The sediment budget of the Kizilirmak River has been disturbed during the last decade because of the flow regulation structures constructed on the river. This disruption has led to coastal erosion at the river mouth and its environs. With the effect of erosion within this period, the Black Sea shoreline has eroded approximately 1.0 km toward the Bafra Plain. In this study, the coastal erosion in the area was examined using physical and mathematical models. A shore protection structure system based on the results of the physical model tests was developed and implemented at the site. A one-line model was also applied for this part of the shoreline to study the problem mathematically. Analysis of the numerical simulation showed similar trends to the results of the physical model and field observation. The one-line model successfully represented the behavior of protection structures on the evaluation of the Kizilirmak River Mouth. One year after the completion of the protection structures, observations in the field showed that the erosion was completely controlled, and certain parts of the shoreline at this reach had advanced approximately 50 m toward the Black Sea. These protection structures have altered the longshore sediment transport along the shoreline of the Bafra Palin nearby the Kizilirmak River mouth. Therefore, the erosion at the adjacent shoreline of this reach has been accelerated at the expected level.