3. Introduction and history.
What is rain water harvesting and It’s Need.
Rain water harvesting techniques in dry land areas.
Benefits of rain water harvesting.
Disadvantages of rain water harvesting.
Future of Rain water harvesting.
CONTENTS
3
4. Only 2.5% of the world’s water is freshwater and most of this
are in The form of polar ice-caps.
Water use has increased by 70% since 1970
A recent report by Credit Suisse stated that by 2025
18countries will experience water demand beyond supply
capabilities
It takes up to 5000 lit of water to produce 1kg of rice.
Every square mile of developed land causes16 million gallons
of rain water to directly enter the rivers on a rainy day.
Each person uses about 150 liters of water every day.
INTRODUCTION
4
5. India is practicing rain water harvesting since 10th century.
In 11th century largest rain water harvesting tank was created by
chola kings and it is 16 kilometer long.
In India drylands are occupying 68% of total cultivated area
India is a water rich country with 4% of world’s water resources
Due to rapid urbanization infiltration of rain water into the sub-soil
has drastically reduced drastically and recharging of ground water has
diminished.
HISTORY
5
6. Major parts of our country have been facing continuous failure of
monsoon and consequent deficit of rainfall over the last few years.
population of India increasing so the use of ground water has
increased drastically leading to constant depletion of ground water
level causing the wells and tube well to dry up.
In some places excessive heatwaves during summer create a situation
similar to drought.
It is imperative to take adequate measures to meet the drinking water
needs of the people in the country beside irrigation and domestic
needs
Out of 8760 hours in a year most of the rain in India falls in just in
100 hours.
Need For Rainwater Harvesting
6
9. Technique used for collecting ,storing and using of rain water
for house hold needs and for irrigation and future storage.
What is rain water harvesting
9
11. Land based rain water harvesting
Directly from roof tops and stored in tanks.
Monsoon run off and water in swollen streams during the monsoon
and storing it in underground tanks.
Water from flooded rivers can be stored in small ponds.
Collection and transfer of rainwater into percolation tanks so as to
facilitate discharge into ground.
Watershed based rain water harvesting.
Pavements , lawns ,gardens & other open places
Rainwater can be harvested in a variety of ways
11
13. • Roof tops are favored because of the large coefficient of run-off
generated from them and relatively less likelihood of their
contamination.
• Average roof collects 600 gallons of water for every inch of rainfall.
ROOF TOP WATER HARVESTING
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14. URBAN MODEL OF RWH
The main components
• Roof catchment
• Gutters
• Downpipe
• First flush pipe
• Filter unit
• Storage tank
• Collection pit.
14
15. Design of rooftop rain water harvesting system at CAET, Akola
Nimkale(2011)
• 82.58%of total rainfall will be collected in recharge pit.
• Cost of construction per m2 is 2.78/- and recharge cost of m2
0.88/-
• Total area of CAET building was 5403 m2 and estimated
annual volume of water recharge from this area was 3414.76
meter3.
International journal agricultural engineering, vol-4 no-1, 113-11915
16. Planning and cost estimation of roof rainwater harvesting structure
Reena Kumari et al.(2012)
• The estimated rainfall at 75 percent probability limit was 547.8
mm with recurrence interval of 1.33 years.
• The economics of harvested water was also estimated considering
the useful life of the structure as 25 years.
• The designed dimensions of the reservoir were estimated
12x10x3.05 m with the storage capacity of 366 m3 and the cost of
storage of harvested water was estimated ` 0.10 per litre.
Intl. J. Agric. Env. Biotech. 5(3): 225-232,
16
17. Rural model of RWH
• Rural areas generally use traditional methods of rainwater harvesting.
• Main motive of rainwater harvesting in these areas is to facilitate
irrigation for agriculture and use of water for domestic and drinking
purposes.
• Now a days practices are also been followed to as to recharge ground
water levels.
• Many of the traditional structures include Tankas, Nadis, Talabs,
Bavdis,Rapats, Kuis, Virdas, Kunds,Khadins,Johads etc.
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18. • Bavadi:- Traditional step wells are called vavadi in Gujarat,
or baoris or bavadis in Rajasthan and northern India.
• Kunds:-Covered underground tank, developed primarily for
tackling drinking water problems
Bavadi
kunds 18
19. • Pits:-recharge pits are constructed for recharging the shallow
aquifer. These are constructed 1 to 2 m wide and 3 m deep. Which
are back filled with boulders , gravels , coarse sand.
• Trenches:-these are constructed when the permeable stream is
available at shallow depth. Trenches may be 0.5 to 1m.Wide 1 to
1.5m deep and 10 to 20 m Long depending on availability of
water. These are back filled with filler materials.
• Dug wells:-existing dug wells may be utilized as recharge
structure and water should pass through filter media before putting
into dug well.
METHODS OF RECHARGING GROUNDWATER
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20. • Hand pumps:-the existing hand pumps may be used for
recharging the shallow/deep aquifers, if the availability of
water is limited. Water should pass through filter media before
diverting it into hand pumps.
• Recharge well:-recharge wells of 100 to 300 mm Diameter
are generally constructed for recharging the deeper aquifers
and water is passed through filter media to avoid choking of
recharge wells.
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22. • the Benefit -Cost ratio was found to be 1.69 and all other financial
viability criteria (IRR and NPV) were also found favorable for
investment on a lined water harvesting tank integrated with a micro-
irrigation system and fish farming.
• MEASURES OF FARM POND
• Top length (Lt) = 36.60 m
• Top width (Wt) = 18.30 m
• Depth (D) = 4.00 m
• Free board = 0.30 m
• A trench of 50 cm depth and 50 cm width was taken all around the
pond to anchor the sheet.
Improving water use efficiency by integrating fish culture and irrigation in coconut based
farming system
samuel et al.(2014)
Int J Agric & Biol Eng Vol. 7 No.2 (36) April, 2014
22
23. treatments Yield(k
g/ha)
Net
returns(Rs)
B:C
ratio
Rain fed cotton 977 6494 1.43
RDF(120:60:60) 1104 2288 1.10
50%RDF as Basal+RDF (50%)THROUGH FERTIGATION 1159 3598 1.16
T3+ZnSO4@10kg/ha 1336 7172 1.32
T3+azatobacter seed treatment 1365 7930 1.36
CD(0.05) 132 - -
Source j. Cotton res.dev. 25(2) 186-196
WATER HARVEESTING A STRATEGIC TOOL FOR DROUGHT MITIGATION IN COTTON
RAJU et.al (2011)
23
24. Treatments Yield (t
ha-1)
Gross return
(Rs. in lakhs)
Net return (Rs.
in lakhs)
B/C
Ratio
#RWHT + CT + DI + Mulch 13 2.4 1.8 2.0
Rain-fed system 8.5 1.5 1.1 1.7
Source:-National Academy of Agricultural Science (NAAS)
Enhancing Productivity of Citrus through Rainwater Conservation and Micro-irrigation in
central India
Panigrahi et al (2003)
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25. Effects of rain water harvesting and sediment deposit of the crop growth stages
Gao et al.(2007)
Plant soil Environment, ss,(4);146-15325
26. Treatment Grain yield (kg
per ha)
Ear mass (kg per
ear)
No. of grains per
ear
100 grain weight
(g)
Pot holes 2384.51 0.12 350.10 26.10
Tied ridges 3233.35 0.15 423.50 27.05
Mulch 3770.80 0.22 450.90 30.33
Flat 1593.36 0.09 237.70 24.58
± S.e.d 195.323 0.0123 27.71 0.650
CV (%) 8.4 1.7 2.9 1.3
InSitu Rain Water Harvesting Techniques Increase Maize Growth and Grain Yield in a
Semi-arid Agro-ecology of Nyagatare,Rwanda ,zimbabwe
Ferdinand Mudatenguha et al. (2012)
Source:-INTERNATIONAL JOURNAL OF AGRICULTURE & BIOLOGY ISSN Print: 1560–8530; ISSN
Online: 1814–9596 13–1480/2014/16–5–996–1000
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27. Evaluation of rain water harvesting technologies in semi-arid areas of Malawi for
crop production
Chilimba et al.(2008)
Chitedze agricultural research station
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28. Effect of in-situ moisture conservation methods on scion shoot length and diameter
and branches of Aonla buddings.
Negi et al.(2007)
HortFlora Research Spectrum, 2(1): 1-7
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29. Prevents water wastage by arresting runoff as well as prevents
soil erosion and mitigates flood.
Sustains and safe guards existing water table through recharge.
Arrests sea-water intrusion and prevents salinization of ground
water.
rainwater percolates into the soil, it forces the salts down and
away from the root zone area. This allows for greater root
growth and water uptake, which increases the drought
tolerance of plants.
Rain-water is a clean and pure source of drinking water which
requires minimal chemical treatment as the amount of
pollutants are not much.
ADVANTAGES
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30. RWH provides a good supplement to water sources thus relieving pressure
on other water sources.
It can supply as a buffer and can be used in times of emergency or
breakdown of public water supply systems.
Helps reduce the storm drainage load and flooding in the cities.
It is a flexible technology and can be built to require meets of any range.
Also the construction, operation and maintenance is not very labour
intensive in most systems.
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31. DISADVANTAGES
• In terms of complex constructions, there is a requirement for high costs,
trained professionals. Maintenance costs may add to the monetary burden.
• If not maintained properly then it can cause various problems in terms of
algal or bacterial growth.
• Tanks if not constructed properly might result in leakages and metal tanks
may also lead to problems such as corrosion harming the water quality.
• All these factors might prove harmful and result in various kinds of Health
issues.
• The system is very much rainfall dependent and hence if there are problems
with the rainfall in the area, it may not be very effective.
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32. FUTURE OF RAINWATER HARVESTING
• Rainwater harvesting systems serve as an alternative decentralized water source
especially in the age when groundwater supplies are depleting and municipal water
infrastructures are facing high replacement costs.
• The use of decentralized rainwater harvesting systems is growing nationally and
internationally, especially in industrial countries like Asia, Europe and the US.
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