FLOOD CONTROL.

Manawatu Herald, Volume XLVIII, Issue 3541, 23 September 1926, Page 1

FLOOD CONTROL.

FURTHER EVIDENCE HEARD. ENGINEERING VIEWS ON SCHEME The hearing of evidence by the Mana-watu-Oroua River District Commission in the matter of the proposed £4SO,(XX) flood control scheme of the ManawatuOroua River Hoard was proceeded with on Monday afternoon. Although the River Board’s case was not concluded, it was decided to hear at the opening of the session, as an opportune time, the evidence of Mr ■Gerald Fitzgerald, a civil engineer in Wellington. Witness stated that he had had 12 years’ experience of river control schemes in the Wairarapa. He had also had experience of the Nelson and West Coast rivers. He had been over the ground where the proposed work was to be done by the ManawatuOroua River Board. He had been a member of a commission which sat in Palmerston North some years ago to consider the question of rating and the abolition of the Palmerston North-Kai-ranga River Board and considered that he knew enough of the scheme to be able to criticise it. It was.not the best scheme, but instructed opinion seemed to have decided that it was the only practical one. Increased velocity of the water was one of the chief disadvantages of the scheme and this would mean that, though large quantities of material would be carried put to sea, the residue would be deposited in the channel, causing the current to contort. He had been informed that the stop-banks were to be placed a quarter of a mile apart. He would prefer to have them half a mile apart because, if a succession of floods occurred, there was scarcely time to repair any damage done between the floods. Apparently nothing had been set down for the protection of the banks during construction. He considered that the velocity of the water due to the operations would be not less than five feet per second, and possibly more, so that the .banks would have to be protected, as also would the ends of the groynes. Willows would be useless in places where the tidal waters reached, as the trees would not grow where there was salt water. Witness said that he offered his remarks not so much as criticism but as a help. There were many facts’ that would have to be faced and he thought that they should be pointed In reply to a question by Mr Cooke, witness said lie considered that a quarter of a mile between stop-banks was too little. Some parts of the channel would have to be protected by concrete. He thought concrete slab work, which he described as costly, but permanent, would prove effective. He could not say what distance of the channel would have to be so protected. This, he understood, had not lieen allowed for. Witness stated that the cost could quite easily be £IOO,OOO plus maintenance, which he thought would be more than two per cent. He himself would allow five per cent. To Mr Cooke, witness said that, above the Longburn bridge, the effect of the scheme would be seen and tins would undoubtedly mean more expense to local bodies above the bridge Mr Cooke: What would be the effectof a breach of one of these banks which are to be placed along the river where necessary ? Witness: The water would get in behind and would take a long time to getawav. Flood-gates might relieve the situation somewhat. There was a possibility of the river returning to its old channel in the event of a breach, added witness. He would allow hall a mile between stop-banks so that the river could zig-zag about without damaging the banks. Mr Cooke: What effect would the scheme have on the Foxton bar? Witness: Nothing, unless training walls were erected. Ho thought that the bar would be worse while the work was going on, owing to the _ great amount of material being deposited on the bar. . To Mr Innes witness said that lie had not gone thoroughly into the figures, but lie thought that proper protection would raise the cost by £IOO.- •'”) He considered that the board should have the whole of the watershed under its control. He thought thatthe scheme, if carried out, would afford considerable relief in that the flood level would be reduced. To Mr Baldwin, witness said that the willows afforded excellent protection, but if, for instance, the banks were scoured to any depth too trees would be left on top of the bank and would thus afford no protection to the bank at water level. _ , WORK IN FLAX AREA. The next witness, who was called by the board, was Mr Alfred Seifert, who stated that he had resided in the district for about 28 years and had been engaged in the flax industry for a considerable number ol years. itness described how the Manawatu Railway Company had constructed a drain between Tokomarti and Linton as well as other - drains to demonstrate that there was a fall sufficient to drain the land. He remembered the big flood of 1902 as lie was in Foxton at the time, and returned to his property in a boat. The 1902 flood was the worst lie had seen. A great deal of money had been spent by his company in draining the property. As the land dropped rapidly when the drains were constructed, some ot‘ the drains had to be re-constructed three times to keep the water moving. In the larger drains timber had made the work more difficult. Before being drained the land was waste, but aftrwards 14,500 acres grew good flax. Blackberry had been spread by floods and birds, and it had cost his company over £6OOO since 1922 in destroying it. Goat’s rue was causing trouble and this was undoubtedly due to floods. The owners of the property, when the “yellow leaf” disease destroyed much flax, decided to engage in flood protection as it was thought that the land would eventually have to be used for ordinary farming and this would have been impossible owing to floods. Witness then explained the steps taken in America to avoid flooding by the Sacramento river. A special channel was made parallel to the river and a number of by-pass channels joined the two. In the event of a rise in the river, the water began to flow down the relief channel. To Mr Baldwin, witness said that the Makerua Drainage Board’s idea was to build banks round the property affected to keep the water out. Some of the company’s land which had been cut up into small blocks was very rich and would carry a cow to 1£ acres. If all the sections were sold and settled, the settlers would be depending for i safety on the stop-banks. (Concluded on Page 4).