Cottes­loe wa­ter line fall­ing

Western Suburbs Weekly - - Westernopinion -

RE­GARD­ING ocean level rises’ af­fect in Cottes­loe, as I pointed out, the ocean level has gone up by about 70mm since 1993, mean­ing 7m loss of av­er­age wa­ter line per­ma­nently off most beaches in the world.

For Cottes­loe I think it rep­re­sents about 50 per cent to 70 per cent of that, be­cause the groyne and the reef for­ma­tions add ex­tra sta­bil­ity, so the loss is about 3.5 to 5 me­tres.

At least 3m has dis­ap­peared since 2004 when I did a re­port for the Town of Cottes­loe, which is ex­actly what I have been say­ing for many years.

That is about 3mm per year, and slowly in­creas­ing, and ex­actly what I have been pre­dict­ing for a long time us­ing pub­lished NASA data.

I fig­ure Cottes­loe per­ma­nently lost three me­tres this year, com­pared with 14-18 years ago, in com­par­i­son with the cor­re­spond­ing high tide sea­sons at that time.

The sand dunes don’t lie. Very high sea­son peak­ing ev­ery 18 years is cor­rect, so good­bye to an­other 4m in 2040 or so. Ev­ery­one will be run­ning to their phone then be­cause that will be highly no­tice­able. A visit to the beach, and view­ing of my pho­tos from this and last year would show the ex­tent of ingress at the beach even now.

I defy any ex­pert say­ing they have seen the sand dunes like this be­fore. One can see the an­cient lay­er­ing of the sand that built these dunes sim­ply chopped off.


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