NATURAL SPILLWAY

Gisborne Herald, Volume LXVI, Issue 20119, 13 December 1939, Page 8

NATURAL SPILLWAY

LAND AT RIVER MOUTH FLOODING OF WAIPAOA EFFECT OF STOP-BANKS That the expenditure of several thousands of pounds, more than the affected land was worth, would be required before the flooding of the lower reaches of the Waipaoa River could he overcome was the opinion expressed to-day by the district engineer to the Public Works Department, Mr. O. G. Thornton. In connection • with the Waipaoa River Flood Prevention Committee’s proposal to spend £4OO as a temporary measure by opening up a fresh channel on Mr. Wall's property, and so straightening the alignment of the River, Mr. Thornton said it would be a gamble. A new watercourse could be prepared, but it was probable that all the good work would be undone before there was a fresh in the river that would be sufficient to scour a deeper course. A great deal more money would be required to maintain the channel and keep the walls from falling in and filling ui) the bed. Low-lying Land He considered that the land at the mouth of the river formed a natural spillway and . was too low-lying. for. any permanent satisfactory deviation to be made at a small cost. Mr. Thornton suggested that it might be tried, but he would not hold out much hope for the success of the scheme. “With the construction of the stopbanks on the lower section of the river conditions will be chaotic for others in that locality, but it is problematical if the effect of the narrowing of the course there will be felt as far up as Waerenga-a-hika,’” he said. "The rain will have to be exceptionally heavy before the river spills over there and comes down the Taruheru River.” Only one-third of the floodwater was carried in the present course of the river down at the mouth of the Waipaoa River, said Mr. Thornton, who contended that it was interferring with Nature to erect stop-banks. In any case, he doubted if the banks would be of much use in a high flood, as the force of water would be too great to hold back. If the banks were made high the danger would be increased because the force of the impounded water would be increased.