Model designs for Rain Water Harvesting

Model designs for Rain Water Harvesting

Model designs for Rain Water Harvesting and Artificial Recharge have been prepared, which can be used depending upon the suitability of the terrain.

Hilly and Inter-mountainous area- Percolation Tanks, Modification of Village tanks as recharge structure, Gabion Structure, Contour Bunds (Himachal Pradesh, Jammu & Kashmir, Uttrakhand, Sikkim & North Eastern States)

Alluvial Area- Percolation Tanks, Recharge Pits (Punjab, Haryana, Uttar Pradesh, Bihar,
West Bengal)

Hard Rock Area- Recharge through Abandoned Dug Wells/ Bore Wells/ Tube Wells,
Modification of Village tanks as recharge structure, Gabion Structure, Percolation Tanks
(Madhya Pradesh, Maharashtra, Karnataka, Tamil Nadu, Andhra Pradesh, Kerala)

Percolation tanks are among the most common runoff harvesting structures in India. A percolation tank can be defined as an artificially created surface water body submerging a highly permeable land area so that the surface runoff is made to percolate and recharge the ground water storage. They are not provided with sluices or outlets for discharging water from the tank for irrigation or other purposes. They may, however, be provided with arrangements for spilling away the surplus water that may enter the tank so as to avoid over-topping of the tank bund.

The hydrogeological condition of site for percolation tank is of utmost importance. The rocks coming under submergence area should have high permeability. The degree and extent of weathering of rocks should be uniform and not just localized. The purpose of percolation tank is to conserve the surface run off and diverts the maximum possible surface water to the ground water storage. Thus the water accumulated in the tank after monsoon should percolate at the earliest, without much evaporation losses.

A percolation tank is designed to ensure maximum capacity utilization, long life span, cost effectiveness and optimum recharge to groundwater. Storage capacity, waste weir, drainage arrangement and cut off trench (COT) are the important features of percolation tank which need proper design. The overall design of the percolation tank is similar to an earthen dam constructed for minor irrigation without canal.