THE Hauraki Plains Gazette With which is incorporated THE OHINEMURI GAZETTE. Motto: Public Service. MONDAY. WEDNESDAY. & FRIDAY. WEDNESDAY, APRIL 19, 1922. RIVER IMPROVEMENT.

Hauraki Plains Gazette, Volume XXXIII, Issue 4403, 19 April 1922, Page 2

THE Hauraki Plains Gazette With which is incorporated THE OHINEMURI GAZETTE. Motto: Public Service. MONDAY. WEDNESDAY. & FRIDAY. WEDNESDAY, APRIL 19, 1922. RIVER IMPROVEMENT.

Hon. J. G. Coates, Minister of Public Works, will be in Paeroa next Tuesday evening, and will be remaining in the district until Thursday. During has stay several matters of public importance will be brought under his notice, chief among which will be the vexed question of river improvement, coming under the heading of the “Waihou and Ohinemuri Rivers Improvement Scheme.” Where there are so many aggrieved persons there is always a danger of unwise proposals being put forward,; the weaknesses of which, on being exposed by Departmental engineers, may . nullify what would otherwise be the good effects of general representations. Whatever private individuals may do or say, it behoves all organised bodies to proceed with JUDGMENT AND-CAUTION if the respectful attention of and investigation by the Minister are to be secured. It would be extremely inadvisable for the deputy of any organisation to urge that any work should be carried out which presents unsolved engineering difficulties, or the scientific factors of whicn are as yet undetermined, er probably adverse to the execution of such project. As an illustration, take the proposed Pereniki cut, which, for a layman, or’ .even' an engineer, appears to be a most

HAZARDOUS PROPOSITION to venture upon. Whenever the “Gazette" has had occasion to refer in the leading columns to this proposed deviation we have been careful not to commit ourselves either for or against this part of the scheme. But since there is a feeling in some quarters that the Minister should be asked to have the cut put through, it is timely to point to the possible dangers ahead. It is well known that a deviation in a river such as Pereniki’s cut would mean reducing about four miles of water travel to a distance of approximately a quarter of a mile, which would bring the river down at a greatly accelerated velocity until such time as it had formed a new hydraulic gradient for itself for some miles above and below the point of artificial interference. In the meantime, there would be a danger of the river, during an ordinary flood, inundating lands lying towards Awaiti and Netherton, while a very high flood might cause the scouring out of a new /channel altogether, the damage bf which would be incalculable. Drastic interference with the course of a river is a dangerous enough experiment at any time, but when dealing with a waterway such as the Ohinemuri, in which the bed in the upper portion is composed of rocks and boulders and that in the lower of sand, silt, and other soft materials, the risks are intensified a thousand-fold. We have stated above that the tendency of a river is to form a new and uniform natural grade once the bed has been seriously disturbed in any part (see Omum’s “Regulation of Rivers”), and this x the Oliincmuri rrfost assuredly would strive, to do were the Pereniki cut made. In the course of this readjustment of grade there would be a grave danger of thousands of tons of rocks and boulders now lying in the Karangahake stretch being washed down into the Paeroa area, and from thence past the junction, and we should have the very undesirable state of things whereby there would be BOULDERS IN THE WAIHOU River—and one does not fancy steamboats navigating over boulders and rapids! There would be a danger of ruining the navigability of both rivers irreparably. And the abovementioned possibilities are not all the risks to be reckoned upon. Any layman can • see for himself that there are layers or bands of solid rock across the bottom of the Ohinemuri River in the gorge area, which the river would not be able to wash away for centuries, and so there would, from the lip

of one of these rock formations, be a steep fall and consequent acceleration of the current, and it would be difficult indeed to say what the effect of this velocity would be' when transmitted into the lower reaches where the formation is soft and peculiarly susceptible to boring by the current. There might need to be another line drawn on the map to denote the course of the river. Notwithstanding the above, we do not say that the Pereniki cut should not be excavated, bur we do hold most emphatically that it is a matter to be settled entirely by responsible engineers of the highest qualifications, without pressure being brought to bear by laymen, however intelligent and conversant with the local rivers they may be. What is wanted more than anything else at the present juncture is information as to the intentions of the Public Works Department in regard to works to be. gone on with, and in this resnect the request of the Thames Valley Drainage Reference Board for a COMBINED CONFERENCE is undoubtedly a move in the right direction. A conference between engineers of the Public Works Department and local bodies’ representatives, at which the undesirable element of suspicion was absent, would do much to clear up misunderstandings. At present all parties outside the Public Works Department are more or less in the dark. Not that the engineers are to blame, for it is a point of etiquette and policy that none but a Minister of the Crown -is entitled to disclose the intention of any Government department, and the degree of candour shewn by departmental engineers even at a conference would depend upon the latitude allowed them by the Minister in charge. This brings us to a point worthy of serjovis consideration. The Public Works Department was instructed by the 1921 Commission to give an estimate of the cost of carrying out the River Improvement Scheme recommended by the 1910 Commission, and the estimate reached the staggering figure of £625,000—a prohibitive cost. Now, it is in the very highest degree probable that the Department has a well-thought-out scheme of its own ; it is morally and in self-respect bound to. So why not strongly urge upon the Minister that the ratepayers should bg informed of the

DEPARTMENT’S OWN SCHEME and the estimated cost thereof The officers of the Department could not disclose their proposals without the sanction of th,e Minister of Public Works, and since the Hon. Mr Coates will be in the district next week it would be folly not to seize the opportunity to request him to enlighten the tributaries to the River Improvement Scheme as to the plans favoured by the officers of his own Department. This, in our view, is the most important request—along with the dredging of the river question involved in it—that could be made to. the Minister, and we trust that the keynote of all representations will be one sounding for complete and definite information.