Hello Cyril,
Use UTM projection for everything. Means the raster file (DEM/TIN), all the vector files and the ArcGIS project. It should work. Try and let me know.
Thanks a lot Cameron. The projection system is GCS_WGS_1984. Actually the geometric data is showing a simplified curve of the XS Cutlines, I don’t know why. But the bank stations are completely deviated.