A: About 100 years ago, rivers and creeks were dammed to prevent flooding. This was effective but overlooked that rivers and creeks carried sediment out into the ocean. This sediment provided the necessary resupply of sand every year to our beaches. Municipalities that regularly resupply their beaches with sand and installed retention systems, such as Newport Beach, are not experiencing erosion issues. In contrast, cities like San Clemente failed to recognize the importance of annual replenishment accompanied with retention systems and are now scrambling to save their beaches.