The Response of Beaches to Sea-Level Changes: A Review of Predictive Models

Abstract

Models are reviewed that have been proposed to predict beach-profile changes that result from a rise in water level, and include predictions of the resulting shoreline recession rates. The best known model is that of Bruun (1962), while more-recently developed models include an entire barrier-island system or focus on the erosion response of beaches and dunes to the brief elevation of water levels associated with a storm surge. Testing and application of the models for beach responses to a long-term rise in sea level have been hampered by significant lag times of beach changes, amounting to months or years, and the importance of sediment-budget balances that can produce shoreline erosion or accretion irrespective of any sea-level rise. Profile changes assumed by the models have been reasonably well verified by laboratory and field studies, but the predictive equations are found to yield poor results when the effects of profile lag times and complete sediment budgets are not included in the analyses. Recommendations are made concerning additional field and laboratory studies that should be undertaken to improve our understanding of beach responses to elevated water levels.