[1] Univ Auckland, Fac Engn, Dept Civil & Environm Engn, 20 Symonds St, Auckland 1010, New Zealand
[2] Natl Inst Water & Atmospher Res NIWA, Greta Point,301 Evans Bay, Wellington 6021, New Zealand
[3] Aon, Aon Ctr, Auckland CBD, Level 21-29 Customs St West, Auckland 1010, New Zealand
[4] Natl Inst Water & Atmospher Res, 10 Kyle St, Riccarton 8011, Christchurch, New Zealand