Topic: Bay of Plenty Flooding (18 May 2005)

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Phenomenal, unprecedented high rainfall affected the Bay of Plenty on the 18th and 19th of May, especially the Tauranga and Matata areas. In the 24 hours to 4pm 18 May 2005, 309mm of rain was dumped on Tauranga. The previous high since records began in 1910 was 239mm in 1923. Landslides and flooding caused much damage to buildings and property and saw a State of Emergency declared in Tauranga at 3.45pm on 18 May 2005.

  • Phenomenal, unprecedented high rainfall affected the Bay of Plenty on the 18th and 19th of May, especially the Tauranga and Matata areas.
  • In the 24 hours to 4pm 18 May 2005, 309mm of rain is dumped on Tauranga. The previous high since records began in 1910 was 239mm in 1923.
  • A shallow low brought warm, moist, unstable air down onto the Bay of Plenty. Convergence zones within the airstream produced high hourly rainfall intensities. One stalled over Tauranga for a time. It was likely that another convergence zone produced the downpour in hills above Matata that night. A high-pressure system to the south of the country was blocking the low from moving.
  • State of Emergency: Declared in Tauranga at 3.45pm on 18 May 2005.
  • Matata: A torrential downpour in the hills in the catchment above Matata, turned small streams into raging torrents and swept down carrying logs, huge boulders and river silt. The heavy rain triggered many landslips, leading to large debris flows, with associated flooding which caused much destruction. The intense rainfall fell in a narrow band only a few kilometres wide, passing across the catchment to the south of Matata from near the mouth of Ohinekoao Stream to Awakapongo. Rainfall was approximately a 500 year recurrence event, and the associated debris flows may have the same recurrence interval. Historical records indicate that smaller events have occurred in the area since 1860.
  • Mauao: Four slips around the base closed the walking track and broke a major water main.
  • Otumoetai: 24 houses evacuated on the Otumoetai ridge area. Water on Ngatai Road thigh deep.
  • Papamoa: Wairakei Stream burst its banks. Over 40 houses evacuated and a motor camp with up to 100 residents affected. A section of Papamoa Beach Road shut after the road started to cave in.
  • Welcome Bay: Numerous vehicles stranded. Cordons placed around the unsafe areas in Otumoetai and Dingadee Street in Welcome Bay, with some houses teetering on cliff edges
  • 11th Avenue: Devonport Rd end water reported to have reached the top of some cars’ doors.
  • 789 properties affected: Council carried out inspections of 1067 homes and properties. 39 houses deemed total losses and 12 had already been demolished or transported to other sites.
  • Airport: Closed by flooding.
  • Cameron Road: Cars came to a standstill between 11th Avenue and Greerton due to stalled vehicles.
  • Evacuations: 400 people evacuated from Tauranga, Mount Maunganui and Papamoa. By October, 82 households still living in temporary accommodation.
  • Insurance Claims: By October 2005 more than 2000 claims made and 625 accepted by the Earthquake Commission.
  • Memorial Park: Traffic backed up around a submerged Memorial Park as water flowing back across the road.
  • Mudslides and floodwaters: Widespread damage to homes at Pillans Point, Otumoetai, Welcome Bay and Mt Maunganui. The worst hit suburbs were Otumoetai (flooding and slips in streets including Vale St, Landscape Rd, Himewa Rd, Whittaker St and Pillans Rd) and Welcome Bay (Estuary View Rd, Corinna St and Dingadee St).
  • Other floods: It was the fourth time in five years that the area was affected by severe flooding.
  • Police, Fire, Army: Along with other emergency services, stretched to the limit. Up to 16 fire engines from as far afield as Waihi and Hamilton circled the city attending up to 150 incidents.
  • Roads and Railway: Roads and railway lines near Mt Maunganui and Welcome Bay damaged. A section of railway line lifted at Maungatapu and trains into Mount Maunganui were stopped.
  • Schools and kindergartens: Closed across Tauranga.
  • State Highway 29: Through Maungatapu closed intermittently.
  • Tauranga HarbourBridge: Closed intermittently.

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