Selection of the Dredged Material Disposal Sites in the Turkish Coastal Areas

Abstract

Approximately 5x10(6) cubic meter of sediment is removed annually from the harbours, ports, marinas and river mouths in Turkey. Uncontrolled dumping of these dredged materials might create contamination based on the assumption that this material is somehow polluted with the human activity related to the surrounding location. Selection of the disposal sites at sea is one of the important steps of dredge material management process described in most of the international conventions. As part of the ongoing "Dredging Applications and Environmental Management of Dredge Material Project (DIPTAR)" project, the dredged material disposal sites in Turkish Seas were determined by identifying: (i) the areas prohibited to disposal of dredged material, (ii) the coastal areas which have frequent dredging activities, (iii) behaviour of the dumped sediment and the area of impact determined by STFATE Model (Short-Term Fate of Dredged Material Disposal in Open Water), (iv) the scientific criteria which the candidate dumping sites should fulfil. The candidate dumping sites were separated into two main classes according to the dredged material volume (more or less than 100,000 cubic meters). Physical, chemical, and biological characteristics of the water column and the seabed properties were taken into account in determination of the limiting parameters for different seas of Turkey by the expert group. The scientific criteria about water currents (velocity, direction), distance from coastal area, depth, bottom slope, deep water oxygen, Dissolved Inorganic Nitrogen (DIN), Total Phosphate (TP), chlorophyll-a concentrations and Secchi disk depth were established by expert judgement, using scientific information about the oceanographic characteristics of each sea and recent monitoring/research project results. Finally 54 dumping sites were determined on the coastal areas of Turkish seas (Aegean 11, Mediterranean 17, Marmara Sea 9, Black Sea 17 sites) for disposal of small and large volumes of sediments accumulated in the coastal sea by natural physical processes.