Shoreline change analysis of the Kizilirmak Lagoon Series

• Shoreline changes of the Kizilirmak Lagoon Series were analyzed between 1962 and 2013.
• The lagoons are threatened by coastal erosion that has occurred after the construction of the dams.
• Rapid erosion, which occurred particularly in the eastern part of the delta, has narrowed the barrier spits.

Comprising many small and large lagoons, the Kizilirmak Lagoon Series is located in the Kizilirmak Delta, which is one of the most important wetlands protected by the Ramsar Convention in Turkey. This study examines the changes that have occurred in the shoreline of the Kizilirmak Lagoon Series between 1962 and 2013. Furthermore, shoreline changes in the delta were also determined to discuss whether there is a relationship between the shoreline changes in the Kizilirmak Delta and lagoons. The shorelines in 1962, 1974, 1987 and 2013 were used to analyze the shoreline changes. Landsat-MSS/TM/OLI satellite images and 1/100,000 topographic maps were used to measure the shorelines. The changes in area, shoreline length and the shoreline development index (SDI) were compared to determine the changes in the lagoon shorelines, and the changed and unchanged parts of the lagoon areas were spatially analyzed using polygon overlay analysis. The Net Shoreline Movement (NSM), End Point Rate (EPR) and Shoreline Change Envelope (SCE) methods were used to determine the changes in the delta shoreline. The results showed that the lagoons tended to shrink in the periods when the Kizilirmak River carried abundant amounts of sediment, prior to the construction of the Altinkaya and Derbent Dams between 1962 and 1987. However, after the construction of the dams, between 1987 and 2013, the delta development stopped due to the disruption of the sediment flow to the delta. As a result, coastal erosion occurred due to an increase in wind and wave erosion, which led to narrowing of the barrier spit in front of the lagoons along the eastern coasts of the delta. The maximum erosion along the coasts of the delta was −827 m, and the total shrinkage in lagoon areas was 963.7 ha between 1962 and 2013. This study reveals that it is crucial to take necessary measures to sustainably manage the Kizilirmak Lagoon Series, which is highly important for the delta ecosystem.