Why does Lake Wakatipu rise and fall?
David Harris
| Last Updated: September 2023 Lake Wakatipu is a jewel in Queenstown, renowned for its scenic beauty, but also harbouring an intriguing secret. Unlike most lakes that maintain a constant water level, Lake Wakatipu exhibits a peculiar ‘tide’ that’s very hard to ignore—a rhythmic rise and fall of its water levels.
So, why does Lake Wakatipu rise and fall? Lucky for you, we know the answer!
Why does Lake Wakatipu rise and fall?
Lake Wakatipu rises and falls due to a phenomenon called seiche. A seiche is a standing wave that occurs in a body of water when there is a difference in water pressure between two points in the lake. This difference in pressure can be caused by wind, storms, or earthquakes.
In the case of Lake Wakatipu, the seiche is caused by the wind. The prevailing wind in the area is from the west.
When this wind blows across the lake, it creates a difference in water pressure between the eastern and western ends of the lake. This difference in pressure causes the water to rise and fall at the western end of the lake.
The seiche in Lake Wakatipu has a period of about 26 minutes. This means that the water level rises and falls once every 26 minutes.
Want to see it for yourself? The seiche is most pronounced in the western end of the lake, where the water level rises and falls by up to 20 centimetres.
The Impact of Lake Wakatipu’s Siche
One of the most significant impacts of the seiche is its potential to contribute to extreme flood risks, particularly when combined with high flow in freshwater coastal rivers.
The seiche also plays a crucial role in the lake’s ecosystem. The rhythmic changes in seiche currents’ direction can lead to horizontal and vertical transportation of heat and dissolved substances.
These movements can influence the distribution of nutrients and temperature in the lake, affecting local aquatic life.
Maori Legends about the Seiche in Lake Wakatipu
The Maori people have long held fascinating tales about Lake Wakatipu. The most famous of these legends tells a tale of forbidden love and a slumbering giant, which explains the rhythmic ebb and flow of the lake’s waters.
According to the legend, a beautiful and talented maiden named Manata, the daughter of a local Maori chief, fell in love with a young warrior named Matakauri. Their love was forbidden, leading to a series of events resulting in the creation of Lake Wakatipu.
The story goes that Matakauri, after rescuing Manata from a gigantic monster named Matau, set the beast on fire while it slept. The ensuing inferno was so intense that it burnt a hole in the ground, which then filled with water, forming Lake Wakatipu.
The giant Matau, however, is said to still be slumbering at the bottom of the lake. The rise and fall of Lake Wakatipu’s waters are attributed to Matau’s heartbeat, as if the sleeping giant’s pulse still beats beneath the surface.
In modern scientific terms, this “heartbeat” is what we mentioned earlier—a seiche. Despite the scientific explanation, though, Maori legend persists, enriching the cultural significance of Lake Wakatipu. It adds a layer of mystique to the already breathtaking Lake Wakatipu.
