A practical example are the so-called “rain gardens”, in their various forms . These gardens are designed to absorb in both lean and flood times an important share of rainfall, preventing it from entering the sewer system (which is often undersized against the rapid and intense rainfall in recent years) and thus preventing its collapse.
The special layering of the gardens (sand, compost, soil), to which are added the plants present suitable for periodically flooded or wet soils, promotes infiltration and, at the same time, ensures phytodepuration to release water directly into the ground or, gradually, to the sewer system.
In addition, consider how such gardens can be realized both for large areas, serving the functions of real reservoirs, and for little areas around urban infrastructure such as parking lots, and forecourts parking areas. Replacing a classic concrete or even shrubbery-lined traffic island divider bed with a small drainage garden can ensure drainage for most rain events of not excessive intensity for the surrounding area.