The beach environment undergoes not only the diverse regular daily and seasonal changes of conditions but also the unpredictable changes due to extreme weather, unusual tides and the impact of people.
Water and wind are two of the most powerful agents of change in nature, and their effects are readily seen on all beaches. Waves can move great quantities of beach material such as sand and shingle and wear away cliffs and rock. Wind can create and reshape sand dunes (tāhuahua). Like waves, wind can also wear away cliffs and rock and even uproot seaside plants.
Change can come from the land as well as the sea. Flood events can send huge amounts of water down rivers, carrying debris such as trees, branches and silt downstream. If this material builds up in estuaries, the river’s course can change, leaving tidal mudflats high and dry. The debris left over from logging operations known as slash causes many problems for the inhabitants of river valleys and the seashore.
Image: Pollution from the Fox Glacier landfill being washed down the Fox River and along the coast, DOC, CC BY 4.0.