STATE TO RESCUE

Evening Post, Volume CX, Issue 110, 5 November 1925, Page 16

STATE TO RESCUE

LANDS LIABLE TO FLOOD

CASE OF THE TAIERI PLAINS

SUBSTANTIAL SUBSIDY TO

COSTLY SCHEME.

The problem of river protection, so far as it affects New Zealand rivers, is best set forth in the directions to the Royal Commission on Bivers appointed in 1919 to inquire into the state of certain rivers, including the Clutha, Orarij Eangitata, Waimakariri, Ashley, ■ Maerewhenuaj Waihi, Wairau, Taieri, and Aparima. These ' directions were:— (1) To inquire into the cause or causes of the silting up of the channel, tlie flooding of the adjacent lands by tho said rivers, the erosion of its banks, and the damage to the surrounding country; (2) To ascertain the nature and extent of the damage done to the lands adjacent to the said river, and what area of land is affected by such floods or erosion, or both, and whether it is practicable at reasonable expense to prevent such flooding and erosion, or both, either wholly or partially; (3) To ascertain the best method of providing for the control of the said river and its tributaries so as to safeguard the lands affected, and to provide for the effective control and improvements of the said river and its banks; (4) To ascertain the nature and extent of any drainage works that may; be required, and the best method of carrying out such works; (5) (a) To furnish estimates of the cost of such remedialmeasures as you may recommend should be taken for the effective control and improvement of the said river and its banks; ■(b) To report, in the case of each river, what area or areas of land I should be constituted a district in re- | spect of which a rate may be levied j to secure and pay the interest on and ! provide a fund for the repayment of ' any loan that may be raised to carry j out any river improvement works I which you may recommend should be undertaken; (c) To report your opinion as to what matters, if any, should be adjusted by legislation; and (d) Generally to report your opinion on all matters arising out of or touching the premises, including the question as to whether or not-one or more competent authorities should be

appointed to control the whole or _ any portion or portions of the said river, aiid what statutory powers should be possessed by such authority. THE RIVERS COMMISSION' ' Tlie Bivers Commission consisted of Messrs.' F. W. Furkert . (Chief Engineer of Public Works), A. J. Hunter, and F. C. Hay the present engineer to the Matiawatu-Oi'oua River Board and the author of the comprehensive scheme for solving the problem., of the Manawatu's low-lying lands subject to flood. It will be noted that this Commission has not yet tackled the problem of the Manawatu, though its reports on the less important rivers mentioned have already been published. The report which has the closest bearing on the Manawatu, is that of the Taieri River and its plain, just south of Dunedin, on the main line to Invereargill. The Taieri' Plain; one of the most fertile areas in New Zealand, has been for more than half a century subject to periodical floods from the Taieri and Waipori Rivers, and extensive damage has been done on j many occasions, estimated by local landowners at £200,000 or more in the worst cases, when as much as 18,000 acres has been under water, many thousand acres for long periods sufficient to kill the grass and ruin crops. The low-lying plain is partially protected from floods by levees or embankments, but these have not been enough to prevent floods right up to the present time. The total area affected by floods amounts, according to the Commission's report, to 30,000 acres. Gravitation is not sufficient to carry off flood waters from the lowest levols, and pumping is required. The railway line from Dunedin to Invereargill is submerged during flood time for considerable periods, traffic being interrupted. Loss of stock has frequently been heavy, when there has been no time to remove it. The area in question subject to floods is drained by the lower Taieri River, which flows through a gorge into the sea. "The capacity of the lower gorge," say the Commissioners in their report, "to discharge the water which has been known to pour on to the plain from the back hill country is inadequate.'' In this respect the^ases of the Taieri and the Manawatu are on all fours. Tho Waihola Lakes form a sort of reservoir for flood waters, in a sense regulating the flow and saving the plain from, worse devastation. Levees have been built along the courses of the rivers —tho Taieri and the Waipori—in their course across the plain, but these have been proved quite inadequate to save the district in the worst instances of flood. The levees were either breached or overtopped by the rising waters.

PLAN RECOMMENDED

On general principles the Commission reports :—"ln order to induce more water to run through the lower gorge

Proposed new channel of Manawatu Eiver in ideal half cross-section. The distance from inner too to inner too of the stop-banks ou cither aide is 1320 foet, or a quarter of a mile. A distance of 100 fact is reserved o» ciu-h side of tlia dredged channel to be planted with pine, poplar, eucalyptus, aud willow uluiijf Uio rivei; edge. Tun levees will be gruascd. and scrub ulluwed. to gtw at the iiuiw tuu. - • • ' \

its fall must be increased. As the sea cannot be lowered, the waters at the upper end must be raised; and, if an adequate • channel is provided to carry waters from the hills into the lakes, and if the levee protecting the plain from inundation either from the-river or by backing up from the lakes is provided,, the water of the lakes will rise possibly a little higher than heretofore; but the combined influence of this storage, together with the increased discharge obtained by the. greater fall, will enable the floods to be successfully conveyed from the hills to the sea under control and without damaging the region which it is so desirable to protect." The Commission also found that the channels of the rivers were much smaller, both in width and depth, than they had been when the plain was first set-, tied, and this was ascribed to mining ! detritus from operations in the upper j reaches. "The artificial conditions," it reported, "created by industries and settlement farther up the river have caused or are mainly responsible for the silting up." , ■ Under order of reference (3) as to "the best method of providing for the control of the said river and its tributaries, so as to safeguard the lands affected and to- provide for the effective | control and improvement of the said river and its Imnks," the Commission recommends that certain works, which need not be described in detail, be carried out. .Uuder reference (5) (a) tho Commission estimates the approximate cost of . these works at £80,000. ONE CONTROLLING AUTHORITY Under clause (d) of the 'same reference as to the .appointment of . proper authorities to control the rivers the Commission recommends that one controlling authority should be appointed, to be named "The Taieri River. Trust' and to be composed of seven local representatives, one member being elected from each river riding, and also of three Government representatives, called "River Commissioners," appointed for three years by the Minister of Public "Works, one of the Government nominees being well versed in local body work, the second an engineer with expert knowledge of river-control, and tho third preferably the District Engineer of the New .Zealand Railways. The powers of the trust are very large, practically covering everything that can possibly affect the relationship of the rivers to the area through which they flow. These include authority to make diversions, deepen and widen channels, erect levees and. other protective works on private lands, divert, raise,' lower, or alter roads, bridges, and culvex-ts, etc. The financial and administrative control of all existing works should be handed over to the trust. The Commission also recommends uniform rates. oyer the district to nlco^ maintenance and administrative charges, but river-improvement and flood-protec-tion works should be considered by the trust .as entirely distinct from drainage works, and separate accounts should be kept for each. In regard to the allocation of costs

of remedial measures the Commission makes an important recommendation which has a distinct bearing on the problem of Manawatu River control. The Commissioners recommend that "in view of the national interests at stake, and particularly in view of the damage done to the rivers by mining and other operations, it would be equitable,.that a contribution from the consolidated revenue equal to one-third of the total cost of river-improvement and flood-pro-tection works should be made." "In view of the national interests at stake," a. claim is made on behalf of the scheme for the control of the Manawatu River for an adequate Government subsidy. The Public Works Statement for this year reports that the "work which is designed to protect the fertile Taien Plains' from periodical inundations svjoh as have occurred in the past is nbw being actively prosecuted. The cost of the scheme is now estimated to be £150,000, and the Government is to pay a half of this in the shape of a £1 lor £1 subsidy. The Eailway Department also contributes £10,000, making a total subsidy of £85,000. Four miles of stopbanks have been constructed by means of ploughs and scoops, and since the bei ginning of this year a stean>shovel with locomotive and trucks has been operating at Outram widening the existing levee. A suction dredge is being in- j stalled mi the Waipori Eiver for stop; barik and river-improvement. The Taierj River is being cleared of willows by means of a traction engine. THE WAIHOU-OHINEMURI PLAN Of a somewhat similar character to that undertaken in regard to the Taieri Plains is the big scheme, for the improvement of the Waihou and Ohinemuri Rivers in order.to safeguard the State s vast interests in.the Hauraki Plains created by the great drainage scheme which commenced, some fifteen years ago_ and has added a new and fertile domain to ! the Auckland Province,and perceptibly ! increased the Dominion's output of dairy produce since the war. It was found that the silting up of the rivers in question as the result of mining operations was causing severe floods over the drained area, the seriousness of which was' brought under the notice of the present Prime Minister, then Minister of Public Works. As a- result the Government has undertaken river protection works on the Waihou and Ohinej muri, and is paying for them out of the j ordinary revenue. Eivers are being I stumped of. willows, extensive dredging j operations are proceeding, and stopbanks are being built. THE RANGITAIKI SCHEME Not all the swamp drainage schemes which have been undertaken in Now Zealand have proved satisfactory in every respect. A notable instance: of disappointment is that, which has occurred'in connection with the draiuiigc of tho famous Kungitaiki Swamp, oil tho East Coast of tho Nprth Island. Tlio total., urea of land covered is about 87,000 acros, and, as iv tho case of tho Mnkorua anil Moutoa Swamps, tho work of draining was iirst attempted by tho local ratepayers unilor tho Land Draiiu'-o Act of 1893, but an appeal' was made to the Government in 3IHO to take over the liabilities of tho .ratepayers and carry out tho suhonio themselves. A special Act was passed that year and a scheme drawn out. The estimate for tho works then proposed was £50,----000. This year, the net liability of the Ernifjitaiki Drainage Account was £481,203.' Costs had gone up during tho war. Tho settlors in tho aroa experienced financial^ difficulties and a commission was appointed to inquiro into the position; The commission found that tho causes of tho financial difficulties lay in tho over-estimate of tho quality of the land, which for the most |>nH had turned out to be poor, and tho' under-ostimato of tho-time and money required to bring tho lands into profitable occupation. Tho land boom was blamed for excessive prices paid by Bottlers and oxc.essivo mortgages. Mortgagees wore reooniuiontlcilfo write down the amounts owing. No sik'li rlilHc.uJty need bo expected with the Mnnawntu area, as tho quality of the laud underlying tho swamps is' kuowu to be of the highest class.