Towards improving the prediction of longshore sediment transport

摘要

Bulk formulae are often used in coastal studies to estimate the net longshore sediment transport (LST) rate. For the same hydrodynamic conditions at a given beach, rates of LST predicted by different bulk formula can vary by factors in a range between 2 and 10, and may not actually reflect the real LST rate. This can have serious economic consequences when designing, for example, beach nourishment schemes. The present paper attempts to reduce these errors and presents a more accurate, site-specific methodology to estimate LST. The study, from four contrasting locations, draws on existing theory and field measurements of' hydrodynamics and suspended sediments in the surf zone to develop a new longshore transport model, LT-MOD. Case studies are used to compare the performance of LT-MOD against existing bulk LST formulae at daily time scales. This inter-comparison is then extended over much larger temporal and spatial scales by examining measured and predicted shoreline changes attributable to LST.