Flood levels in western Wellington region

Unlike the Wairarapa and Manawatu, major rivers in the western part of Wellington region have generally sustained moderate flood flows in the southerly storm that swept the lower North Island last night, although there is a lot of surface flooding.

Greater Wellington Regional Council staff have been monitoring river levels on the Hutt, Wainuiomata, Waikanae and Otaki rivers, as well as the Waiwhetu and Pinehaven streams, since yesterday afternoon.

Of most concern is the Wainuiomata area where about 212mm of rain has fallen in the last 24 hours. Peak flow readings for the Wainuiomata River show a greater than 20-year flood return period. This is the largest recorded flow in the Wainuiomata River since records began. The river flow seems to have peaked at 8am this morning and appears to be dropping. Staff are in Wainuiomata checking for any potential damage to the flood defences, but these are expected to hold.

Other rivers in the region have sustained flood readings of about a five-year event. Smaller streams in the Hutt Valley have received significant flows. The Waiwhetu and Pinehaven streams have had some water entering garages and houses, and water up to car windscreens.

The Hutt River has reached around five-year peak flow levels. While there is some riverbank erosion, there are no reports of significant damage to the flood defences on the Hutt River. The flood peak has passed Birchville and is now at Taita Gorge, and river flows appear to be flattening out or dropping, according to Laura Watts, Greater Wellington hydrologist. However, as further rain is forecast this morning, it is possible this could be short-lived, and high tides could aggravate the situation at the Estuary Bridge later in the day.

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