IMPROVING THE AVON.

Lyttelton Times, Volume CXVII, Issue 18286, 23 December 1919, Page 6

IMPROVING THE AVON.

WjitLi much has been done to improve the banks of the Avon in recent years, the stream itsolf has suffered from neglect, and for reasons which need, not bo hero discussed, the volume of water and average depth of the river in its upper and middle reaches have suffered a marked diminution within the last decade. Public interest was aroused in this matter some fivo years ago, when a fund was raised for the improvement of the stream, but tho Great War intervened and the subject, up till a few months ago, was shelved, save for tho preparation, in 1916, of a very comprehensive report on the whole subject by the three leading civil engineers of the city. Necessarily the subject is one on which there is considerable room for differences of opinion, and the controversy cut short by the ■sne*- an a oscu renowed lately at about Gie point where it was left off. It is an old controversy, almost as old a 3

tho province, and it invariably takes the same old linos. The lack of unanimity as to what ails the Avon and what will best oure it has for long years been the most powerful factor in ensuring that nothing should be done. Tho deputation from the Domains Board which waited on the City Council last evening made tho excellent suggestion that a committee representative of all bodies interested should be formed to improve the river, but we cannot escape tho fear that the committee, when formed, will merely prove another debating society to discuss the old pros and cons and arrive nowhere. Throughout all the recent discussions on this subject tho one authoritative and expert opinion on the subject, that of the engineers who framed tho report of 1916, has been ignored. We find, for instance, a member of last evening’s deputation to the City Council urging that the remedy is to clear out tho tributary streams at the head of the river. Tho point was reported upon in 1916, tho text of tho reference being as follows:Adding water to the stream by diverting thereinto the whole or part of tho water from other streams is an elementary device, tempting in its apparent simplicity, but much less effective than is popularly supposed, because the one effect of increasojn the volume of the stream is to Increase the velocity. This effect militates against the increase in tho depth, so that doubling tho quantity of water only adds 50 per cent to the depth of water in the stream. . . . The effect is, of course, to raise the water surface, hut at the partial sacrifice of the stream's efficiency as, a drain, and usually at a prohibitive cost.

We do not wish to pose as oxperts on this subject. It may be that Sir E. F. Stead’s proposals are likely to bo less costly and more efficient than those of Messrs Dobson, Williams and Cuthbert, but we have a feeling that tho reoommendations of those gentlemen should form at least the basis of any new discussion. A portion of their recommendation, in regard to ~ tho dredging of the lower reaches of the river, is to be put into effect in any case, and unless something is done with the city portion of the river the result will bo to still further' reduce the depth of water available there. The engineers’ report should certainly bo laid before the conference which the City Council proposes to convene.