HOKITIKA RIVER

Hokitika Guardian, 6 August 1930, Page 2

HOKITIKA RIVER

11 ARBOUR CONDITIONS. Tn the course of a report to the Hokitika Harbour Board as a result of reent investigations, Mr T, Johnston, District Engineer of the Public Works Department at Greyinciltli states: — I. have fully investigated tlie position ily a study of the portion of the rivet between the proposed cut and theKahieri Bridge on the main highway, Tlie river flow over the major part of the length referred to, is carried in two well-established beds which can conveniently be referred to a.s the north and south channels. These channels ,after junctioning a short distance upstream from the proposed cut, merge into the “middle'channel” which now carries the whole river volume as distinct from the anginal channel. The middle channel flow, and the bio kage of tlie old channel has .gradually developed from natural changes in tlie river and river bed c-vcr a. distance of 2i miles upstream, combined with tlie absence- of any effective or established requisite flow in tlie wharf channel. Where the river is running in' the north and south channels, the north stream is carrying the larger volume of water. This, of course, possibly has varied and may continue to vary both in normal and flood flow, hut it is apparent that tlie direction of the resultant flow from these" two channels is an important factor in the deposition of the detritus now blocking the wharf channel. It has been proposed that tlie flow in tlie middle channel should be, partially diverted to the latter by the direct means of excavating a cut through the shingle bank as a definite step towards the restoration of river, flow to the wharf. From levels and- cross sections that have been taken over a limited length, it lias been ascertained that a cut 100 feet in width and depth at the intake of one foot below normal water level in the middle channel, ' would necessitate an approximate excavation of 17,000 cubic yards. It is considered unlikely, even if tenders were called or the work undertaken by mechanical methods, that the cost would be less than £BSO, i.e. or less than tlie rate of Is per cubic yard. lam of tlie opinion that the expenditure involved in the cut—a work which can chiefly he considered as experimental—is hardly warranted, particularly when there is nothing to indicate that the natural agencies which have caused the blockage have been in any way reduced or modified, and that consequently a further deposition of shingle in the cut could be anticipated during floods. For the present I do not see any solution of the problem that is facing the Board that would not involve a very considerable, expenditure, but I would recommend that the Board should apply to the Marine or Public Works Department to- have a detailed survey made from the river entrance up to the Kanieri Bridge with soundings where necessary, so that remedial measures in relation to the wharf channel berthage- and training walls could be fully investigated. So long as the river channel is uncontrolled it would appear that no improvement in the present position is likely to occur. Apart from the question of berthage and the town discharge into the wharf channel, portions of the training walls are being adversely affected bv the condition of the river flow which new prevails.