Student Seminar Report & Project Report With Presentation (PPT,PDF,DOC,ZIP)

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INTRODUCTION
Rainwater harvesting is the accumulating and storing, of rainwater for reuse, before it reaches the aquifer. It has been used to provide 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. Water collected from the ground, sometimes from areas which are especially prepared for this purpose, is called Stormwater harvesting. In some cases, rainwater may be the only available, or economical, water source. Rainwater harvesting systems can be simple to construct from inexpensive local materials, and are potentially successful in most habitable locations. Roof rainwater can be of good quality and may not require treatment before consumption. Although some rooftop materials may produce rainwater that is harmful to human health, it can be useful in flushing toilets, washing clothes, watering the garden and washing cars; these uses alone halve the amount of water used by a typical home. Household rainfall catchment systems are appropriate in areas with an average rainfall greater than 200 mm (7.9 in) per year, and no other accessible water sources (Skinner and Cotton, 1992). Overflow from rainwater harvesting tank systems can be used to refill aquifers in a process called groundwater recharge, though this is a related process, it must not be confused with Rainwater harvesting.
Basic configuration
Rainwater harvesting systems channel rainwater that falls on to 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.
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.
The subsurface dyke at Krishi Vigyan Kendra, Kannur under Kerala 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.
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.
Advantages in urban areas
Rainwater harvesting can (a) assure an independent water supply during water restrictions, that is though somewhat dependent on end use and maintenance, (b)usually of acceptable quality for household needs and © renewable at acceptable volumes despite forecast climate change (CSIRO, 2003). It produces beneficial externalities by reducing peak storm water runoff and processing costs. In municipalities with combined sewer systems, reducing storm runoff is especially important, because excess runoff during heavy storms leads to the discharge of raw sewage from outfalls when treatment plant capacity cannot handle the combined flow. RH systems are simple to install and operate. Running costs are negligible, and they provide water at the point of consumption. We are consuming this water for our basic needs.

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Rainwater harvesting information in marathi

Rainwater Harvesting
What is rainwater harvesting and why is it Important?
Water is our most precious natural resource and something that most of us take for granted. We are now increasingly becoming aware of the importance of water to our survival and its limited supply, especially in such a dry continent as Australia.

The harvesting of rainwater simply involves the collection of water from surfaces on which rain falls, and subsequently storing this water for later use. Normally water is collected from the roofs of buildings and stored in rainwater tanks. This is very common in rural Australia. Water can also be collected in dams from rain falling on the ground and producing runoff.

Either way, the water collected can be considered to be precious.

Rainwater harvesting techniques
The collection of rainwater from the roofs of buildings can easily take place within our cities and towns, not just in rural Australia. All that is necessary to capture this water is to direct the flow of rainwater from roof gutters to a rainwater storage tank. By doing this, water can be collected and used for various uses.

If you are reliant on collected rainwater and are not connected to a towns water supply, then the water collected will be especially important to you. If you are from the city, then it is possible to replace all or at least a substantial portion of your fresh water requirements by the capture and storage of rainwater from your roof. Being largely self sufficient in water supply is possible for a vast majority of Australian households and buildings.

What are the Benefits in Rainwater Harvesting?
By capturing water directly, we can significantly reduce our reliance on water storage dams. This places less stress on these dams and can potentially reduce the need to expand these dams or build new ones.

Collecting and using your own water can also significantly reduce your water bills.

By capturing water, the flow of stormwater is also reduced and this minimises the likelihood of overloading the stormwater systems in our neighbourhoods.

What About Dirty Roofs?
There are a number of devices (first flush devices) which allow for the first flow of water to the rainwater storage tank to be diverted from the tank. By doing this, any dirt on the roofs of buildings that has built up prior to the rain can be excluded from the tank.

Sizing of Rainwater Storage Tanks
The most appropriately sized rainwater storage can be chosen by quantitatively assessing the performance of various sized storage capacities. By assessing the performance of various sized storage capacities, it is possible to make an informed decision as to what would be the most suitably sized storage capacity for the given application. The input for the assessment is historical daily rainfall data, and the performance of a particular storage capacity can be judged by how much water is required to be supplied from other sources to makeup for any shortfall in demand.

Water Balance for Estimation of Rainwater Storage Capacity
The size of the area of capture or roof area must also be known when estimating the amount of rainfall that is able to be collected. The larger the roof area, the more rainfall that is able to be collected.

Assessing Performance of Different Sized Rainwater Storage Tanks
The performance assessment of various sized storages involves the calculation of the amount of water in storage for a given day. This calculation is based on the water balance shown above. This is a simple calculation, however, using a computer allows this calculation to be completed for many consecutive days of rainfall data. This is equivalent to trial sizing a storage tank size over the period of assessment (over many years).

The computer model completes daily water balance calculations, so that any roof runoff generated from rainfall in that day is calculated. The computer model also calculates the daily level status of the water storage used to hold this rainwater.

During any one day the storage could overflow depending on the amount of roof runoff generated. Likewise, the storage could also be emptied if the volume of water used exceeds the amount of water available from the storage. In this case, water must be supplied from other sources in order to fulfil the water demand. The computer model calculates and sums the amount of water supplied from other sources over the period of assessment. This information can then be used for a comparative assessment of the different amounts of makeup needed with use of different size water storages.

Rainwater harvesting techniques
The collection of rainwater from the roofs of buildings can easily take place within our cities and towns, not just in rural Australia. All that is necessary to capture this water is to direct the flow of rainwater from roof gutters to a rainwater storage tank. By doing this, water can be collected and used for various uses.

If you are reliant on collected rainwater and are not connected to a towns water supply, then the water collected will be especially important to you. If you are from the city, then it is possible to replace all or at least a substantial portion of your fresh water requirements by the capture and storage of rainwater from your roof. Being largely self sufficient in water supply is possible for a vast majority of Australian households and buildings.

What are the Benefits in Rainwater Harvesting?
By capturing water directly, we can significantly reduce our reliance on water storage dams. This places less stress on these dams and can potentially reduce the need to expand these dams or build new ones.

Collecting and using your own water can also significantly reduce your water bills.

By capturing water, the flow of stormwater is also reduced and this minimises the likelihood of overloading the stormwater systems in our neighbourhoods.

What About Dirty Roofs?
There are a number of devices (first flush devices) which allow for the first flow of water to the rainwater storage tank to be diverted from the tank. By doing this, any dirt on the roofs of buildings that has built up prior to the rain can be excluded from the tank.

Sizing of Rainwater Storage Tanks
The most appropriately sized rainwater storage can be chosen by quantitatively assessing the performance of various sized storage capacities. By assessing the performance of various sized storage capacities, it is possible to make an informed decision as to what would be the most suitably sized storage capacity for the given application. The input for the assessment is historical daily rainfall data, and the performance of a particular storage capacity can be judged by how much water is required to be supplied from other sources to makeup for any shortfall in demand.

Water Balance for Estimation of Rainwater Storage Capacity
The size of the area of capture or roof area must also be known when estimating the amount of rainfall that is able to be collected. The larger the roof area, the more rainfall that is able to be collected.

Assessing Performance of Different Sized Rainwater Storage Tanks
The performance assessment of various sized storages involves the calculation of the amount of water in storage for a given day. This calculation is based on the water balance shown above. This is a simple calculation, however, using a computer allows this calculation to be completed for many consecutive days of rainfall data. This is equivalent to trial sizing a storage tank size over the period of assessment (over many years).

The computer model completes daily water balance calculations, so that any roof runoff generated from rainfall in that day is calculated. The computer model also calculates the daily level status of the water storage used to hold this rainwater.

During any one day the storage could overflow depending on the amount of roof runoff generated. Likewise, the storage could also be emptied if the volume of water used exceeds the amount of water available from the storage. In this case, water must be supplied from other sources in order to fulfil the water demand. The computer model calculates and sums the amount of water supplied from other sources over the period of assessment. This information can then be used for a comparative assessment of the different amounts of makeup needed with use of different size water storages.