Wateer Harvesting

8/3/2019 Wateer Harvesting

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Water

Harvesting:

a lifeline for

human

well-being


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Rainwater harvesting is the accumulating

and storing, of rainwater for reuse, before

it reaches the aquifer. It has been used toprovide drinking water water for livestock

water for irrigation, as well as other typical

uses given to water. Rainwater collected

from the roofs of houses, tents and local

institutions, can make an important

contribution to the availability of drinking

water.It can supplement the sub soil water

level and increase urban greenery.


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Rainfall pattern

Geomorphological set up

Drainage

Sand mining

Hydro geological factors

Over exploitation

Reclamation of land for settlement


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Water availability per capita has been on the decline in India. Two

reasons have been the increasing demand for water and the increasing

population.The quantum of water available to the country being fixed

the increasing demand reduces per capita water availability.

Agriculture continues to be the single largest consumer of water

however industrial demand for water shows the fastest growth.

Especially South India and in particular Karnataka is a drought prone

region. The state enjoys the dubious distinction of having the second

largest area prone to drought next only to Rajasthan.

Bangalore gets most of its drinking water from a distance of 95 kms.

and a depth of 500 mts.It makes ecological and financial sense not to waste a pure natural

resource available in large quantity on ones roof.

In the case of a homebuilder, at an initial stage of construction,

investments in time, design and money are minimal for adopting roof

rainwater harvesting.

WHY WATER HARVESTING?


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Ground water sources are increasingly getting depleted or are getting

polluted. Borewells are either silting up, getting short of water or are drawing

polluted water.

Private purchase of water from tankers is unreliable in quality and is also

expensive.

It encourages water conservation and self-dependence.it is being recognized that people from various sectors have to become

partners in the solution process and not remain simply as institutional

beneficiaries.

India is blessed with adequate rainfall as a whole, yet there are large swathes

of dry, drought prone area. In many other places the quality of groundwater is

not good. In such places rainwater harvesting can provide lifeline water forsurvival and more.


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Uses /Benefits of Rainwater Harvesting

Water supply (Domestic, Industrial &

Agriculture))

Water Saving, ( as supplementary

source)Flooding control,

Drought mitigation

Water quality control

Disaster prevention (fire fighting)

Ground water recharging

Improve quality of ground water

Energy saving


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In Rural households where water is scare, dry zone where ground water is mineralized

coastal belt where ground water is saline, ( tsunami effectedareas)

hilly areas where ground water table is low where it is notpossible to extract ground water or have no other

water sources

In urban areas where water is expensive,

for washing, and gardening and to prevent

local flooding In public and commercial buildings with

large use of water


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Rainwater is harvesting systems channel rainwater that falls on to a roofinto storage via a system of gutters and pipes. The first flush of rainwaterafter a dry season should be allowed to run to waste as it will becontaminated with dust, bird droppings etc. Roof gutters should haveenough, and large enough to carry peak flows.Storage tanks should becovered to prevent mosquito breeding and to reduce evaporation losses,contamination and algal growth. Rainwater harvesting systems requireregular maintenance and cleaning to keep the system hygienic.
http://en.wikipedia.org/wiki/File:Simple_Diagram_to_show_Rainwater_Harvesting.pnghttp://en.wikipedia.org/wiki/File:PressurizedRooftopRainwaterHarvester.svghttp://en.wikipedia.org/wiki/File:Simple_Diagram_to_show_Rainwater_Harvesting.png


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There are two main techniques of rain water harvestings.

Storage of rainwater on surface for future use.Recharge to ground water.The storage of rain water on surface is a traditional techniquesand structures used were underground tanks, ponds, checkdams, weirs etc. Recharge to ground water is a new concept of

rain water harvesting and the structures generally used are :-Pits :- Recharge pits are constructed for recharging the shallowaquifer. These are constructed 1 to 2 m, wide and to 3 m. deepwhich are back filled with boulders, gravels, coarse sand.

Trenches:- These are constructed when the permeable stramis available at shallow depth. Trench may be 0.5 to 1 m. wide, 1to 1.5m. deep and 10 to 20 m. long depending up availability ofwater. These are back filled with filter. materials.

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

RAIN WATER HARVESTING TECHNIQUES :


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Hand pumps :- The existing hand pumps may be used for recharging

the shallow/deep aquifers, if the availability of water is limited. Watershould pass through filter media before diverting it into hand pumps.

Recharge wells :- Recharge wells of 100 to 300 mm. diameter aregenerally constructed for recharging the deeper aquifers and water ispassed through filter media to avoid choking of recharge wells.

Recharge Shafts :- For recharging the shallow aquifer which are

located below clayey surface, recharge shafts of 0.5 to 3 m. diameter and10 to 15 m. deep are constructed and back filled with boulders, gravels &coarse sand.

Lateral shafts with bore wells :- For recharging the upper as well asdeeper aquifers lateral shafts of 1.5 to 2 m. wide & 10 to 30 m. longdepending upon availability of water with one or two bore wells are

constructed. The lateral shafts is back filled with boulders, gravels &coarse sand.

Spreading techniques :- When permeable strata starts from top thenthis technique is used. Spread the water in streams/Nalas by makingcheck dams, nala bunds, cement plugs, gabion structures or apercolation pond may be constructed.


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The Millennium Development Goals (UN MDG, 2009) and the role of rainwater

harvesting

Millennium Development

Goal

Role of rainwater harvesting Relevance1. End poverty and hunger

can act as an entry point to improve agricultural production, regenerate

degraded landscapes and supply water for small horticulture and livestock

can improve incomes and food security

2. Universal educationcan reduce time devoted to tedious water fetching activities, enabling more time

for schooling

3. Gender equalityinterventions have been shown to improve gender equality and income group

equity by reducing the time spent by women gathering water for domestic purposes

provides water so that girls can attend school even during theirr menstrual

cycles, thus increasing school attendance


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4. Child health

contributes to better domestic water supply and

improves sanitation reducing

the incidence of water borne diseases which are

the major cause of deaths

among the under fives

5. Maternal health

supply better quality domestic water, which helps

suppress diarrhoea etc.

can release time from tedious water fetchingactivities

6.Environmental sustainability

interventions provide fresh water for humans and

livestock

can regenerate ecosystem productivity and

suppress degradation of services bysoil erosion and flooding

rainwater harvesting can improve environmental

flows by increasing base flow

where groundwater is recharged


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A NOBLE GOAL - A COMMON RESPONSIBILITYGround water exploitation is inevitable is Urban areas. But the groundwater

potential is getting reduced due to urbanisation resulting in over exploitation.

Hence, a strategy to implement the groundwater recharge, in a major way need to

be launched with concerted efforts by various Governmental and Non-

Governmental Agencies and Public at large to build up the water table and make

the groundwater resource, a reliable and sustainable source for supplementing

water supply needs of the urban dwellers.Recharge of groundwater through storm run off and roof top water

collection, diversion and collection of run off into dry tanks, play

grounds, parks and other vacant places are to be implemented by

Special Village Panchayats/ Municipalities /Municipal Corporations

and other Government Establishments with special efforts.

The Special Village Panchayats /Municipalities/Municipal

Corporations will help the citizens and builders to adopt suitable

recharge method in one's own house or building through

demonstration and offering subsidies for materials and incentives,

if possible.


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