A cheap improvisation will soon save the precious lifeline in Jharkhand.

The groundwater directorate of the state government plans to erect two gabions — large containers made of wire and packed with rocks — accompanied by recharge pits on the nullah near Ranchi College to replenish the groundwater aquifer (a layer of rock or soil that can absorb and hold water).

This will arguably be the first such unique attempt at water conservation in the entire state.

According to groundwater director S.L.S. Jageshwar, a gabion acts like a check dam and controls the flow of water, but at the same time allows water to percolate downstream unlike the cement check dam.

“Each gabion will have eight recharge pits — four on its either sides — which will help the water seep into the soil and balance the water table. The foremost advantage is that a gabion, unlike cement check dams, will not deprive aquatic life in the nullah. Besides, we estimate to set up gabions at nearly one-fourth the cost of check dams,” he told The Telegraph.

Ranchi being a plateau, recharge of the water table by rainwater harvesting is of immense importance. More so when frequent deep-boring in the capital threatens to deplete the groundwater reserve.

Over the past 10 years, the groundwater directorate has come up with more than 100 rainwater harvesting systems, mostly atop government buildings in Ranchi.

The gabion is a fairly new concept to conserve rainwater without disturbing aquatic life. The wire baskets have some advantages over loose riprap because of their modularity and ability to be stacked in various shapes. They are resistant to being washed away by moving water and have advantages over more rigid structures because they can conform to ground movement, dissipate energy from flowing water and drain freely.

In the medieval era, gabions were round cages with open tops and bottoms, made from wickerwork and filled with earth for use as military fortifications. These were used to protect gunners.

Jageshwar said two check dams with 16 recharge pits on the nullah near Ranchi College would cost the directorate nearly Rs 40 lakh. “But the same number of gabions with 16 recharge pits will cost us around Rs 11 lakh. This is an added advantage of the technique, which is eco-friendly,” he added.

The nullah near Ranchi College, where the gabions will be set up, originates behind the tribal and regional language department of Ranchi University and passes by the Central Library and meanders towards Morabadi. It drains into Potpoto rivulet near Tagore Hill.

The director reiterated that a gabion, made of big rocks and stones bound in a wire cage instead of cement, restrained the flow of water and allowed it adequate time to seep through, both below the surface to replenish the water table as well as downstream for aquatic life.

“To my knowledge, gabions were never used in this region. The project will revolutionise the concept of rainwater conservation,” he summed up.

 

What is a gabion?
Gabion comes from Italian gabbione meaning “big cage”. These are containers made
of wire and filled with rocks, sand or soil and used in civil engineering as well as
military operations

How is it useful?
It acts as a check dam and controls the flow of water. But it is cheaper than the concrete dam and facilitates percolation to recharge the aquifer and balance the water table