The Wirokino Floodway

Description

Opiki, Makerua, Moutoa and Wirokino had large areas which originally were swamps. The Wirokino Cut, about two kilometres downstream from the Wirokino bridges, was put in, diverting the river from the long loop past Foxton in 1944, enabling floodwater to run out to the sea much quicker. The Manawatu Catchment superseded the River Board in 1945.

A natural floodway of low ground exists on the north side of the river from the Foxton Shannon Road about four kilometres from Foxton to about 11/2 kilometres below the Wirokino Bridge. The Trestle Bridge is over the floodway.

A system of spillways with nine gates was built at the head of the floodway to divert the floodwater from the river, by the Manawatu Catchment Board. This was designed by Mr P G Evans being finished in 1961. The nine gates can be operated by power or manually any, or all at the one time.

The floodway is not activated until the river flow is over 50,000 cusecs (cubic feet per second). This amount is needed to flush out silt from the river otherwise the river would silt up needing ever higher stopbanks.

The area of the floodway is 640 hectares. The river from the spillway to the end of the floodway is 10.5 kilometres and the river with its many curves, is 28 kilometres. The floodway enables the water to reach the Cut much faster, saving flooding of land in the Opiki, Makerua, Moutoa and Wirokino areas. The gates of the spillway were first opened in 1963 and have been operated 13 times to cope with serious floods.

The spillway land is owned by the Catchment Board being leased to farmers for grazing. Ample warning can be given to shift stock to high ground.

With thanks to Mr Colin Cochrane, Foxton, and Mr Jeff Law for help in research.

THE NEWS, WEDNESDAY, FEBRUARY 11, 1987

Identification

Object type

Multi page

Date

February 11, 1987