REVIEW OF FLOOD DAMAGE

Press, Volume LXXII, Issue 21730, 12 March 1936, Page 12

REVIEW OF FLOOD DAMAGE

EYRE AND CUST RIVERS WAIMAKARIRI TRUST TO ASK FOR SUBSIDY The damage done in the recent floods by rivers under the Waimakariri River Trust's control was re» viewed at som* length at a meeting of the trust yesterday. The trust had before it a report prepared by its engineer, Mr H. W. Harris, in which it was estimated that repairs and relief works on the Cust and Eyre rivers would cost 42400. "The time of the floods was probably the most anxious the trust or the members of its. staff have ever been through," said the chairman, Mr J H. Blackwell, when the engineer's report and also a report on the floods by the foreman, had been read. The anxiety bad been caused, he said, not so much by the Waimakariri as by the smaller rivers from the foothills, the Cust and the Eyre. On the engineer's recommendation, the trust decided to ask the Government for a subsidy on the money needed for repairs. "The flood oh February 20 was probably the greatest that has ever been experienced in both the Cust and Eyre, and was undoubtedly much greater in discharge than that of May, 1923," Mr Harris said in his report, "All the rivers except the Waimakariri were called on to carry very much more water xhan they were safely rated to carry, and on the whole did so with comparatively little damage to property or construction work. The Eyre designed to carry 8000 cueecs, was discharging about 18,000, and the Cust's additional discharge was almost as big. Value of Diversion

"The Eyre diversion again demonstrated its great value, as a relief channel to all the countryside lying to the eastward of it, -including the borough of Kaiapoi, and Collier's creek diversion undoubtedly saved the country belcw it right down to o#hoka0 # hoka from tremendous damage from* its flood waters. The Waimakariri, although nine feet and a half above normal on February 20, did no dam* age. A flood of similar discharge before the present protective works were built would have resulted in damage to the extent of some thousands of pc/tmds, It may reasonably be said that the protective works put in by th-a trust have been well justified, and have in great measure so far performed well up to their designed standard. "It must be remembered that the floods of February 20 were exceptional, and although a recurrence is possible at any time, a similar flood would not occur, under the laws oi periodicity, for probably 100 years. In these circumstances, protection from such a flood is not justified from an economic standpoint, and it is cheaper for the district to be protected from smaller floods only, which occur so much more often, and carry the risk and resulting damage from the great floods which occur so seldom. Expense of Complete Immunity "In most places where overflows occurred, partial protection would be of little use, and could only result in overflow at other points. To give complete imn.unity along the whole length of the Eyre river would cost many thousands of pounds, and be much beyond the capabilities of the districts to carry by way of additional rates, which would be necessary. Neither of the floods on March 3 and 9 caused overflow. '*lt is estimated that repairs and relief works on both rivers Will cost about £2400. This includes the replacement of three groynes lost, re-* pairs to others damaged, and additional works required. The floods have amply demonstrated the need for keeping the beds clear of growth, as the flood waters have little, if any, effect in clearing them, especially in the lower reaches. The growth greatly retards the flow in higher flood levels and increases danger." Mr Harris suggested that as the original works on the Eyre and Cust were subsidised, the Government ShoUld be asked for a subsidy on the expenditure needed for repairs and relief, and this the trust agreed to do. OUTLET NOT YET COMPLETED LAKE FORSYTH RISING PART OF ROAD STILL FLOODED Though it was considered last evening that there was no immediate danger of further serious flooding at Little River, Lake Forsyth was still rißing and the outlet on which work had been begun during the day had not yet been completed. The road between Little River and Birdling's Flat was covered with water in several places to a depth of about a foot and reaching well up to' the running boards of cars. The toad is undermined in places. Mr A. C. Renner, the county engineer, said he hoped that the outlet would be completed by this morning. Though there'was a southerly wind he did not consider that this was strong enough to cause any trouble in the

work through driving the shingle back. There is still a great deal of water running down the creeks, which will continue to raise the level of the lake till the outlet is made. A further rise of six inches would make the road impassable. The road which was being formed over the slip at Red John's Gully, half way up to the Hill Top, enabled small cars to get across yesterday, but ser-j vice cars were Unable to get through,' and mails had to be carried over the i slip. It has also prevented the collec-1 Uon of cream from the Peninsula since last Friday week. It may be necessary, to collect the cream from the isolate* area.and carry it over the slip, which cannot be cleared away for about a fortnight. At Okain's Bay the creaitt was being removed by boat. Great damage has been revealed now that the storm is over. Gardens have been washed out, and the cross on the Roman Catholic Church has been blown down. Thefe are innumerable slips round the hills and nearly all the tracks are impassable. Okuti was still flooded yesterday. Chains of fences had gone. Losses of stock are being discovered in the slips. Both tfain and telegraph services have been restored.