|A well dressing at Wynds Point (UK) |
The theme of this year’s World Water Day was Groundwater – the hidden treasure beneath our feet. Its aim was to make the “invisible visible.”
It’s little wonder that earlier cultures regarded manifestations of groundwater such as wells, soaks, springs and oases as sacred. Even today, many places still have ceremonies such as the blessing of the waters in spring and you might still come upon well dressings – beautiful flower arrangements to celebrate the life -giving properties of their water. Many springs such as Lourdes in France and hot springs from Iceland to Machu Picchu, the spa towns of Europe, the UK, Russia and Japan, were also sought out for the healing properties their minerals were said to confer. With 80% of the world’s population still relying upon groundwater for drinking, for hygiene and sanitation and for agriculture and industry, we would do well to at least treat it with more respect.
Though science can now tell us much more about the nature of
such waters - their origin, their composition and their extent, they are no
less remarkable or mysterious. For example, most of the water in the Great Artesian Basin
which underlies much of Australia’s arid inland was laid down millions of years
ago, in the time of the dinosaurs – when the interior of the continent lay
below sea level. Only a trickle comes from rainfall, run-off, or springs,
making recharge very, very slow. Nor is it a single basin. There are several layers
with some being interconnected and others not. The beautiful blue Mataranka
Springs in the Northern Territory are no less miraculous for having been found
to originate in the mountains of New Guinea and it is certainly not less so for
weary travellers who have travelled through 2600 Km (1620 miles) of red dust and gibber plains to get there
from Adelaide. Some subterranean streams also give rise to rivers or add their flow to them.
Unfortunately, the more we learn, the more we discover that
such waters are neither infinite nor static and how little we know. Although we can’t see much of them,
they are subject to the same vicissitudes as their surface relatives
-namely pollution and over -exploitation, as well as a few of their own such as seawater
intrusion in coastal aquifers where over -pumping has occurred and the newly
recognised risks of fracking. We'll discuss some of those a bit more fully below.
Pollutants and Overuse
Pollutants and over use are generally self -explanatory, but worse when they happen underground because we can’t see what’s going on until it’s too late. Leaching can occur from rubbish dumps, farm chemicals and fertiliser, industrial plants or anything spilled on the ground. Inadequate sanitation can cause bacterial contamination which can lead to disease outbreaks. This can also occur when heavy rain or flooding overwhelms sewerage works or when septic tanks leak or don’t function properly. More recent concerns include the presence of pharmaceutical residues, including those from the contraceptive pill.
Industrial Pollution (South Australia)
Fracking involves the fracturing of deep bedrock and using chemicals, sand or water injected at high pressure to release gas and oil, some of which may leak into ground water. See more about fracking here.
Seawater Intrusion (USA)
A further problem is that when extensively used for irrigation, groundwater can raise the water table and bring salts to the surface, making the land infertile. It has been estimated that at least 20% of the world’s agricultural lands are affected by salinity with India, China and Pakistan accounting for approximately half. This is especially true of hot dry places, including Australia and is likely to worsen under hotter, windier and drier conditions of climate change.
The impact of Climate Change on Groundwater
The potential impact of climate change on groundwater should not be under estiminated and should be planned for now. A preliminary study of seven of the world’s major aquifers has shown that those in hot dry areas are most likely to experience reduced recharge, due to rising temperatures leading to more evaporation from the landscape and because additional pumping usually occurs during dry spells and hot weather. Those in more humid regions such as the Guarani Aquifer in South America and India’s North West Aquifer are likely to experience more recharge as a result of heavier rainfall. However, where recharge depends on snowfall it is also likely to diminish. Obviously increasing demand due to population growth and or having more land under cultivation will exacerbate this.
Groundwater Contamination and Depletion and climate change (USA)
- Test your water frequently
- While local authorities generally test and clean public water supplies which is
very expensive, domestic wells are less likely to have frequent scrutiny. You
should learn to test your water yourself and do it at least once a week. You
can also add a filter to taps which you use for human consumption i.e. drinking and cooking and avoid many contaminants.
- Dispose of any chemicals – especially oil, batteries and paint, properly. Your local council will know what to do and should have a sealed facility with high berms around it to prevent leaching. Otherwise return any left -overs to the place where you bought them. Try to reduce your use of these and also lawn care products, fertilisers, detergents and personal care products and stop them going go down the drain too. Farmers should ensure proper use and secure storage of farm chemicals and prevent runoff of farm manure and fertilisers so that they do not cause algal blooms and contaminate water sources.
How farmers can protect Groundwater (UK)
- Use less water. Don’t let
taps drip. Check bores and wells for leaks, also nearby facilities like petrol
stations, particularly those using
underground storage. Some aquifers, like the Great Artesian Basin are not as extensive as previously thought, and others will be vulnerable due
to climate change, so mapping, monitoring and measuring will be doubly important.
Cap unused wells. We should also be considering the use of recycled water for industrial activities
such as mining, forestry and tree growing (silviculture) and ornamental parks and gardens. Mulching will help
to reduce the need for water by retaining soil moisture and preventing evaporation as will drip irrigation on farms. Retention
of wetlands will slow run -off after rain, help to retain moisture and filter water before it reaches underground supplies.
- Check septic tanks regularly for leaks and proper functioning - sometimes the bacteria required for digestion die, especially if using disinfectants unsuitable for septic tanks. (Read the labels!). Support global efforts to improve water supplies and sanitation to prevent bacterial contamination and waterborne diseases.
- Join community groups which monitor water and support the national and international groups which work towards clean water. Encourage schools to stress the importance of taking care of our water supplies. Urge the relevant authorities to make national or basin -wide plans, because underground water doesn't always conform neatly to lines on the map.