FORESHORE EROSION

Evening Post, Volume CIX, Issue 119, 23 May 1925, Page 13

FORESHORE EROSION

TROUBLE ON RONA BA'tf

GROYNES TO PREVENT W|AV^

ACTION

•SS? ... •. ... .:.Jb For'eoms y©ar« there fcai beeri'-veontidr' erable difficulty along, the foreshore* af Eastbourne in preventing eroeion, whicli hRa been serious in many pkvcei, especii ally during heavy southerly weaiheft Some timo ago a concrete wait was tmil^ at Mantell's Point; but thia nai' under? mined by wave actiou and. about a iuM dred feet was breached.- Nearthe Red reation Ground there had also been eeti* ous erosion, as well as at several place* to the south of that ground. For som«< time tho Eastbourne Borough Council naa been seeking a solution of the dim* culty, which has become a serious meai ace to thoEe living along the beach front, and last evening the council received; »' lengthy report on the subject, from! Messrs. R. \V. Holmes and Son, who are* acting a* the council's consulting en* ers in reeard to the matter. The report submitted by the engineer*suggested that seven timber groyne* should bs constructed nlong the fore* shore at what waa called Kiosk Point-* ™own,,nmon?«t residents generally ai Mantella Pomt-at perpendicular dw| tancea about 100 ft apart and about 60f« l? n?' groynes Bhould be two planks high, one being below the present beachl level and one above. Such groynes will prevent further erosion taking place and{ will trap a certain quantity ot saud'oa it travels along the beach. As the bcacbi is rawed by this accumulation of sandi further planks will have to be added toi the groynsa, thus trapping further said* The groynes would have to be of miflij went strength to resist the seas at this point. '^

It is not possible to foretell the exacl/ results that wili be obtained by constructing groynes," said the leport, "because) the conditions are not exactly similaf iiJ any two places. The only way ia toT construct a few groynes and carefully) study the effects produced. ' It will them be possible to ascertain- whether the! groynes are too far apart or can " bs# spaced further apart to produce Uie de 4 sired results. If they are tod far apart] then another groyne will have to be con* str mutedl between ■*{»• existing ones " The effect of this building up. on th# point would be to cause the beach to) the south to also build up, but to whatt extent the engineers were unable.to iayi The sand thus trapped will naturally del plote the beach to the north by wav<} action, alto caused by the northward set! of the littoral drift. This beaoh will have to be carefully watched, and ifi iound necessary, & portion of the drift! sand could be allowed to paes thai groynes. ' 7 "By careful Tratcbing," declares thii report, and by tha manipulation of tlia groynes we can ccc no reason' why the! iuosk_ Point should not be extended s3 that uicreaeed shelter will be afforded! tn e Rona Bay, wharf from southerl* seas. £.

"We do not recommend that airy roi pairs be undertaken to the concrete wali at Mantell's Point where it has beeri breached, as we consider that ampla protection will be afforded by thai groynes. It must fc« clearly understood; shat the raking o{ the beach entirelsr depends on the quantity of sand drifting! alow the beach from Penoarrow but judging from the extent of the accretions that have formed in the last 20 yearaJ appreciable results ehould be obtained ia a Bhort period of time. The report, reviewing the cost of tha seven > proposed groynes, etated that M experimental purposes the groyne* would cost about £36. each, a total for th* seven of £262.

Councillor Jenkinsoa, •when the report was being discussed', questioned whether the groynes would not affect the dopthi of water at the wharf.- -Ha thought tha matter should be looked into before de-> ciding anything. .Councillor Black «aid that southerly: weather affected the whatf mostly, and; theso groynes will prevent the 'sand! drifting in that direction. The report was referred to the work* committee with power to act. !