Newcastle's coastline is subject to a range of coastal hazards including:
- erosion and recession
- cliff instability.
is the offshore movement of sand from the sub-aerial (above water) beach during storms (1)
. Erosion is a natural process, with beaches subject to cyclic erosion and accretion (when sand builds back up on the beach) (1)
. During periods of erosion, storm waves move sand from the beach and the dune to offshore storm bars (1)
. When the calm weather comes back and accretion begins, sand from the offshore bar moves back onshore to establish the beach and onshore winds blow sand back into the dunes (1)
. When a beach is stable, erosion will not result in a long term landward movement of the beach (all of the sand that moved offshore during a storm eventually moves back onto the beach).
is the long-term movement of the shoreline landward caused by a loss of sand (1)
. Recession occurs when some of the sand is lost from the system. For example, a breakwater can interrupt the flow of sand to adjacent beaches, which results in less sand being available for the beaches to re-establish and long term landward movement of the shoreline.
(Source: DLWC (2001)(2)
is the flooding of land by ocean water and waves.
Coastal cliff instability
is the possible structural incompetence of cliffs and slopes along the coastline (3)
. Instability can be caused by erosion, scour and water seepage (3)