Coastal erosion is the loss of land due to coastal processes such as waves and tidal currents wearing away that land suddenly or overtime.
Coastal inundation is flooding from the sea. Coastal inundation modelling shows which areas might be flooded in the event of a storm surge and to what depth they may get flooded.
Flooding is the covering of normally dry land as the result of extreme rainfall. Flood modelling shows which areas might be flooded in an extreme rainfall event and to what depth.
Land instability refers to land which has the potential to slip when saturated with water. Generally, it is steep slopes and cliffs prone to slipping.
Liquefaction happens when saturated soils lose strength and stiffness (behaving as a liquid rather than a solid) in response to earthquake shaking.
A tsunami is a series of waves generated when a large volume of water in the sea is rapidly displaced.