ST. CLAIR BEACH.

Evening Star, Issue 17328, 16 April 1920, Page 8

ST. CLAIR BEACH.

TO THE KDITOF. Sir, —According to your sub-leader, tinai arrangements have now Ikcii made to carry .out the protective works to save the sam! S.iank from being washed away. Driving piles as groynes is t.t be resorted to as the ideal work —the same us we ahe.nly have. Any person not posing as an authority on marine engineering, but possessing a certain amount of common sense, should know that the groynes cannot cope with the velocity ar.d volume -ol wave action that has caused the breach in the Sandhills. It has already proved that groyne? arc not the right thing; but a further experiment *is to be launched—mure groynes, f:ail in their construction, and with little or no rcsistar.ee to the iidlow of wave action. This proposed w,;rk seems not to b? the right idea; but it is a case of try ajraiii, and see what more wiil do. Such is the position now. and \ the results to be obtained cannot require I a master of marine engineering to solve. ! Has it ever occurred to any known local authority on such works that it would j pay tiie controlling board to build a stone j causeway at the rocky bluff near the baths ] to assist to break the velocity of ike wave I action before reaching the scene of the: piesent trouble. It such a work was. car- I ried out, the effect would be satisfiu-tory. ] It would not only be the means of lessen- ; I ing the velocity of the waves, but would | create almost dead water at the back of the causeway, and pile up the sand that is at present being swept out to sea. Members of the board of control should i freshen up their memories, and go back ; to the time when the beach at Timaru I was once a rough boulder beach, and of ' no use. because the sea had full control. : As time went on the Timaru pe:ple bu'U causeways, and used them as wha'Vi_s, ' and these works prevented the ocean from having free play on the banks, anil thus j piled up the sand on a beach that was • hitherto useless The work at Timaru ; has proved beyond doubt whnt a causeway will do ; but I do not suggest works of such magnitude to be undertaken, but had to draw attention to results obtained by building a causeway. It has proved a success, and a good beach is to be seen. '. which is of inestimable value to 'j.imrmi! Tt matters little what the cost of protecting the beach at St. Clair ; the work has to be done, and the first cost is the cheapest, it will eventually be found that the work must stc.it at the rockv bluff, and_ a causeway built for three .:r j four chains from the' shore line, to pre- ' vent the Sindhilis from being washed away. If this is not done, then we mav have a much larger proposition to fac/, ■which will remind people of the dav of the main encroachment at St. Clair. Suai i a repetition of_ affairs is n-.t eagerly looked j to by those who own property within the precincts of the beach.—l am, etc.. A P«I 15- Si. Claje.

TO THE £i)ITOK. Sir,—l have had the. privilege of seeing several letters in your column* on the above subject. Some of.the writer s*eifi to think that all knowledge in connection with this ruatti/ will dio with them. Most of them have not the slightest idea of the methods adopted m other countries and places under similar circumstances; and so, therefore, they pose as experts when their common sense should keep them quiet. I woidd suggest that .some of them take a course of surf-bathing along the beach and find out what is happening out in the water. They would then discover that a channel is working close along the beach parallel to it. fhev would al?o find that for about 25 hours out of the 24 a decided set or current flows down this channel. This cuirent carries .ri'av the sand which has been churned up by 'he action of the breakers. Thus it follows that if we break the force, of this current we get the sand deposited again. There is only one ehV:tive*method of doing this, and that is by means of grovnes built out into this channel. Tho main trouble with this scheme is that it will be exp-in-ive; but that should not be allowed to stand in its way, It will be too late when the sand is gone to trv to remedy things. The trouble is that the engineers are expected to do wonders with a few paltry hundreds, when thousands should bo placed at their disposal. What is wanted is a comprehensive scheme for the whole of the beach, as there is no doubt that tlie sand is disappearing at an alarming rate between St. Clair and St, ,Kilda. In conclusion. T would like to point out that it is possible that the engineer who recommended the groynes knew what effect they would have. It is not his fault that they are in their present useless condition. To be effective thev must be practically water-tight, so as to stop the force of the current. Marine currents and protective work? are matters for the expert, as the average man. has not the data_ and knowledge necessary to form opinions on the subject,—l am" etc.. April 15. _£_]?