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For internal circulation of BSNL only E1-E2 Civil Technical Rain Water Conservation & Harvesting

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Page 1: E1-E2 Civil Technical - mptender.bsnl.co.in

For internal circulation of BSNL only

E1-E2

Civil Technical

Rain Water Conservation &

Harvesting

Page 2: E1-E2 Civil Technical - mptender.bsnl.co.in

WELCOME

• This is a presentation for the E1-E2 Civil Technical

Module for the Topic: Rain Water Conservation &

Harvesting.

• Eligibility: Those who have got the Upgradation to from

E1 to E2.

• This presentation is last updated on 19-3-2011.

• You can also visit the Digital library of BSNL to see this

topic.

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Page 3: E1-E2 Civil Technical - mptender.bsnl.co.in

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AGENDA

Importance of Water for Life

Availability of Water in Nature

Advantage of Rain Water Harvesting

Different Harvesting Methods

Page 4: E1-E2 Civil Technical - mptender.bsnl.co.in

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• jfgeu ikuh jkf[k;ks] fcu ikuh lCk lwuA

ikuh Xk;s u mCkjs] eksrh ekul PkwuAA

• Rahiman Pani Rakhiyo, Bin Pani Sab Soon

• Paani Gaye Na Ubre, Moti Maanas Choon.

• Rakhiyo – To Protect

• Soon – Empty

• Ubre – Not Survive

• Moti – Pearl

• Manas – Man, Choon – Hydrated Lime

Page 5: E1-E2 Civil Technical - mptender.bsnl.co.in

Importance of Water

• Next to air, water is the only other resource in the

nature which sustains life on Earth. If we can not

live without air for more than a few minute, we can

not live without water form more than a few hour.

Life without water is impossible, with scare water

extremely hard and with water is blessing. In

reorganization of this fact Nature has covered two-

third of our planet with water.

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Page 6: E1-E2 Civil Technical - mptender.bsnl.co.in

Importance of Water

• Indiscriminate mining of water due to rapid

industrialization as led to its acute shortage at an

alarming rate.

• Lowering of water table leading to drying up of bore

wells has become common occurrence.

• Government of India has since undertaken a

number of steps aimed at preventing its excessive

mining and harvesting and conservation.

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Page 7: E1-E2 Civil Technical - mptender.bsnl.co.in

Availability of Water

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3%

97%

Fresh water

saline water

77%

11%

11%1%

Glaciers 77%

Deep Aquifers>800 m

11%

Deep Aquifers<800 m

11%

rivers,ponds,streams

1%

Page 8: E1-E2 Civil Technical - mptender.bsnl.co.in

Availability of Water

• In fact the total freshwater available on earth is only 3%

as against 97% saline water in Oceans. Out of this 3%

fresh water, 77% water is in the form of glaciers and

icecaps, 11% water is in deep aquifers which is 800

meters below ground and only 12% is available for

drinking and other purpose out of which 11% is in

acquires which are up to 800 meters below ground and

remaining 1% is available in rivers, lakes, ponds and

streams.

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Page 9: E1-E2 Civil Technical - mptender.bsnl.co.in

What is RWH

• Rain water harvesting is the technique of collection

and storage of rain water of surface or in sub-

surface aquifer by recharging it for future

requirement so that it is not lost as surface run-off.

Rain water is the purest form of raw water available

on the earth.

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Page 10: E1-E2 Civil Technical - mptender.bsnl.co.in

Solution of Water Problems

• The solution of drinking water problem of the vast

majority of population in our country lies in the

appropriate use of Rain water harvested through

roof and from built up catchments where annual

rainfall is sufficient. It has been estimated that the

amount of rain water that falls on the terrace of a

medium house can take care of the drinking-water

requirement of an average family of four members

for one year.

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Page 11: E1-E2 Civil Technical - mptender.bsnl.co.in

Advantages of Rainwater Harvesting

• Conservation of valuable ground water and

enhancing the availability.

• Recharge ground water level and improve it.

• Provides sufficient water for home needs

• Reduction in flooding and drainage problems.

• To arrest seawater ingress.

• Conserve urban water waste & controls soil erosion

• Improves the underground water quality.

• Saves the energy for lifting ground water.

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Page 12: E1-E2 Civil Technical - mptender.bsnl.co.in

Rainwater Harvesting Systems :

• There are basically two main techniques for

harvesting rainwater: Conservation by providing

storage tank on the ground or under ground and

recharge of aquifer.

• A rain water harvesting structure can incorporate

either of these two techniques or a combination of

both depending upon various factors as shown (In

next slide).

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Page 13: E1-E2 Civil Technical - mptender.bsnl.co.in

Rainwater Harvesting Systems

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RAIN WATER

HARVESTING

SYSTEMS

CONSERVATION

GROUND

WATER

RECHARGE

STORAGE

TANK

CHECK

DAMS

LAKES &

PONDS

CONSERVATION

& RECHARGERECHARGE

PIT

RECHARGE

TRENCH

RECHARGE

SHAFT

RECHARGE

BORE WELL

DUG

WELL

CAVITY

WELL

HAND

PUMP

Page 14: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

Recharge Pit

• It is suitable for areas where sandy formations occur

within 1-2m from the ground surface.

• This is ideally suited for small buildings up to 100 sq. m

roof top area.

• It can be circular, square or rectangular in shape.

• These are generally constructed 1-2m wide and 2-3m

deep.

• After excavation the pits are refilled with pebbles and

boulders.

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Page 15: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

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RECHARGE

PIT

Page 16: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

Recharge Trench

• It is suitable when permeable strata of adequate

thickness are available at shallow depth and the roof

area of the building is 200-300sqm.

• Recharge trench can be of any dimensions.

Generally it is 1-1.5m deep, 0.5-1m wide and of any

length depending upon the availability of water to be

recharged.

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Page 17: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

• Recharge trench can be straight, zig-zag, L-

shaped, U shaped.

• The recharge trench should be filled with filter

media which can grade from boulders (5-20cm) at

the top for filtration of water.

• The sides of the trench should slope at low angle

for stability.

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Page 18: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

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Page 19: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

• Recharge Shaft:

• This is the most efficient and cost effective

technique to recharge unconfined aquifer overlain

by poorly permeable strata.

• This is like an open well but filled with filter media.

• Diameter of the shaft generally varies from 1-3m

depending upon the availability of the water to be

recharged.

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Page 20: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

• It is constructed where the aquifer to e recharged is

located at medium depth.

• The recharge shaft end in permeable strata to be

recharged. It may not touch the water table.

• In the upper portion of 1-2m depth, the brick

masonry work carried out for the stability of the

structure.

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Page 21: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

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Page 22: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

Recharge/Injection well

• This is used to recharge deep aquifer or where

multiple aquifers are met interspersed with

impervious strata.

• In case of recharge well single diameter pipe

assembly is used and it should have the provision

of slotted pipes against the water bearing strata.

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Page 23: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

• The rainwater is allowed to pass through the filter

media before it is channeled to the well under

gravity flow conditions.

• The number of recharging wells depends upon the

roof top area and aquifer characteristics.

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Page 24: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

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Page 25: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

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Page 26: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

Dug Well

• Dug wells may be utilized as recharge structure

after cleaning & de-silting the same.

• A filtration chamber may be constructed so that the

water can be made silt free before entering the dug

well.

• The recharge water is guided through a pie to the

bottom of the dug well and it is converted into dug-

cum-bore well.

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Page 27: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

• It is suitable for large buildings preferably having

the roof area more than 1000sqm from where the

rain water can be diverted and recharged.

• Periodic chlorination should be done for controlling

the bacteriological contaminations.

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Page 28: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

Abandoned Tube-wells/Hands Pumps:

• These water abstraction structures act as good

recharge structure.

• The hand pump is suitable for small building

having roof area up to 150sqm.

• Water is diverted from the roof top to the hand

pump through pipe of 100 mm dia.

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Page 29: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

Contour Bunds

• These are suitable in low rainfall areas where

monsoon runoff can be impounded by constructing

bunds on the sloping ground all along the contour of

equal elevation.

• Flowing water is intercepted before it attains the

erosive velocity by keeping suitable spacing

between the bunds.

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Page 30: E1-E2 Civil Technical - mptender.bsnl.co.in

Methods of Rainwater Harvesting

• Spacing between the two contour bunds depends

on the slope of the area as well as the permeability

of soil.

• Contour bunding is suitable on lands with moderate

slopes without involving terracing.

• Contour bunds are effective methods to conserve

soil moisture in watershed for long duration.

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Page 31: E1-E2 Civil Technical - mptender.bsnl.co.in

Cost of Rain water Harvesting

• The cost of implementation of rainwater harvesting

systems in a house/flat complex will vary from

Rs.5000 – Rs.50,000 depending on the size of the

premises as well the nature of the soil. Once put in

place, the harvesting structure do not require any

serious maintenance and hence there is no

recurring expenditure involved.

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Page 32: E1-E2 Civil Technical - mptender.bsnl.co.in

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