Soft Measures Against to Coastal Flooding as A Result of Expected Sea Level Rise in Izmir Bay

Date

2023-09-04

Author

Türkseven, Onur Deniz
Kısacık, Doğan
Baykal, Cüneyt
Güler, Işıkhan

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This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

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Sea level rise is expected as a result of climate change. Consequently, there will be an increase in the number and magnitude of coastal flooding, increasing the coastal cities’ vulnerability. The Izmir Bay offers a significant expanse of the residential area. Coastal flooding from rising sea levels can pose vital problems for people living close to structures in these habitats. The municipality of coastal cities like İzmir should consider increased risk levels. Mainly two different measure types exist: hard and soft measures. Preventing coastal flooding with soft solutions is an environmentally friendly approach since it is not using artificial structures. The natural shoreline will soon adapt to new sea-level conditions to minimize incident wave energy. Under the new circumstance, the flood level behind the shoreline should be determined to check whether it is above or below the threshold values. In the case of any risk, beach nourishment can be considered a solution. Beach nourishment is considered a soft solution that restores the beach and provides a protective zone that absorbs the energy of the incident waves and sea level rise conditions. Many natural shores exist along Izmir Bay (Figure 1). Soft solutions will be developed based on the specific characteristics of the selected coastal regions. The seabed changes under new hydrodynamic conditions due to sea level rise will be examined by numerical models. XBeach is an effective and powerful tool developed at Delft University for the simulation of morphological changes under extreme conditions. It has the capability to simulate dispersive and non-dispersive wave conditions. Hydrodynamic condition, seabed sediment characteristics, and model bathymetry were determined from selected site specifications. XBeach model is calibrated with the results of physical model tests conducted in the wave flume of Middle East Technical University (METU) (Işık, 2019). The dimensions of the wave flume are 29.0 meters in length, 6.0 meters in width, and 1.0 meters in depth (Figure 2.) The physical model simulates shoreline and seabed changes under different wave conditions. Tests start with an initial condition of an artificial uniform coastline created with uniform sand. After each test, bathymetry is measured to obtain the newly formed seabed geometry. Physical test results showed that beach erosion is influenced by an increase n significant wave height and wave steepness. Then XBeach model results are validated with the different physical tests set up, which are not considered in calibration processes. Finally, the calibrated model will run for the conditions of the natural coastline of İzmir Bay under the changing sea level and extreme wave conditions to evaluate the soft solution option as a measure against coastal flooding.

URI

https://hdl.handle.net/11511/106194

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Department of Civil Engineering, Conference / Seminar