Attenuation elements

If rainwater run-off is collected temporarily in an available storage facility, the time during which it can be finally discharged can be extended over a longer period. If water is discharged into a sewer, attenuation elements can help reduce capacity overload, and if an infiltration element is used to discharge the water, its dimensions can be reduced proportionately in accordance with the rate of attenuation. Detention elements are only useful for rainwater management if they have available capacity at times of rainfall. This means tanks for collecting rainwater for watering gardens or flushing toilets can only be included in the dimensioning either if they are fitted with extra capacity that automatically drains off in the period immediately after rainfall, or are so large that every tank supplies several households, and a certain level of consumption can therefore always be guaranteed. Other detention basins must be emptied in the course of a few days.

Figure 1: Attenuation (Pictogram: Marit Reisegg Myklestad)