Assessment of Reservoir Sedimentation Effect on Coastal Erosion and Evaluation of Sediment Removal Techniques for Its Reduction — The Case of Nestos River, Greece

Nestos is one of the most important transboundary rivers flowing through Bulgaria and Greece. In the Greek part of the river, two reservoirs, the Thisavros Reservoir and the Platanovrysi Reservoir, have already been constructed and started operating in 1997 and 1999, respectively. In the first part of the chapter, the reservoir sedimentation effect on the coastal erosion is investigated, for the case of the Nestos River delta and the adjacent shorelines, through a combination of mathematical modeling, modern remote sensing techniques, and field surveying, while in the second part, the mechanical removal as well as the flushing of sediment from the reservoir of Platanovrysi and its disposal in the subbasin downstream of the Platanovrysi Dam up to the Nestos River delta are investigated as potential treatment methods of reducing coastal erosion, using a modification of the same mathematical model that is utilized in the first part of the chapter. The overall findings and conclusions arising from the work presented and discussed in the present chapter contribute to the overall need to thoroughly understand the direct effect of dam construction on coastal erosion, as well as to examine the effectiveness of potential sediment management treatments.