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A comprehensive study of swash-zone sediment transport was conducted on a macro-tidal beach in Perranporth, UK. The unique study is the first to simultaneously measure suspended sediment and sheet flow sediment concentrations and near bed velocity on a natural beach. Data collected during the study will be used to address the importance of sheet flow processes on swash zone sediment transport and morphology, the variability in the near bed velocity profile and the importance of alongshore and vertical flows, cross-shore advection of turbulence and the inference of swash zone forcing and momentum transfer from remotely sensed data.

A sediment budget analysis model was applied to the Tweed River entrance, and was used to evaluate different coastal management scenarios. Construction of training walls at the Tweed River entrance resulted in the accretion prior to 1994 of an estimated 7 million m3 along Letitia Spit, New South Wales (to the south), and erosion of beaches at the Gold Coast, Queensland (to the north). The Tweed River Entrance Sand Bypassing Project (TRESBP) was established in 1994 and is responsible for bypassing sand from south to north, through dredging campaigns and a permanent bypass jetty. The Inlet Reservoir Model was developed by Kraus (2000) as a tool to analyse morphology changes at inlets. The inputs for the model were the estimated monthly longshore sediment transport rate, and the monthly pumping and dredging volumes from the TRESBP. Side-scan sonar surveys of the entrance bathymetry were used to validate the model over the period from 2000 to 2009. The validated model was used to examine bypass pumping strategies to manage the Letitia and Gold coast beaches, maintain navigability and minimise dredging costs. According to the model results, annual bypass pumping needs to be less than 325,000 m3 to manage the recovery of the Letitia Spit shoreline, and annual dredging of approximately 125,000 m3 is required to maintain full navigability in the Tweed River entrance.

Robust measurements of bed shear stress under wave runup flows are necessary to inform beachface sediment transport modelling. In this study, direct measurements of swash zone bed shear stress were obtained in medium and prototype-scale laboratory experiments on steep slopes. Peak shear stresses coincided with the arrival of uprush swash fronts and high-resolution measurement of swash surface profiles indicated a consistently seaward sloping swash surface with minimal evidence of a landward sloping swash front. The quadratic stress law was applied to back-calculate time-varying friction factors, which were observed to decrease with increasing Reynolds number on smooth slopes, consistent with theory for steady flows. Additionally, friction factors remained relatively constant throughout the swash cycle (except around flow reversal), with a variation of approximately ±20% from the mean value and with only small differences between uprush and backwash. Measured friction factors were observed to be larger than expected when plotted on the Moody or wave friction diagram for a given Reynolds number and relative roughness, consistent with previous field and laboratory studies at various scales.