Logical solution is to store water

Hort Talk
with Mike Chapman
HorticultureNZ CEO

For a country with a plentiful supply of water, it seems wrong to say that we are progressively facing more water shortages.

The December 2017 Ministry for the Environment report, Adapting to climate change in New Zealand, observes that: “New Zealand will experience increased frequency and intensity of extreme events such as higher temperatures, flooding, droughts and wildfires, increased sea-level rise, and warmer and more acidic oceans.

“This will threaten our coastal communities, cities, infrastructure, human health, biodiversity, oceans and resource-based economy (Intergovernmental Panel on Climate Change (IPCC), 2014). “These changes may also bring opportunities and we need to plan how we can best position ourselves to take advantage of these.”

Last winter, spring and now the summer are prime examples of what may be coming our way in the future. A cold and wet winter that hampered vegetable production has been followed by a hot and very dry December that saw many areas going into drought. If this is the way of the future, we need to prepare and plan for it.

In New Zealand, we have times when there is an abundance of water and then times when there is not enough. A little known fact is that, according to NIWA, of the average of 550 billion cubic metres of rain each year, 80 per cent flows out to sea (18 per cent of rainfall evaporates, and around two per cent is used for irrigation, urban and industrial use).

The logical solution is to store water when it is plentiful for the times when it is scarce.

Dams and ponds

Aquifers are nature’s way of storing water and there are projects running where the aquifer is re-charged when there is plenty of water available. But the more traditional way to store water is in dams and ponds.

In the New Zealand of the future, it seems we are going to have to do more water storage to ensure we can sustain our domestic food supply through the weather extremes. When it rains a lot, water storage schemes, such as dams, take and store the excess water preventing flooding.

When it is dry, they provide water for urban consumption, to keep rivers and stream running, to provide drinking water for animals and irrigation for pasture and crops.

Without water there is no life and high levels of food production cannot be maintained.

Providing water when it is dry also has enormous benefits for our rural communities and that, in turn, helps the financial viability of our urban communities. Without water, production stops and jobs are lost.

Irrigation’s contribution

In the November 2014 NZIER report to the Ministry for Primary Industries, Value of Irrigation in New Zealand, it was estimated that in 2011/12, irrigation contributed $2.17 billion to net farm gate GDP. That figure is increasing every year and has been estimated by Irrigation NZ to increase to $3.5 billion by 2021.

NZIER believes that New Zealand’s real GDP would be 2.4 per cent lower ($4.8 billion less) without irrigation and all households in New Zealand would earn lower wages.

So this is not just something that affects rural communities. It impacts all of New Zealand. We all need water to survive - humans, animals and plants.

New Zealand’s economic prosperity is linked to water being in plentiful supply all year around. Without sustainable water supplies, we cannot feed New Zealand and grow the produce that drives our export returns.


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