Siltation Problems at the Landeyjahöfn Harbour, Iceland : Governing Processes and Coastal Evolution

Sammanfattning: The Landeyjahöfn Harbour, located on the south coast of Iceland, has since its opening in 2010 been suffering from siltation problems. Sediment deposited in the harbour entrance, preventing the ferry to run at full capacity. The problem was addressed in previous studies, but without arriving at a sustainable solution, stimulating the present study with the overall objective to investigate the sediment transport, coastal evolution, and the influence on the harbour. Wave data, measurements of bathymetries, shorelines, and beach profiles were used in the analysis to provide sufficient information for reaching a solution that improves the conditions at the harbour. The wave transformation model EBED, together with a 58-year long time series of input wave data, was used to simulate the nearshore wave climate. The resulting nearshore waves were further used as input to the longshore sediment transport model Qtrans and the regional shoreline evolution model Cascade. The model simulations showed that the location of the harbour is in an area with a complex transport pattern. Accumulation is likely to occur in this area, which would be one reason for sedimentation inside the harbour. Placing long groins or jetties that reach past the bar could be a solution to decrease the longshore sediment transport at the harbour. However, further investigations are warranted to find the most appropriate solutions to improve the conditions at the harbour.