Chungungo, a remote village in the arid coastal
desert of northern Chile, has more than doubled its per capita water supply by collecting
fog. Their success has inspired similar efforts around Chile, Ecuador, Mexico and Peru.
It all started in 1992, when researchers from International Development Research Centre
(IDRC), Canada, decided to harvest fog as a supplementary source of drinking water.
This is how fog is collected
The idea is rather simple. The condensed water droplets
present in the fog precipitate when they come in contact with an object like net. As water
collects on the net, the droplet joins to form larger drops that fall under the influence
of gravity into a trough or gutter, from which it is conveyed to a storage tank. The
storage and distribution system usually consists of PVC pipe connected to water hose for
conveyance by gravity. Before usage the water needs to be chlorinated.
A fog collector is a flat, rectangular nylon net (1 mm wide
and 0.1 mm thick, in a triangular weave) supported by post at either end. It is arranged
perpendicular to the direction of the prevailing wind. Alternatively, the collector may be
a more complex structure made up of a series of such collection panels joined together.
Local topography and quality of the net material determines the complexity and the cost of
the system. The installation, operation and maintenance of the system is affordable
requiring little skill.
As per the IDRC studies, "Although the technique is
not flawless, it work best in both coastal and mountainous areas. In Chungungo village,
the fog harvesting efficiencies were found to be highest during the spring and summers,
and lowest during the winter months." The frequency of fog occurrence, fog water
content, wind patterns and topography are some of the suitability factors determining its
application. However, its effective implementation depends on the involvement of locals
like in Chungungo. Here, a total of 88 fog collectors are managed by a village-based local
committee. The operation and maintenance of the system is managed by the households.
Techno tit bits
A low cost drip irrigation system, drum kit, has been
developed by Integrated Development Enterprises in Nepal. It has the potential of
enhancing the average annual income of small farm holders by allowing them to take up
income generating projects like horticulture. The kit consists of a drum and a series of
pipes that need to be annually replaced. The size of the drum varies as per the need. A
200 litres drum can irrigate 125 cubic meter plot.
In Nepal, about 15,000 kits have been installed. Even in
India, similar kits are increasingly used by the people in Junagadh, Gujarat.
This is a water efficient landscaping method for creating lush
green lawns with little water. No additional work is required. Careful planning not only
reduces water usage by 75 percent but also cut down the need for fertilisers and
pesticides. Plants with varying watering needs are sown in the lawn divided into four
zones: oasis, hardscaped, drought tolerant and natural.