NEW BRIGHTON SAFE.

Press, Volume LVIII, Issue 17471, 3 June 1922, Page 11

NEW BRIGHTON SAFE.

NO DANGER FROM WAIMAKARIRI. EEASSUEING EXPERT OPINION. To investigate the merits of tlie alarm recently raised that New Brixton was about to be engulfed and overwhelmed by a watery invasion from the YYaimakariri river, a party of professional and other gentlemen interested organised bv the Canterbury Progress Lengiie, made a visit of inspection I to the rivers mouth yesterday after- i noon. . , I •The T»artv comprised the following: . Mc-.sr/l>.'Jones, M.P. for hniapoi, Cvrus J. R. Williams (engineer LyttdtJn Harbour Board), A. D. Itobs'an, formerly city engineer), C. H.. Opio ~cnairman' South. Waimakami River Boaid , V YV. Freeman (engineer Newliriyi - ton Boroimh Council. J. L.. .i«nne:-ly secretory Y\ aimakanri Rnei H.>ard). J. Gamble (Mayor U,-) Cr= F. 1>- Muivsou, J. AY. Bisselt, J. S'ott, A. liuhne, and Mr li. *-■ Jenkins (town clerk). Messrs Campbell and G. G. Calvert.Ca.nterl.nrv Collese Engineering School), UB Evans (chairman boor Board). T. deal <°7"*er YYaimakariri River Board), 1.. S>. *wKenaio. an.l P. R. Olimio (organiser Canterbury Progress league). Oil iirriV::] :it Kaiapoi, a motorla unch iva? chartered, and the party is »t out to insoert the river and.its acticn on the adjoining hanks. -U Kairaki the first stop was made. Here, on the northern bank, evidence of pst an'! present souring was only too apparent, i Information placed at the disposal of the partv l.v 3lr V. YV. Freeniim, who hod cloV.v investigated %he matter, I was that in 1350 the northern bank was five chains to the northward o_t the I p-t-ent landing jetty at Kairaki. n 1900 it was two chains distant Irom the jettv. Some twelve houses whieii roriiicriv btof,.i on ixnu land well away from , tlie 'northern bank, had to be slutted las the bink was eaten into. That.pro- «■?-* of attrition is still m operation, jd<Wto the small protective meaw'irei taken, and had the alarm come irom, Kairahi tliere would certainly have been some foundation for it. Mr L. p ; I Evans, chairman of the YYaimakanri Harbour Board, stated that ten years ! i'"o the' river" emptied itself into the sea ju.it below Kairaki, at a spot where tho new.trainiim; wall-was to be built. I Since then, owing to the influence ot the coastal current moving to the eolith, tho mouth moved away from Kairaki until it had reached its present) position. The training wall, however, would confine it to its old out.et. pom Kairaki the party journeyed almost to tho mouth of the river. Hero tho launch was anchored, and a smah squadron, part of the mam body, lauded by means of a punt on the southern shore. This consisted in the main of a series of past or _ present lagoons, all containing at. high tide slack water. At one point certainly a scouring process was in operation, but expert oniuion was to the effect that what was being scoured away was a portion of an earlier accretion, and that a new lagoon was being formed which by tho very reason of its containing the slack water would act as a buffer to direct tho mam stream out to sea. No- expert present considered it at all iikelv that the river would mako its way "inland. An interesting pieco of information supplied to the party was that during its progress to the south from Kairaki the river had never actually taken away any portion of its southern bank, but that if anything the ultimate process was one of accretion. Tho sandspit formed on the seaward side was in reality a new creation due to the action of the ocean current- in with the action of the river, and that even assuming that southern working were to continue indefinitely, tho worst that would happen would be an extension of the present spit not an inundation and destruction of the southern, or, what is more correct, the western bank. The general opinion was that in the event of a heavy flood, coupled with other circumstances such as was imagined gave rise to the alarm., the river would follow the line of loas't resistance, and make its way out to sea by the direct route just below Kairaki. The very existence of the lagoons near the mouth,.which would bo well filled with slack water in tho event of the circumstances postulated occurring would protect the southern bank, just as the

pools or lagoons formed by the groynes I established by the South YYaimakariri j River Board* along that bank of the j river for t';ie safety of Christchurch j meet the force of the current, and so protect the hanks. The whole of the; River Board's operations are based on j the theory that water can most effec- j ! tively be fought with water. I j PROFESSIONAL OPINIONS. J

At the close of the inspection, the leading professional gentlemen present issued their opinions as follows: Mr Cyrus J. R. Williams (engineer to the Lyttelton Harbour Board and an -authority on the action of tidal and other waters) : "I am not at all anxious and I do not flunk there is any occasion for tho New Brighton people to bo anxious." Mr A. Dudley Dobson (formerly Provincial engineer and encineer to the Christchurch City Council, and an authority on the YY'aimakariri river) : "Tho rive- is bound to-cut out sometime, but it will bo out to sea by the most direct route. It will not go to New Brighton. You could not get it there if you tried." Mr P. YV. Freeman (engineer to the New Brighton Borough Council, and an authority on tho past action of the river, at its mouth): "The tendency of the river in flood is to scour towards the north. Tho records as to the position of th-3 northern bank near Kairaki as taken in 1850, in 1906 and again in 1022, show a total erosion of the north bank of five chains at the Kairaki landing stage. The river hits in at the storm water dr.ain at Kairaki and cula out tho deepest and narrowest channel, which has.a depth of about 30ft at low water. Tlie river then widens out and opposite where tho training wall will be" the depth' at present is only o or <3 ft at low water. The extreme range of tho river from Kairaki to the mouth is two anda-half miles. What the river is eating into at. .the mouth is an old accretion. If; this process continues it will form a lagoon of dead water which will act as a buffer for the protection of the southern bank. Should tlie combination of circumstances as feared actually occur, namely a flooded river, a strong wind and a high spring tide, the river will riso to such an extent that it will break through near Kairaki. The lagoon near the mouth will prevent any damage in that d rectio'-i. A study of the surveys of the southern bank from 1850 onwards shows that no erosion has taken place. There »has actually been an accretion. After all, during the last seventy years of which we have records of the river and with all the big floods that have occurred from time'to time, what has she done? Her mouth is approximately in the same position as it was seventy years ago, for' the range from Kairaki to the mouth has never varied beyond two and a-h-lf miles at the most. I 6ee no danger to New Brighton. The distance from the mouth of the river to tho pier is fully five and a-hali' miles, and it has never been more than eight miles." Mr P. R. Climie (organiser of tho Canterbury Progress League) : "Tliere has been a certain.amount of encroachment south towards New Brighton, but not to any extent that could possibly cause alarm. Should an extreme flood occur the river will break through at Kajraki and then, repeating its former process, gradually work south again. Of course if the retaining wall is built by tho Harbour Board that will hold it for all time."