Posts
Chronicling
progression of el-Nino in New Zealand
Soil
moisture deficit and comparative flow rates for the Hutt River,
Wellington
Seemorerocks
As the Pacific region and New Zealand head into what has been described as a "Godzilla el-Nino" it is my intention to chronicle this process and back that up with real figures
One of the best ways to do this is to look at NIWA figures for rainfall deciles and (perhaps even more indicative, soil moisture deficit figures)
My subjective observation has been that we have had several dry seasons in a row (whether or not they were identified as drought) and that the last two winters at least have not provided the recovery needed over the winter period.
On a cursory look at flow rates for our local river, the Hutt River, this seems to be borne out in the figures.
I shall be updating these figures regularly as we head into summer and the driest period in February - March.
2013 saw an emergency that was declared very suddenly with restrictions on domestic water use that were withdrawn jsut as quickly when the main crisis was over
Here were flow rates for that period -
January this year saw drought over several parts of the country - especially in Canterbury in the South Island. I became sufficiently worried about this that I did some research of flow rates in the Hutt river and recorded my findings here -
| Site | Description | Average flow for Feb 1st 2015 (litres/second) | Average flow for January 2015 (litres/second) | Average flow for January 2013 (litres/second) | Longterm average flow for January (litres/second) | Average flow (litres/second) |
Hutt
River at Kaitoke (NIWA site)
|
Upstream
of water supply weir at Kaitoke
|
1215
|
1880
|
6710
|
5355
|
7771
|
Hutt
River at Birchville (NIWA site)
|
Mid-catchment
just upstream of Totara Park footbridge
|
3216
|
5129
|
20901
|
13761
|
22225
|
Hutt
River at Taita Gorge
|
Lowest
site in catchment. Opposite Manor Park golf course
|
3786
|
5838
|
24198
|
17116
|
23918
|
Source:
Greater Wellington Regional Council
| Site | Description | Average flow for February 2013 (litres/second) | Average flow for February 2014 (litres/second) | Longterm average flow for February (litres/second) |
| Hutt River at Kaitoke (NIWA site) | Upstream of water supply weir at Kaitoke |
3849
|
2832
|
4718
|
| Hutt River at Birchville (NIWA site) | Mid-catchment just upstream of Totara Park footbridge |
11542
|
5740
|
11249
|
| Hutt River at Taita Gorge | Lowest site in catchment. Opposite Manor Park golf course |
14473
|
6240
|
14049
|
By late February the authorities caught up with my concern and again hit the panic buttons over the water situation
Out on the farm where we keep our two horses, in Makara, the drought was very noticeable and the wetlands on the farm dried up for the very first time in the eight years we have been there.
In winter the land typically turns into a muddy quagmire but this year it didn't and we observed that the land remained relatively dry and didn't recover over the winter period.
Subjective impressions are one thing and figures are another, so I have collected river flow rates (in m3/second) for the same period for 2013. 2014, 2015.
What can be seen is that flow rates see to have declined over the period, even, seemingly in comparison with March this year.
Unfortunately the graphs are set out differently, but the picture is clear
Wait for updates and brace for impact!
October, 2015
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