This thesis.uses a novel composite approach to investigate the long-term dynamics of sediment transport on Shelly Beach, Otago Harbour, New Zealand. This approach combines qualitative and quantitative methods including field measurements of coastal processes and morphological change, numerical modelling, analysis of bathymetric charts, comparison of oblique and aerial photography, and evaluation of anecdotal data in order to better understand aspects of both natural and anthropogenic systems forcing the evolution of this coastal system. Shelly Beach is a narrow sand spit that has been subject to significant human modifications. The approximately 1 km long beach is constrained between two rock groynes and. backed by a single line of dunes. The main hydrodynamic conditions acting upon this mixed low-energy environment, wave and tidal processes, are in a very delicate balance with the medium, well-sorted sands composing Shelly Beach. The chronic erosion experienced by the coastal system up until 1985 represented a serious hazard for human activities. To mitigate the erosion hazard, a combination of dune management and renourishment of the nearshore was implemented. Sediment transport paths were infe1Ted from the interactions between natural and anthropogenic processes and morphological responses. Results from process-based empirical models of sediment transport and long-term morphological evolution evidenced that artificially nourished sediment is moved onshore from the inner nearshore of Shelly Beach towards the subaerial beach and along the surf zone. In the subaerial beach, sediment is transported by wind and accumulated in the dunes. During high-energy wave conditions, a cell-circulation of currents is induced and sediment is transported offshore along the edges of the beach. Based on the composite approach analysis of sediment transport patterns and a sediment budget formulated for Shelly Beach between 1987-2004, a simple, yet accurate, conceptual model was elaborated. The model depicts a thorough understanding of the long-term morphodynamic evolution that strictly qualitative or quantitative approaches do not allow. The qualitative character of the conceptual model makes it a robust tool for coastal management, applicable to any environment where human influence is a significant process of coastal change.