Water flow
Water flow is naturally influenced by the catchment and the shape of the river. Humans can alter water flow by straightening channels, building dams and taking water from rivers for irrigation or other uses.
Dr Eloise Ryan explains the effect of water flow on native species.
The following resources explore river catchments, native fish habitats and water flow and human influences on water flow.
Articles
Interactives
Transcript
DR ELOISE RYAN
There are a lot of things that impact river flow. For example, the steeper the land, the faster a river will flow. Also the width and the depth of the river – deeper, wider rivers seem to flow faster. Also the shape of the river. If it’s a straight channel, that can raise a number of issues. For example, when you straighten channels the river will flow faster, and when it flows faster, it will remove the soil from the stream bank and add more sediment in. Also high water flow during flood events will rip out any type of planting along the stream bank and make it more susceptible to being impacted by what’s on the land. Water flows slower round natural rivers that are curvy, and we call that meandering. This is important, because a lot of New Zealand native species are adapted to slow-flowing water. So if we go and straighten out our rivers or concrete the channels, a lot of our fish aren’t going to be able to be adapted to that and that will negatively impact them.
Acknowledgements
Dr Eloise Ryan
Waikato Regional Council
Flooded river footage, Bart van der Wee. Released under CC BY 3.0
Footage of flooded farmland, Henk van Zyl
Acknowledgement
This video has been developed in partnership with the Waikato Regional Council as part of the Rivers and Us resource.
