Southshore levee plan hailed

Christchurch Mail - - YOUR PAPER, YOUR PLACE - ANNA PRICE

A new de­sign con­cept shows that Southshore can be pro­tected against pos­si­ble in­un­da­tion from high wa­ter lev­els in the es­tu­ary by cre­at­ing a sim­ple berm from Caspian St to the end of the Spit.

The re­port, com­mis­sioned by the Southshore Res­i­dents’ As­so­ci­a­tion led by chair Bill Simp­son, was pro­duced pro bono by Gary Teear, man­ag­ing di­rec­tor of OCEL NZ Ltd.

‘‘The solution is quite sim­ple and well-known in­ter­na­tion­ally, par­tic­u­larly to the Dutch – cre­ate a levee to pro­tect the es­tab­lished houses and in­fra­struc­ture on Southshore,’’ Teear said.

He pro­poses a mix­ture of berm and plant­ings, and rock walls as flood pro­tec­tion along the es­tu­ary edge. A berm would also form an el­e­vated walk/cy­cle­way link­ing to other es­tab­lished and planned walk­ways and tak­ing ad­van­tage of spec­tac­u­lar views across the es­tu­ary.

The orig­i­nal 640 houses in the area re­duced to 480 af­ter the 2011 earth­quake, but with new builds un­der way that num­ber had re­cov­ered to close to 500, all served by the es­tab­lished in­fra­struc­ture, Teear said. ‘‘It makes eco­nomic and so­cial sense to pro­tect a com­mu­nity of this size against the start of sea level rise.’’

The berm height was set to al­low for the cur­rently fore­cast one-me­tre sea level rise in 100 years.

Con­struc­tion cost would be con­sid­er­ably less than the cost of the seawall pro­tect­ing Beachville Rd, Red­cliffs.

‘‘What is re­quired is a rel­a­tively sim­ple berm struc­ture, sim­i­lar to what the coun­cil has al­ready em­ployed around the New Brighton area to keep the Avon River from over­flow­ing into New Brighton,’’ Teear said.

The re­port, hailed by the com­mu­nity, has the full back­ing of the Coastal Bur­wood Com­mu­nity Board. Board chair Kim Money said a meet­ing would be called ‘‘as soon as pos­si­ble’’ between the board, the res­i­dents’ as­so­ci­a­tion and Re­gen­er­ate Christchurch.

‘‘With the ram­i­fi­ca­tions of the Tonkin and Tay­lor (2015) re­port, this com­mu­nity suf­fered an­other dev­as­tat­ing blow with no­ti­fi­ca­tion on their LIMs. De­spite it all, they’ve ral­lied and done out­stand­ing con­sul­ta­tion,’’ she said.

Tonkin and Tay­lor com­put­er­mod­elled the im­pact of a 40-cen­time­tre sea rise over the next 50 years and a one-me­tre rise over the next 100 years. The data was used to map out ero­sion and in­un­da­tion zones across the re­gion.

Bill Simp­son, left, and Tim Sintes have wel­comed an OCEL en­gi­neer­ing re­port on es­tu­ary in­un­da­tion de­fence..

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