Wetlands can act like an emergency brake in flooding situations, according to Nelson Lebo.
Dr Lebo is keen to raise awatreness of wetlands - and also to mark World Wetland Day which falls on Thursday, February 2.
He and wife Dani have turned a portion of their Whanganui farmlet into a wetland, by putting up 500m of fence to exclude stock and planting 1400 native plants and trees.
The Purua Stream runs through the gully. It turns into a torrent in heavy rain and the long grass, harakeke (flax), rushes and trees will slow its pace on the Lebo property.
The vegetation in the valley will also have other values for wildlife.
The Lebos have had lots of help with the project. Two schools, the public and the late Chris Cresswell all helped with planting, and there were donations from Whanganui garden centres, the public, Bunnings and Horizons Regional Council.
The farmlet is now an accedited place where visiting interns can earn their Permaculture Design Certificates after 10 weeks of part-time work and learning. On Tuesday two interns were hand weeding and watering the native plants.
Mr Lebo said those more than a metre above the valley floor were extremely dry, despite a wetter than usual start to summer. They have all been hand weeded monthly, and were sprayed with a mixture to repel hares.
Only one has died, and 400 more have been potted up, ready for planting this winter.
The movement of water through that section of valley is already slowed, Mr Lebo said.
"What's most dramatic is just getting stock out of the water allows the grass to grow right into the water."
It's only a small patch of wetland, but he said every little bit helps.
"It's the collective effect of every piece of land use that makes the impact."
WETLANDS
+ are permanently or temporarily covered with water
+ trap sediment
+ return nitrogen to the atmosphere
+ maintain water tables
+ create habitat for wildlife
+ slow flooding
+ store carbon
+ in New Zealand more than 90 per cent have been drained