Saturday, September 7, 2013

About Sustainable Water Supply Systems

By Kate McMahon


Sustainable water supply systems are critical components of planning processes for both urban and rural development. Potable water is needed in every place. Rural communities additionally have to provide for agricultural needs, while urban planners have to ensure adequate supplies for industrial as well as commercial requirements.

There are completely different economic, social and environmental issues to be addressed at the supply and demand ends in both rural and urban areas. The array of factors to be considered can be broadly categorized under either watershed management or water usage, and will vary depending on local climatic conditions, population and existing resources. The one thing that is common to every community in the world is that the presence of water is directly linked to survival and growth.

On the supply side, watershed management requires a lot of planning and resources. The key is finding the right balance between the needs of the human population and maintaining the natural ecosystem. Practical work that comes under this includes water rights, cross-jurisdiction agreements, land use, stormwater runoff, drainage, and compliance with environment law.

The planet's surface freshwater distribution is highly uneven. For instance, Canada is blessed with more than 50% of the world's available supply of lake freshwater. Everyone else has to construct dams and block rivers to create and fill reservoirs. More than half of all freshwater is available in the form of groundwater that must be accessed by digging wells and pumping it to the surface.

By comparison, rainwater harvesting is a highly sustainable method which does not deplete or pollute natural resources. There is no danger of overexploitation at the moment, and the harvested supplies are clean and suitable for human consumption. The limitations include the setup cost and the need for treatment of stored rainwater to prevent contamination.

Another good choice is a desalination plant, which also does not affect the existing quality and quantity of freshwater. The process of separating salt from seawater is not as sustainable as rainwater harvesting, but it is infinitely better than damming rivers or exhausting all the groundwater. The main barrier is again the system cost, and also the fact that the reverse osmosis required for desalination needs a lot of energy. It ends up causing Co2 emissions and other byproducts that can be dangerous for marine life.

Limiting the generation of wastewater is probably the best way to ensure sustainability on the usage side. It requires a certain amount of innovation to implement waterless car washes, dual-flush toilets, artificial lawns, astroturfs, etc. It also helps to have bigger and more efficient treatment plants. The municipal distribution system has to be optimized to reduce losses because of leaking pipes.

All of this merely scratches the surface in terms of what it will take to ensure sustainable water supply systems. It's going to take a lot of technological advancements, cross-jurisdictional agreements and changes in regulations to achieve sustainability at the community level. A good place to start is with potable supplies. Contaminated H2O still causes 1.8 million deaths every year, according to the latest WHO statistics. With climate change causing severe flooding and droughts, it becomes even more important to ensure resiliency by implementing plans for long-term sustainability.




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