Nadis
Rajsamand ditrict in western Rajasthan has a rich legacy of
rainwater harvesting structures. Nadis (ponds) once served as
the principal drinking water sources in this area. They received
their water supply from erratic, torrential rainfall. Since
the runoff was from sandy and eroded rocky basins, large amounts
of sediments were regularly deposited in them, resulting in
quick siltation.
A local voluntary organisation, the Mewar Krishak Vikas Samiti
(MKVS) has been working in the district for the welfare of
local farmers. They have constructed 20-30 nadis with a command
area in excess of 500 ha in Lambodi, Gudlia, Kharasan, Hakiawas
and Bhairu Das Ka Kheda.
The organisation has added systems like spillways to the
nadis, in the absence of which these structures were damaged
earlier. To prevent siltation, the MKVS has promoted afforestation
of the drainage basin and constructed silt traps. Since farmers
construct these structure on their own fields using locally
available materials, the cost of construction ranges between
Rs 2,500-10,000 and is thus affordable.
Polymer
Kundis
Churu District in Rajasthan is facing acute water scarcity due
to poor ground water quality and lack of water resources such
as rivers and canals. To deal with this problem Bhoruka Charitable
Trust (BCT) is encouraging villagers to build and renovate Kundis
(tanks), Johads (ponds), Talabs(permanent ponds) and dugwells.
The kundi consists of a circular catchment area sloping towards
the centrally located storage structure. The quality of water
from kundi is good and if maintained properly no serious water
contamination occurs. Its maintenance is easy. Local materials
such as clay, silt, lime,ash and gravel are traditionally used
to construct the catchment area of a kundi. They do not make
completely impermeable layer. As a result some part of rainwater
is lost due to uncontrolled seepage.
Efforts are now being made by BCT to enhance runoff in collaboration
with Hyderabad based National Geophysical Research Institute
and Indian Institute of Chemical Technology. The project has
identified ways to generate 60-70% runoff depending upon the
intensity of rainfall, using new technique of polymer science.
Water based non-toxic polymer solution that permeate the highly
porous sandy soils are used to increase runoff from Kundis.
These polymers act as binders and reduce permeability and
infiltration rate of sandy soils. Use of water repelling chemicals,
in combination to some binding agents result in better runoff.
Read more about Traditional
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