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La nina empties rain gauges, lowers rivers

Wednesday 28 November 2007, 6:21PM

By Taranaki Regional Council

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TARANAKI

Taranaki’s environmental watchdog is keeping a close eye on rainfall gauges and river levels as the current La Nina weather pattern begins to bite.



The Taranaki Regional Council, which monitors rainfall and rivers at more than 20 sites across the region, is warning those who take water for municipal supplies, irrigation or other purposes to also keep a close eye on the situation.



The Council’s Director-Resource Management, Fred McLay, says dry conditions can be expected to continue under La Nina this summer and some rivers will be at or near the point where water-take must be restricted if there is no rain in Central or South in the next three weeks.



“Although we’ve had a reasonably wet winter, not much of that rainfall is stored in our soils so we don’t have much in reserve to cope with prolonged dry spells,” he says.



“Rivers can easily come under pressure and that is what we are keeping a close eye on, and what those who use river water need to be aware of.



“Those waterways with riparian planting are able to cope much better with increased temperatures and reduced flows.”



So far this month, less than a third of normal November rainfall has been recorded at Tawhiti, near Hawera, while Cape Egmont and Pohukura Saddle have had less than a half. New Plymouth has had 65%.



September was also dry, though October was damper. Year-to-date rainfall is between 75% and 95% of normal at the four sites.



Three Taranaki rivers were below their mean annual low flows (MALFs) today (28 November). Another five rivers are near their MALFs.



Rainfall and river flow statistics in detail:





Rainfall

New Plymouth (Mangorei Reservoir):

September 62.5mm (41% of normal September’s 153mm).

October 158.5mm (85.6% of normal October’s 185mm).

November (to 28 November) 97mm (65% of normal November’s 150mm).

Year to Nov28 1436.5mm (85% of normal 11-month’s 1684mm).



Cape Egmont:

September 61.5mm (54% of normal September’s 114mm).

October 153.5mm (124% of normal October’s 124mm).

November (to 28 November) 44mm (45% of normal November’s 98mm).

Year to Nov28 992.5mm (75% of normal 11-month’s 1297mm).



Hawera (Tawhiti)

September 33.5mm (42.5% of normal September’s 79mm).

October 114mm (122% of normal October’s 93mm).

November (to 28 November) 30mm (31.5% of normal November’s 95mm).

Year to Nov28 839mm (94.5% of normal 11-month’s 886mm).



Pohokura Saddle

September 97mm (50% of normal September’s 195mm).

October 216mm (105% of normal October’s 206mm).

November (to 28 November) 83.5mm (44.65% of normal November’s 187mm).

Year to Nov28 1480.5mm (81.6% of normal 11-month’s 1814mm).



River flows



Below mean annual low flow (MALF) at 28 November:

Patea River at Skinner Road (also near reduction/cut off point for those with consents to take water from the river).
Manganui River at Midhurst.
Mangaehu River at bridge.


Nearing MALF and/or resource consent reduction or cut-off point at 28 November:

Kapoaiaia River at Cape Egmont.
Punehu River at Pihama.
Waingongoro River at Eltham Road.
Waiongana River at State Highway 3A.
Waiwhakaiho River at Egmont Village.