THE WAIMAKARIRI.

Star (Christchurch), Issue 16750, 3 June 1922, Page 13

THE WAIMAKARIRI.

VISIT OF INSPECTION. A very reassuring view of the probable course of the AYaimakariri River was brought homo to a large party of representative Canterbury men who visited Kaiapoi yesterday and made a launch trip t-o the mouth, at the instigation of the Canterbury Progress league. Any fears that the river might break through in the direction of New Brighton were diseipatod by the opinions of engineers and others of the party who were in a position to speak with authority. The party consisted of Messrs P. R. Cliraie, organiser to the Progress Teague : D. Jones, member for Kaiapoi ; Cyrus 'Williams, engineer to the Lyttelton Harbour Board; A. I>. Dobson: C. H. Opie, chairman of the Waimakariri River Board ; F. IV. Freeman, engineer to the New Brighton Borough Council ; J. L. Scarvell, late secretary- to the Waimakai*iri River Board ; J. Gamble (Mayor), F. D. Muirson, J. W. Bissett. J. Scott, A, Hulnie and H. L. Jenkins, (town clerk), representing the New Brighton Borough Council ; R. A. Campbell and G. G. Oalvert. of the Canterbury College staff; L. B. Frans, chairman of the Waimakariri Harbour Board : T. Jenl, overseer to the Waimakariri River Board ; arid R. S. M.’Kcnzie. MOVEMENT OF MOUTH. The Waimakariri. as it approaches the sea south of Ivaiapoi. forms a big lagoon or estuary, ns tbe earliest charts show. Towards the northern end of this body of water lies Kairaki, and there is a fairly substantial strip or land at that point between tbe river and the sea; but as the river runs southwards seeking an outlet tbe sandspit narrows, and disappears finally wherever the river elects to overflow into the Pacific. The mouth moves north or south over u range of two and a half miles. At present it .s situated at the southernmost end of what may be called, the lagoon, although tho current runs swiftly in flood and eats awuv tho bank in one directiou, while sand-spits form whore previous! v there was only a sheet, of water. Hie , question which yesterday's party set out; to investigate was whether tbe river, having secured the most southerly outlet in the area shown on the charts ns a lagoon, was not likely to overflow inland towards New Brighton, and sweep down on the sandhills, thus creating an enlarged estuary in the direction of the city. Contrary to this view, the consensus of opinion was that the next big flood would wash out a new mouth on the low spit of pur© eand just smith of Kairaki, where the stream has previously discharged itself in a deep channel, an.l that as years went on the month might shift gradually south under the Influence of north-easterly winds and sea currents, until nature took a hand again and broke through at Kairaki once more. TRAINING WALL PROPOSED. 1 As a permanent solution of the diffiIcultv of a moving bar. the Kaiapoi tf arbour Board proposes t-o put. a trainI ing wall diagonally across the main stream just south of Kairaki, to create, and maintain a. permanent mouth and channel ot that point, where in times i past the most satisfactory entrance has * existed. This proposal was explained to the party by Mr L. B- Evans, chairman of the harbour board, ns the launch passed tbe spot. He stated that the training wall, 1200 ft long, had been reported on favourably by two firms of engineers. Tt would cost. £ LI ,000 and authority for raising the money had been given at a poll of ratepayers, but it was necessary to obtain Government authority to pay the- extra rate of interest to ensure the flotation of the loan. However, it was not intended to rush the work ahead. The wall would send the river out to sea at a point where it had not broken through for the Inst ten years; hut where there had always been a good bar while the river was discharging there- This would put an end to the | river problem and create a good bar for shipping coming to Kaiapoi. EROSION NEAR KAIRAKI. The effects of erosion near Kairaki were apparent n_s the launch passed the spot, and it was state* 1 tliut since 190« J twelve houses had had to he moved, while others were at pre>ent near tho edge, and local residents had strewn logs and trees along the waterfront to prevent further erosion. From this yioint southwards the low hank of saml between the river and the sea was followed as it gradually narrowed down to the point, at which the river discharged. Here a party went ashore on the city side of the mouth. At this point the stream, Indore turning sharply to the left to flow out to sea, was striking against a substantial clay bank, but was getting past the l>oiik on the eastern side, and it was in this direction that danger had Wn said t > exist. An examination of the dry land, however, showed that it was the bed of a former shallow lagoon, which appeared to haxo extended another halfmile towards a distinct honk of Binidliills surmounted by gorw bushes and lupins half a mile away. At what level this range of sandhills lay. and what was tho level of the land behind it. it was impossible to say, ami the shore party did not investigate, ns a strong wind was blowing; a penetrating rain heavily from the northward. Mr Bisset !• here left tho party to walk along the beach to New Brighton. The launch returned to Kaiapoi at o p m., and after a. Into afternoon tea at Mr J. H. Blackwell’s establishment, motored bock to town. EXGIN KER *S OP INX >XS. Mr Freeman, who has had ample i first-1 end opportunities to investigate the river, and who is engineer to the New’ Brighton Borough Council, gave his opinions to Press representatives present at tho request of the Mayor of New' Brighton, who professed himself reassured by wlia.t lie had heard during the visit. Mr Freeman said that the tendency for the river in flood waa to scour towards the north. That it had done so was shown from plans he had prepared of the north bank from Kaiapoi to the mouth. From 1850 to 190(1 the erosion at the Kairaki landing stage had brew throe, chains, and from 1900 to the present day a further two chains, or fire chains in all. Tho rivor was striking in n.fc Saltwater Stream, just north of Kairaki. and gouged out the deepest and narrowest channel to a dopt of 30 feet at low water. It then widened cut until opposite tbe. site i of the proposed training wall, where it. r as -ix feet deep at low water. The month changed its position from time to time over ; n extreme range of two and a half miles. The river at- the southern end was striking either an secretion from the time when the mouth was going north, or it might be new land. But there was no cause for alarm, for when a combination of circumstances occurred, such a a strong flood in the river, with suitable winds and a. high tide, the present course of tlie stream would become dead water, and it would rise and break through at Kairaki. The prevailing wind and currents being from lh« north-east. J would then -ause a southerly drift of the mouth, and in ten years or so u

might work south again to where if na« now. Measuring the distance of the pre6ont month from New Brighton Pier, Mr Freeman showed that in was five and k half miles. The mouth, he said, had never been further from the pier than eight miles. He added that he had looked up the surveys of land at Brooklands made in 1863, and taken up in 1863, end conld find no erosion. "Tn fifty years.’’ Mr Freeman added, “what has this river done? The mouth has Keen changing over an extreme' range of two and a half miles.’* OTHER OPINIONS. “ T am not at all anxious, <*nd I don’t think the people of New Brighton need, b© anxious,” said Mr Oy rus "Williams. He added that without data to co on he would not express a more detailed opinion. Mr A. D. Dobson, speaking from n long experience of the river, expressed r view almost identical with that of Mr Freeman, that a break through at Kairaki was most probable. This view was also taken by Captain Featherston. harbourmaster tit Kaiapoi. Mr Cliraie said that lie saw no reason to change the opinion lie had previously expressed, that although there had been a certain amount of encroachment south toward* Now Brighton. it had not been by any means alarming. With an extraordinary flood, which was now overdue. the river would break through at Kairaki. From that on. unless the training wall was built, the river would commence, to work southwards again.