Question

suggest different methods and make a project for ground water recharge keeping in view the conditions of towns. Explain in detail.(in 15 pages).

Answer 1

RECHARGING GROUNDWATER AQUIFERS

Various conditions of recharge structures are possible which can ensure that rainwater percolates in the ground instead of draining away from the surfaces. Some of these are :

1. Borewells and Dugwells - These are used to raise the groundwater table by collecting rainwater on the roof top of the building which is then diverted by drainpipes to a filtration tank. From there it flows into the borewells or dugwells.

2. Recharge pits - These are excavated into the ground, lined with a bricks or stone wall with openings at regular intervals.

3. Percolation pits ( Soakaway) - It is a board hole of up to 30cm diameter drilled in the ground to a depth of 3 to 10 m.

4. Recharge Trenches - These are excavated on the grounds and refilled with porous media like pebbles, boulder or brickbates to harvest the surface runoff.

5. Permeable Sufaces - These are like a patch of grass is used to retain a large proportion of the rainwater falling on it, yielding only 10-15 per cent as runoff.