Build breakwaters, jetties, and groynes perpendicular to the beach. This does indeed catch sand on one side of the jetty as ocean current flowing along the shore flows past the jetty. Unfortunately, on the leeward side of the jetty, sand disappears faster than ever because the current-deposited sand isn't reaching it. When a row of seaside property owners all build their own jetties, this results in an unappealing, unnatural looking, spiky shoreline.
Build seawalls parallel to the beach. However,seawalls "may accelerate beach erosion by reflecting wave energy off the facing wall, impacting adjacent property owners as well," says "Dr. Beach", also known as Dr. Stephen Leatherman of the National Healthy Beaches Campaign. In short, as with jetties, the problem just gets moved around along the beach. Attempts to stabilize coastal property by nailing it down with bulkheads or seawalls risks "complete wetland loss", according the Delaware's Department of Natural Resources and Environmental Control. Since coastal wetlands help defend the coasts against erosion, this only worsens the problem.
Maintain a berm and dune system. When not blocked by infrastructure, dunes naturally migrate inland over time, leading to some semblance of a restored natural system of beach replenishment. However, development upon these areas then brings that process to a halt; the dunes have nowhere to go.
Dredge huge tonnages of sand from off-shore sources and deposit the sand upon threatened beaches. Beach nourishment can indeed rehabilitate a stretch of coastline several miles long, delaying deterioration for several years, especially when supplemented by planting sea oats or other shore-loving vegetation to hold down the dunes.. But it is hugely expensive and, in the long run, temporary.
Stop building dams and levees on rivers. Rivers depositing sandy sediment accumulated upstream are the chief mechanism for replenishing beaches. When rivers are tamed and curtailed for human convenience, this starves the beach of fresh sand. Instead, this material silts up along the riverbank. The levees along the lower Mississippi River have resulted in New Orleans settling ever lower until it is below sea level, because the Delta has been starved of he sediment that created it.
Solve global warning and stop contributing to greenhouse gases, which are warming the planet faster than expected, which is melting the polar ice-caps, which is raising sea levels and increasing the total energy stored within the atmosphere, which ramps up the violence of ocean storms, which digs harder into beaches and carries more sand away.
Stop building and developing directly upon vulnerable beaches. Research by Orrin and colleagues of Duke University demonstrate that one factor in increased beach erosion is over-development.
