MORPHOTECTONIC ANALYSIS BY COUPLING A DIGITAL TERRAIN MODEL, RADAR DATA (SENTINEL-1C) AND FIELD DATA FROM THE EASTERN PART OF THE OUADDAI MASSIF (EASTERN CHAD)

The study area lies between latitudes 13 15 and 13 45 North and between longitudes 21 24 and 22 2 East. Administratively, it is located in the department of Asougha, province of Ouaddai. The aim of this work was to carry out a morphotectonic analysis by coupling a digital terrain model, radar data and field data. We used SRTM images, Sentinel 1-C radar and field campaigns. The satellite images were analysed using cartographic software (Argis, SNAP, Geomatica PC, RockWork, Global Mapper, Surfer) and Steronet. Observations from the 3D map were used to divide the study area into three morphological units: Unit I, the lowest (altitude 700m) where the watercourses are located it is made up of plains andvalleys. Unit II, the largest, has a medium to high altitude (700-900m). This geomorphological unit is made up of hills and plateaux and Unit III is that whose altitude is  900m.This unit is made up of circumscribed hills and mountain ranges. The lineaments obtained from Sentinel -C radar gave two main fracture directions: ESE-WNW and SE-NW. Field data provided the lithological type, mainly granitoids. These granitoids are fractured almost everywhere in the study area. These fractures follow the directions of their host rocks.