The Big Wet by the Numbers

Published: 24-Jul-2017

Yep it was wet last Friday and Saturday. No kidding, but just how wet makes for impressive reading. Congratulations Oxford. You were the wettest!

20170724_TheBigWetByTheNumbers_thumbCheck out these rainfall figures:

WDC Rain gauge Rainfall Summary (all figures in millimetres): (Friday + Saturday)

  • Oxford: 81.8 + 9 = 90.8mm
  • Woodend: 77.8 + 10.6 = 88.4mm
  • Rangiora: 74 + 6.6 = 80.6mm
  • Kaiapoi: 60.8 + 13.6 = 74.4mm
  • Bradleys Road: 45.2 + 11.2 = 56.4mm

By way of comparison, here are some of the rainfall figures for other areas, predominantly on the other side of the Waimakariri river:

  • Cust Main Drain (downstream of Threlkelds Road): 58.5 + 10 = 68.5mm
  • Eyrewell (near the intersection of Poyntz and Morrison Road): 81.5 + 15.5 = 97mm
  • Kaianga (opposite Ready Mix): 47.5 + 13.5 = 61mm
  • Papanui (Firestone Complex): 28.4 + 29.4 = 57.8mm
  • Christchurch Botanical Gardens: 33.6 + 44.4 = 78mm
  • Hoon Hay (Sparks Road): 59.8 + 28.4 = 88.2mm
  • Ridgens Road ( Selwyn River between SH1 and Bealey Road): 82.5 + 16 = 98.5mm
  • Mt Sommers: 50 + 16 = 66mm

Further information on the rainfall levels that accumulated across the Canterbury region can be found at https://www.ecan.govt.nz/data/rainfall-data/

River flows

On the river flow front, the levels were up, but they didn’t run as high as perhaps might have been expected, given the rain levels.

The peak flow in the Ashley River gorge was recorded at 11pm on Friday night at a flow of 572 m3/sec. By comparison, the Waimakariri was running at a flow of 680 m3/sec from the old bridge at 6am on Saturday. This was well below ECAN’s mean annual flood value of 1495 m3/sec.

The Cust Main Drain recordings reached their high water mark at 1am on Saturday morning with a flow of 93.7 m3/sec.

Further information on river flow for all of the Canterbury region can be found at https://www.ecan.govt.nz/data/riverflow/

The weather for the next few days

The good news is that we have a few days of reasonably fine weather ahead of us with a north west pattern locked in until Thursday. Although a southerly change is then forecast, it is only expected to bring moderate rain for a few hours on Thursday morning, and certainly nothing like the deluge we’ve just experienced. It might not be that warm though. A visit from Jack Frost is definitely on the cards!

Enjoy the sunshine!

Name: Matt McIlraith

Phone: 0800 965 468