The Modern
methods of rainwater harvesting are
categorized as under
1. Percolation pit
A Percolation pit is meant for a small catchment area like in individual houses. It is hand bore made in the soil with the help of an augur and filled with pebbles and river sand on top. The depth of these pits will be anywhere between 4 and 8m depending on the nature of soil.
2. Absorption
well
These are constructed using cement
rings, with diameter ranging from 60 to 80 cm, readily available in the market.
The depth depends on the nature of soil and the diameter depends on the number
of rooftop pipes that are likely to be connected to each one of these wells. These
wells are left unfilled and are covered with RCC slabs.
3. Percolation
well cum bore pit well
In areas where the soil is clayey, this
type of bore pit with a depth of 3 to 4.5m can be used for rain water
harvesting. Generally, a hand bore pit is dug with in this well and a PVC pipe
of 15 cm diameter is inserted in to the bore for the entire length.
4. Recharge
trench cum injection well
This is ideally suited for areas where
the horizon within 3 to 5 m is sandy and permeable and continues up to the
water level under unconfined conditions ,by which copious water that is
available can be easily recharged.
In this technique, a 1-2 m wide and 2-3
m deep trench is dug, the length of which depends on the site availability and
volume of water to be handled. An injection well of 100 to 150 mm diameter is
constructed, piercing through the layers of impermeable horizons to trenches.
Depending upon the volume of water to be injected, the number of injection
wells can be increased to enhance the recharging rate.