GREEDY WATER’S TOLL

Evening Star, Issue 19198, 15 March 1926, Page 2

GREEDY WATER’S TOLL

THE HUMP-BACKED WAIAPU A RIVER WITH A CAMBER BRIDGE BUILDERS’ LONG FIGHT. The Waiapu River—the nearest big river to the East Cape—and its feeders, rising 5,000 ft in, twenty miles, amid country whore rain has been known to fall to the extent of 30in in six days, is credited with delivering the bridge site at a speed of -011 a second, with a midstream crest estimated to be sft higher than the bank level of the water. - This river defeated the bridge builders for fifteen years; destroyed £15,000 to £20,000 worth of bridge material; swept away complete bridge, sections; scoured out and threw down individual piers; dragged one of them 29tt upstream; drove a bole, ranging Lorn 3ft to ].oin in width, through a 12in thickness of standing reinforced- concrete pier, and is credited with transporting boulders 7ft in diameter. The evil which has been wrought has, it is stated, been facilitated by deforestation. The Prime Minister, the Right Hon. J, G. Coates, recently opened the Rotoknutuku Bridge over the Waiapu. Incidentally, Mr Coates is reported to have mentioned that Waiapu means, in Maori, Greedy Water. If so, it is well named (remarks the ‘Dominion’). Over a period of a decade and a-half the Waiapu has devoured half a dozen times or more, the successive efforts of the bridge builders. Incidentally, it has destroyed or carried away at least 1,000 acres of high quality land in fourteen years. Attempts were made at two different sites, eleven miles apart. The river demolished each of the incomplete structures from time to time, and in 1916 it overwhelmed them both at the one time. Eventually the lower site, at Tikitiki, was abandoned. Efforts were concentrated at Rotokautuku, and the contractor (Mr Nichol) fought the river for four years, two and a-half of which represented progressive building, while the balance of a year and a-half was occupied in watching the river knock over the work and in repairing damage. The estimated cost was £21,530, and he eventually completed his tremendous task for £23,570 —which is cheap if it be known that the wasted efforts at the two sites, before the final contract, bud already accounted for £16,000 or £l7,ooo—a sheer sacrifice to the Greedy Water. AN OLD STORY REPEATED. A little above the Rotokautuku Bridge two rivers junction. They are flic Mata and the Tapuwaeroa. Below the junction they go by the name of Waiapu. The .basin which these rivers drain rises sharply. The rise is estimated at 5,000 ft in twenty miles. In such conditions floods must be severe even with an untouched forest holding together the banks and the hillsides and regulating the water flow. But deforestation—about which Government engineers sounded a warning in 1914, if not earlier—has told its tale. _ln deforested, denuded country of this character the run-off is terrific. The old story of rivers overleaping their alleged maximum flood levels—after the country has been “ opened up ” —was repeated by the Waiapu. Sometimes individual piers, unsupported by a complete superstructure, wore knocked down and swept away. Sometimes a completed section of bridge was similarly treated. Once when the bridge was determinedly forcing its way out from one bank toward the other, the river ran round behind it and turned into an island. These remarkable facts are drawn from files of the Public Works Department and from statements by eye-witnesses and residents made to Public Works officials, by whom they were partly recorded in writing. UNEVEN HEIGHT OF FLOOD.

Not only were previous flood levels exceeded. Tho Waiapu also achieved in its 1016 flood an astonishing height of midstream level over and above the water level at tho hank. It is declared that the Hooded river not only rose in the middle, but that the middle water was about sft higher than the water-at the bank edge. One has beard of tho camber of a road. When gathering the material of this article the writer first hoard of the camber of a river. The evidence on which it rests includes not only what people saw of tho height of the waters in midstream, hut tho actual depositing of driftwood on the decking of hridgework or known height. Timber already on the decking was moved by tho water.

This evidence of tho depositing and movement of heavy articles—recorded in the department’s files—of course, goes beyond any mere visual observation of tho height of some portion of this raging torrent. From the closelyobserved level of the water at tho bank' and tho evidence of what happened on midstream decking of a known height it is deducted that the camber of the Grectiv Water was not less than 511.

While turning over the files, the Chief Engineer of Public Works, Mr F. W. Furkert, said that, many engineers would reject this statement, but he would not. Ho would be prepared to accept it. Ho, had himself .seen evidence of flood water being all over the deck of a bridge in midstream, hut at the hank, not, up in the corbels.