Catchments saturated in Waimakariri

Nicole Mathewson Reporter from Northern Outlook

From local democracy reporter David Hill:

Waimakariri is awash after the recent rain, as the risk of major flooding increases.

After three heavy rain events last month, Waimakariri District Council three waters manager Kalley Simpson says groundwater levels are similar to the levels after the June 2014 flood event.

‘‘The catchments in the district are saturated and groundwater levels are high, therefore there is an elevated risk of flooding due to rainfall events over the coming months.

‘‘We will continue to closely monitor and respond to any future wet weather events, taking into account this elevated risk.’’

Simpson said the July 26 rain event was the largest, and it followed heavy rain events on July 12 and 20.

Woodend (119.6mm) and Kaiapoi (109.6mm) received the most rainfall, followed by Rangiora (78.6mm), Mandeville (72.2mm), Summerhill (near Oxford, 61.8mm) and Oxford (47.2mm).

Undercurrents were also flowing at a particularly high level in the Mandeville area, he said.

‘‘This event (July 26) was more of a coastal event and was in the order of a 20 to 30 year event over 24 hours for Kaiapoi and Woodend, which experience the higher levels of rainfall."

The council did major infrastructure work following a series of heavy rain events in 2014, while stormwater work had begun in Kaiapoi as part of the Government’s Covid-19 ‘‘Shovel Ready’’ funding.

Simpson said the upgrades had generally performed well, while the stormwater improvement areas in Kaiapoi, including Feldwick Drive and Otaki St, had experienced flooding as predicted.

‘‘There was surface flooding across the wider district, most of which was in known areas of flooding where we have investigations or upgrades under way.

Some areas flooded unexpectedly, such as in McDougal Place in Kaiapoi.

‘‘We had staff and contractors out responding to and observing the event and have identified the source of flooding which we will address.’’