Ripples under combined flow: Gediz and Büyük Menderes cases

Seabed forms, which are the micro components of the sediment transport, varies according to the hydrodynamic conditions and sediment characteristics. Although the studies on the determination of these variations under either wave or current are much, the studies on the development of seabed forms under combined flow conditions are relatively rare. On the other hand, there are not any studies focusing on these forms for the Turkish coasts. The thesis study was performed with this motivation, by conducting fieldworks in different seasons at Gediz and Büyük Menderes river mouths, in order to investigate the development of seabed forms and their dynamics under combined flow. The studies included the in-situ determination of the ripples via underwater photography and the measurement of ripple dimensions. Additionally, current-wind measurements and seabed sediment sampling were made in order to determine the hydrodynamic conditions and sediment properties of the study areas, respectively. Furthermore, the physical properties of the seawater was measured at both sites. The phase diagrams and analytical models from the literature were tested with the parameters obtained from the results of these measurements and their analysis. Further to that, new approaches for ripples were developed by the determination of the parameters affecting the ripples using dimension analysis and regression analysis. As a result of these approaches, three new phase diagrams were developed and ripples were categorized using these proposed phase diagrams. Additionally, an analytical model was developed using the thesis data. This model enables to determine the dimensions of the ripples under two different conditions.