What is rainwater harvesting ?
Collection of rainwater using different techniques and then then storage and using of that water for drinking and agriculture purpose is known as Rainwater harvesting
By the help of rainwater harvesting ground water recharge rate also increased then the natural rate.
The term water harvesting refers to harvesting done by the help of collection and storage of precipitation and also include other activities done at harvesting surface and ground water.
Why there is need of Rainwater harvesting in Urban Areas
Mostly the urban areas demanded concentrated water due to high population density and obviously population of urban areas are increasing day by day and due to which it require more and more water day by day.
Urban areas are facing issues related to water are :
- lack of water from traditional sources so in this condition rain water can be used as supplementary source
- Mostly in the monsoon season flooding occurs in urban areas & for rain water can be referred as mitigation measure
- As we know that decreasing of groundwater level beneath the surface so rain water harvesting acts process of groundwater recharge in this case
- As natural resources are disappearing like lakes and wells these resources can be restored by rainwater harvesting.
One of the biggest benefits of recharging ground water level is saving energy 1m rise in water level saves 0.4kWh of energy and also reduce the soil erosion as well. By promoting the rainwater, harvesting the culture of conservation of water increased.
Techniques and types of Rainwater harvesting in urban areas:
There are different types of rainwater harvesting system that can be used in the city, the cost varying with the complexity and size of the technology being installed. All have one thing common that is to utilize our natural rainfall to supplement the mains supply. The major benefit of rainwater harvesting is that it can be done on small and much larger, even industrial scales.
The process of water collection and storage in urban areas should be designed in a way such that is do not take large space or area for there implementation.
Water Butt:
water butt technique is the most common technique of rain water harvesting in this techniques water has been collected in water pots from drain pipes or directly from direct rain and then the stored water can be used for different use but mostly this water is used for watering of garden and it act as a supplement to the main water.
Roof top Harvesting:
It is a process of collecting of rainwater where it falls. In rooftop harvesting, the roof becomes the catchments, and the rainwater is collected from the roof of the any building. Then the collected water can either be stored in tank or diverted to artificial groundwater recharge .This method is not expensive and very effective if implemented properly. It also helps in raising the groundwater level and also saves energy as well.
For Roof top harvesting main components are:
Catchments:
catchments is surface on which rain directly falls it can be any type of surface weather it is a paved or unpaved ground it may be a terrace, balcony etc. So its the first contributor of Rain water harvesting.
Transportation:
The water which has been collected in catchments will be transported through any medium to any destination where it will be stored or utilized mainly that medium is water pipes or drain. That water pipes should be UV resistant pipes.
First Flush:
First flush is a device or technique which is used to clean the water by flushing the first shower that falls on catchments that first shower should be flushed because in first set of shower there are impurities and contamination of atmosphere and that first set of shower also remove the material deposited on the surface of catchments. First rain separator should be installed on every outlet of drain pipe.
Filtering:
some there is some impurities deposited on surface and when the water is collected it pulled the whole water for the filtration of that impurities filtration techniques should be used so that get clean water can be obtained .
For the filtration purpose there are different filters which can be used such as sand gravel filter ,charcoal filter, PVC pipe filter & sponge filter .
Advantages:
- First and most basic advantage of rain water harvesting is that water that comes from is absolutely free and you can use it where ever you want.
- Rainwater harvesting can reduce the need if water supply & reduce the burden of water supplying authorities and also decrease your water bills as well.
- Water that has been harvested by the help of rain can be used as backup in emergencies.
- Rainwater harvesting can reduce the stromwater runoff from surface of lands.