Many options
It can be necessary to build a reservoir if there are insufficient possibilities of detaining water before a flow regulator. This can be done by enlarging the pipeline dimension along a short section or by building a basin. The basin solution prevents damage downstream from the basin.
Installing a flow regulator in an overflow structure enables the downstream pipeline to handle the water volume without flooding. The remainder is diverted into a lake, watercourse or other receiving waters.
A flow regulator makes it possible for a property to meet regulatory requirements to limit discharge during downpours, such as from large car parks or roof surfaces.
Similarly, a flow regulator can prevent the overloading of waste water treatment plants, protecting the plant's function from being damaged. The same is true for an oil/grease trap, pumping station, etc.