Question

What is water harvesting mention any two water harvesting systems?

Answer 1

Rainwater harvesting is the method of collecting rainwater for future use. Harvesting of rainwater is essential for ensuring the availability of usable water. The underlying concept is to make rainwater percolate below the ground, so that the level of groundwater gets replenished. 
Khadins and Nadis are two water harvesting structures that are prominent in Rajasthan. Small pits, lakes, earthen dams, sand and limestone reservoirs, and rooftop water collecting units are some of the structures that are used for water harvesting. 

Answer 2

The water that we get as rainfall just flows away.This is wastage of precious natural resorces.we can prevent wastage of rainfall by water harvesting.
There are two technique;
1 .Roofwater harvesting.
2.Another way to harvest rainwater is to precollect rainwater thorugh roadside drain.