Accounting for the Local Wave and Morphodynamic Processes in Coastal Hydraulic Engineering

Abstract

Purpose. Estimates of wave parameters in the coastal waters are of great practical importance for designing and operating coastal infrastructure facilities. On the example of the Saki bay-bar region (Western Crimea), the experience of studying the wave and morphodynamic processes in the coastal zone is presented being applied to the tasks of designing and building protective hydraulic structures. Methods and Results. Mathematical modeling of the wave and morphodynamic processes in the area under study was done using the following: spectral model of the wind waves SWAN, hydrodynamic model SWASH, complex morphodynamic model XBeach and integral model of the coastal zone evolution GenCade. The wave regime was analyzed using the 41-year time series (1979–2019) of wave parameters resulted from the retrospective calculations of wind waves based on the SWAN model and the ERA atmospheric reanalysis data. The operational and extreme characteristics of wind waves were obtained. The spatial structure of the wave fields for different types of wind effects was modeled. The most intense waves are shown to occur during the southwest wind. The height and length of wave run-up on the coast and the coastal zone profile deformations for the storms of different durations were estimated. The values of the total annual along-coastal sediment flow in the design area were obtained for 1979–2019. In 70% of the cases, the sediment flow was established to be directed towards the Evpatoriya coast. Conclusions. The studies have shown that neglecting scientifically based recommendations when designing coastal infrastructure facilities can lead both to disruption of the existing system of the coastal zone natural formation, and to significant negative consequences for the coastline of almost 10 km length. These consequences can be manifested in a reduction of the beach zone width, a decrease in elevation marks, and replacement of sand with the pebble-gravel fractions in some areas that worsen recreational features of the beaches. Having been analyzed and taken into account, the planned location of the base of the enclosing wall shows that in some parts, the embankment wall can be possibly washed away and damaged. These conclusions were confirmed in practice already during the facility construction. Based on the results of the performed study, the constructions contributing significantly to the changes in the coastal zone morphodynamics were recommended for exclusion from the project