Leaky wells – Oz way to recharge groundwaterMarch 15, 2008
Leaky wells to the rescue
|When it comes to water management, the Aussies can sure part with several lessons to many parts of the world|
Australia has been in the news for many reasons recently. When it comes to water and its management there indeed are some lessons that Australia can teach the rest of the world. Faced with a prolonged drought and climate change impacts, the Aussies have perforce been taking a look at better water management practices. Since Australia happens to be terribly well urbanised, urban water has fit in as an important blip on their radar.
Amongst other things, storm water has been seen as too good a resource to be wasted and therefore has featured in the solution paradigm for supply of water to their cities.
A handbook for storm water management has been the result. Do we in India have one? The answer is ‘no.’ Do we need one? ‘Yes.’ All our municipal authorities, property developers and even individual house owners will benefit from one. Who then will get one out? A million-dollar question which remains to be answered.
As in India, the responsibility of managing storm water lies with local governments. As the handbook “Introduction to storm water management in Australia” puts it, although urban storm water and treated wastewater are recognised increasingly as important economic resources, they are not widely used to augment supplies in expanding urban areas.
Recent research and demonstration projects have shown that storm water and treated wastewater can be exploited in a cost- effective and environmentally-sensitive manner for new urban developments. In this context:
Water reclamation can reduce potable water demand by as much as 50 per cent.
Properly managed storm water flows provide important flow return to streams, offsetting the environmental impact of upstream water supply diversions and reducing the need for costly in-ground storm water infrastructure.
The enhanced use of natural drainage corridors and depressions can provide open space, landscaped and recreational areas and conservation benefits, increasing the amenity of new urban developments (multiple-use corridors).
Treatment of storm water and wastewater closer to source minimises uncontrolled discharge of water containing high suspended solids, nutrients and organic material.
Almost similar to tanks which our ancients had managed to finetune as a water harvesting technique, are detention ponds. The ponds, in the Australian context, are designed to hold back a design flood, let us say one occurring every 20 years.
Since urbanisation and city development leads to increased run-off, this run-off is stored in water bodies specially designed by the property developer or the city council. This prevents flooding downstream and recharges ground water. Topping up the aquifer then provides water for the future. Detention ponds, however, are still seen as not doing enough to control soil erosion and vector breeding. Lack of bio remediation is also a problem.
Designing a combination of urban wetlands and detention ponds seems the way forward because wetlands do a good job of bio remediation as well provide bio diversity and remedy soil erosion.
A new concept called bio basins is being tried, where the basin lined with gravel will remain dry and not allow for mosquito breeding. When water fills up, it will quickly be allowed to percolate into the ground and the basin itself will dry up and remain a dry landscape feature.
Akin to our recharge wells, leaky wells do the reverse of what an ordinary well does. Instead of providing water it takes storm water and recharges it to the aquifer through a soil medium adequate to filter pollutants, if any.
Detailed design guidelines are emerging for leaky wells, which enable designers to include them in best practices for storm water management and thereby mitigate the negative impacts of uncontrolled storm water and convert rain into a positive resource.
The way forward
A combination of the use of mass media and education is seen as crucial in bringing about behavioural change amongst policy makers and designers to make storm water management a reality.
Investment in R & D will be essential to learn from ‘on the ground’ experiences and translate them into a easy-to-understand-and-use handbook for developers, architects, landscape designers, urban planners and even the home owner so that water is managed wisely. A systematic and structured approach to addressing a water problem and turning adversity into advantage is water wisdom. Will we rise to the challenge?