Flood warning systems cope well with downpours

River monitoring systems in the Coromandel region have coped well with the significant rainfall that has fallen in the area over the weekend, says Environment Waikato chairman Peter Buckley.

The heaviest measured falls have been at the Pinnacles where 217 mm was recorded over a 24 hour period, peaking at 32 mm an hour during Saturday afternoon. Further south, the Golden Cross rainfall recorder above Waihi received 181 mm over the same period, and the Te Aroha recorder received 76 mm.

Mr Buckley said the council’s systems for measuring river rises have worked well during the deluge.

“For example, the Kauaeranga River near Thames climbed four metres to a peak of 10.8m. That triggered a series of early warning alarms and a spillway at State Highway 25 operated correctly to the south of Thames to divert some water from the main river at one point.”

Also, early warning alarms were triggered as the level of the Ohinemuri River rose in the Karangahake Gorge, and staff were deployed in case stoplogs needed to be put in place to help contain flood waters at the Criterion Bridge in Paeroa. Fortunately, the eventual peak level did not require full closure of SH26 into Paeroa. However, SH2 through the Karangahake Gorge was closed due to slips and the risk of flooding.

Meanwhile, the Waihou River is above a second early warning level at Te Aroha but the speed of the rise in the river has slowed.

The Waitoa River at Mellon Road on the Hauraki Plains continues to rise strongly, although the level is not a major cause for concern at this point.

Mr Buckley said monitoring and field staff would continue to keep a close eye on all of the various rivers in the area and alert landowners and other agencies if rivers rise to levels that require action.

“While the MetService has lifted all weather warnings for the Waikato region, the long-term weather forecast is suggesting that further significant rainfall and wind may occur during the middle of this week.”