“Fantastic” Rainfall Caused Recent Floods

Press, Volume XCVII, Issue 28481, 10 January 1958, Page 8

“Fantastic” Rainfall Caused Recent Floods

The cause of the serious flooding by the Waimakariri river near Belfast recently was explained by the chief engineer of the North Canterbury Catchment Board (Mr H. M. Reid) to a meeting called by the Waimairi branch of Federated Farmers. The meeting was attended by those affected by the flood and members of the board. About 130 were present in the Ouruhia Hall. “Fantastically heavy rainfall” in the catchment areas since early October, and waterlogged stop banks at Englebrechts caused a breach in the main stopbank, and a later breach in the loop bank behind the main bank, said Mr Reid, answering questions. Most of the meeting was taken up with the replies to questions asked by Mr C. J. McFadden, a farmer, who early in the meeting handed written questions to Mr Reid.

"We cannot answer some of your questions because they are a matter of future policy,” said Mr R. M. D. Johnson, chairman of the Catchment Board.

“We had a series of high rainfalls during the last few months. We have had trouble in the back

country—more in three months than in the last 30 years,” said Mr Johnson.

The board was planning a major control plan for the river. This would take some time to complete, he said.

One of the most important questions concerned work done near the Downes road area. Hundreds of acres of land had been lost in this area over a period, said Mr Johnson. Work on North Bank “The work on the north bank is imperative to the welfare of your people' down here. They stood up to the recent buffeting well,” he said. “The railway alignment of the new embankment on the Kaiapoi side has been investigated by us and it is considered that sufficient waterway has been left there. “The recent flood and its implications will be discussed at a meeting we are holding tomorrow,” he said. “Technical points would be best answered by technical staff. We could not answer Mr McFadden’s questions here tonight.” Mr McFadden: I recognise the board is not in a position to answer policy matters, but eight of the 12 questions I have asked could be answered now by Mr Reid.

Answering some of these questions, Mr Reid said that the recent flood was bigger than the 1950 flood.

The river bed at the Main North road bridge had built up over the last 10 years, and the Waimakariri (“an immature river”) would continue to build up, but he hoped that the arresting of bank erosion in the upper reaches would assist the work.

He hoped that the banks would not have to be built-up. The work should be able to be done without this.

He did not think the rail and road bridges increased a flood build-up, but the question of length of bridges would be considered in the major control plan. Protection of City

The protection of Christchurch from flooding by the placing of stopbanks in the upper reaches, and the effect this would have on Kaiapoi and Belfast, was a matter which would have to be given further consideration, said Mr Reid.

The removal of shingle from the river was a policy matter. He agreed that shingle should be taken from the river bed instead of from nearby pits. A small royalty was asked by the board, mainly to keep a check on persons coming into the river because of the likelihood of protection being endangered. In the last three or four years there had only been one application for the removal of shingle, dependent on a company finding a suitable site for its plant, said Mr Reid. South Branch Stopbank The board did not consider it was wise to have broom growing on stopbanks, but a small staff had been unable to handle all the work which had been planned for the year. He was aware that the bank was not in good condition, but excessively bad weather had the board’s staff working full time and staff had been kept on work which was considered of more importance, Mr Reid said A south branch stopbank near Coutts Island, which had in other years saved Belfast and Kaiapoi from flood disaster, said Mr C. Wilson, a farmer, was “the thinnest and lowest and weakest in the river while still being the most important Broom has grown on this for 10 years, and it is a complete disgrace. Labour shortage—five men with a gorse knife could clear this in a day,” said Mr Wilson.

“I thank Mr Wilson for his remarks. He has told me some things I did not know. I don't think the broom would have altered the situation. It is just a very weak bank which we will investigate,” said Mr Reid.

Floodgates were patrolled regu- ■ larly, he said in reply to a ques- • tion. A blockage could be caused i within a few hours. Holes in paddocks where breaks I had occurred would be filled by the board, said Mr Reid. i The main stopbank was not : blown up to save the loop bank, at Englebrechts, as it was not : thought this would have had great effect on the flood level. Any such work would only be carried out as a last resort, Mr Reid said. Flood Warnings Flood lists were kept in the board's office and flood warnings were given by him personally on the Thursday night, said Mr Reid. Many persons in Coutts Island and in Kaianga who could be affected were personally told. He did not consider a radio broadcast was necessary just before the major break-through, but when the break did come, "things happened so quickly we did not have time to do anything other than get around and do all we could.” Radio warnings should have gone out, he said, but had they been given he was sure many persons would still not have acted upon the warnings. Often warnings were broadcast, and actual floods did not eventuate. An article in “The Press” reporting a weather forecast for further heavy rain and possible return of floodwaters had caused complete panic, said Mr Reid. Many families in Kaianga had reevacuated their homes and telephqnea the board’s office all day for information. “This is a sample of the trouble broadcasts can cause,” said Mr Reid. Englebrechts Engelbrechts had been known as a dangerous part of the river for more than 25 years, said Mr E. B. Dalmer (assistant engineer of the board), replying to a question asking for an outline of the history of protective work in the area. Lateral protection work had been undertaken five months ago. The river had been in fresh since early October and there had been nine floods before the major flood. Each of these had waterlogged the banks and on December 12 a 10-ehain breach had occurred.

Work had been carried but from daylight to dark every day after the major flood. A large shingle stopbank, had been erected nine hours before the major flood swept through the river and destroyed the bank.

Mr Reid supplemented this information by saying: "It was primarily the waterlogged country that caused the breakthrough. Fantastic rainfall since early October in the catchment areas caused the trouble."