Also, if the amount of sand from the seaward side is reduced, a beach will erode the land behind it to maintain a constant sand supply. This creates a condition called coastal erosion. Beaches on eroding coasts still undergo seasonal profile adjustments, but they slowly shift their position land-ward as the land erodes. Hardening a shoreline can interfere with necessary profile adjustments because the dune can no longer share its sand with the beach. As a retreating beach encounters a seawall or revetment it can no longer draw upon a land-ward sand supply and it begins to erode.
Beach erosion leads to narrowing and, soon, beach loss.
Much of Hawaii's beach loss could have been avoided if houses were not built so close to the water. The law presently allows homes 40 feet from the shoreline. On coasts experiencing chronic erosion this is too close and leads to hardening in order to protect houses from the waves. Beaches are threatened any time supply of available sand is reduced. The purpose of the CLP is to establish a strategic and comprehensive framework to protect and conserve the state's beaches.