KING tides are somewhat mysterious events, but for the people of Swansea they are part of life.
They are the highest tides that occur twice a year, once in summer and the other in winter.
They are related to the rotation of the Earth, the alignment of the sun and moon, and the gravitational pull they exert on water.
Brigid Phelan, who grew up in Swansea, said king tides were exciting when she was a kid.
‘‘We loved to see the water rising up,’’ Ms Phelan said.
King tides rise to about one metre above mean sea level in Lake Macquarie.
That’s the level climate change scientists predict the lake will be in 2100.
Lake Macquarie City Council has joined a program called Witness King Tides, which aims to raise awareness of the phenomenon.
Council sustainability manager Alice Howe said the program was an opportunity for people to ‘‘become more aware about what the impacts of future sea-level rise might be’’.
Dr Howe said king tides particularly affected Black Neds Bay and the ‘‘granny’s pool’’ at Blacksmiths on the ocean side of Swansea Bridge, where the tidal range was highest.
But they cause flooding in some Swansea streets, with salt water penetrating drains.
‘‘In the future the whole lake would get pushed up by sea-level rise, so the level you see around Swansea in a king tide would be around the lake,’’ Dr Howe said.
Green Cross, an organisation that former Soviet Union president Mikhail Gorbachev started, runs the Witness King Tides project.
Project co-ordinator Caitlin Calder-Potts said the project involved people taking pictures of king tides in their neighbourhoods.
‘‘The purpose is to understand what rising sea levels will mean for coastal communities,’’ she said.
High tides occurred every month and, ‘‘If there’s weather events that coincide with them, they can be bigger than king tides.’’
Swansea Commercial Fishermen’s Co-op has a picture, right, of its flooded building in the Pasha Bulker storm in 2007.
‘‘It hasn’t flooded like that since,’’ a worker said.