Our planet’s water is a finite resource that needs protection
Industrialisation’s impact on our fresh water resource
The water on earth is continuously recycled inside our closed ecosystem. There are no pipelines to another source. As longterm shortages of fresh water can have devastating consequences for humanity, we must therefore ensure that what we have now can be sustained.
Prior to industrialisation, rainwater generally flowed overland at low velocity, in the process transporting nutrients across ecosystems and charging the aquifer. But in today’s urban environments, the removal of natural impediments from the landscape means stormwater typically flows at high velocity, with seepage, soil water table replenishment and aquifer recharge all adversely affected. And inevitably, stormwater from areas of human activity carries various types and concentrations of contaminants. As the human activity increases, so too does the range of contaminants.
Fresh water is fundamental
for human existence
In recent decades scientists have concluded that the presence of freshwater on planet Earth is the fundamental support resource for human existence. It is the presence of water in its three physical states of solid, liquid and gas that provides the essence of our unique environment, from which a complex eco-system has evolved.
The water resource is approximately 3.5 billions years old and was delivered to Earth in the form of ice meteors as fresh water. Gradually our seas have become saline – the interaction of carbon dioxide and water causing breakdown of minerals, resulting in sodium chloride or salt.
Fortunately, as seawater evaporates, the salt stays behind and fresh water is then delivered to us as rainfall. However, only 0.01% of the water on the planet is available for human use. This 0.01% is all we have available for our many human activities – not only direct consumption (drinking water) but also fresh water for agriculture, animal husbandry, industry and domestic use.
Rainfall and Natural Run-Off
Not even rainwater in an undisturbed, natural environment is ‘pure’ H2O. As rainwater falls through the atmosphere, which is 78 per cent composed of Nitrogen, it gathers up various types of ions in very small concentrations.
In an undisturbed environment, organisms rely on these naturally occurring ingredients in rainfall as nutrients. Furthermore, vegetation, rocks and detritus, reduced the physical impact of rain drops, causing water to flow at relatively low overland velocity, gradually transporting nutrients, soaking into soils and charging the aquifer. Eventually this water flows into water bodies and streams, delivering nutrients to the sub-ecosystems.
Urban Run-Off (Stormwater)
Pollutants suspended in the atmosphere are the first source of rainfall contamination. However a greater range and higher concentration of contaminants occurs from human-impacted environments, particularly urban built environments. While agriculture contributes excessive nutrients and suspended solids, the built environment completely changes the interrelation between rainfall and the landscape.
The impact of rainfall on hard surfaces is increased. The thunderous noise of rain falling on a roof is indicative of energy release, which on hard surfaces dislodges particles and strips the surface clean. The rain water then flows at high velocity due to the lack of flow impediments, taking these particles with it.
These human-made impervious surfaces, whether roofs, concrete/asphalt landscapes etc, eliminate seepage, soil water table replenishment and aquifer recharge. Additionally, the absence of bacteria and other organisms in these artificial landscapes (as opposed to the natural ecosystem, where they are present) causes the transported particles to be present at much higher concentrations than in the pre-industrial environment.
All this creates multiple issues that need to be corrected to maintain sustainably health clean water:
- Water flow velocities have increased
- Flow volumes from catchments have increased
- The range of contaminants has increased
- The concentrations of particles/materials have increased, and
- The state of these substances is less processed (basically ‘raw’)
Water Sensitive Urban Design (WSUD) recognises these impacts and works to alleviate them. The low-cost Enviro EPS, designed in accordance in WSUD principles, has an important role to play in helping to purify our most precious natural resource.
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