Date: 25 July 2017
The Waimakariri District Council has provided figures regarding the recent floods last week:
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
The Ashley River was recorded 11pm on Friday night at a flow of 572 m3/sec.
In comparison, the Waimak river ran at 680 m3/sec from the old bridge at 6am on Saturday.
For reference m3/sec refers to cubic meters per second.
The five days before the floods the average at low tide was roughly 70m3, and before that it was roughly 120m3. This chart from ECAN also puts into perspective the changes in river flow:
Thankfully there is no more heavy rain forecast in the near future! Although there may be moderate rain later in the week.
UPDATE 26 July 2017: Canterbury Weather Updates are reporting low level snow could hit North Canterbury.