Surf’s up with 10m waves in cy­clone record

Townsville Bulletin - - News - by Emily Mac­don­ald

WAVES of up to 10m w e r e r e c o r d e d i n Cleve­land Bay at the peak of Cy­clone Yasi.

The re­cently re­leased data was col­lected by sen­si­tive marine mon­i­tor­ing in­stru­ments placed in the area by the Port of Townsville as part of an en­vi­ron­men­tal i mpact as­sess­ment to guide fu­ture port de­vel­op­ment.

The wave and cur­rent mea­sur­ing in­stru­ments were put in place in Oc­to­ber and study l eader Greg Fisk from en­vi­ronm e n t a l c o n s u l t a n c y group BMT WBM said the in­stru­ments recorded s o me o f t h e h i g h e s t waves ever ex­pe­ri­enced in Cleve­land Bay.

‘‘ Based on the data coll e c t e d , w a v e s i n Cleve­land Bay dur­ing the cy­clone were con­sis­tently over five me­tres for a num­ber of hours,’’ Mr Fisk said.

‘‘ In­di­vid­ual peak waves would have been sig­nif­i­cantly higher than that, pos­si­bly up to 10m.

‘‘ Ex­treme waves such as those ex­pe­ri­enced dur­ing Cy­clone Yasi have the po­ten­tial to cause sign i f i c a n t d a m a g e t o coastal struc­tures if they are not of an ap­pro­pri­ate de­sign stan­dard.’’

The in­stru­ments were housed in frames to prev e n t t h e m b e c o mi n g buried in sed­i­ment and placed at a depth of 15m which en­sured they re­mained in po­si­tion.

One de­vice was dep l o y e d o f f s hore f r o m Arthur Bay im­me­di­ately to the east of Mag­netic Is­land while the sec­ond was sit­u­ated off Cape Cleve­land close to the port’s ap­proved dredged ma­te­rial place­ment area.

Mr Fisk said oceanographic data logged dur­ing the cy­clone would now be com­pared against me­te­o­ro­log­i­cal data such as wind speed and direc­tion to pro­vide a greater un­der­stand­ing of how C l e v e l a n d B a y f u n c - tioned and re­acted duri n g e x t r e me wea t h e r events.

‘‘ The in­for­ma­tion gath­ered will pro­vide a valu­able in­sight for the de­sign and lay­out of fu­ture port and other fore­shore i n f r a s t r u c t u r e i n o r around Cleve­land Bay,’’ Mr Fisk said.

He said the real-time wave and cur­rent data col­lected in the months prior to Cy­clone Yasi woul d h e l p c a l i b r a t e c o m p u t e r m o d e l s o f Cleve­land Bay to simul a t e e x i s t i n g o c e a n o - graphic pro­cesses.

The mod­els will be used t o p r e d i c t p o t e n t i a l c h a n g e s t o c o a s t a l pro­cesses when new de­vel­op­ment in Cleve­land Bay was pro­posed.

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