It seems to me, following recent publicity on the selling of New Zealand’s fresh water, that there is a general lack of knowledge regarding the role that water plays in nature. In recent discussion, opinions have been expressed which clearly show that water is considered a 'right' and will always be available to humans.
Concern seems to be more about selling water too cheaply rather than any adverse affect it may have on our beautiful country or the planet. A brief summary of the hydrology cycle may aid in understanding that water is very important – far beyond the uses that human beings have found for it.
A phrase often heard is that flooding or smoke or gases will flow or blow 'away'. There is no 'away'. We exist in a giant bubble, enclosed by layers of atmosphere which prevent anything from entering or leaving, apart from energy from the sun. Thus, the air and gases we have are those from millions of years ago.
The same applies to water which falls as rain or snow, soaks the earth, evaporates into clouds or flows into streams to go into the sea in a continuous cycle. It never decreases or increases but gets redistributed by weather systems. A university lecturer drove this home by telling us that we have all drunk Jesus’ urine, more than once!
While the water that enters the sea appears to go 'away' it is actually continuing an important part of the hydrological cycle unseen by most people.
Run-off from land masses enters the sea and creates changes in the local conditions which support many life forms; some such as embryo and hatchlings would not be able to thrive without the saline dilution and warmer water from the land. There are many different situations and types of water mixing depending on the geography of the land mass and the volume of freshwater flowing. The natural ecology has adapted to utilise this essential variety with many marine species existing only close to land masses and at limited locations. Crayfish and paua are NZ examples.
I believe extreme care should be exercised before we take large quantities of water out of the natural system as we do not know what effect it may have on the balance of that system.
In the late 1980's in the coastal town of Kaiapoi, just north of Christchurch, residents found that their groundwater had a high saline content. Investigation showed that aquifers inland had been tapped to the extent that the natural balance of water flowing toward the sea had been greatly reduced and seawater was pushing in under the town. Kaiapoi suffered great subsidence in subsequent earthquakes.
As well, 'dead holes' used to dispose of animals and poultry inland had contaminated existing aquifers so badly that towns such as Wood End have such a high percentage of chlorine in reticulated water that residents regularly carry tanks to Christchurch for drinking/cooking water.
If we interfere with the natural hydrological system by depleting water flow from our shores and hinterland the consequences may be far reaching and longer-term than the ozone depletion has been. It may not be just a matter of ceasing to take the water out of the system and waiting for the next downpour. In parts of the USA whole land masses have subsided where underground reservoirs drained. Groundwater takes a long time to accumulate, sometimes tens of thousands of years.
Surely we can learn from past mistakes and use the science already at hand to protect our planet from human folly, and have a greater understanding of what a precious resource we appear to be squandering for short term monetary gain.
- BY JILL NICHOLLS