Vanishing ground water – will it happen here?

Vanishing ground water – will it happen here?

A recent report in USA Today highlighted the risks associated with over abstraction of groundwater around the world. Interestingly, the report didn’t mention New Zealand. Maybe because the scale of some of the areas they’re talking about is far larger than the whole of New Zealand –India, for example.

Now I’m not a ground water hydrologist and don’t pretend to know much about the subject. However, it stands to reason that all resources are limited - oil, gas, groundwater. It’s a really simple mathematical equation; if we extract more than can be recharged, eventually we will run out. It’s that simple. Determining how much is recharged and how much will be recharged as climate change hits is way beyond me - but I think it’s safe to say that if we’re losing now, things aren’t going to get any better as the climate changes.

So what should we do to meet the current needs? We can’t just stop pumping, can we? Well, in some places in the world they’ve had to – there’s nothing left to pump. This is a bad position and we don’t want to get there. But we can’t stop pumping and neither should we, but that pumping must be at a rate that doesn’t exceed what’s coming in.

Given that our demand for both potable and irrigation water is ever increasing, we need to look at alternative sources. Invariably those sources are either socially or environmentally unacceptable, or in the wrong place, or all three.

I arrived in New Zealand in 1999 and at that time there was a proposal being considered to take water from the outlet of Manapouri in Milford Sound and tanker it by ship to the Middle East. I believe such projects have been proposed on and off for decades. These proposals are generally rejected because we don’t want hordes of huge tankers going in and out of Milford Sound with the risk of an accident causing an environmental catastrophe.

In Auckland, there’s a river of about 300 million litres per day that just flows out into the Manukau Harbour – the effluent from the Mangere wastewater treatment plant. No matter how well we treat this, the public perception is that it’s sewage. It is not.

In Canterbury, there have been all sorts of ideas about how water could be harvested on the West Coast and transferred over the mountains.

We need to look at non-traditional methods of harvesting water and start thinking of ideas that, although they might have been rejected in the past as unworkable or too risky, are worth pursuing.

What I’m saying is that something needs to give – either the extremely low tolerance to environmental risk or the social acceptance of alternative water sources. We can’t continue with our prejudices and zero risk approach to the environment if we wish to meet the needs of the present without compromising the ability of future generations to meet their own needs.

This thought leadership article by Iain Rabbitts, a water and wastewater manager in our water resources team, is intended to provide you with insights and relevant information on the risks of over abstracting groundwater. Our thought leadership articles on topical and specialist issues are designed to present the key points in an easy to digest and interesting manner.

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