Sand Storage at New Zealand's Tidal Inlets

The ebb and flood tidal deltas of inlets act as sinks for sand derived from the adjacent beaches and the inner shelf. In response to the need to evaluate coastal sedimentary budgets and assess the availability of sands for industrial supply and beach nourishment, sand volumes in ebb tidal deltas on the New Zealand North Island coast were estimated and the factors controlling sand storage investigated. Morphological and empirical analysis showed that the quantity of sand stored and the shape of the sand body were determined by the tidal prism, the configuration of headlands at the tidal inlet, the alignment of the outflow jet with respect to the shoreline, the wave climate, and the amount of littoral drift. The implications of these results to sand management and for predicting the impacts of rising sea-level are explored.