Bhungroo, in detail

Bhungroo is a disaster-mitigating and climate-change (mitigation and adaptation) technology. In the peak monsoon it frees a farmer's land from waterlogging; in the post-monsoon period it lets the farmer access good-quality irrigation water at the farm gate. It is a filtered injection method: water from the topsoil is injected under pressure through a narrow but high-gauge perforated pipe, so higher-momentum filtered water is released into the subsoil, where "water lenses" form within the unsaturated zones.

The lenses form through filtration to a natural density that is different from the water already present in the subsoil. Because of that difference, the water is held in lens forms within the unsaturated zones rather than dispersing.

Water is released underground and held in lens forms within unsaturated subsoil strata, identified through soil testing. That stratum needs at least a 1-foot ribbon height and can sit anywhere from 10 to 120 ft deep. Water collects in sequence and can stay for long periods — and can be lifted again within 45 to 180 days. No underground civil structure is needed; the unsaturated soil works like a sponge.

The number of Bhungroo units is configured to the flood's momentum, the duration water stands on the plot, and the suspended particles in the flood water. For a series of floods, their timing and technical parameters are studied and the Bhungroo design is modified to suit — and multiple units can be erected so recurring flood issues can be tackled.

Bhungroo works in all soil strata wherever an unsaturated zone exists — and every piece of land has one, so it can be erected on any strata. The water-injection rate varies with the level of saturation in the subsoil. In high-clay soils, extra earthwork may be needed to achieve a higher water catchment, which increases the cost of erection.

Salinity is a boosting factor — not an essential one, as is sometimes assumed. Salt deposits make topsoil non-porous, so waterlogging is more likely, which actually makes Bhungroo easier and cheaper to erect. It injects water underground from day one thanks to good standing-water height and gravity, and lets non-saline storm water reach the subsoil. Where subsoil water is more saline, that layer itself acts as an unsaturated zone, letting lower-density water collect above it.