Feasibility study of an artificial sandy beach at Batumi, Georgia

Abstract

This master thesis aims to determine the best design option and the feasibility of an artificial sandy beach along the Old Boulevard of Batumi, Georgia. The coastline south of Batumi is affected by erosion problems. The coastal stretch between the port in the north and the Chorokhi River south of Batumi should be protected. In 2010 Alkyon/ARCADIS proposed a detailed design to protect this coastal stretch. The beaches of Batumi originally consist of pebble. In the northern part of the coastal stretch, the so called Old Boulevard, a lot of tourist activities takes place. For this reason sandy beaches where requested by the client along this part of the coast. In the design proposed in 2010, pocket beaches have been envisaged here. In this thesis an alternative design for the pocket beaches are proposed. This design should contain more sand and less visual structures, opposed to the pocket beaches proposed in the 2010 study. In order to determine suitable measures and alternatives, the morphological impact of the measures and the corresponding sediment transports have been considered. The sediment transport rates have been computed using numerical models. For the longshore transports the model UNIBEST-LT is used and the cross-shore losses are determined with the use of the XBeach model. With the use of gained information of the behaviour of a sandy beach and possible measures to optimise the design of an artificial sandy beach, 7 alternatives are proposed. The 7 alternatives are compared and assessed with the use of a Multi-Criteria analysis (MCA). From the MCA can be concluded that a perched beach with a beach placed parallel to the boulevard is the most promising alternative. A preliminary design has been prepared for this alternative. The perched beach consist of a sandy beach with a width of 135 meter. At approximately 180 meter from the shoreline a submerged breakwater is present with a submergence of 0.5 meter. The pocket beaches as designed in the 2010 study and the preliminary design of the perched beach as designed in this study are finally compared. The pocket beaches have a partly sandy beach and contain some undesirable visual structures. The perched beach fulfils the wish of a fully sandy beach with almost no visual structures, the costs are however considerably higher than for the pocket beaches, 25.5 M€ versus 56.6 M€. It can be concluded that the two options have their own benefits and drawbacks. The preference depends on which aspect is valued as most important and/or which aspect is valued as least important.