SILT-PONDING PLANS FOR UPPER WAIPAOA RIVER

Gisborne Herald, Volume LXXV, Issue 22820, 15 December 1948, Page 10

SILT-PONDING PLANS FOR UPPER WAIPAOA RIVER

Four methods of raising the levels of riverside lands by trapping silt from flood-waters were outlined in a report submitted to yesterday's meeting of the P.B. Catchment Board by the engineer, Mr. A. D. Todd, in reference to on area in the upper Waipaoa river valley. One of the four measures referred to by the engineer was the growth of a crop of chou mollier, which a station manager proposed in the hope that silt would be trapped among the stalk of the crop in flood periods without destroying the cron. The other three proposals involved construction of different types of silt-traps, under subsidy by the Soil Conservation Council funds under the river bank protection scheme. In one area above Te Hail bridge the engineer proposed to build a stopbank from higher ground at right angles to the river’s course and then turning up-stream for a short distance to partially enclose an area of 51 acres. This was intended to create a pond in which silt would settle as a result of the slow circulation, of impounded water.

In the second proposal, an area of 15 acres downstream from Te Hau bridge would be partially bounded by a stopbank at an angle to the river's course, with a restricted outlet filled with felled willow growth. This outlet was calculated to slow up (he escape of flood-water and promote precipitation of silt. A further area of 25 acres was subject to the third scheme, which consisted of a scries of stop-banks designed to force overflow water from the river to follow a circuitous course, the force of the flow being broken at various points with the object of encouraging silt precipitation. All three of the physical schemes had been approved on an experimental basis, the board was informed and the Soil Conservation Council had made an initial subsidy of £3 for £1 available for the experimental programme.