Upper Waitaki braided rivers
IntroductionBraided rivers are important features of the upper Waitaki Basin. Their distinctive wildlife and plant communities make them unique worldwide.
Braided rivers are characterised by their wide gravel beds, numerous channels and highly variable flows. They are geologically unusual and support plant and animal communities that are found nowhere else in the world.
Plains of the upper Waitaki Basin were formed some ten thousand years ago, following the end of the last glaciation. As glaciers retreated, they left behind beds of gravels and boulders.
Rivers spilled out of the Tekapo, Pukaki, Ohau and Ahuriri catchments to deposit more gravels and silts. Together, these combined to form the flat inter-montane (between mountains) basin criss-crossed by meandering river channels that we now call the Mackenzie Basin.
The processes of geological uplift, erosion and alluvial transport continue to maintain our braided river and associated wetlands today. Only Alaska, Canada and the Himalayas have extensive braided river systems similar to New Zealand’s.
Some braided river plants and animals are only found in, or only breed in, the South Island’s upper Waitaki Basin. Project River Recoverywas set up to maintain and restore braided river and wetland systems in this region.