In step 1 of Pondmaker, what does the “design scenario” and “target scenario” represent?
The Design scenario represents the scenario which you are designing the pond for. It is typically the Post-development conditions, where catchment runoff is higher than the predevelopment conditions. The Target scenario (when using scenario as the target flow/volume source type) should be the scenario describing the conditions that your pond will be designed to reduce flows down to. So, it is typically the “predevelopment” scenario for the same return event. You will design the pond and outlet to attenuate the peak flow from the Design scenario down to the target value from the Target scenario.
