Rainwater Harvesting and Artificial Recharge - unesco

8/9/2019 Rainwater Harvesting and Artificial Recharge - unesco

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RAIN WATER HARVESTING

AND

ARTIFICIAL RE CHARGE

TO

GROUND WATER

A GUIDE TO FOLLOW

SEPTEMBER 2000

CATCH THE WATER - WHERE IT DROPS

CENTRAL GROUND WATER BOARDMINI STRY OF WATER RESOURCES

INTERNATIONAL HYDROLOGICALPROGRAMME (IHP)

UNITED NATIONS EDUCATIONAL,SCIENTIFIC AND CULTURAL

ORGANIZATION


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MESSAGE

Prof. MoegiadiDirector UNESCO New Delhi Office and

UNESCO Representative to Bhutan, India, Maldives, and Sri Lanka

Although the total amount of water on Earth is generally assumed to have remained virtuallyconstant, the rapid growth in population, together with the extension of irrigated agriculture andindustrial development, are putting stress on the quality and quantity aspects of natural system. Inthe face of growing problems, society has begun to realize that it can no longer subscribe to a useand discard philosophy either with water resources or any other natural resources.

Thus, as a contribution to solving worlds water problems, UNESCO began in 1965 the firstworldwide programme of studies of the hydrological cycle, the International Hydrological Decade(IHD). The research programme was complemented by a major effort in the field of hydrologicaleducation and training. Conscious of the need to expand upon the efforts initiated during theInternational Hydrological Decade and further to the recommendations of Member States,UNESCO launched a long-term intergovernmental programme in 1975, the InternationalHydrological programme. Although IHP is basically a scientific and educational programme,UNESCO has been aware from outset of the need to direct its activities towards finding practicalsolutions to the worlds very real water resources problems.

Under IHP Programmes of UNESCO New Delhi Office we are happy to collaborate with theCentral Ground Water Board (CGWB), Ministry of Water Resources in educating the NGOs andother interested organizations in the country as well in the region through this guide on rainwaterharvesting and artificial recharge.

As you read this guide, seriously consider conserving the water by water harvesting and managethis natural resource by artificially recharging the system. The examples covering several dozeninstallations successfully operating in India constructed and maintained by CGWB, provide anexcellent snapshot of current systems.

In bringing out this guide, Dr. D.K. Chaddha, Chairman, Central Ground Water Board has playeda key role and he deserves all appreciation. I would like to acknowledge UNESCO New DelhiOffice staff Dr. R. Jayakumar for his help in compiling and editing this guide in the final form.


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RAIN WATER HARVESTING AND

ARTIFICIAL RECHARGE TO GROUNDWATER

WHAT IS RAIN W ATER HARVESTING

The principle of collecting and using precipitation from a catchmentsurface.

An old technology is gaining popularity in a new way. Rain water

harvesting is enjoying a renaissance of sorts in the world, but it tracesits history to biblical times. Extensive rain water harvesting apparatusexisted 4000 years ago in the Palestine and Greece. In ancient Rome,residences were built with individual cisterns and paved courtyards tocapture rain water to augment water from city's aqueducts. As earlyas the third millennium BC, farming communities in Baluchistanimpounded rain water and used it for irrigation dames, build of stonerubble, were found in Baluchistan and Kutch in Gujarat in India.

ARTIFICIAL RECHARGE TO GROUND WATER

Artificial recharge to ground water is a process by which the groundwater reservoir is augmented at a rate exceeding that obtaining undernatural conditions of replenishment. Any man-made scheme or facilitythat adds water to an aquifer may be considered to be an artificialrecharge system.

WHY RAIN WATER HARVESTING

Rain water harvesting is essential because:-

1. Surface water is inadequate to meet our demand and we have todepend on ground water.


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2. Due to rapid urbanization, infiltration of rain water into the sub-soilhas decreased drastically and recharging of ground water hasdiminished.

3. Over - exploitation of ground water resource has resulted indecline in water levels in most part of the country.

4. To enhance availability of ground water at specific place and time.

5. To arrest sea water ingress.

6. To improve the water quality in aquifers.

7. To improve the vegetation cover.

8. To raise the water levels in wells & bore wells that are drying up.

9. To reduce power consumption.

RAIN WATER HARVESTING TECHNIQUES

There are two main techniques of rain water harvesting.

a) Storage of rain water on surface for future use.b) Recharge to ground water.

The storage of rain water on surface is a traditional technique andstructures used were underground tanks, ponds, check dams, weirs,etc. Recharge to ground water is a new concept of rain waterharvesting and the structures generally used are:-

1. Pits:- Recharge pits are constructed for recharging the shallowaquifers. These are constructed 1 to 2 m. wide and 2 to 3 m.deep which are back filled with boulders, gravels & coarse sand.


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2. Trenches:- These are constructed when the permeable strata is

available at shallow depths. Trench may be 0.5 to 1 m. wide, 1 to1.5 m. deep and 10 to 20 m. long depending upon availability ofwater. These are back filled with filter materials.

3. Dug wells:- Existing dug wells may be utilised as rechargestructure and water should pass through filter media beforeputting into dug well.

4. Hand pumps:- The existing hand pumps may be used forrecharging the shallow / deep aquifers, if the availability of wateris limited. Water should pass through filter media before diverting

it into hand pumps.

5. Recharge wells:- Recharge wells of 100 to 300 mm. diameterare generally constructed for recharging the deeper aquifers andwater is passed through filter media to avoid choking of rechargewells.

6. Recharge Shafts:- For recharging the shallow aquifers whichare located below clayey surface, recharge shafts of 0.5 to 3 m.diameter and 10 to 15 m. deep are constructed and back filledwith boulders, gravels & coarse sand.

7. Lateral shafts w ith bore wells:- For recharging the upper aswell as deeper aquifers lateral shafts of 1.5 to 2 m. wide & 10 to30 m. long depending upon availability of water with one or twobore wells are constructed. The lateral shafts is back filled withboulders, gravels & coarse sand.

8. Spreading techniques:- When permeable strata starts from topthen this technique is used. Spread the water in streams / Nalasby making check dams, nala bunds, cement plugs, gabion

structures or a percolation pond may be constructed.


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BENEFITS

1. An ideal solution to water problems in areas having inadequatewater resources.

2. The ground water level will rise.

3. Mitigates the effects of drought & achieves drought proofing.

4. Reduces the runoff which chokes the storm water drains.

5. Flooding of roads is reduced.

6. Quality of water improves.

7. Soil erosion will be reduced.

8. Saving of energy per well for lifting of ground water a one meterrise in water level saves about 0.40 KWH of electricity.

COST

The cost of each recharge structure varies from place to place. Theapproximate cost of the following structures are as under:-

S.No. Recharge Structu re Approx imat e cost(Indian Rupees)

1. Recharge pit 2500 5000

2. Recharge Trench 5000 10000

3. Recharge through hand pump 1500 2500

4. Recharge through dug well 5000 8000

5. Recharge well 50000 80000

6. Recharge shaft 60000 85000

7. Lateral Shaft with Bore well Shaft per m. 2000 3000Bore well 25000 - 35000


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EXPERIENCES

IDEAL CONDITIONS FOR RAIN WATER HARVESTING ANDARTIFICIAL R ECHARGE TO GROUND W ATER

Artificial recharge techniques are adopted where:-

1. Adequate space for surface storage is not available especially inurban areas.

2. Water level is deep enough (> 8 m.) and adequate subsurface

storage is available.

3. Permeable strata is available at shallow / moderate depth.

4. Where adequate quantity of surface water is available for rechargeto ground water.

5. Ground water quality is bad and our aim is to improve it.

6. Where there is possibility of intrusion of saline water especially incoastal areas.

7. Where the evaporation rate is very high from surface waterbodies.

In other areas, rain water harvesting techniques may be adopted.


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Check Dams

This is a spreading technique of rain water harvesting implemented inJNU & IIT area of Delhi. The recharge through 4 check dams hasbeen 76000 cum with a rise in water level from 1 to 13.7 m.


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Percolation Tanks

It is also a spreading technique of rain water harvesting, and isimplemented in Maharashtra.

- In Jalgaon district, the recharge through 6 percolation tanks isabout 681 Thousand Cubic Meter (TCM) with a rise in water levelfrom 1 - 5 m. The benefited area is 545 hectare.

- In Amravati district, the recharge through 3 percolation tanks hasbeen about 298 TCM with a rise in water level from 4-10 m. it hasbenefited an area of about 280 hectare.


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Cement Plugs

Artificial recharge through 10 cement plugs in Amravati district,Maharashtra has been about 47 TCM with a rise in water level from0.5 to 4 m. and benefited area of 86 105 hectare.


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Sub Surface Dykes

Sub surface dykes are suitable for valley and streams where:-

1. Base flow is available for longer duration in the stream.2. Impervious layer exists at shallow depth.

- In order to harness the ground water that was flowing from asmall nala, a sub surface dyke of 160 m. length and 5 m. deep hasbeen constructed by using plasterd brick and tar felt sheets in theState Seed farm Ananganadi. This has shown a considerableincrease in availability of ground water in upstream side.

- Another sub surface dyke of 80 m. length and 8 m. deep has beenconstructed in Kerala Agriculture University by using plasteredbricks and LDP sheets. There has been a considerable rise of waterlevel in upstream side.


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Injection well

This technique has been tested at various places such as:-

- Recharge through injection well in Jalgaon district of Maharashtrahas been about 3.8 TCM with a benefited area of 0.75 hectare.

- Recharge through 2 injection wells in IIT Delhi has been 830 cumwith a rise in water level from 0.29 to 0.87 m and benefited areaof 1 hectare.

- At CSIO, Chandigarh, the recharge through injection well has been3794 cum with 2 m. rise in water level.


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Recharge Shafts

The recharge through 2 shafts in Jalgaon district has been 12 TCMwith a benefited area of 4.7 hectare.


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Dug Wells

This technique has been employed in Maharashtra and Delhi.

- The additional recharge to ground water in Jalgaon district ofMaharashtra has been 6.6 TCM with a benefited area of 1.3hectare.

- In Presidents Estate, Delhi, the rise in water level upto 2.58 m.has been noticed through this technique.


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Lateral Shaft with bore wells

This technique has been employed in Shram Shakti Bhawan, Delhi. Aerise in water level from 1.43 to 2.15 m. has been recorded.


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Some more designs of Artificial Recharge Structures

Artificial Recharge-Shaft cum I njection Well

Gabion Structure


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Recharge Through Trench

Recharge Pit


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Shaft with Borewell


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Nala Bund


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Brahm Sarovar, Kurukshetra


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Recharge Pit


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For further technical information and inputs please contact:

Dr. D. K. ChadhaChairman

Central Ground Water BoardJamnagar House, Mansingh Road

New Delhi-110011Tel: 011- 3383561Fax: 011- 3386743

Email: [email protected]

or

Dr. R. JayaKumarUnited Nations Educational, Scientific and Cultural

Organization (UNESCO)Unesco House8, Poorvi MargVasant Viha r

New Delhi-110057Tel: 011- 6140038/ 39,7310, 6146308

Fax: 011 - 6 143351, 6142714Email: [email protected]
mailto:[email protected]:[email protected]

Rainwater Harvesting and Artificial Recharge - unesco

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