Özet:

Deltas, which are produced as a result of the buildup of material transported by rivers, are the primary reservoirs of terrestrial sediment flow, biologically significant ecosystems, and significant morphological units that filter and lessen the impact of pollutants coming from the upstream. In this study, it is aimed to reveal the change in the shoreline of the Gediz River Delta wetland during the 1989-2022 period by using the GIS-based Digital Shoreline Analysis System (DSAS). In order to achieve these goals, it is important to understand how the Delta's shoreline has changed over the last 34 years, forecast how the coast will move in the future, and identify any potential impacts on the coastal ecology. The shoreline was identified using Landsat images with a 30 meter resolution from the summers of 1989, 2000, 2011, and 2022. At first, the Normalized Difference Water Index (NDWI) was used to identify shorelines as a boundary between land and water. After that, Shoreline Change Envelope, Net Shoreline Movement, End Point Rate and Linear Regression Ratio indicators were computed to identify shoreline changes like erosion and accumulation processes with DSAS. Additionally, the future positions of the shorelines for 2032 and 2042 were estimated in accordance with the sedimentation dynamics modeled by considering 10-year periods. As a result, it was determined that the wetland of the Gediz Delta was generally exposed to sea intrusion and the barrier splits and bay barriers were destroyed during the research period. The Ragip Pasa fishing weir, Kirdeniz and Cilazmak lagoons were indicated to have the largest coastline regression against land. According to the findings, the delta's wetlands would see localized coastal erosion disturbance in the years to come if the current situation is not changed. Strong coastal erosion near the northern coast of Gediz Delta, as seen in the study's findings, indicates that the volume of water and sediment entering the delta has reduced. The findings of this study will aid in the development of future policy guidelines by encouraging a thorough and systematic strategy to prevent further deterioration of priceless ecological assets in the coastal area of the Gediz Delta.

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