Other formats

    TEI XML file   ePub eBook file  

Connect

    mail icontwitter iconBlogspot iconrss icon

Nelson Historical Society Journal, Volume 2, Issue 5, November 1971

Waimea River Estuary — Changes During The Last 120 Years

page 26

Waimea River Estuary — Changes During The Last 120 Years

The map on the opposite page shows the course of the Waimea River in 1850 from information on a chart of Nelson anchorage surveyed by Captain Stokes R.N. (H.M.S. Acheron). Superimposed on this is a simplified modern map of part of the Tahunanui-Nelson present day shoreline.

In 1850 the Waimea Bank extended from Rabbit Island to opposite the dressing sheds, and tide water from the Waimea River entrance (shown on the 1850 chart near where the Hounsell Circle is now situated) sounded about 25 feet at low water.

The sketch made in 1843, on the cover of the November 1968 issue of this journal (Vol. 2. No. 3) shows deep water and cliffs at the site of the present day junction of Rocks Road and Tahuna Beach.

Bolton Hole, between Haulashore Island and the Waimea Bank, then about 53 feet deep at low water, is still deeper than the sea bed being about 35 feet lower than the surrounding shoals. During northwest gales vessels used to take refuge about a mile upstream from the river mouth behind the Waimea Bank. The Tahuna Beach sand-spit now occupying part of the area formerly covered by the Bank, has built up notably during the last two or three decades.

Reports of the City and Harbour Board Engineers made ten years ago emphasise the tendency for the beach to build up towards the north, there being evidence of at least five beaches formed northwards from about Quarantine Road.

By about 1875 the Harbourmaster (Captain J. S. Cross) had observed heavy shoaling in the channel and a breach cut itself through the Waimea Bank so that the estuary emptied out to sea just to the east of Rabbit Island. This led to the formation of the Tahuna Beach, its mudflats (including the Back Beach) replacing the river bed and covered nowadays only at spring tide. Many Nelsonians remember the swampy nature of the present playing fields, their filling up at high tides, and the large sandhill, Tahunanui meaning large sandhill or sandbank.

As is the habit of rivers in wide, low beds the main tidal stream of the Waimea River meanders from side to side, in this case apparently about once every 150 years, or more. Whether or not the outflowing river will complete its present meander and return to flow along the Beach and Rocks Road, possibly cutting off the sand-spit, or whether the Waimea Bank will reform or rearrange in some other formation is unpredictable. Present day conditions governing the tidal flow are quite different from those of 120 years ago—the Boulder Bank has a wide cut through it and there has been extensive shoaling outside the Haven; and bush has disappeared from the ranges allowing erosion and flooding, while the watertable of the Waimea Plains has been systematically lowered by drainage, and more recently by irrigation, reducing the normal flow of the river.

The effect of these unknown and variable factors on the sand-page 27spit at Tahuna Beach will continue to be watched with considerable interest and concern.

The map was kindly drawn by the Lands and Survey Department, Nelson. Information was also obtained from Nelson Harbour Board charts and from reports in the "Nelson Evening Mail."

The map was kindly drawn by the Lands and Survey Department, Nelson. Information was also obtained from Nelson Harbour Board charts and from reports in the "Nelson Evening Mail."