MR BREMNER'S REPORT ON THE WAIPOUA OVERFLOW.

Wairarapa Daily Times, Volume 6, Issue 1789, 16 September 1884, Page 2

MR BREMNER'S REPORT ON THE WAIPOUA OVERFLOW.

Gentlemen,—ln compliance with the request expressed by you, I have the honor to submit to you a ehort report on the subject of the Waipoua overflow at Pairau; and to offer such recommendations as may tend to prevent a similar occurrence, and also to mitigate the evils which have arisen through the late heavv flood. '

I have been unable, through pressure of other work, to thoroughly inspect'the ground, and my suggestions are based only on a rough examination,

From the sketch map of the locality which I append to this report, you will perceive that the first point of outbreak occurs at the point A, distant about 30 chains below the confluence of the Miki« Miki' 'creek' with the Waipoua. The direct cause of this outbreak has beon the lodgment across the old channel of a quantity of both green and dead timber whioh has been carried down the river by the reoeut. flood,

A larpe deposit of shingle has formed across the former ohannel, and foroed the water through the low lying flats to the east, •

From this point the river lias entirely abandoned its old course and out a fresh ohannel for about half a mile through the ploughed properties, of Messrs R. and J. Welch in sections 35 and 34, returning to its old ohaunel about 15 ohains above the old Native pah. .

About half way between these points, the new channel passes in dangerous proximity to one of the former watercourses, aorosa the plain, whioh is of such depth as to render the diversion of the river to its old oourse, if it should once break into this depression, a matter of great difficulty and expense.

The river continues to occupy its old ohannel from here- tor a distance of about 6 or 8 ohains until opposite the pah, when it adopts a fresh oourse bvor the Pairau flats, leaving its former bed to the west, The course of this channel is approximately defined on the map: from the jast. mentioned point passing along through the Pairau Swamp road, drains into Mr Herbert's swamp, and following the couwe of the drain on. his property .finds its way through the break in the terraoe, lying east of the north base trig., then following along the main Forty Mile Bush road and across MrH. Weloh's land to the north of the race comae; the overflow discharges itself into the Ruamahanga about a mile below the-junction of the Kopuaranga with that river. 1 Having roughly described the course which the river threatens to permanently adopt, I would wish to impress upon this meeting the imminent danger to. which all the properties as well as v the publio works whioh lie in the line of encroach* ment are exposed, and to urgently recommend that every available 1 means | be adopted to deal with the, matter of diverting the river into its former ohannel,' and to ensure its retention there by permanent and substantial protective works. : ... ; - ,::

From the point of defleotion at A', all the country to the S.E ' lies at a level .considerably below the bed of the river, and should the matter be neglected undl another; heavy ' flood occurs, and -the river continues, as it at present threatens, to work to the east, the total, destruction of this low, lying country is inevitable, The drains opened up along the'line of road reoently constructed through the Pairau swamp are at present carrying the waters of the river, and the road and land on both sides are flooded for many

chains |n length, and suffer much harm, The drain's, .throusjli Mr Herbert's property are.'filletfto overflowing, and : in;the lower y lovels of the swamp the surface of the ground is covered with water, "which, as I before stated, is* Adding its way on to the main coach road 'through Mr Cameron's property, to the. imminent danger of destruction to both ir and the, railway works. The whole of the lowerOpaki plains wiU'be subjected to heavy inundations,-and from the flatness of .the country in this locality it is probable that the river will continually alter its channel ti< the deatraction of hundreds of acres of private property. In order to permanently avert the dangers to .which I havo referred it will be necessary to incur a considerable expenditure, but I' am of opinion that the immediate danger may be successfully baffled at the upper point A. by constructing a substantial protective wall of mannka fasoines Beourely staked and backed with pitched boulders across' the present river bed, and opening up the old ohannel for a distance of say 3 chains. I would propose further to firmly anchor bushy' saplings' with their tops' down stream along the face of the embankment, so as to break the force of the water and allow the shingle deposit to lodge. The old channel will have to be cleaned of logs and rubbish by burning and cutting'them into Bhort lengths, This latter work must be continued throughout the length ot the river as far as the Pairau. It will benecossary to construct another length of protective wall, B, at this point and to open a new ohannel through a short length of standing bush into the old course a little above what 'ib known as the old ford, '

It will be neceiSa'ary also to olear the creek bed of all obstruction and to blast out the roots so as to allow the force of the water to cut and widen its channel through the bush. ; ■

The black lines upon the map at A. and B. indicate approximately the position of the walla I propose should be constructed, and I have every confidence in the success which I feel Bure will attend the careful execution of these works, The limited time which has been at my disposal has not enabled me to go into exhaustive details regarding cost, &c., but I am disposed to think that a Bum of £l9O if carefully expended should suffice o complete the works suggested, substantially and efficiently. ! I have, &0., 0. E. Bremner.