Ero­sion sig­nalled

Cockburn Gazette - - NEWS -

SCI­EN­TISTS will have to dig up 6km of ca­bles in sand dunes to move a radar sta­tion’s aeri­als which record ocean cur­rents.

The aeri­als are threat­ened by dune ero­sion at Port Beach, North Fre­man­tle.

“It’s a ma­jor prob­lem, as the in­for­ma­tion col­lected by the aeri­als is used for search and res­cue, nav­i­ga­tion, coastal en­gi­neer­ing and cli­mate change re­search,” Univer­sity of WA Aus­tralian Coastal Radar Fa­cil­ity leader Si­mone Cosoli said.

The nine-year-old ImosA­corn Rot­tnest Shelf Ocean Radar is part of a na­tional net­work funded by the Fed­eral Gov­ern­ment and op­er­ated by the uni­ver­si­ties of WA and Tas­ma­nia.

At Port Beach, it com­prises 20 fi­bre­glass aeri­als on dune crests which, with a Guilder­ton sis­ter sta­tion, use 9.3 mega­hertz ra­dio sig­nals to record waves and cur­rents up to 200km off­shore.

Dr Cosoli said his site had found cur­rents with ed­dies up to 2km wide that trapped nu­tri­ents, recorded wave heights used by re­new­able en­ergy makers, and could track oil spills to Don­gara.

How­ever, se­vere win­ter ero­sion at the al­ready heav­ily eroded beach de­stroyed two of the aeri­als and now threat­ens to add more cen­time­tres to 5m drops from the beach and into the sea.

“I moved here three years ago and in that time the amount of ero­sion at Port Beach has re­ally shocked me,” Dr Cosoli said.

Can­berra is fund­ing all the re­search na­tion­wide in 2018-19, in­clud­ing $25,000 to dig up 400m of ca­bles laid 1m deep for each Port Beach aerial, and there is a com­mit­ment to keep the re­search go­ing un­til 2029.

Dr Cosoli said dunes nearer Fre­man­tle Surf Life­sav­ing Club at Leighton Beach would be bet­ter once a new site was agreed and the weather al­lowed a move with min­i­mal dam­age to coast plants.

Fre­man­tle Coun­cil met the sci­en­tists in May about the ero­sion’s im­pact. A spokesman said it also wanted the at-risk aeri­als moved with least dis­tur­bance to the dunes, given the po­si­tion of most ca­bles.


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