Physically similar extensive braided rivers are rare world-wide and occur only in Alaska, Canada and the Himalayas. Canterbury contains 60% of the braided- river habitat in New Zealand, and the Mackenzie Basin contains some of the most pristine of these rivers.
Globally, braided rivers are rare. They occur only where a very specific combination of climate and geology allows rivers to form ever-changing and highly dynamic ‘braided’ channels across a wide gravelly riverbed.
New Zealand is a braided river hot-spot. Almost 64% of our braided rivers are in Canterbury, with a catchment of over 164,170ha. Indeed, the entire Canterbury Plains was formed by sediment and gravel carried from the Southern Alps by braided rivers as they flowed to the coast. Southland, the West Coast and Otago regions also feature spectacular braided rivers.
Braided river systems are a rare geological feature evident in only a handful of other countries. New Zealand has a significant number of these riders.
A braided river (also called braided channel or braided stream) consists of a network of river channels separated by small, often temporary, islands called ‘braid bars’ or, in British English usage, aitsaits or eyots. (Wikipedia)
These unique river systems support a vibrant and diverse ecosystem that stretches from the mountains to the sea, ki uta ki tai. A wide variety of birds, fish, reptiles, invertebrates, plants, lichens, mosses and fungi, many of which are now threatened or endangered, have adapted to thrive in these challenging and dynamic environments, each of them dependent on one another.
Over time, the ecological and biodiversity values of our region’s braided rivers have deteriorated as a result of weeds and pest animals, water abstraction, land development, river control works and encroachment, climate change and damage from recreational use. These once-thriving biodiversity hotspots need our help to protect their endangered ecosystems from extinction.
Sources: https://braidedrivers.org/rivers/#1; https://www.ecan.govt.nz/your-region/your-environment/our-natural-environment/our-regions-biodiversity/braided-rivers/canterburys-braided-rivers/
