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Artificial
Glaciers
A great example of how decentralised approaches to water harvesting
boost innovation comes from Ladakh in Jammu and Kashmir. Chewang
Norphel, retired engineer of the department of rural development,
has found a way to make 'artificial glaciers'. In the cold desert
that is Ladakh, the only source of water is met from glaciers. But
this comes in late in the summer. Norphel has developed a way to bring
glaciers closer to villages, which is a bonus for farmers as water
reaches their fields in spring. Norphel's innovation involves channelizing
water to the shadow area of a mountain close to a village. After going
through metal pipes, the water freezes, creating a glacier close to
the village.
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.
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Chauka
System
The people of Laporiya of Dudu block, Jaipur, Rajasthan have dyked
degraded pastures to harvest rain. In the 1970's the pastures of Laporiya
were barren and degraded. In 1990, the Gram Vikas Navuyak Mandal Laporiya
(GVNML), a civil society group of Laporiya mobilised the vilage community
to undertake the revival of its ecology.
A gram sabha (village assembly) consisting of 11 village elders
were formed. Four years later, work was initiated on 50 hectares
(ha) of pastures to integrate the denuded land into a single project
unit. To complete the project, the villagers contributed labour
as shramdaan (voluntary labour) and the result was a system of chaukas.
Chaukas are rectangular plots in a dyked pasture and store rainwater.
They are 66 metres (m) long and 132 m wide enclosures arranged in
a zigzag pattern and lie along small gradient. Dykes, 1.5 m high
are built along the three sides that lie towards the lower part
of the land/gradient. Trees are planted on these dykes to give them
additional support to withstand rain.
When it rains, water collects in the dyked lower half of the chauka.
As the amount of water stored in the enclosure rises, it flows into
the neighbouring chauka, and so on, gradually seeping over the entire
pasture. This means that fields are never inundated with water.
Grasses can grow. After reaching the last chauka, the water flows
into a monsoon drain. This system not only provides adequate water
for villagers, but also promotes the recharge of groundwater.
The key to the success of the project is its adaptability. The
dykes have been built keeping in mind the pathways that he people
use. There was no restriction on grazing in the chaukas earlier
as the emphasis was on impounding water and improving the soil.
Now the people of the village plan to restrict grazing to alternate
chaukas.
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Jaldhar
Model
To harvest rain and save paddy crops from frequent rain failures,
a team of Professional Assistance For Development action (PRADAN)
has found a simple solution termed Jaldhar. In this technique, a portion
of the farmland is left aside for rainwater harvesting, holding back
rainwater in the land itself. Depending upon the land type there are
two variations of design. One design is applicable to small plots
where slope is less than 2 per cent and the other design is applicable
for plots where slope is between 2-8 per cent and for slopes greater
than 8 per cent, the technology may need some little modification.
The five percent model: The main objective of this model is to
ensure that all small land holdings should have their own water
body for harvesting rain. These pits are usually 1.5 square metre
in size, occupying 5 per cent area of individual fields. The plot
is levelled properly and bunded to allow water to accumulate to
a height of 100mm, this pit also facilitates the subsurface flow
of water to downstream plots and improves the moisture regime of
the area as the whole.
The jaldhar 30x40 technique: The name comes from calculations done
in terms of feet. Lands having an average slope of 3-5 per cent
upland areas are divided into smaller plots and the water collection
pit is dug in each plot. The pit area should consist of 3-4 per
cent of an individual plot with depth around 1 m and located at
the lowest point of the plot.
Plots should be chosen in a staggered fashion so those pits are
also staggered as far as possible to enable uniform seepage of water
across the slope. Each plot size is maintained at 9m (along the
slope) x10.7 (across the slope), hence area of each plot will be
111.5-130sqm. The volume of each collection pit is around 3,000
litres.
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Tudum
or monga
Tudum or monga are mechanisms used to draw water from Kohli tanks
for irrigation. Different mechanisms are used depending on the size
of the tank.
For a small tank or a bori, a straight tunnel across the base of
the bund is constructed using stones. A log is pitched at the mouth
of the tunnel and plastered with clay. It is removed when water
is required.
For a medium or large tank, a straight tunnel across the base of
the bund is constructed using stones over which a stair-like structure
(monghad) is built, with a opening (dachcha) on each side. This
is stopped with a stone slab or a wooden log carefully plastered
with clay.
Sometimes, a hollow tree trunk is also placed across the base of
a tank, to which another hollow tree trunk with holes at regular
distances is placed vertically. These holes are plugged with cogs,
which are removed to draw water. This system requires frequent repairs
as tree trunks rot quickly. Besides, there are stringent forest
laws, which make it difficult to obtain wooden logs.
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Networking
of Farm Ponds
The Institute for Rural Development of the Bharatiya Agro-Industries
Foundation has undertaken the excavation of 330 farm ponds in Adihalli
watershed, spread over an area of 700 hectares in Arasikere taluka
of Hassan district in Karnataka. The approach is based on a traditional
concept where structures were dug out in strategic locations, locally
known as kalyani. This overcomes the shortcomings of constructing
check dams, which cannot be constructed in all terrain and the benefits
of which are not available to upstream communities. A series of ponds,
constructed along contour lines and connected to one another, allow
easy access to water and a better soil moisture regime. In the Chotanagpur
plateau in Orissa, the Professional Assistance for Development Action,
an NGO, has also worked on farm ponds. It has promoted the idea of
leaving a small part of the farm for water harvesting.
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Horizontal
Roughing Filter/ Slow sand filter
The introducton of horizontal roughing filter and slow sand filter
(HRF/SSF) to treat surface water has made safe drinking water available
in coastal pockets of Orissa. The major components of this filter
are described below.
i) Filter channel : With an area of one square metre in cross-section
and eight metre length, to be laid across the tank embankment. The
filter channel consisted of three uniform compartments, the first
being packed with broken bats, the second with coarse sand, followed
by fine sand in the third compartment. The HRF usually consists
of filter material like gravel and coarse sand that successively
decreases in size from 25 mm to 4 mm. The bulk of solids in the
incoming water is separated by this coarse filter media or HRF At
every outlet and inlet point of the channel, fine graded mesh is
implanted to prevent entry of finer materials into the sump. The
length of a channel varies according to the nature of the site selected
for the sump.
ii) Sump: A storage provision to collect filtered water from the
tank through the filter channel for storage and collection.
While HRF acts as a physical filter and is applied to retain solid
matter, SSF is primarily a biological filter, used to kill microbes
in the water. Both filter types are of an equal technical level
and their operation is characterised by stability. These make full
use of the natural purification process of harvested surface water
and donot require any chemicals.
Making Water Everybody's Business
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