Rainwater Harvesting

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Rainwater Rainwater Harvesting Harvesting Presentation by- Presentation by- 1. 1. Swapnil Hire Swapnil Hire 2. 2. Diyvang ingle Diyvang ingle 3. 3. Nikhil Jagirdar Nikhil Jagirdar 4. 4. Devashree Joshi Devashree Joshi Class-F.E Class-F.E Div-G Batch-G1 Div-G Batch-G1 Roll Nos.-17,18,19,20 Roll Nos.-17,18,19,20

Transcript of Rainwater Harvesting

Page 1: Rainwater Harvesting

Rainwater Rainwater HarvestingHarvesting

Presentation by-Presentation by-

1.1. Swapnil HireSwapnil Hire

2.2. Diyvang ingleDiyvang ingle

3.3. Nikhil JagirdarNikhil Jagirdar

4.4. Devashree JoshiDevashree Joshi

Class-F.EClass-F.E

Div-G Batch-G1Div-G Batch-G1

Roll Nos.-17,18,19,20Roll Nos.-17,18,19,20

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IntroductionIntroduction• Rainwater harvesting is the gathering, or accumulating and

storing, of rainwater. Rainwater harvesting has been used to provide drinking water, water for livestock, water for irrigation or to refill aquifers in a process called groundwater recharge. Rainwater collected from the roofs of houses, tents and local institutions, or from specially prepared areas of ground, can make an important contribution to drinking water. In some cases, rainwater may be the only available, or economical, water source. Rainwater systems are simple to construct from inexpensive local materials, and are potentially successful in most habitable locations. Roof rainwater is usually of good quality and does not require treatment before consumption. Household rainfall catchment systems are appropriate in areas with an average rainfall greater than 200mm per year, and no other accessible water sources

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ContentsContents

• 1 Ground catchment systems• 2 Roof catchment systems• 3 Subsurface dyke• 4 Groundwater recharge• 5 Advantages in urban areas• 6 Quality• 7 System sizing• 8 Around the world• 9 Conclusion

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Ground catchment Ground catchment systemssystems

• 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.

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Roof catchment systemsRoof 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.

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Subsurface dykeSubsurface 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.

• The subsurface dyke at Krishi Vigyan Kendra, Kannur under Kerela Agricultural University with the support of ICAR, has become an effective method for ground water conservation by means of rain water harvesting technologies. The sub-surface dyke has demonstrated that it is a feasible method for conserving and exploiting the groundwater resources of the Kerala state of India. The dyke is now the largest rainwater harvesting system in that region.

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Groundwater rechargeGroundwater 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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Advantages in urban Advantages in urban areasareas

• 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

• In New Zealand, many houses away from the larger towns and cities routinely rely on rainwater collected from roofs as the only source of water for all household activities. This is almost inevitably the case for many holiday homes.

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QualityQuality

• 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 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.

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System sizingSystem 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.

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Around the worldAround the world

• Currently in China and Brazil, rooftop rainwater harvesting is being practiced for providing drinking water, domestic water, water for livestock, water for small irrigation and a way to replenish ground water levels. Gansu province in China and semi-arid north east Brazil have the largest rooftop rainwater harvesting projects ongoing.

• In Rajasthan, India rainwater harvesting has traditionally been practiced by the people of the Thar Desert.

• In Bermuda, the law requires all new construction to include rainwater harvesting adequate for the residents.

• The U.S. Virgin Islands have a similar law.• In the Indus Valley Civilization, Elephanta Caves and Kanheri

Caves in Mumbai rainwater harvesting alone has been used to supply in their water requirements

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Around the worldAround the world

• In Senegal/Guinea-Bissau, the houses of the Diola-people are frequently equipped with homebrew rainwater harvesters made from local, organic material.

• In the United Kingdom water butts are oft-found in domestic gardens to collect rainwater which is then used to water the garden.

• In the Ayerwaddy Delta of Myanmar, the groundwater is saline and communities rely on mud lined rainwater ponds to meet their drinking water needs throughout the dry season. Some of these ponds are centuries old and are treated with great reverence and respect.

• Until 2009 in Colorado, water rights laws restricted rainwater harvesting; a property owner who captured rainwater was deemed to be stealing it from those who have rights to take water from the watershed. The main factor in persuading the Colorado Legislature to change the law was a 2007 study that found that in an average year, 97% of the precipitation that fell in Douglas County, in the southern suburbs of Denver, never reached a stream—it was used by plants or evaporated on the ground. In Utah and Washington State, collecting rainwater from the roof is illegal unless the roof owner also owns water rights on the ground. In New Mexico, rainwater catchment is mandatory for new dwellings in Santa Fe.[6]

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In BriefIn Brief

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ConclusionConclusion

• The effectiveness of a rain water harvesting system lies in its ability to meet the site specific requirements and end use preferences. Though simple, these systems are site specific and need to be detailed out before implementation.With the decreasing availability of water, rain water harvesting presents the best option for times to come.