FLOOD MENACE.

Press, Volume LXII, Issue 18625, 25 February 1926, Page 8

FLOOD MENACE.

CONTROL OF WAIMAKARIRI. RIVER TRUST'S SCHEME. To hear an outline of the scheme in connexion with the loan proposals for tho control of the Waimakariri river by Mr F. C. Hay, A.M.1.C.E., Consulting Engineor, a number of farmers, representatives of local bodies, and members of the publio met last evening at tho Chamber of Commerce HalL Mr A. Manhire, who presided, 3aid that as tho Waimakariri River Trust was in favour of "raising a loan of £200,000 for protective work, it was considered fair to those interested that the scheme should be explanied. Apologies for absence hg,d been received from tho Mayor (Mr J. K. Archer), Hon. L. M. Isitt, M.L.C., Mr D. Jones, MP., Crs. A. D. Ford, G. P. Agar, A. McKeilar, Messrs J. H. Blackwell, and P E. Climie. A New Channel. Mr Hay said it was proposed to construct a,channel, which would carry oft' a greater amount of flood water than had so far bocn in the river. With the aid of a largo plan he explained the work in detail. The first operation would be the stabilisation of the river mouth, to help the spit fropi wearing away, and the mouth from altering to the south. This would bo done by means of a bulkhead, of which the estimated cost was £SOOO. A channel would bo made as far as Stewart's Gully bridge, and the bridge over tho Gully would be extended. In addition, the rock barrier would be romoved. A main highway bridge would take the place of the Empire bridge, and the North road would be shortened. The Empire bridge would remain. The structure replacing it would cost about £21,000, of which it was proposed to apply for £IO,OOO from the Main Highways Board; it would be 1120 ft long. The material used in the piles would be reinforced concrete, and tho bridge would have steel joißts. The nextwork was a diversion across Mr Wright's property, finishing at Stewart's Gully.

Protection of Chrislichurch. About 16,000 acres of tho riverbed could bo reclaimed and utilised. Stopbanks would be erected where required for the protection of Cliristchureli, and groynes' along its course would assist in confining the river to its channel. Similar defensive work would be done on the north bank for tho protection of Kaiapoi, and the work already done by tho Eiver Trust would bo incorporated into the scheme. The undertaking would finish at Courtenay, and at this part of the river it was proposed to put in extra strong and heavy groynCß to cheek the shifting of shingle downstream in flood times. _, A second object of the groynes would be to check the addition of shingle to the riverbed by erosion. Eyre and Oust Bivers. Mr Hay then explained the plan again, beginning at the works it is proposed to undertake near. Courtenay. The Eyre and Oust rivers wero also to be dealt with under the scheme of works to cost £45,000. The former would be diverted to the Waimakariri river.

In reply to a question as to whether tho works at the mouth were intended to be effective or merely experimental, Mr Hay said that former works of the nature proposed had already proved successful. Danger to Ohristdiurdi. Replying to further questions as to whether Christchurch was in any danger from the Waimakariri river, Mr Hay said the highest observed flood was 120,000 cubic feet per second, and an abnormal flood might discharge 150,000 cubic feet. Ho was certain a flood of this sizß was possible in tho Waimakariri, perhaps once in fifty or sixty years. Christchurch would then be in danger, as it would receive the bulk of the water. It was quite apparent that the riverbed was getting worse, and must continue to do so. Dredging Impracticable. Dealing with tho proposal that dredging should be undertaken, Mr Hay said that to do this thoroughly would cost £2,500,000, and would take about one hundred and fifty years. The proposition was not feasible. No modified scheme could be adopted to give sufficient protection meanwhile, and any substitute would be more costly than that favoured by the Trust. The scheme could not possibly be carried on out of rates.

The scheme adopted would entail the expenditure of from £IOO,OOO to £150,000 on labour, and the employment of about 200 men for three years. Two alternative schemes had been considered by the Trußt, but both had. been rejected in favour of that adopted. The use of open groynes had been considered, and experiments were being carried out with them where the, force of tho river was not great; Criticism of Scheme.^ Mr J. Wright condemned the scheme, contending it would convert a great deal of the best agricultural land, including his own, into riverbed. All the roads in the district would be wiped out by the scheme. He had held his land for forty years, and had made no claim for compensation through the recent floods. Mr Hay said it was for the Trust to say whether the interest on the loan should take the place of the present rate, or be raised by an' additional rate. Mr C. Morgan Williams said the scheme had been adopted by the Trust without the preparation of sufficient data, but this statement was contested by Mr Hay. At the conclusion of the meeting Mr Hay was accorded a vote of thanks.