River flood management defences pass test

While yesterday’s flooding caused major disruption to the Wellington region one positive outcome was Greater Wellington Regional Council’s river-based flood protection systems worked well preventing any further inundation.

The flooding experienced yesterday arose from high levels of rainfall overwhelming local stormwater systems, with water draining and pooling in urban areas such as Korokoro, Tawa, Paraparaumu and Paekakariki.

Flood levels exceeded a 1:20 year level flood in the Porirua Stream and a 1:10 year level year flood in the Waikanae River but there was less than a 1:2 year level flood in the Hutt River.

No stopbanks were breached and flood protection systems performed as expected.

“In recent years we’ve have focussed on strengthening “river based” flood protection throughout the region to meet higher standards. Extensive work has gone ahead on the Waikanae River and the Hutt River with standards moving to a minimum 1:100 year level flood.

“It’s an investment worth making. Further work to a higher standard is planned for the lower Hutt River partly in anticipation of higher and more volatile climate-change related rainfall,” says GWRC Manager, Flood protection Graeme Campbell.

GWRC’s flood protection personnel are now inspecting flood protection infrastructure throughout the region and have commenced clean-up activities including the removal of blockages, clearing of culverts and floodgates and the removal of debris.

ENDS

© Scoop Media