Right on Auckland’s doorstep is an area of absolute beauty. I’d been there many times as a child but only recently discovered it is a hot spot for learning about science. Come with me as we explore the Hunua Falls!
This post is also available as a video:
The Hunua Falls are on the Wairoa River, near Hunua. The land around was bought by Auckland for water supplies between 1940 and 1960.
The falls are around 30 metres (100 feet) high with the cliff face extending another 20 or so metres below the surface of the water and are an example of a Horsetail waterfall. This is where descending water maintains some contact with bedrock, and it looks kind of like a horse’s tail.
The falls were formed when the Wairoa River encountered and flowed over resilient basalt rock of volcanic origin on the Wairoa Faultline. Over time this created falls with a large pool at the base of the falls. In the side of the cliff faces on either side of the falls, you can see volcanic tuff rings and lava bombs present. The Hunua Falls Volcanic Neck is a geopreservation site of regional importance and is identified as an Outstanding Natural Feature in the Auckland Unitary Plan.
The Wairoa River is the largest river system in Tāmaki Makaurau and drains a large section of the Hunua Ranges and surrounding farmland. This is why after heavy rains the falls can go from an outflow a few centimetres high to one that is metres high and washes out everything it encounters, as is seen in this this picture from the Auckland Star in 1928.
The area is of special ecological significance to the region, featuring endangered herb lands.
At the falls, the flat area around the pool and the spray zone surrounding the falls have a huge biodiversity value. This is because the vegetation includes good examples of lakeshore turf, and there are few remaining quality examples of lakeshore turf in the region. The ecosystem here has been noted as Critically Endangered in the region.[7]
The lakeshore turf supports a wide range of native herb species. These grow in fine soil particles that have accumulated on rocks or rock platforms.
Lakeshore turf is also known as herbfield. This is a narrow band of habitat on the shallow slopes of lake shorelines, between the permanent aquatic vegetation and taller lakeshore sedge or shrub ecosystems. This zone is an ephemeral wetland, which is seasonally wet. Soils are generally raw sand or fine gravels and may also contain silts and clays.
A diverse range of herb species are present, with few species taller than 20 mm high. These are joined by a wide range of wetland birds. At Hunua Falls this was almost entirely ducks on the day we visited.
Several herbs have been identified near the falls – water starwort (Callitriche petriei), Crassula hunua, water pennywort (Hydrocotyle microphylla), and wood-sorrel (Oxalis magellanica).
The banks of the river feature plants that are flood resistant. They bend over backwards as the water level rises and bounce back up when the flooding subsides. These include carex grasses, umbrella sage, and toetoe.
The plants hanging over the edge of the water provide shade, which keeps the water comfortably cool for those who live in it. They also help stabilise the banks and the shade they create reduces weed and algae growth.
The water itself is quite murky because much of the water has drained over ‘soft geology’ – things like mud and clay, rather than rock. The water flow loosens the clay particles, and the river starts to look like mud soup!
While fish can’t fly, they can certainly climb. Young eels (elvers) and kokopu wriggle up the wet edges of the waterfall, inching onward and upwards on their fins, resting up in pools and eddies along the way. This allows them to reach the best habitat where the water is clean and clear, and their favourite foods are abundant.
Surrounding the falls is the Hunua Ranges Regional Park. The largest area of native forest in Auckland, the ranges cover roughly 400 square kilometres along the southeastern side of the Auckland region, of which 140 square kilometres or 14,000 hectares are the park.
The park has over 450 species of native plants, and many native birds and other vertebrates, including the rare North Island kōkako and the Hochstetter frog (one of the world’s most unusual which makes no noise and doesn’t have webbed feet).
Many of the walking tracks around Hunua Falls are closed due to Kauri Dieback precautions. Ensure you clean your shoes thoroughly at the marked stations. Swimming at the falls is not recommended due to many dangers, including variable depth (and hidden rocks), strong currents, and underwater obstacles.
If you’d like to check out Hunua Falls, they’re located 45-60 minutes’ drive, around 50 km from Auckland, and sadly there is no public transport option. There is a large carpark with picnic and toilet facilities, with a very accessible walk for a few hundred metres from the carpark to the base of the falls, or another path that takes 10-15 minutes, which is the one we took.
We visited on 5th January 2022
For more information:
https://www.tiakitamakimakaurau.nz/discover-tamaki-makaurau/learn-about-your-area/bfa-hunua-falls/
https://en.wikipedia.org/wiki/Hunua_Falls
https://waterfalls.co.nz/types-of-waterfalls#Horsetail
https://www.iexplore.com/destinations/new-zealand/Hunua-Ranges-Auckland
https://www.aucklandnz.com/visit/destinations/auckland-east/hunua-ranges
https://www.newzealand.com/nz/feature/hunua-ranges/
https://www.myguideauckland.com/things-to-do/hunua-ranges-regional-park
Note: This article and video were made purely for the purposes of research and education and to entertain others through learning. The author takes no commercial gain from images included for which he is not the copyright holder. This article was not sponsored or funded.
consilience 
thanks for sharing your guided walk and talk via your uTube video…
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