Theory 69/Engineering & infrastructure/Stormwater detention
Detention Is Storage Against Inflow
The claim
Peak flow attenuation is set by the ratio of detention storage to inflow volume, so a small basin reduces peaks only for small storms.
01Mechanism
Storage must hold the excess while outflow is limited.
02Prediction
Attenuation should track the ratio.
03Refutation
Attenuation tracking outlet size would remove storage.