Describe various methods of rain (=water) harvesting.

Various methods of rain water harvesting are as follows

● Surface runoff harvesting- Rainwater that flows off from surface is collected and used to recharge aquifers.

● Roof top rainwater harvesting- Roof acts as a catchment where the rainwater is collected. This collected water is stored in a tank or diverted to artificial recharge system.

Methods

1) Terrace, courtyard, paved or unpaved ground acts as catchment that receive rainfall directly. This rainwater is carried down through UV resistant water pipes or drains to a storage system. The water that is received in the first shower is flushed off to avoid contamination from the roof/ atmosphere. Then, filters are used for treatment of water to remove turbidity, color and microorganisms. The filters are very importan in keeping the rainwater in the storage tank.

2) Another method involves collecting the water from roof of a building and diverting it to a storage tank. Water from the storage tank can be used for secondary purposes such as washing and gardening. It is the most effective way of rainwater harvesting.

3) Ground water aquifers can be recharged by various kinds od structures to ensure that the water percolates in the ground. Recharge pits, trenches, sak ways, percolation tanks, recharging of bore and dug wells are some of the common recharging methods.