THE WAIKATO RIVER

Pukekohe & Waiuku Times, Volume 9, Issue 562, 31 August 1920, Page 2

THE WAIKATO RIVER

AND PROBLEMS TWAIN.

NAVIGATION' AND RECLAMATION

RANGIKIRI FOREST PERIOD

RESTORATION OF CONDITIONS

SOLUTION OF DIFFICULTIES

("Times" Staff Reporter,)

The ways of the mighty Waikato River have provided interesting material for research by the geologist and scheming by engineers. In the dim distant past, say, 100,000 years ago, the Waikato River, we are told, came not out to sea by its present course, which is the ancient but enlarged bed of the Waipa River", only. The Waikato rushed down the liinuera Valley and out to sea in the Thames district, assisting to form the Piako plains in the process, which soil in some places is of exactly the rame constituents and proportions as contained in the Mercer swamps. The Waikato, according to some authorities, had yet another course, running through the Bay of Plenty, the changes being due to earth disturbances, probably by earthquakes. But the period that interests us to-day in a practical sense, as distinct from the academic, is that stretching from about So years ago to the present time, because it is assumed that during this short space, which is merely a flash in the aeons of time, the Waikato River has silted up, causing overflowing of its banks during floods, a permanently higher water level, and the creation of water-log-ged swamps. An interesting address was delivered to a large meeting of ratepayers and others interested in Waikato River problems in the Mercer Town Hall on Saturday afternoon. Mr. A. C. Glass (chairman of the Waikato River Board) presiding. The speaker was Mr. C. H. McCutchan, of Onehunga, who was at one time prominent in connexion with the Rangltniki drainage scheme, and he held his audience very attentive indeed throughout, Referring to engineers' reports on the Waikato River levels. Mr. McCutI chan said:-

"One would have expected that any report of a comprehensive nature dealing with present day Waikato River conditions would have made interesting reference to two remarkable features which strike theordin-

(try layman as highly suggestive. The tirst is the fact that tributary streams are uniformly deeper than the parent river—Whangaramino, for instance, being some 15ft deep—and the second, no less surprising, that swamp areas at present more or less water-logged were at one time dense forest country, as evidenced by stumps and boles up to four feet in diameter showing not a branch for "in and 60 feet.

"Now deducing from the engineers' reports, it is quite impossible that such forests could ever have existed! We have, therefore, to evolve for ourselves a working hypothesis based on the facts as we find them. "The question naturally arises: Was tidal action the same during the forest period as it is to-day '! I suggest an affirmative, with the possibility that tidal affects extended to Churchill or nearby. "And, secondly: What were the liver levels ?

"Now, at Rangiriri, where I had the opportunity of observing these old-time forest giants, it is obvious that the river levels must have been 7ft, if not 10ft lower than at present in order to obtain forest conditions. Working back from this point on the engineers' levels, which no doubt are correct, to the bar at the mouth, we cannot get the river dowfe at Rangiriri unless we lower the serf four to six feet! Therefore there never could have existed a forest- at Rangiriri! But the evidences are there nevertheless in silent moclcery of ourselves, our engineers, and piei' reports and estiinates,.Ja'om A tt> Z ! " What we have to/doVthen, Is to reconstruct we/can. the conditions ©btfining dWinJ the forest period, and if we suweed in doing this we shall have possibly solved the Waikato River problem. " Now, those of us who remembei the Waikato before the Tarawera eruption must be Cognisant of a deadly process of deterioration, slow, silent, relentless, unremitting. " Again, as regards tradie conditions before the advent of the railway, wharves'andytat ions that were worked in those-ffays could not now be handled by the'same craft. Going baok further to the time of the war in 'Jhe sixties, river steamers carrying groups would have little hope of flatting through to-day; obviously the-, river is constantly shallowing. " For evers effect there must be :. relative cause! Every tree that tumbles into the river is a prospective islet: every ijpel causes a put-hole with a relative shallow: the river bet! is a series of tjbese obstructions, visible and invisible, which, collectively, have destroyed' the scouring forces which were operative during the forest period. These conditions arc cumulative. Kven since the recent high flood, existing islets have grown visibly, and others have appeared. It is marvellous indeed to see cows being milked on miniature farms in the midst of the river. Where willows have encroached the river's course is further dispuY'd. and so al; these obstructions and impedimenta create swirls and cross currents which, in turn, cause erosion on either bank until the natural momentum is so diminshed that its scouring force is rendered futile and the process of silting- up, at an ever-increasing rate. as already observed, goes on relentlessly and unremittingly." j

Remedial Measures. Nature's Corrective.

" We now come to the crux of my argument. We have considered tide action and rising river levels, and discovered secondary causes. But 1 suggest that the primary and determining cause is the gradual encroach ment of the bar.

" A bar is a sand deposit caused bj two opposing forces—the sea on the outside and the river's momentum from the inside. We have seen thai the river's punch or hitting power has weakened, and is still weakening, due to obvious causes. This has given the sea the ascendancy, and consequently the bar has been gradually shoved inland, involving a correspondingly given loss of fall, which, by a natural process, has been, in ihe course of decades, registered back upstream against the levels of the forest period. The only alternative 10 this theory is land subsidence, but is it possible that the river-bed would escape a general subsidence?

" It is only left for us to assume (hat if in ?A hours we could remove all obstructions, confine the water to its old-time bed and banks, and thus lestore the river to the conditions obtaining during the forest period-• and anticipate results--the Waikato would recover its old-time scouring capacity, the present pot-holes and shallows would disappear in the matter of weeks; its restored hittingpower would drive the bar back to its old-time position; the extra depth or "fall" regained would again, by the same natural law, be registered upstream, and so the levels of the forest period would be won back. "Having thus suggested nature's!

Corrective .1.-, the onl> true and economic solution of the Waikato River problem, and bearing in mind ihe terms of the resolution, it is necessary perhaps that 1 draw your attention to the following extracts from the Government engineer's report of August, 1913: ". i > . it is quite impracticable for the summer level of the river dt Mercer to ije lowered foui . , . feet as represented by the Waikato River Board." Again: "Mr. Kennedy, will have great difficulty in securing a lowering of summer water level at Mercer by two feet, such being only possible by great expenditure and constant dredging. . . ."

Again: "That the adjoining swamp lands will be extremely difficult to drain in the Ordinary way. . . .'" " Considering that according to the engineer's own computation or guess, onp million tons of debris are being carried down annually, and considering the river's high scouring capacity when brought under control again, one wonders at an engineer planning to lower a section of the river levels at Mercer by machinery, seeing that he would have to cope with silt in million ton lots. " But if we are at all correct in anticipating that Nature's corrective intelligently applied will deepen the river-bed and restore the water levels to those of the forest period, what the chief drainage engineer declares to be 'quite impracticable' will not only prove practicable but must follow as night follows the day. Equally, we are perplexed when he says: 'Any lowering of summer level will only result in tidal action being thereafter experienced at Mercer.' And why not ? It will only mean more salt and less fresh water. "Is that any objection from the point of view of navigation ? " Moreover, the greater the tidal intake the. greater the scour; the greater the scour the better the bar. What engineering objection can there be to that ?

" When the Waikato is given the opportunity of putting the bar back in its proper place, and the river levels fall in consequence, tidal effects will probably reach miles further inland, and the further the better, for that will mean datum conditions for land drainage. Land Reclamation.

" It only remains for us to touch briefly on the question of finance. Apart from the advantage of improved navigation facilities, when 250 miles of inland waterways will be operative, there is the supremely important question of land drainage. There are approximately 100,000 acres on both banks . above Mercer, and 150,000 acres below, and practically all butter-fat Country. Now, in Taj ranaki and oser parts £l2*and ,tl# an acre is tb§ average annual&arnUß; capacity o|pdairy farms. lydve reduce^ifJfou likf to *:G'an acre, and I thinlCjPu credft the present waste : «juls as capable of retutting oneVajwf a-half millions Ai, Vivid Ejcampie. " When trr*dj£loJre Rangitarki settlers in theirSMWmity cried to the Government for help all they asked for was a credit equal to six months' approximate milk cheque. The result to-day is that a £160,000 expenditure has lifted .the public valuation of Rangitaiki Jo U ,600,000! And so 1 suggest tojj'ou that you want similarly an%j|jlvance equal to half-year's income. ri _ Future Prosperity. ' the rest, if you are willing *to subordinate every personal advantage, real or imaginary, and co-ordin-mte for the benefit of your district fas a wl ole, no Government will have &he temerity to resist your claims. Ind you will- retrieve results you litdpe dreamed. Equally, you will be rendering a service to the State of which you form a part, and you will have the satisfaction of knowing that you have been instrumental in converting a waste and a wilderness into one of the brightest spots in the Dominion,"

Relief of Railway.

Mr. McCutchan also referred to the need of improving the navigation on the river in order to relieve the congestion on the railways. If there'was a great increase in the volume of production the railways could not cope with it.

Mr. Hamilton supported Mr. McCutchan's motion, quoting examples in support from Northern Wairoa, where tl e sand was heavier, but there were not the obstructions there were in the Waikato, which destroyed the moment mi. But the Waikato had the advantage in a greater fall. It could be lowered another 7ft or 10ft and then have more fall than eithei the Northern Wairoa or the Thames. While comprehending Mr. McCutehan's theory that previous conditions must be restored in order to lowei the river-bed, the "Times" representative present wondered how the speaker intended to achieve the preliminary object of so harnessing and confining the river that it would have the required velocity and momentum to wash the bar further uut against the opposing force of the tide. Did he intend to do the trick by means of retiining walls, straightening bends, widening shallow reaches, putting in groynes, etc., etc.? Questioned on this point Mr. McCutchan said the method was merely a matter of detail, the main thing was to get down on to a logical, sound basis, and true foundation, and the rest could be accomplished. The work was of such magnitude that it might cost half-a-million sterling, but what was that compared with' the annual production made practicable 7 However, it was so huge a project that the Government "would have to step in and handle it.

The motion referred to was to the effect that the Government be urged to appoint a commission. The matter is dealt with in another column.