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8/3/2019 Tech Rain Water BST

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RAIN WATER HARVESTING

Author : Bhawani Shankar

Sch. No. : 091110232

2nd semester, B.Planning

ABSTRACT :

Water has been an essential resource for every living being. Thus it has

been very important to use it judiciously and conserve it. The world has been facing theproblem of shortage of water. Thus many influential steps had been taken to overcome

the situation, one of which is rain water harvesting, ground water recharge, water

recycling and treatment plants etc.

INTRODUCTION :

The serious need for conservation of water has led to the introduction of

new method of conservation of water i.e. rain water harvesting, which takes care of

ground water recharge, it is economical, successful, and an important method of

conserving water.

The method of Rain water harvesting system doesnt uses any power

instead it is installed in the houses or buildings. The roof of the building collects the rain

water and the slope of the roof provides direction to the water to flow through a

channel which has got a filter to clean the water and then the water directly flows down

to the underground tank which collects the rain water that can be used afterwards for

the household purposes and the tanks sometimes doesnt have plastered walls which

means it is directly for the purpose of ground water recharge . Thus it is an efficient and

productive method of conserving water.


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A house installed with rain water harvesting system

1. Consumption of water and its availability :More than 85% of the earth is covered from water out of which 2.5% is

fresh water & the rest water is saline water. The fresh water are found in rivers and

lakes, ground water and the glaciers, which cover 0.3%, 30.8% & 60.9% of freshwater respectively in them. However the sad part is industrialization, population

explosion, pollution etc. had become threat to the water bodies since these are the

main cause of creating the problem of shortage of water by polluting the water

bodies.

The per capita consumption of water across the world

Activities Litres per person per day

Drinking 3

Cooking 4

Bathing 20Flushing 40

Washing clothes 25

Washing utensils 20

Gardening 23

Total 135


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In many parts of the world people dont get drinking water so they are

bound to drink dirty water and thus they are easily prone to diseases.

2. Rainfall across india :India is receiving rainfall, annually counts within the top 6 countries in the

world, even then our country faces scarcity of water since we do not conserve the

rain water the north eastern part of the country receives the highest amount of

rainfall though that area is rural but it can be used up there. Rainwater harvesting in

urban areas can have manifold reasons. Some of the reasons rainwater harvesting

can be adopted in cities are to provide supplemental water for the city's

requirements, to increase soil moisture levels for urban greenery, to increase the

ground water table through artificial recharge, to mitigate urban flooding and to

improve the quality of groundwater. In urban areas of the developed world, at a

household level, harvested rainwater can be used for flushing toilets and washing

laundry. Indeed in hard water areas it is superior to mains water for this. It can also

be used for showering or bathing. It may require treatment prior to use for drinking.

Whereas in rural areas the rain water harvesting is done by collecting rain water in

ponds, checking river water making stop dams etc.


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Rain water harvesting in rural areas

3. Components of rain water harvesting :3.1. Ground catchment systems :

Ground catchments systems channel water from a prepared catchment area into

storage. Generally they are only considered in areas where rainwater is very scarce and

other sources of water are not available. They are more suited to small communities than

individual families. If properly designed, ground catchments can collect large quantities of

rainwater.

3.2. Roof catchment systems :Roof catchment systems channel rainwater that falls onto a roof into storage via

a system of gutters and pipes. The first flush of rainwater after a dry season should be

allowed to run to waste as it will be contaminated with dust, bird droppings etc. Roof

gutters should have sufficient incline to avoid standing water. They must be strong enough,

and large enough to carry peak flows. Storage tanks should be covered to prevent mosquito

breeding and to reduce evaporation losses, contamination and algal growth. Rainwater

harvesting systems require regular maintenance and cleaning to keep the system hygienic

and in good working order.

3.3. Subsurface dyke :A subsurface dyke is built in an aquifer to obstruct the natural flow of

groundwater, thereby raising the groundwater level and increasing the amount of water

stored in the aquifer.

3.4. Groundwater recharge :Rainwater may also be used for groundwater recharge, where the runoff on the

ground is collected and allowed to be absorbed, adding to the groundwater. In the US,

rooftop rainwater is collected and stored in sump In India this includes Bawdis and johads,

or ponds which collect the run-off from small streams in wide area.

In India, reservoirs called tankas were used to store water; typically they were

shallow with mud walls. Ancient tankas still exist in some places.


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3.5. Quality :As rainwater may be contaminated, it is often not considered suitable for

drinking without treatment. However, there are many examples of rainwater being used for

all purposes including drinking following suitable treatment.

Rainwater harvested from roofs can contain animal and bird faeces, mosses

and lichens, windblown dust, particulates from urban pollution, pesticides, and inorganic

ions from the sea (Ca, Mg, Na, K, Cl, SO4), and dissolved gases (CO2, NOx, SOx). High levels of

pesticide have been found in rainwater in Europe with the highest concentrations occurring

in the first rain immediately after a dry spell the concentration of these and other

contaminants are reduced significantly by diverting the initial flow of water to waste as

described above. The water may need to be analysed properly, and used in a way

appropriate to its safety. In the Gansu province for example, harvested rainwater is boiled in

parabolic solar cookers before being used for drinking In Brazil alum and chlorine is added to

disinfect water before consumption. So-called "appropriate technology" methods, such as

solar water disinfection, provide low-cost disinfection options for treatment of stored

rainwater for drinking.

3.6. System sizing :It is important that the system is sized to meet the water demand throughout

the dry season. Generally speaking, the size of the storage tank should be big enough to

meet the daily water requirement throughout the dry season. In addition, the size of the

catchment area or roof should be large enough to fill the tank.

4. Advantages of rain water harvesting :

An ideal solution of water problem in areas having inadequate water resources. The ground water level will rise. Mitigates the effect of drought & achieves drought proofing. Reduces the runoff which chokes the storm water drains. Flooding of roads is reduced. Quality of water improves. Soil erosion will be reduced. Saving of energy per well for lifting of ground water one meter of rise in water

level saves about

0.40 KWH of electricity.5. Disadvantages of rain water harvesting :

The disadvantages of rainwater harvesting technologies are mainly due to

the limited supply and uncertainty of rainfall. Adoption of this technology requires a

bottom up approach rather than the more usual top down approach employed in

other water resources development projects. This may make rainwater harvesting less


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attractive to some governmental agencies tasked with providing water supplies in

developing countries, but the mobilization of local government can serve the same basic

role in the development of rainwater-based schemes as water resources development

agencies in the larger, more traditional public water supply schemes.

CONCLUSION :

The weight of merit over to the demerits, in context of rain water

harvesting is much higher and thus it is the best way of conserving rain water and

solving out the problem of scarcity of fresh water. All parts of the world must practice

out this method and the stored water must be supplied to the areas receiving less

rainfall and facing shortage of water. Thus practicing rain water harvesting may give us

better life with an eco friendly approach.

REFERENCES :

1. Definition of rainwater harvesting2. Rainwater Harvesting and Water Purification System.3. Geology , Parbin Singh4. Internet

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