Stilling wave basins for overtopping reduction at an urban vertical seawall - The Kordon seawall at Izmir

Reduction of wave overtopping at urban coastal structures is a significant concern as uncontrolled flooding, and the wave forces disrupt the daily flow of the urban life causing damage to people, structures and economy. However, the design of these structures needs to consider the spatial and visual demands of the urban function that restrict the crest heights. Therefore, crest modifications such as a storm wall, a bullnose or a combined structure like Stilling Wave Basin (SWB) can be used to optimize the crest height for lower overtopping values. Although reduction factors of these modifications have been studied for sloped structures in EurOtop (2016), there is relatively limited dataset regarding the vertical structures. This paper presents the results of wave overtopping experiments for an urban vertical wall with low crested Stilling Wave Basin structure with foreshore, under impulsive wave conditions. Over 150 tests have been carried out using a model of a seawall and promenade combined structure based on the urban vertical seawall of Kordon, Izmir. A variety of design parameters such as the pattern of gaps, blocking coefficients, and promenade are investigated under constant hydraulic conditions to optimize SWB design for this urban vertical wall structure. The hydrodynamic conditions for overtopping experiments are designed to test the applicability of the empirical formulas of overtopping over vertical walls for impulsive waves in EurOtop (2016). A method, calculating reduction factors, is determined for the finalized SWB design for a broader spectrum of hydraulic boundary conditions (0.40 <= H-m0/d(w) <= 0.90, 1.22 <= T-m-1,T-0 <= 2.02 s, and 0.106 <= d(w) <= 0.20 m) of the impulsive wave with 0.708 < R-c /H-m0 < 2.091.