment. The horizontal displacement is determined as the Euclidean norm of the difference between the Easting/Northing components. The comparison shows large displacements in the first-order (0.6 m), second-order (2 m) points and small displacements (15 cm) in Merowe control points.