Dry spell or a global drought?
The Wellington region’s January rainfall was the lowest since records began in 1879. Is it a passing dry season or the start of something worse?
Alicetown river observer Robin Westenra says we could be heading for catastrophe.
Karori Reservoir recorded 3.8mm of rain during the month, the lowest since 1879, compared to the long- term average of 81mm, according to Wellington Regional Council.
Wainuiomata Reservoir got even less, with 1.8mm, the least since 1890.
Hutt River’s flow rate at Kaitoke on February 1 was 1215 litres per second, down 35 per cent on January’s average, which was in turn 65 per cent below the long-term average for January.
If the level were to drop below 600 litres per second, the regional council’s resource consent requires it to stop taking water at Te Marua.
Westenra has been observing Hutt River’s changes for several years.
He said the long-term trend was grim.
‘‘ It seems we’ve had three really dry seasons in a row. I don’t see this finishing any time soon,’’ he said.
Westenra said it was far from a local dry spell.
California faced a 1000-year drought, and declared a state of water emergency in January.
The water supply for Brazil’s largest city, Sao Paulo, was critical in the middle of the rainy season.
Westenra said the situation was the same around most of the world – other than eastern Europe – as a result of global warming.
With the Arctic ice melting, the jetstream had changed its pattern, taking cold, Arctic air south into North America and Europe.
At the same time, warm air from the south had entered the Arctic through the Bering and Farm Straits, warming the southern hemisphere and bringing drought.
‘‘The worry in my mind is not so focused on sea-level rise.
‘‘It’s desertification of the land and habitat, so we won’t be able to grow our food.
‘ To assume New Zealand’s drought, and Wellington’s water crisis is a one-off local situation appears to be wishful thinking.’’
Wellington Regional Council is responsible for supplying the
region with water and its staff have taken a low-key approach, calling for restraint with garden watering and enforcing a sprinkler restriction.
Deputy chairwoman Barbara Donaldson said the council was developing more emergency storage.
‘‘The council acknowledges the reality of climate change, which will result in more droughts and more frequent intensive storms,’’ she said.
A cross-harbour pipeline was in the council’s long-term plan as well as a dam at Takapu Valley to provide extra storage.
A large- scale irrigation scheme in the planning for south Wairarapa could conceivably be used for urban water supply in an emergency, she said.
Sentinel: Robin Westenra at the Hutt River.