First steps to renew Waiohine flood defences
New flood hazard information for the Greytown area will help the community and councils plan better flood defences for the future, says Greater Wellington Manager Flood Protection Graeme Campbell.
This is the first step of a plan to review the flood risks on the Waiohine and lower Mangatarere floodplain, indentify areas unsuitable for development and build better flood defences.
The new information shows the extent that floodwater would spread on the floodplain of the Waiohine and lower Mangatarere rivers in a 1 in 100 year return period flood event.
The information will be used to develop a Floodplain Management Plan with the community. This information was sent to landowners and residents over the past week.
Greater Wellington gathered this information for the Waiohine and lower Mangatarere rivers using aerial surveying equipment (LiDAR – Light Detection and Ranging) and using rainfall and river modelling techniques to determine flood risk areas.
Mr Campbell says: “Now we know where the water is likely to go in a major flood, we can work out how best to protect property and which areas are too risky to develop.”
He says Greater Wellington is very keen to work with the community.
“It’s the community’s property at risk so we need the community to be involved in managing the risks. We’ll be talking to the people of Greytown and the surrounding areas about this to build a picture of their expectations as we go.
“The current flood defences in the lower Waiohine River are designed to protect Greytown for a 1 in 20 year flood event. There is plenty of room to improve on that.
“We have set up a committee of locals who know the river well, along with district councillors and hapu to help with advice and gathering people’s views.”
Mr Campbell says developing the Floodplain Management Plan will take time.
“There will be a couple of years of planning before we turn the first sod, but the end result will mean better flood protection for Greytown and people affected by the Waiohine and Mangatarere rivers.”