Alluvium, which is composed of sand, rubble, stone and soil, is carried by stream and rivers into harbors, bays and dams. Transported alluvium is accumulated as the time went by at the bottom and causes decrease in depth level. Degirmendere watershed receives lasting and heavy precipitation. This precipitation occasionally causes overflowing of the Degirmendere Stream and therefore causes flood and heavy erosion. In this study, images belonging to the years 2000, 2003 and 2008 were determined using satellite. In this, alluvium resulting from the erosion is carried by the Degirmendere Stream into the Black Sea and discharged from the closer district into the harbor entrance of Degirmendere. This is done in comparison with previous years because of the Black Sea Coastal Road construction. Three dimensional map (shaded relief) showing submarine topography of Trabzon Harbor was made and compared with the map made in 2000 using the same method. In the conducted application, horizontal position data were determined with RTK GPS and also depths were measured with prepared mechanical sounding lead. A total of seven sections on the digital maps obtained with the sounding measurements conducted in the years of 2002 and 2009 were transected with the aim of investigating the transformation that is occurring in time. Transformation was examined by forming graphics from the transected sections. Increase was observed in depth values in the courses frequently used by heavy tonnage ships, but decrease in depth was determined in the area where small ships and boats existed.