الفهرس 
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Abstract
This study aims to investigate the ability of DGPS and PPP techniques for detecting crustal deformation. A geodetic network along the Nile Valley area is used for this purpose. The observations are collected using Global Positioning System (GPS) instrument in the different epochs and different adjustment methods are used to analyze the network. Lately, one of the important methods for studying crustal deformation, through space techniques, is the Global Positioning System (GPS). A geodetic network containing 9 points was established early in 2010 along the Nile Valley. This network was observed five times in different campaigns throughout the period 2010 – 2016. The observed data were analyzed using Trimble Business Center (TBC 3.5) software, APPS service and AUSPOS service to determine velocity vectors along the Nile Valley area. The aim of the present work is to demonstrate the use of GPS in static mode to provide data for use in the assessment of crustal deformation in the Nile Valley area and for understanding the geodynamics of this region. Three different methods of GPS-data processing were adopted and a comparison between them was determined to get the most precise results. Study of recent crustal movements is considered as an important task for geodesists, geologists and geophysicists. This is due to other part this phenomena is very dangerous on the human life in the world, so all constructed projects must be secured against the crustal deformation at local, regional and global scales. Study of recent crustal movements means the determination of the magnitude, direction and the rate of these movements. Nowadays, crustal deformation within Egypt relates to the regional and local tectonic forces. The displacement vectors for each epoch of observation were calculated from the coordinate changes. Considering the confidence limit, most of these displacement vectors could be mainly attributed to the movement within the Nile Valley study area in those epochs of measurements. The relative movements between the epochs of measurements are estimated. The main objective of this work is to monitor the surface crustal deformation around the Nile for understanding the geodynamics of this region. Also, an attempt has been made to investigate the recent crustal movements by two solutions , by using APPS (Automatic Precise Positioning Service) service for precise point positioning (PPP) solution and once again by using AUSPOS service for relative solution and their relation to the induce seismicity in the areas vicinity of the Nile Valley area.