Which of the following is an alternative type of rooftop disconnection?

Rainwater harvesting is recognized as an alternative type of rooftop disconnection because it involves the capture and storage of rainwater that runs off rooftops. This method reduces the volume of stormwater that contributes to runoff, effectively disconnecting the rooftop from the stormwater management system. By collecting rainwater for beneficial uses, such as irrigation or non-potable uses in buildings, rainwater harvesting not only mitigates flooding and erosion but also promotes water conservation.

The other options do not align with the concept of rooftop disconnection. A soil-composite filter may be used in treatment systems but does not specifically pertain to rooftop runoff. An impervious surface channel is designed to convey water rather than disconnect it. A pollutant discharge system implies a method of releasing contaminants rather than managing stormwater runoff effectively. Hence, rainwater harvesting stands out as a proactive approach in stormwater management practices.